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Rebuilding a TTR250 Teikei Y30P Carburettor
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First of all, I would like to warn you that this is a MASSIVE thread and it will take some reading. By the end of it, you should have learned all there is to know about rebuilding a TTR250 Teikei T30P Carburetor (with any luck). I have simplified this as much as possible so I hope that it is understandable and easy to read. Let me know if you have any problems and I will guide you through as best I can (on the internet). Hope you enjoy reading! wink
 
Differences between the 1993~1999 and 1999~2013
The black carb below is a 1994 OE and the gold carb is a 2004 model. There is slight differences between the two, like the main jet nozzle is shorter on the 1993~1999 model, the choke plunger is slightly different (but still is interchangeable), the colour of some of the internal parts are different, the older 1993~1999 carburetor used a #48 pilot jet compared to the #50 on later 1999-current models (In AU at least) and the carburetor top cover is slightly different  (but still is interchangeable).
Carb comparison.jpg

Tools needed for the job
Small Flathead screwdriver
Medium Flathead screwdriver
Medium Philips head screwdriver, preferably JIS (Japanese Industry Standard).
8mm spanner
6mm spanner
12mm open ended spanner
Toothpick or probe to remove old seals
Blunt nail or similar to remove the float pin.
External cir-clip pliers (if removing throttle shaft).
1.5mm drill bit to make float pin holes a bit bigger. wink
 
Parts needed for the job
The parts for this job are pictured below, please take note that the jets pictured below are not standard. Upgrading the exhaust, air filter etc. would be needed to use these (in most cases). 

parts needed.jpg
 
Standard jetting sizes
 In AU the standard sizes for the older 1994~1999 carb is #48 pilot, #147 main, and the newer 1999~current model is #50 pilot with a #147 main. In the UK it appears to be the same. However, it has been suggested in the FAQ that some UK models were fitted with a #137 main and #50 pilot jet. Coincidentally though, US standard sizes are #50 pilot and #137 main. Is this a coincidence or are these imported from the US?- I think imports.
 
Checking the Accelerator Pump
Before dismantling the carburetor, it is advisable to check that the accelerator pump is working correctly. I should advise you now that petrol is not good for your eyes so be CAREFUL! The accelerator pump nozzle will have a hole (not the side shown in picture below) and it must be clean! To test this- remove carb and make sure it is full with fuel. When the throttle is applied it should squirt a nice stream of fuel into the intake. If it does not squirt (common problem), unblock the nozzle with a fine piece of wire. I use compressed air, fuel (or solvent), an old throttle or bike cable after cutting and splitting the strands apart and a pair of pliers to assist with holding the wire and prodding. Check that the one way valve is not blocked (shown below) by filling the carb bowl with fuel and pressing GENTLY down on the diaphragm, it should squirt fuel from the top of the check valve if working correctly (be careful as it could squirt fuel in your eye or shoot the 'one-way check valve' across the room). Also check that your diaphragm is not perished, if it is it will have cracks or it will be hard and brittle. Use Rubber Grease to extend the life of the diaphragm and all O-rings.
553027_562393563794119_1622177328_n.jpg
 
Dismantling the float bowl and components
Remove the float bowl by unscrewing the three screws and remove the float retaining pin. To remove the float pin , use a blunt nail or pin (or something small enough) making sure that you remove it the right way. It only goes one way and it can be a little hard to remove sometimes. You will see an arrow to indicate which way it was put in, remove it the opposite way that the arrow points. The float retaining pin only goes one way into the float posts also. Absolute care MUST be taken when removing the float pin to ensure that you do not break the float posts-YOU HAVE BEEN WARNED!!! I like to drill the float posts larger using the 1.5mm drill bit so it's easier to remove the pin. This also prevents the float posts from breaking (highly recommended).  Once the retaining pin has been removed the float and float needle slides out.
The following picture was from when I was helping someone and they got it wrong (as seen in picture below), but you should get the point...
 
