A forum for owners of Yamaha TTR250 trail and enduro bikes!

Members Login
Post Info TOPIC: TTR carb guru required


Member

Status: Offline
Posts: 7
Date:
TTR carb guru required
Permalink  
 


Hi,can anyone help with a problem I have with my TTR 250 its  2004 blue model very low milage.

I bought it some time ago and with being stood most of its life it ran terrible when I first used it.I changed the fuel and give the carb a basic clean and if ran alot better but did have a slight bog down/hestitation around 1/4 throttle so it was tricky to plod along at low throttle but cleared once you opened her up so you could live with it which I have until recently.

Recently the slight bog has turned into a real problem where the bike is hard to ride.....

It starts and ticks over lovely but between 1/8 and 3/4 throttle it just coughs and splutters (it is fine flatout)

I have read many forum pages and going off what I have learned I did a basic strip down of the carb as it sounds like dirt in the jets.

The inside of the carb looks very clean and in good order but still I have gave the carb another good clean inc jets and all passages and pipes,I adjusted the float height.(jet sizes are standard as is exhaust)

The one thing I did not do is take the float off as I was a little nervous about removing the float pin as I have read lots of horror stories regarding breaking the posts and also because after reading alot about it was totaly confused as to which way to remove the pin with the arrow/against the arrow most pictures explainations seemed to contradict each other?

Anyway I put everything back together and took it for a test ride......still the same!no

I took the airfilter cover off just the same,did a plug chop and it was black sooty,running very rich I guess.

I took the tank off and with fuel still in the carb started the engine to check for coil plug lead shorts.....as the carb started to empty of fuel the spluttering cleared and the bike ran perfect (obviously until it ran out of fuel)? I put the tank back on and took it for a ride it did it usual spluttering at 1/4 throttle so I turned the fuel tap off and within seconds the bike ran perfect right through the rev range!   (as it ran out of fuel I turned it back on and the spluttering returned)

Any helpful comments would be greatly appreciated as I am totally confused and the knowledge required to fix this is beyond me!confuse

Thanks in advance Dave.



-- Edited by uncletooty on Sunday 30th of July 2017 09:34:17 PM



-- Edited by uncletooty on Sunday 30th of July 2017 09:36:01 PM

Attachments
__________________


Super Guru

Status: Offline
Posts: 6629
Date:
Permalink  
 

Sorry to hear of your problems Dave.

Couple of suggestions:

1. Did you ream the pilot jet when you had the carb apart? They are notoriously difficult to clean thoroughly with carb cleaner etc as the hole is so small and it is common for the jet to remain partially blocked if not reamed.

2. Could the main jet be loose?

3. If you open the drain screw on the float bowl is there a steady stream of petrol?

Brian

 



__________________

Exeter, Devon, UK

http://www.ttr250.com  - The one and only dedicated TTR250 FAQ! 
 

TIP: For easy viewing bookmark the "Recent Posts" view - http://ttr250.activeboard.com/p/recent/ 



Member

Status: Offline
Posts: 7
Date:
Permalink  
 

Thanks for your reply Brian much appreciated.
I have spent alot of time reading posts on this very helpful site and because of this can confirm I have already reamed the pilot jet as you have suggested on previous posts with a small piece of copper wire,main jet is tight and the drain screw when opened provides a steady stream of petrol.
To me (although far from an expert) it does seem carb related,and points to the engine getting far to much fuel (at least between 1/8 to 3/4 throttle) but I have ran out of ideas.??

Dave.

__________________


Guru

Status: Offline
Posts: 693
Date:
Permalink  
 

also check the accelerator pump is working OK  , and the inlet boot for air leaks . if you have recently cleaned the air filter its easy to apply too much of the filter oil (sticky stuff ) and that can cause the bike to run over rich as well rare but possible  (some brands have a color added so you can see when its evenly dispersed and not too thick) .

Ive done the pre ride oil change and air filter clean and made it run worse a couple of times over the years .

 

good thing is that the bike ran OK before so no need to change any settings just find the problem

 

edit , i recall someone having strange problems recently , Brian helped  track it down to a loose screw above the slide somewhere  ( disclaimer my head has had a few knocks over the years memory isn't that great  ).

 



-- Edited by ttboof on Monday 31st of July 2017 05:32:41 AM

__________________


Super Guru

Status: Offline
Posts: 6629
Date:
Permalink  
 

I'm stumped!

One last check. Does the TTR run better if you leave the airbox cover off?

