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

dlee22 · Senior Member

Carb seems to drag in air...

ttr steve · Super Guru

Hi Dan

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

dlee22 · Senior Member

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.

ttr steve · Super Guru

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

ttr steve · Super Guru

Oh Dan

You have checked the Inlet stub?

dlee22 · Senior Member

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

dlee22 · Senior Member

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:)

dlee22 · Senior Member

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.

micccki · Veteran Member

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.

dlee22 · Senior Member

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

dlee22 · Senior Member

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.

TTRfan · Super Guru

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

micccki · Veteran Member

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.