 Float post repair 2.jpg
 
Use a small Flathead screwdriver remove the pilot jet and remove the main jet using the 8mm spanner.
 
Fuel metering screw O-ring
Remove the fuel metering screw anti-clockwise and make sure the O-ring is not perished. Blow out the passage using compressed air. Install the air fuel mixture screw making sure the spring is fitted. To adjust this turn all the way in & one & a half out (usually better at two & a half). To check this, start the bike & turn in until you notice a change in revs. Then turn one & a half out (usually) or until it runs smoothly. Warning- Do not go further than three turns out or the fuel metering screw will drop out.
Pilot_screw_set.jpg
 
 
Cleaning tips
Carb strip 007.jpg
 
 
The float needle valve has a filter (small white plastic part) that cannot be reached without removing the float valve/seat  (not recommended unless you have the correct slide hammer and a replacement float valve). 
Float_valve_filter.jpg
 
Flush out the float needle valve/seat with petrol with the carb upside down, then use compressed air to blow any contaminants that may have got in the fuel line. WATCH YOUR EYES!
Location of float valve filter.jpg
 
Make sure all holes in your jets are spotless including sideways, you should see the holes below.
jets.jpg

Make sure that the air jets are not blocked by using compressed air in them. 
553027_562393563794119_1622177328_n.jpg
 
Enlarging the float posts
It would be a good idea to drill the float pin holes out a bit so it's not hard to install & doesn't break in the process. Quite simple- drill both float posts using a 1.5mm drill.
 
Installing the float bowl
If fitting a larger main jet unscrew the main jet using the 6mm & 8mm spanners (if standard)...
 
 
Then screw the new one in tight.
Fit your needle & float. To do this, slip the needle retaining clip over the float. Then install so that you can see the TK on the float...
 
Installing float pin.jpg
 
Then slip the cover over...

(Photo not loading)  

Now turn the bowl over & install the check valve... Note: this can get lost easy so be careful!
Carb strip 008.jpg
Now fit the gasket & tighten the three screws.
 
Installing the accelerator pump
Moving onto the accelerator pump, fit the diaphragm & o-rings into bowl, making sure they are seated properly....
Carb strip 006.jpg
I like to use a smear of rubber grease for a long lasting result (as previously mentioned). Any excess grease must be wiped off with a clean rag.
Now the tricky part, installing the spring...
To install the spring, place it on the top of the diaphragm with the bowl upside down. Now install the cover making sure that the spring stays seated properly and tighten the two screws.
 
Air flow chamber O-ring
Remove the two screws, use a toothpick (or similar) to remove the old O-ring. Smear the new O-ring with rubber grease and install the side cover 0-ring making sure it's seated properly...
Carb_sideplate_O_ring.jpg
Now fit cover & tighten the two screws.
 
Removing the carburetor slide
First remove the four Philips head retaining screws from the top cover...
Choke_stuck_pics 001.jpg
 
Now remove the slide arm retaining screw...
 
 892372_558389970861145_387802991_o.jpg
 
Remove the accelerator pump lever arm retaining screw from the side of the carb (read below in regards to spring first)...
 75269_500004746699668_698364556_n.jpg
Remove the accelerator pump lever arm being careful not to loose the spring (spring pictured below).
 
You can now remove the slide retaining screws by lifting the slide up until in the correct position to do so...
 18284_500000990033377_937854016_n.jpg
 
Replacing the needle set
First thing to do is buy the part....
 Needle_set.jpg
 
Un-clip the plastic needle holder & spring.
 
(Photo not loading) 
 
Now undo the circlip & put the new one on.
Standard setting is the middle setting...

(Photo not loading) 

 
Now install locking washer making sure it goes in it's locking position...
 
(Photo not loading) 
 
Fit the plastic needle holder making sure that the new spring goes on first.
 
Put the needle in & fit the slider arm with the two screws making sure that the cut-out in the slide goes to the back of the carb as pictured below...
 
