Airhead

Stop shouting...Caps PM me your email and I'll send you one ...Paul

You could try emailing Electrex World Here they list the DT175 but I didnt see the 250, worth contacting them though. I bought an ignition source coil fro there for my DT175 and although it wasnt right in the resistance value band quoted by yamaha it seems to work ok and was a lot better than the rusty old thing it replaced. Heres the old one and the new one fitted Even if they dont list one for your bike, they may be helpful and if you email them a picture and quote the mounting hole centres they may find it is the same as some other models that the list for.

Surely if your de compression valve is faulty...compression would be your problem!

You have already been given a link to the aircooled rd club earlier, obviously this would be of benefit to you. you could also try the VJMCc if you want to. VJMCC = Vintage Japaneses Motorcycle Club

Check continuity of the ground connections to the battery negative (the outer shell of the bulb holders?)

This is a widowmaker, you gotta get married first though

I would continue with the exhaust repair now in case thats the problem or adding to the problem, its not just a matter of adjusting the throttle stop screw though is it?

so have you had the pilot jet out and held it up to the light....can you see through it?

Fit new plug Water in carb?

Bed of roses, J Bonjovi...

cue the cigar ad...

I'm sure I counted five.

Its the Black / White, ground that and the engine stops.

All the kill switch does is ground out the ignition coil, when the switch is off there should be no path to earth (chassis) and vice versa. You could rig up any switch to do this, connect one side to chassis and the other to where the original did connect to., or you could stop the bike using the ignition key which does the same thing

Here

yep, not bad for a small scale show, plenty of variation in the show hall and the bikes parked outside, cant grumble for a pound and we were lucky with the weather....

Dont recommend that myself, better to sort the pump. does oil free flow through the pump to the pump outlet spigot? If so and yo checked out the check valve, perhaps there is some sh1t on the valve seat, personally I would continue to sort the pump, or source another pump, premix is a pain in the arse unless its a competition only bike IMO.

Spark plug HT cables are almost definately the problem, HT shocks hurt I know (got the T shirt) theres a hell of a lot of voltage in them. Have a good look round, are the cables secured right and fully home at both ends? Wherever it is it will be the one nearest the petcock.

Too near to me not to go, heres a sample Yes I know its a boat...

Great news, Congratulations Goff and new guy....

You post started with, 'Last week my bike started to misfire' thats a good reason to check the plug in my book, I've seen it before all manner of fiddling with the carb and then it turns out to be an ignition issue. You seem to have solved it though with removal of the filter and replacing it with something, personally I wouldnt be happy with that and would have fitted a new filter. be careful with reducing the jet sizes though.

It has been mentioned before i think, I'll mention it to alex again...

Fair comment, I'll get my eraser out when I find them.

ok as a paid member you should be able to post there, we'll check it out for you.

Glad youre having fun with it Shaun, the reeds will never seal when turning the motor by hand as you say. There is a specification for the bend of the reed petals of something like 0.3mm if memory serves me correct, that coupled with a lack of pressure to blow them closed will mean you saw this little leak. ...Paul