I recently acquired a 1977 Yamaha XS500D It ran but very rough and had a top end of about 40 mph. I have cleaned the gas tank. pitcocks & carbs. Replaced needle valves & seats & one float. When replacing the plugs I discovered that one of the heads had been drilled out and a larger plug (diameter) was installed. I replaced the plugs with NGK plugs that according to the numbering system are the same depth and heat range.

It finally ran good after I replaced the points and condenser. But only for about 20-25 miles then it started doing the same thing.

I suspect the condenser is the problem, since the points still look good. Can anyone explain what might be ruining my condenser?

Thanks,

Rusty

I recently acquired a 1977 Yamaha XS500D It ran but very rough and had a top end of about 40 mph. I have cleaned the gas tank. pitcocks & carbs. Replaced needle valves & seats & one float. When replacing the plugs I discovered that one of the heads had been drilled out and a larger plug (diameter) was installed. I replaced the plugs with NGK plugs that according to the numbering system are the same depth and heat range.

It finally ran good after I replaced the points and condenser. But only for about 20-25 miles then it started doing the same thing.

I suspect the condenser is the problem, since the points still look good. Can anyone explain what might be ruining my condenser?

Thanks,

Rusty

do the contact breakers spark with the engine running? if so either the condensor is not earthed properly or is faulty. if there is no sparking, then i would suggest

a) timing check

b)a carbs strip down and thorough clean with ultrasonic tank

drewps

do the contact breakers spark with the engine running? if so either the condensor is not earthed properly or is faulty. if there is no sparking, then i would suggest

a) timing check

b)a carbs strip down and thorough clean with ultrasonic tank

drewps

thanks Drewps

I'll check that out. I know I've done nothing with the timing yet.

I'll let you know what happens.

Rusty

thanks Drewps

I'll check that out. I know I've done nothing with the timing yet.

I'll let you know what happens.

Rusty

How idi you go ????