Slider arm.jpg
 
Removing the throttle shaft
While you have the throttle shaft retaining screw out, it would be a good chance to re-grease the throttle shaft. To remove this- Remove the C-clip using Cir-clip pliers or two screwdrivers to start it off then turn it around & remove it when in the right position to do so.
 
(Photo not loading)
 
Then remove the throttle shaft making sure the plastic washer does not get lost.
 
(Photo not loading) 
 
Choke plunger
Remove the choke plunger using a 12mm open ended spanner and check that the choke seal is not perished...
Choke_stuck_pics 007.jpg
 Fit choke plunger with the 12mm open ended spanner.
 
Installing the throttle shaft
To install the throttle shaft, first use lithium grease (or copper slip) on the shaft. Install the large rubber seal to shaft & small rubber seal to the hole above (middle of the spring),making sure the spring is installed correctly...
 
(Photo not loading)
 
Then make sure the plastic washer goes on...

(Photo not loading)
 
Then pre-load the spring. To do this install the spring to throttle levers & turn until it goes into place making sure that it does not ''catch'' on the carb body when turning. When fitted it should look like so....

(Photo not loading)
 
Once that is in, fit the clip (at the top). This will go on where the plastic washer sits.
Note: The plastic washer goes closest to throttle lever.
.
(Photo not loading)
 
 
Installing the slide arm
First thing to do is fit the diaphragm lever spring..
 
(Photo not loading)
 
 
Then fit the diaphragm lever arm. To do this, push it down with a Flathead screwdriver while tightening screw...
The screw is pictured below.
 
Diaphragm lever arm.jpg
 
75269_500004746699668_698364556_n.jpg
 
If you have not already fitted the slider screw you should now do that...
 
(Photo not loading)
 
Now fit the top gasket & install the top cover. Four screws at the top...
 
(Photo not loading)
  
Adjusting the throttle stop screw for performance
If you want to get a little bit more out of the top end the throttle stop screw can be adjusted in most cases (it may be already at the optimal setting already in some cases). To do this loosen lock nut & adjust until it does not touch when the throttle is turned to full throttle then screw it back in until it just buts up on full throttle. Warning- if you over adjust this or remove it, the slider will go too far up the chamber and may do damage.
 
(Photo not loading)
 
 
Copper washer
There is a copper washer underneath the Philips head screw that may need annealing, but not likely...
 
(Photo not loading)
 
 
Job done clap.gif
 
Hope this answers all questions/queries, but if it doesn't & you would like to know more or unsure on something, let me know & I'll guide you through as best I can.
 
Good luck! wink
 
Jarrah



-- Edited by TT-R250M on Tuesday 17th of June 2014 05:10:15 PM



-- Edited by TT-R250M on Saturday 1st of October 2016 07:23:43 AM



-- Edited by TT-R250M on Wednesday 8th of February 2017 05:00:09 AM

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Excellent update to an already brilliant thread Jarrah! It's definitely a sticky wink

Cheers

Brian



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Hi All
Am having a bit of a problem with my bike - it runs reasonably well but after throttle close down and low revs - junctions, downhills roundabouts etc when I open it up it hesitates a lot and then goes. I've stripped the bottom end of the carb and cleaned it with air and solvent but as yet to no avail, When looking at the accelerator pump nozzle I noted that it squirts fuel towards the side of the carb not into the center, (using the method below) so not straight down the barrel - is this likely to be the nozzle out of line and can I turn it or is it just a partly blocked nozzle or normal? Have tried air and solvents but not yet the wire methods. Any help appreciated. I quote Jarrah's accelerator pump notes from above below to try to explain what I'm getting at
Thanks Dave




