Yamaha Malta problems

[Tarka1]

Hi folks,
I've got a Yamaha Malta that won't run properly, struggles to start then won't rev cleanly unless the fuel tap is closed (a very short term solution!) which suggests to me that it is flooding.
I've thoroughly cleaned the carb and replaced the float valve as the tip on that wasn't too clever. Float height is set at 14mm.

I'm at a loss of what more I can check or clean so any advice would be appreciated

Thanks

 

[sailaboutvic]

It sounds like a carb problem , just check the choke isn't stuck open .
There been a bit about carb laterly on here .
If it flooding then the needle isn't seating , make sure there nothing in the needle seat , give it a good blow or better clean it with brake clean or carb clear and while your at it give the rest of the carb a good clean , I find the small bit of crap with give you a problem and some time , it will take a lot blowing and cleaning before it all comes out .

 

[VicS]

I too would look again at the float and needle valve.

Make sure the choke is opening fully, not stuck closed or partly closed

You say you have thoroughly cleaned the carb ... then look it everything you disturbed again , Make sure all the parts are correctly fitted with the appropriate gaskets, seals etc in good condition and fitted correctly .

Check the mixture adjustment is set correctly .

Its always a good idea to check that there is a good spark. It should jump best part of a cm. Try a new plug too.

 

[Tarka1]

Choke is fine and I've cleaned the carb with a sonic cleaner and carb cleaner.
I would have thought if the float valve wasn't seating then the carb would be leaking petrol.

Any other ideas?

 

[VicS]

Choke is fine and I've cleaned the carb with a sonic cleaner and carb cleaner.
I would have thought if the float valve wasn't seating then the carb would be leaking petrol.

Any other ideas?

You say you cleaned the carb but did you tear it down fully and rebuild with a carb repair kit ?

I take it you only put metal parts in the carb cleaner ?

 

[Boathook]

Choke is fine and I've cleaned the carb with a sonic cleaner and carb cleaner.
I would have thought if the float valve wasn't seating then the carb would be leaking petrol.

Any other ideas?

The slightest bit of muck in the jet causes no end of problems. Best way is to look at the jet through a magnifying glass and if the jet is displays a slight 'bump' in it, you will need to clean again. very basic engine but the carb is something else !

 

[Tarka1]

I put everything in the carb cleaner - could that be a problem?

 

[VicS]

I put everything in the carb cleaner - could that be a problem?

You should not put rubber or plastic parts etc in carb cleaner .... the w'shop manual tells you that.

 

[sailaboutvic]

Question .
When you say it flooding , how do you know ?
Is it because petrol is poring out of the carb or because you can smell petrol or because the plug very wet ?
Petrol poring out of carb ,, needle or seating .
Smell of petol wet plug , , not firing so could be plug as VicS said
After that it could lot of things like lost of compressing , valves
I still say your problem carbs ,
I have an Yamaha I had to clean my carb out no end of times the other month , each time works fine half hour later starts to flood ,
Dirty somewhere in carb .
By the way check Jet , I found in mine there a fine mesh and the slightest bit of dirty trap will couse you on end of problem .