yamaha 2 hp ,2 stroke problem ?

grafozz

grafozz

Well-Known Member
Joined
11 Jan 2004
Messages
785
Location
kefalonia ,greece
Visit site
My old faithful BF 2 hp , 2 stroke yamaha wont run unless the choke is constantly opened and closed ,as if it has an air leak ? I have stripped the carb and its all clean inside, fuel tank is clean , new petrol , plug , any ideas please ?
 
Clean the carb again. Those bits of goo that block them are a devil to get out. Do you have access to an air-line? Poke the jet with soft wire.
As a last ditch attempt, get some carb cleaner solution that you can soak it in.

Is it the carb in this .pdf document? More tips on poor running there.
 
grafozz said:
My old faithful BF 2 hp , 2 stroke yamaha wont run unless the choke is constantly opened and closed ,as if it has an air leak ? I have stripped the carb and its all clean inside, fuel tank is clean , new petrol , plug , any ideas please ?
Click to expand...

The way the little carb attaches looks somewhat flaky- there should be an o-ring sitting in the recess -which goes over the "inlet" to the engine. If it is missing or hardened - or not sealing well - the engine will draw excessive air here - requiring lots more fuel to burn properly- hence needing the choke too much...
Strange design -it would have been easier to make this connection air-tight several other ways!
I cleaned my carb parts in an untrasonic bath (designed for jewllery etc) -not expensive and very effective - not much >£25 on ebay or Lidl - where I found it!

Graeme
 
I agree with both previous posts.

make sure the O ring is in position, in good condition and that the carb is pushed fully home before tightening the clamp.

( Dunno about flakey, its how Villiers carbs were fitted... no O ring either as far as I know)

Make sure the main jet really is clean.
Make sure the nozzle is clean correctly fitted.
Make sure the needle is correctly fitted in the throttle valve and that that is correctly fitted into the carb body.

Diagram HERE is of a Yamaha carb. You describe your engine as old but dont say how old or give the year letter. This diag is the earliest I can find (1984)
 
thanks ,

many thanks to you all , for your input , I think the o ring has had it , the results will follow !

it is a 1998 engine which I dont see listed on the link ?
 
yamaha 2 stroke now sweet !

Stripped down the carb , again , ... O ring ok - but main jet had a little lump of rubber in it , reducing fuel flow now blown away and engine back in old "rude£ health . it pays to be thorough when stripping down small parts like mini carbs , thanks all .

Not that I can find any petrol for it . Greece has a national tanker drivers strike in its 6 th day now , the whole country is running on fumes ! sooooooo glad I have a sailboat !
 
You must log in or register to reply here.

Share this page

Top