Checking the Accelerator Pump
Before dismantling the carburetor, it is advisable to check that the accelerator pump is working correctly. I should advise you now that petrol is not good for your eyes so be CAREFUL! The accelerator pump nozzle will have a hole (not the side shown in picture below) and it must be clean! To test this- remove carb and make sure it is full with fuel. When the throttle is applied it should squirt a nice stream of fuel into the intake. If it does not squirt (common problem), unblock the nozzle with a fine piece of wire. I use compressed air, fuel (or solvent), an old throttle or bike cable after cutting and splitting the strands apart and a pair of pliers to assist with holding the wire and prodding. Check that the one way valve is not blocked (shown below) by filling the carb bowl with fuel and pressing GENTLY down on the diaphragm, it should squirt fuel from the top of the check valve if working correctly (be careful as it could squirt fuel in your eye or shoot the 'one-way check valve' across the room). Also check that your diaphragm is not perished, if it is it will have cracks or it will be hard and brittle. Use Rubber Grease to extend the life of the diaphragm and all O-rings.
553027_562393563794119_1622177328_n.jpg

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Hey Dave,

As long as there is a nice stream of fuel, the accelerator pump nozzle should be fine. It does not squirt directly into the intake, rather against the carb throttle body IYKWIM. I would NOT try to turn it as it is a press fit!

As your profile suggests that you are in France and your profile picture seems to be up on a mountain, I would suggest to move the main jet needle position 1~2 settings towards the leaner position(s). It seems to be your problem, however without more info I can't be sure.

Also make sure that your fuel metering screw is between 1 1/2 ~ 2 1/2 turns out from fully seated (as mentioned above).

Does the problem happen from idle to 1/3 throttle? or at or after 1/3 throttle?

Any other symptoms?

It would be helpful to know what jets are fitted, elevation, mods, climate also.

Cheers!

Jarrah



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TT-R250M wrote:

Hey Dave,

As long as there is a nice stream of fuel, the accelerator pump nozzle should be fine. It does not squirt directly into the intake, rather against the carb throttle body IYKWIM. I would NOT try to turn it as it is a press fit!

As your profile suggests that you are in France and your profile picture seems to be up on a mountain, I would suggest to move the main jet needle position 1~2 settings towards the leaner position(s). It seems to be your problem, however without more info I can't be sure.

Also make sure that your fuel metering screw is between 1 1/2 ~ 2 1/2 turns out from fully seated (as mentioned above).

Does the problem happen from idle to 1/3 throttle? or at or after 1/3 throttle?

Any other symptoms?

It would be helpful to know what jets are fitted, elevation, mods, climate also.

Cheers!

Jarrah


 Hi Jarrah

It's all standard jets and air intakes, problem is from zero to 1/3 throttle and only when revs have dropped on deceleration, I'm at 600m - 2000ft valley bottom and this is happening at this altitude as well as higher up in the hills. Screw is set at 2 turns but have tried it at everything from 1 1/4 to 3 without solving this problem.

Cheers

Dave



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Padowan wrote:

My accelerator pump nozzle also exits towards the wall of the carb, so I don't think it's unusual. From an operational perspective I expect the air speed flowing along the walls is high enough during an induction stroke to pull that fuel through the carb, even on tick over.

I coukd do some sums to work it out, but even at around 1200rpm (for ease of maths) that's 10 intake cycles per second or 2.5lt/sec of air being drawn in, through an orifice of about 30 mm across, (about 7cm2) assuming linear flow that'll mean it's moving at 3.5 metres per second.

 

Edit: Actually it's twice that speed as the intakes are happening on every other stroke.



-- Edited by Padowan on Monday 16th of June 2014 03:28:25 PM



-- Edited by Padowan on Monday 16th of June 2014 03:29:46 PM


 Thanks - at least that rules out that one and I'm glad i didn't try to force the jet round!

Dave



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Flying Dodo wrote:

 Hi Jarrah

It's all standard jets and air intakes, problem is from zero to 1/3 throttle and only when revs have dropped on deceleration, I'm at 600m - 2000ft valley bottom and this is happening at this altitude as well as higher up in the hills. Screw is set at 2 turns but have tried it at everything from 1 1/4 to 3 without solving this problem.

