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

Scarth28 · Member

From bad to worse why wont this thing start?! Ttr250 open enduro

JOHNYBOY · Super Guru

if you have got a spark is it crisp & blue if so i cant see it would be the cdi when ive had problems like this i have sprayed brake cleaner down air cleaner tube be very carefull if it fires up you have got fuel problems BRAKE CLEANER IS FLAMMABLE NOT TOO MUCH YOUR DECISION v

Scarth28 · Member

Aah yes i forgot to say, i did try spraying a bit of brake cleaner down the inlet and it still doesnt fire up on that. So i guess spark timing must be wrong from cdi

JOHNYBOY · Super Guru

is it turning over fast enough

Scarth28 · Member

How can i tell if its fast enough? Seems ok mind even with jump leads on it

TTRfan · Super Guru

Does it fire at all or spit back - any sign of life?

Spark plugs can be problematical from new (on rare occasions) so maybe try a different one just to be sure?

Is the petrol clean and fresh? And definitely petrol and not diesel? Don't ask disbelief

Bearing in mind the float bowl drain plug is rounded out, could you lean the TTR right over and check the carb floods?

Brian

PS If all else fails, there is a very comprehensive check list, albeit generic, here.

Scarth28 · Member

Yeah ive tried a couple of plugs, the petrols fresh. I know when i took the float bowl off it had fuel in. It doesnt pop back or anything. What are the symtoms of a cdi normally? Could it be something valve related

Ill take a look at the check list. Cheers

-- Edited by Scarth28 on Sunday 31st of January 2021 07:43:05 PM

ttr steve · Super Guru

Rob

It is sounding like the cdi, you can send it to me for testing. Make sure you mark it properly as I have a few here and don't want to mix it up.

Don't think it is bent valves , as you would have no compression.

Steve

-- Edited by ttr steve on Sunday 31st of January 2021 09:20:54 PM

fast fazer · Member

I would be inclined to look at the coil first. A failing coil will struggle to produce a spark under compression.

Cheers, ff.

Scarth28 · Member

Cheers steve, i will send it down even if its just to eliminate it. cheers

mossproof · Super Guru

Is the plug wet after spinning it over? If not I would still suspect fuel issues.
If the cdi had fried during jump lead shenanigans, why would that affect the spark timing? Surely it would just give up altogether? Is the stator and pickup sensor all bolted into the LH case correctly?

Not sure if you would get a spark if the pickup sensor was damaged or not connected, but generally I would say that if something stops working after you've done a job, look at the things you've done first before going off on a tangent.

https://ttr250.activeboard.com/t62021383/ignition-pickup-coil-or-sensor-replacement/

-- Edited by mossproof on Monday 1st of February 2021 08:27:43 PM

ttr steve · Super Guru

I was testing cdi's on my own bike with Brian, the bad ones would turn over the bike but not start the bike.

I don't know all about cdi's, but that was the only way I could test them.

tripodtiger · Senior Member

My only thought is the air gap at the pick up coil.

Scarth28 · Member

Still nowhere, but ive had the cdi tested on another bike and its fine. Is there any specialists out there that could look at it for me.? Tia

TerryK · Super Guru

The basics are

1. compression
2. air
3. fuel
4. spark
5. timing if 1-4 are all ok, what about valve timing
6. lack of compression due to valve clearance or decomp stuck or not adjusted correctly

Cheers Terry

ttr steve · Super Guru

Can you upload a picture of the cams in TDC