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Post Info TOPIC: Carb seems to drag in air...


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Carb seems to drag in air...
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Hi all,

I have a 93 oe with a few raid parts, which recently has had new pisyon rings, cam chain etc.

 

Before i took the bike apart it was running 142/48 jetting and started reasonably well and idled perfectly.

 

Since then i have "rebuilt" the carb using an all balls kits from the ttr shop. I tried to run the bike on 142/48 jets after and it was a real struggle to start and very lumpy.

Since then i have put a different carb (50/147) and it ran well. I would like to revert back to its original carb as the inside of the carb looked all gummed up and the shaft attached to the diaphragm looked rusty.

When i put the original carb back on today i did put the 50/137 on it and whilst it didnt idle at consistant revs it pulled much better up top.

Low revs feel very lumpy, revs change at random when idleing.

I have tried spraying brake cleaner on it to see if revs pick up but it does not. 

Things i don't think are the issue...

Valve clearances

Clips to the front and rear too loose.

Weak spark

Lack of fuel

Air mix too far off.... 1.8 turns out.

 

My guess is that i have put the carb back together wrong... does anyone know if there is an internal part that is sensitive to air flow?

 

Sorry about the rambling, i hope ive overlooked something simple.

 

Thanks

 

Dan



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Super Guru

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Hi Dan

Did you use the extra O ring that I supplied in the all ball kits, for the air screw?

 



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Hi Steve,

I think so, it was the smallest o ring right? They all seemed I little loose in the inner diameter, I have tried Malcolm's raids one to see if it felt any tighter fit but it wasn't.

Ive attached a photo to show the original vs All balls. the older one seems to fill the gap better too... 

What do you think to the photos?

All I have attached n update of how the bikes looking currently.



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Hi Dan

I don't have any all balls repair kits in stock, so I am unable to check the following for sure.........

In your picture it seems that the all balls air screw has a bigger recess on the shaft? The original rubber looks a bit bigger, but that is because it has been flattened by being in there for so long ( how a compressed rubber looks). I am attaching a photo that shows the original air screw and the original rubber bottom right, saying that the original rubber is really hard to get over the shaft, onto the recces and the aftermarket that I supply with the all balls fits really nicely (as in the picture). Do you think or can you measure the recces on the shaft between the original and the all balls, to see if there is a difference please.

air screw O ring.jpg

Has anyone else had troubles with the all balls kits, I have sold about 30 of them so far.

Feedback would be appreciated.

Steve



-- Edited by ttr steve on Sunday 25th of February 2018 08:32:54 PM

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Oh Dan

You have checked the Inlet stub?



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Hi Steve,

The inlet stub was fine on the 147/50 carb so i do believe its my one that is the issue...

Thanks for the information, i am almost 100% sure it's my fault somewhere down the line, ill measure everything up tomorrow:)

As ever thanks for your help!

Dan

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Hi Steve,

The original air screw has a longitudinal distance of 1.75mm wheras the all balls has 2.05mm in the recess. The diameter of the ridges either side seem to be consistent at 5.95mm (from memory) but no rubber seems to grip the centre or protrude futher than the 5.95mm dia.

I do now believe that i have the correct o ring already fitted, the additional 0.3mm in the gap would reduce the o rings effective width as its sitting at an angle? I imagine simething so minor shouldnt be a problem though.

I'll try again tomorrow:)


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I the bike starts on the button, i have put the original air screw back in but it still idles odd and when i open the throttle and close it quick the bike dies.

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Spray a fine mist of water (using something like a household plant spray or used cleaning spray) around the Inlet stub and carb. It should indicate an air leak, and idle better for a few seconds if it is pulling air. Also slacken the whole air box off, and raise and lower it and move it slightly from side to side to try if that seals a possible crack in the stub.

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Hi Micki, I've tried the first part already but ill try the airbox trip after dinner, thanks!

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Unfortunetly the airbox trick made no difference. I took ot for a test run and it was coughing and spluttering at a low rpm, once i built up the revs it rode pretty smoothly at speed.

I decided to swap over carbs again and use the 137/50 and the better condition diaphragm and shaft.

The bike idles great and rides well now

I still have the other carb and want to fix the issue... i was wandering if the choke could drag in air? The shaft on the dodgy carb is much easier to push and pull... it feels like there is a bit of play too.



20180227_215123.jpg



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You can check if your choke isn't seating correctly by folowing the guidance hee http://ttr250.activeboard.com/t52237312/freeing-off-a-jammed-choke/?page=1#lastPostAnchor wink



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I know it is a long shot, but i went through a huge pool of water last summer and the bike spluttered and cut out. First time it has ever died on me. Anyway, i drained the carb using the drain screw and ran some petrol through. I got the bike started but it ran rough but managed to get home. When i removed the bowl there was still some water in the bottom. Could there have been some water in your fuel and settled in the carb, and now having replaced the carb, clean fuel is in the replaced carb? Glad your bike is running well now though.


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