Cheers

Dave


 Your problem could be either-

The main jet is slightly rich causing it to stumble when the throttle is let off quickly and applied again.

 The pilot jet is partially blocked or varnished.

The air jets are partially blocked.

Air-filter needs cleaning.

Wrong idle speed.

Partially blocked needle and seat (AKA float needle valve).

Incorrect float height (not likely unless it has not been taken care of.

Accelerator pump return spring faulty (or not installed).

Diaphragm return spring faulty.

Spark plug gap.

Electrical problem (not very likely).

Fuel metering O-ring perished.

Things to try-

Move the jet needle clip position towards the leaner setting 1 ~ 2 settings.

Take the air filter side cover off to see if it helps.

 

If you can let me know a little more about your problem, I may be able to help to eliminate some of the possible causes.

Good luck!

Jarrah



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Great post Jarrah.

The only thing I would add is in the tool section to use JIS (Japanese Industrial Standard) Philips head screwdrivers if possible. You will see the small indent in the head of the screw heads - this specifies they are JIS. They make a big difference and you wont chew out the heads of the screws.

I realise it makes it a pain for us that only touch the carb once in a blue moon but I thought I would bring it up. Everyone blames the poor materials used in Japanese carbys, but it is the screw standard, not the material.

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TT-R250M wrote:
Flying Dodo wrote:

 Hi Jarrah

It's all standard jets and air intakes, problem is from zero to 1/3 throttle and only when revs have dropped on deceleration, I'm at 600m - 2000ft valley bottom and this is happening at this altitude as well as higher up in the hills. Screw is set at 2 turns but have tried it at everything from 1 1/4 to 3 without solving this problem.

Cheers

Dave


 Your problem could be either-

The main jet is slightly rich causing it to stumble when the throttle is let off quickly and applied again.  - It's more when throttle left off on deceleration to low revs and then applied rather than sudden shut off?

 The pilot jet is partially blocked or varnished. -  Have cleaned this several times - next step maybe to order and replace jets

The air jets are partially blocked. - Again have tried to clean thoroughly and otherwise it runs OK

Air-filter needs cleaning. - cleaned and re oiled within last week

Wrong idle speed. - I think this is OK and it idles fine.

Partially blocked needle and seat (AKA float needle valve).

Incorrect float height (not likely unless it has not been taken care of.  -  Didn't think this mattered too much so will re check.

Accelerator pump return spring faulty (or not installed). -  Checked OK

Diaphragm return spring faulty.  - checked OK

Spark plug gap.  checked OK

Electrical problem (not very likely). Don't think so or it wouldn't be so specific?

Fuel metering O-ring perished.  All O rings OK though side cover one a bit flat!

Things to try-

Move the jet needle clip position towards the leaner setting 1 ~ 2 settings.  Will try to do this today!

Take the air filter side cover off to see if it helps.  Maybe I'll try this first.

 

If you can let me know a little more about your problem, I may be able to help to eliminate some of the possible causes.

Good luck!

Jarrah


 Thanks Jarrah  for a very comprehensive answer - will try leaning the mixture a couple of stops - have made notes against your suggestions above which may?? help explain it clearer

Ta David



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Hey David,

I think your problem is the side cover O-ring. It should not be flat and needs to seal or you will get the symptoms that you described. The only other possibility is that the pilot jet is varnished (but not that likely) or loose. The airway could also be blocked so it may be worth blowing compressed air through the fuel metering screw passage (after taking the fuel metering screw and spring out of course).

I would buy the fuel metering screw set at the same time to be sure the fuel metering O-ring is sealing correctly, it should be cheap enough.

Link to parts in the US

Good luck, let me know how you go.

Jarrah

 

 



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Slightly off topic but may be of interest.

I recently fitted a carb to a TTR and forgot to adjust the pilot screw and left it fully closed.