Brian



__________________

Exeter, Devon, UK

http://www.ttr250.com  - The one and only dedicated TTR250 FAQ! 
 

TIP: For easy viewing bookmark the "Recent Posts" view - http://ttr250.activeboard.com/p/recent/ 



Guru

Status: Offline
Posts: 920
Date:
Permalink  
 

float level to high ..



..

__________________

 

.....................................................................................................

 http://www.kiwibiker.co.nz

Bikes... 06 TTR250 / 09 XT660R / 1977 Montesa Cota 348 MRR / 1979 Montesa H6 125 Enduro...

O yer and a Quad...



Guru

Status: Offline
Posts: 693
Date:
Permalink  
 

petenz wrote:

float level to high ..



..


 Second that good call 



__________________


Super Guru

Status: Offline
Posts: 1292
Date:
Permalink  
 

Have you tried adjusting the pilot screw?



__________________

totallyttrs.com

 



Member

Status: Offline
Posts: 7
Date:
Permalink  
 

Many thanks for the suggestions.
Just to recap the TTR is fine on tickover or full throttle but inbetween coughing and sluttering.
Runs good a few seconds after shutting the fuel off?
Plug sooty carbon black....running rich.

Taking the airbox cover off...no difference
Pilot screw adjustment... no difference
Acelerator pump squirting ok.
Everything clean.

I took the whole airbox off to have a better look and looked down the carb when it was running fuel was bubbling out of where the slide needle goes in that much little waves where heading the airbox way.
I think you guys are correct the float is set to high....
When I first tackled the problem and had the carb in bits I did adjust this but I have obviously done it wrong (I blew down the fuel inlet and manually lifted the float until the float needle jet would not let air through and then measured from bottam of float to where the carb bowel gasket goes and adjusted NOT the way to do it as when I checked it today using the clear pipe attached to the carb drain the height was way up (above the bowel gasket) I have now adjusted it hopefully correct (9mm below the carb bowel gasket and will test tomorrow.

One question when looking down the carb the slide needle is straight but kinda sits to the side of the hole it goes in? is this ok,will this effect performance? can you adjust/centralize it?

Thanks again Dave.



-- Edited by uncletooty on Monday 31st of July 2017 10:32:22 PM



-- Edited by uncletooty on Tuesday 1st of August 2017 12:42:32 AM

__________________


Guru

Status: Offline
Posts: 693
Date:
Permalink  
 

sounds like progress 

quiet normal for the needle to wobble around 



__________________


Member

Status: Offline
Posts: 7
Date:
Permalink  
 

Update.
TTR running 100%....
Ticks over like a sewing machine and revs smooth and strong right through the rev range.
It has never ran this good before and is a pleasure to ride.

I would like to report exactly what the problem was and a little frustrated I can not.


It was running crazy rich,coughing/spluttering and spitting,virtually drowning in over consumption of fuel,it reminded me of the mother-in-law on a Saturday night.(Wish I was joking)

The diagnosis: float to high was correct but I suspected there was more to it than that as the float height was inconsistent each time I measured it,I suspected the float was leaking/not floating correctly.
I decided I must tackle the dreaded float pin and remove the float.I very gently tap,taped,taped and after a long while it did work lose and I managed to remove it with float posts intact.
However after a simple test the float was ok floated fine, no leaks.
I then removed the float valve and small filter under there to find a few specs of dirt (maybe this was the problem,consistently cutting of the fuel?)

I then decided to check slide needle and position,it did seem to be to one side and not central but not bent and was very ridged...no movement (although maybe not a problem)
I adjusted the needle to factory spec. middle and reassembled.
When reassembled the needle was central in the hole and had a little bit of "give" in it I am wondering if orginally the little locking washer that the needle sits on was orginally seated correctly?

I can not pin point what was wrong maybe a number of things? but so happy it is now running spot on.

This is the first time I have tackled a problem like this so many thanks for peoples suggestions and to the excellent posts/instuctions on this site which really helped.
Thanks again Dave. (Happy Days)

__________________


Super Guru

Status: Offline
Posts: 6629
Date:
Permalink  
 

biggrinbiggrinbiggrin

Thanks for reporting back wink



__________________

Exeter, Devon, UK

http://www.ttr250.com  - The one and only dedicated TTR250 FAQ! 
 

TIP: For easy viewing bookmark the "Recent Posts" view - http://ttr250.activeboard.com/p/recent/ 



Super Guru

Status: Offline
Posts: 1292
Date:
Permalink  
 

+1smile



__________________

totallyttrs.com

 

Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard