Can't start the 1980 yamaha tt250

[road king]

ok, so i thought i might try my hand at a we bit of off road motorcycling for shits and giggles, so i got my hand on this 1980 tt250. its just had a engin rebild and the guy i got it off said he had it running but it was a bitch to start.

he wasnt wrong, i cant get it to start
its got spark, fuel and air. i tried using some "start ya bastard" to no avail, took the plug out and sprayed some in there, it just spat and kicked back

anyone got any ideas???

[Pedrostt500]

Could be a few things, try a new plug, also check the timing, if the motor has been apart the timing could be out, get the CDI checked, also the coil and ht lead, it may have spark but not enough to fire her up. also pul the carb down and give it a good clean. its just a case of working through every thing mehodicaly, and not jumping to to many possibilities. start with the easy and basics.

[road king]

i start pulling things apart and ill never get it back together again, think i mite just have to take it to a shop

[Katman]

I'd be checking the cam timing.

[road king]

I'd be checking the cam timing.

how do i do that?

[Katman]

how do i do that?

See post #3.

[Wired1]

I've had a few of these and rebuilt a few and they are a pretty simple motor. If it has been running then I doubt the cam chain is out of alignment and it isn;t that common to need a new cdi as they are solid state devices. The capacitors in any 1980's bike cdi are always going to be suspect but again, if it has been running then I would ignore the cdi and if it has spark I would assume the coil is right too.
The only thing left then is the a dirty carb (assuming it has been running that is!). I have had bikes that get gummed up if they sit for too long and then won't start. The carb is fairly straight forward and can be cleaned without a manual if you are methodical but if you are a bit nervous then get yourself a workshop manual and a can of carb cleaner and have a crack at it. Lay it out carefully on a clean table and keep the parts in the same order and laid out as they need to go back on. Don't remove any of the jets, just blast them with carb cleaner, slide the slide thing up and blow that sucker out, and squirt each opening you find - they all lead somewhere and all should be open. It will cost you most of $100 at least for the bike shop to do this so a manual for $60 and a can of carb cleaner at $18 is a bargain - plus you can do it again next time for free!
Of course if the previous owner was bullshitting you and it wasn't running then you have a whole lot of possibilities ...

[avgas]

are you actually kicking it through compression?
"Pah PAH pah" - must have 3 beats from 1 kick
or are you just hacking it like axe?

[smudge]

Most likely to be the carb as Wired said or the ignition timing is out or there is air leaking into the inlet side of the carb.

[road king]

are you actually kicking it through compression?
"Pah PAH pah" - must have 3 beats from 1 kick
or are you just hacking it like axe?

umm, kinda mixing it up, trying a few slow ish, 3 beats per kick sounds about right, then i just get frusterated and jump on the fucker hard and fast. never realy had to kick start a bike before so yea, i was kinda wondering if i was doing it wrong???

[slimjim]

so it won't crash start either.....?

[Katman]

Why is it unlikely to be the cam timing?

If the motor has just been rebuilt (and has been difficult to start since then) it is quite possible that the timing is a tooth out.

[road king]

so it won't crash start either.....?

havnt tried that yet, wating for my flatmate to come home so he can give me a push

[smudge]

to be fair I've never tried to start a bike with the cam timing out, but if it is hard to start because of that I would think it is most unlikely to run fine. Easy to check though.

[Katman]

I don't recall the original poster saying it runs "fine".

Most engines will 'run' with the cam timing a tooth out - if you can get them started.