The TTR started and ran absolutely fine and ticked over no problem confuse

Now adjusted wink

Brian



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Hmm, just leaned it - raising the collar from it's middle setting where it was to the top - now tends to stall after running when on idle as if starved of fuel or air (idles OK when stood) - only been for a short run - will try it further this afternoon then maybe try the needle the other way (full rich) - will at least give you guys who understand these things some stuff to work on in the hope you can solve it for me!!
Thanks again
Dave

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TTRfan wrote:

Slightly off topic but may be of interest.

I recently fitted a carb to a TTR and forgot to adjust the pilot screw and left it fully closed.

The TTR started and ran absolutely fine and ticked over no problem confuse

Now adjusted wink

Brian


 Thanks Brian - Will maybe try a range of pilot screw positions when I run out this afternoon. Cheers Dave



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TTRfan wrote:

Slightly off topic but may be of interest.

I recently fitted a carb to a TTR and forgot to adjust the pilot screw and left it fully closed.

The TTR started and ran absolutely fine and ticked over no problem confuse

Now adjusted wink

Brian


 Just pointing out that if the screw can be turned all the way in without the engine stalling, a smaller pilot jet is required. It could also mean that the the pilot air jet is partially blocked or the side cover seal is not sealing. Either way, something is not right.

Jarrah



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Hi All
Well took it out with the leaner setting and it was a disaster (except at tickover???) - wouldn't run without choke, stalled, hesitated and in the end had to set 90% choke to get it to run anywhere - without choke was missing and hiccuping at up to 60% throttle - but OK at WOT and stalled as soon as throttle closed out of gear.
Have gone for the opposite setting on needle - 2 stops down from centre to see what happens - sadly rain (well thunder and lightening) has stopped play for the day so will try a run out tomorrow morning and let you know the results.
Sorry Jarrah missed your post re the flat o ring - will check the assorted o ring box and see if there's one that'll fit. If this doesn't work then will abandon for the moment and replace the jets and remaining o rings and gaskets later in the summer as work now becons! Will let you know anyway.
Thanks
Dave

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Sounds like some progress has been made.

If raising the jet needle produced that result, I would say that the lower setting would be better for you. A bit of playing around with it and you should get it perfect. The reason I asked you to raise is to eliminate the possibility of running rich on main jet( it effects low revs as well as high if rich). With that possibility ruled out it is fair to say that your problem lies with the side cover O-ring. However, it still could be the pilot jet varnished, the pilot air jet or passage blocked.

 

553027_562393563794119_1622177328_n.jpg

The O-ring is more of a special seal than an O-ring but the right size O-ring might suffice.

Jarrah



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Hi Jarrah
Have put an O ring the right size in for now (I've kept the seal) as its easy to swap back and if it ever stops raining I'll go out and give it a try - looking like tomorrow now though.
But do feel progress is being made - we'll see tomorrow.
Thanks for the help - I'll let you know.
Dave

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Just to verify the first picture in my last post- the blue lines represents the pilot air passages- these MUST be spotless!

The more possible causes that you eliminate, the more chance you have of finding the problem so not finding the problem can be a good thing. smile

I'll be waiting on the update (go away rain!). wink

Jarrah



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Your knowledge of the TTR carb is amazing Jarrah! Thanks you for sharing - the pics are priceless.

Brian



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TTRfan wrote:

Your knowledge of the TTR carb is amazing Jarrah! Thanks you for sharing - the pics are priceless.

Brian


 Thanks Brian,

I am going to add how to check the float height using both methods stated in the manual. It is not very clear on the difference between the float height and the fuel height, I intend to make it VERY clear, stay tuned! wink

AGman wrote:

Great post Jarrah.

The only thing I would add is in the tool section to use JIS (Japanese Industrial Standard) Philips head screwdrivers if possible. You will see the small indent in the head of the screw heads - this specifies they are JIS. They make a big difference and you wont chew out the heads of the screws.

