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

jackvine · Member

Hard to start from Cold

Cubber · Super Guru

Perhaps it's now time to check the manifiold for leaks. confuse

The rubber covering has been known to part company with the alloy which forms a sneaky leak point. bleh

Martyn

jackvine · Member

Unfortunately I've already replace the inlet manifold and gasket

Cubber · Super Guru

Oh, well - it sounds like you are in the same boat as Apollo 13. confuse confuse

"Houston, we have a problem." hmm

Martyn

TTRfan · Super Guru

If the fuel level in the carb is OK (and I am guessing it is if it runs OK when warm) then I am baffled. The symptoms indicate no fuel flow through the pilot jet but it ticks over OK with no choke when warm confuse

Maybe it's not the carb. Have you checked the valve clearances recently?

Brian

jackvine · Member

Yeah im not convinced that its the carb either now !

Will look in manual and see how hard it is to do the valve clearances, bike was sitting for about 10 years so not been done for very long time.

locky · Guru

Yes i think it's worth checking the valve clearances even if it's just to eliminate them. Follow your manual, they are very easy to check but there's more involved to adjust them. It sounds like you've gave the carb a good look at but there's still a chance that there could be a partial blockage somewhere. I'm very interested in the outcome so keep us updated.

TTRfan · Super Guru

locky wrote:
It sounds like you've gave the carb a good look at but there's still a chance that there could be a partial blockage somewhere.

That is my thinking but the TTR runs OK when warm confuse

Otherwise I would have said take the carb fully to pieces and blow some air through all the internal fuel/air tubes to make sure they are all open....

Brian

ttboof · Super Guru

if its been sitting for so long , best way to start is check the valve clearances (fairly easy ) , strip and clean the carby check the oring around the choke shaft , inlet stub has already been done .

other things to check . air filter perished or oil has thickened /dried out but would make it a bit rich , around here we get wasp nests in the exhaust , and prob a fresh spark plug likely to be the problem but can help .

Just thinking out loud

jasparach · Senior Member

10 years is a long time for it to sit, as ttboof said everything has to be checked out as rubbers perish over time,it sounds to me like it is choke problem
as when it gets enough fuel it runs and it runs when hot.

jackvine · Member

I think my next step will be to check compression, Im pretty sure the carb is fine, when I had it apart I used compressor to blow through the airways, and really it was quite clean inside.

Could it be the exhaust valve not seating correctly and not enough compression to suck the fuel in ?

jasparach · Senior Member

i have two ttr's a 2005 and a 1996 and when starting first from cold,they are started on full
choke they both start then cut out, i then start them again on full choke and they start and then settle
down to running, still on full choke. Will your bike not start on the second attempt with the choke still
on full? Sorry for the questions but just trying to get a feel for what is happening?

jasparach · Senior Member

www.thumpertalk.com/topic/580333-bike-wont-start-when-cold-fine-when-hot/

It may be of help to you.

jackvine · Member

HI if I start with full choke from cold it starts for a few seconds then dies, when I try again it just turns over but won't fire.

If I then take choke off and twist the throttle to pump fuel in it starts and dies, but once Ive done this 4 or 5 times it will pickup and start and idle.

Looking at the other forum it would suggest it is a valve issue

domski1 · Senior Member

I had a similar problem on a 1995 Ttr, if it was left for more than a day if I didn't give it about a dozen twists of the throttle it wouldn't start. Had the carb in bits and tried different jets, checked a double checked valve clearances, all ok, I ended up selling the bike but I came to the conclusion it was a valve issue, it ran fine when warm but did seem to be running a little lean as the front pipe would glow after a good run!

TTRVN · Veteran Member

Is your bike electric starter only? This may seems obvious but did you check the battery? If your battery is unused for a very long time it might degrade, making it harder to start. I had a similar problem with my Raid. First I thought it was the carb clogging but when I stripped it, it was fine. Then I replaced the battery and my bike runs fine now.

jasparach · Senior Member

ttr250.activeboard.com/t45346670/cold-starting-issue/. I found this previous thread which seems to have
experienced the same issue as you in regards to the cold starting, it may help you on your mission.

jackvine · Member

Thanks for all the info, at the weekend, I may strip the carb once more to triple check for dirt, also will check valve clearances.

Battery has already been replaced, and so has spark plug, will check the gap though.

jackvine · Member

OK just to update, I managed to get hold of a good used engine and carb, swapped the carb over and started straight away on choke and ran fine. So I will endeavour to strip the carb once more and see if I can fine anything.

jasparach · Senior Member

That was my thinking is that it was carb related, at least now you have a definite
cause and can sort it.