Airhead

The thick line leading down to the pump is the feed from the tank, the tank is higher than the carb so it matters not that it is uphill from the pump to the carb. The check valve is an integral part of the oil pump. Testing by the method i already said would have proved it good or bad.......However Now you have commented on thick white smelly smoke...that is more likely gearbox oil, Replace the seal on the clutch side of the crank perhaps a minor leak there? Can you smell petrol slightly in the oil filler hole?

Greetings Lars

Yeah bring em round mate, i'll beat them.

Not unless it's a rat bike! Pipes are often run between the swing arm pivot and the rear of the engine.

Greetings Craig, we havent 'met' so , we have an new members section if you want to intro yourself there perhaps. maybe I can have a look for your model in my file but i will need some numbers. I am wondering with such an old bike...what condition the carb diaphragms may be in, possibly perished / cracked etc ?

Greetings oudou Loving the chappy...nice job

yamaha 2 stroke pumps have a spring loaded ball which serves as a check valve to stop the oil tank contents from just free flowing through the pump. Obviously thes can fail from time to time...though i have no experience of it myself. As a check why not remove the thin oil pipe from the inlet manifold (or carb) and secure it over a container overnight to see if you have this problem. If you do ...remember to prime the line when re-fitted.

Greetings Bill

Good advice but generally it can only be done with the 'dry' seal behind the generator, if the other ones duff it will burn oil and smoke some

Greetings Carol ...Lincoln eh? was down there a few months ago for the bike show ...Got drenched

Very... Very... nice merv

Like a kid at chrismas haha

Thats something special

Greetings Simon

main thing is... is it safe to ride/ wheelie/ jump ??? is the grafted on front a good strong welding job or just an amateur pigeon sh1t garage welder bodge-up ?

Harry I would keep it as a field bike, not worth spending much on it for road use ...unless i'm mistaken it hads had a new front end welded to the original...see how the frame headstock juts out from the front of the tank? you'll never get a V5 for it in my view and would be best to source a frame with V5, not an easy task! as for god lol...no it comes with owning one of these for 30 years or so

I would say option 2 mate but as it's a classic and crooks is your best option...youre stuffed mate, anyhow the bike is 35 years old or so...whats a few more days

we have been suspecting a fuelling issue as this is most likely, not as likely now though as you have addressed this? how about an electrical fault, is it out of action for long enough to check for a spark at that time?

Nice find Harry. Oh and as we havent 'met' Cant comment on £200 as it's meaningless without knowing what you are buying. so tell us about the seat then, is the foam good and so just a re-cover task? and what do you mean 'importing' one off evilbay? Rear shocker...well how do you know its seized, its bloody hard to compress them by pushing down on the floor! so is this why you think that way? Front wheel and forks are not original, they were drum braked. I see the back has been 'jacked up' either by an extension to the damper or the cheaper method of drilling a new pivot hole in the frame spine. I also see some extensive welding, a complete new front headstock has been welded onto the original frame...for the vin number??? could be trouble Edit, lets start a new topic in a more appropriate place or this hello intro will be severely OFF TOPIC...Paul

is the fault still the same as you reported? Have you got a strong fuel flow now with your 'new' tap ? yeah check these points too, also I once found chips of rust in a carb, situated between the fuel inlet spigot and the float valve seat, had to remove the valve seat and blow it out.

how is the 'fit' between the HT cap and HT lead...loose?

Any Yamaha dealer I expect

Err yes you are , didnt you read my last post then? is there a pointer on the clutch arm and a mark on the engine case?? they should align if you push the arm by hand until you meet resistance, do the clutch adjustment until this is achieved then finally re fit the cable and adjust for 3mm of lever slack. I might add that i am guessing at this as i have not seen the manual!

disconnect the CDI

might be worth asking these guys ? Here