I realise it makes it a pain for us that only touch the carb once in a blue moon but I thought I would bring it up. Everyone blames the poor materials used in Japanese carbys, but it is the screw standard, not the material.


 Thanks Agman and point taken, you may notice the change. If you have any more suggestions, please don't refrain from posting them. It was a lot of typing but I am pretty sure it is okay now? smile

Enjoy!

Jarrah

 

 



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Update - took it out this morning and the hesitation at low revs is cured - hooray! Need some more fiddling as there's a bit of a bogging down at around half throttle and struggling to get the tickover right it wants to die or over rev but loads better than before I started which was driving me nuts; it also now goes like a bomb at WOT - thanks all - will maybe try the next up from maximum rich on the needle to see if that's the best compromise but that may have to wait till i've got more time to fiddle - unless it rains again this afternoon!!
Thanks all and especially Jarrah for the tips and encouragement.
Dave

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Hey Dave,

You have the right idea, move the clip to setting two from the sharp end and it should be good.

Amazing how much difference it makes dialing the needle in. aww

Glad you got it sorted!

Jarrah



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2000 TT-R250M-

Spoiler



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Your post was amazing Jarrah but not so good now that most of the photos aren't loading. Any chance of restoring them please?

Thanks in advance.

Brian



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Most of the new parts, gaskets, O rings, jets, etc., that might be needed are available next day for UK owners from here - nothing on back order - all on the shelf wink

We post abroad but obviously the parts will take longer to arrive.

Brian



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DC


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Refurb a TTR250 Teikei Y30P Carburettor
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This is a great post, thank you Jarrah.  

I think I need to do a complete refurb on my carb, and being a carb virgin I am a bit nervous about doing it.  Should I be?  Or is it just a case of being methodical.  I don't mind if you reckon I should take it to a shop for a refurb, its important to me to know if I should attempt it or not.  Anyway, in prep I have already ordered the gasket and O rings from Brian.

Anyway, let me share what I have found so far.  I had a problem starting the bike after about 18-months rest, in fact it would fire with Easy Start sprayed in to the airbox but not run.

Firstly, I charged the battery and inspected the spark plug.  I have removed the carburettor for inspection.  To note: there was no fuel in the bowl when I drained it, although I have checked that fuel flows from the tank ok.  This is what I have initially found in the bowl.  I assume this is not good.  But is it normal over time?

IMG_3528.JPG

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

It is like an almost gritty paste.  Deposits can be seen on the jets and the surrounding surfaces too..

IMG_3530.JPG

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I was quite shocked that there is no filter on the fuel line.  Is this because it is a plastic tank or something?  

I've seen you can get in-line filters (read that 8mm is best).  Is this a good mod to do?

Comments warmly welcomed. Thanks, Paul.



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TTROOKIES.  Three Blokes. Three TTRs.  All the gear and no idea.



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RE: Rebuilding a TTR250 Teikei Y30P Carburettor
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Great thread here but be very careful when removing the float pin. On the attached drawing it says to install the pin in the direction of the arrow whereas on my carb the pin is REMOVED in the direction of the arrow. I don't know if this is a typo or if some carbs have been manufactured wrong but it may explain why so many guys break the post trying to remove the pin.

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Correct!

Carb float pin removal.jpg

But the manual also says:

Carb float pin installation.jpg



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Good info guys. Here's my carb challenge with my 2002 TTR 250

Altitude: 7500-8500 feet (2300-2600 meters, moderate temps <80F (<27C) 
Main Jet = 128
Pilot = 50
Needle = 5C9C
Needle position = 2nd slot from leanest (two slots down from the top/most lean slot). 
Accelerator pump = new diaphragm and post.  Squirts fuel like it should.
Mixture screw: out 1.75 - 2.75 turns (seems little difference)

Airbox = OEM not modified

Exhaust pipe = stock w/baffle removed.


Carb cleaned all orifices open, engine rebuilt, good compression. Runs strong and starts well cold (choke hardly needed) and hot. Runs well from idle to WOT. Pulls reasonably strong.

ISSUE: After WOT for a bit, when the throttle is reduced, the engine stumbles. (I assumed main jet rich or lean?)
Also, on whoops (closely spaced 2-3 foot bumps at moderate speed standing on pegs), the bike stumbles (carb bowl splash?). Carb bowl has plastic piece installed around main jet location. (bowl level too low?, seems odd if rich).

Spark plug is lightly sooty (black) after WOT then kill switch and coast to the garage (I suspected the main jet was too rich and was testing WOT rich/lean condition).

Based on the spark plug color (black and slightly sooty), easy start cold w/little choke, I assuming too rich, therefore:

Attempt #1: Leaned needle one slot to leanest position = top slot. Result: Poor idle, poor running.

Odd: Spark plug says too rich but when we leaned the needle, engine was not happy. 
Weird: I did not expect the needle to impact idle and <1/3 throttle (much). 

What should I try next? Many thanks.

Rick

Colorado Springs, CO 

PS Posting this in a couple of places as I am not sure about traffic. Kindly excuse the duplicate posts.



-- Edited by zzrdd on Tuesday 11th of August 2015 09:20:43 PM

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Crap....!!!!!!  He warned me....in all caps.........Dismantling my carb tonight......got to the float pin....was being unbelievably gentle as to not break the damn posts!  I had the pin 97percent out and here is what I believe happened.

I was using a nail as my punch.....I had pin almost out but my nail was going through both holes to keep it straight......I guess on my last hit with float already removed......I made the strike w my hammer...it hit the nail which broke the pin free.....but I guess the nail was so short that my hammer hit the first post breaking it off clean.  Man was I pissed.  Oh well.....gotta move forward.  I think JB Weld should work......anybody try this yet? 



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Removing the float pin safely - see 

The tool is available in Halfords - see here.

Thanks to Mike for the links biggrin

Brian



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pug


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Like that top tip I would never have thought of using the punch for that and should the need arise in just happen to have one in my Engineers box so thanks

Mike an brian for the tip



-- Edited by pug on Thursday 14th of January 2016 01:16:11 PM

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Yeah handy that. Takes the stress off it. Smart tip! biggrin



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Pete. South Somerset, England.

03 Blue model. Renthal bars, (13/48), CRD AP2 zaust, Totally ttr's bash plate

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I have one in my tool kit. Great idea.

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2004 TTR250. White Brothers E series exhaust, modded airbox, rejetted, 13/48 c&s & many more mods..



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been stripping carbs down for years broke many pin posts never thought of that good idea just ordered one of those punches cheers great forum this we all think we know it all you are never too old to learn

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Checking the Accelerator Pump
Before dismantling the carburetor, it is advisable to check that the accelerator pump is working correctly. I should advise you now that petrol is not good for your eyes so be CAREFUL! The accelerator pump nozzle will have a hole (not the side shown in picture below) and it must be clean! To test this- remove carb and make sure it is full with fuel. When the throttle is applied it should squirt a nice stream of fuel into the intake. If it does not squirt (common problem), unblock the nozzle with a fine piece of wire. I use compressed air, fuel (or solvent), an old throttle or bike cable after cutting and splitting the strands apart and a pair of pliers to assist with holding the wire and prodding. Check that the one way valve is not blocked (shown below) by filling the carb bowl with fuel and pressing GENTLY down on the diaphragm, it should squirt fuel from the top of the check valve if working correctly (be careful as it could squirt fuel in your eye or shoot the 'one-way check valve' across the room). Also check that your diaphragm is not perished, if it is it will have cracks or it will be hard and brittle. Use Rubber Grease to extend the life of the diaphragm and all O-rings.



Response to this..

What would be the result, or how would the bike run if it were clogged? Any thing helps!

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