1981 GS550 won't rev

[amadeus3]

I've got a GS550 that won't rev. I've cleaned the carbs out, replaced the coils, new battery, new stator and rectifier but it just won't rev cleanly, it starts to rev then 'chokes'. It's electronic ignition so no dizzy.

Does anyone have any suggestions? 

Thanks

Steve

[Poldark]

How did it rev before cleaning cars and replacing coils?

[canamant]

It will have an electronic advance.  Get a strobe on it to see if it is advancing.  Circuit might have fried.

 

[canamant]

If the back plate is slotted you could try manual advance and see if it improves.

 

[Poldark]

Electronic advance?  All the ones I worked on (8 valve engine) had mechanical advance.  Whether electronic or breaker point, they had the fly weights and springs on the end of the crank.

[Ben Slabby]

Yep,  mechanical advance,  even on the ones with electronic ignition. Make sure the advancer unit isn't stuck. 

Edited August 17, 2015 by Ben Slabby

[wraith]

At what revs is it doing what?  e.g. :

How far is it reving to, and then what happens? Is this consistent? Will it rev through or does it stutter or just die straight away? (If it revs above 3000rpm, ish, I'd think it wasn't the ATU but fuel/air or overall bad running.)

Will it tick over ok? Is it running well at tick-over and low revs? What happens if you can leave it ticking over for a while?

Is it doing it just when hot or cold? Does it change when warmer?

 

Other thoughts:

Is there a good spark on all 4 and are all 4 zorst down pipes getting hot equally?

Is the fuel filter/gauze in the tank clean at the tap and does it have an inline fuel fillter which could be blocked/dirty?

What colour are the plugs and are they dry or wet? (are they in good nick and correct gaps?)

Is the vent hole in the tank cap clear? (Is it a standard cap?)

Is the air filter clean?

Are the HT leads good and have sound connections (check for earthing out, sparking/smoking with Duck Oil, etc)?

 - and so on.

 

Could be a lot of things. Check the obvious and then if no joy try to describe exactly wht the symptoms are and when, etc. Also, when exactly did they start and what had you just done (or not)...  How was it running before this problem started and did it just start or has it got worse over time?

Good luck  ;-)

Edited August 21, 2015 by wraith

[DanT]

+1 on HT leads. I recently had the same experience with my GSX 1100 , replaced the spark plugs and HT leads. Started and ran with no choke went for a test ride and and only lasted about a mile. Bike would start but not rev and when put into gear would stall. Went home got the old leads out of the bin, re-cut the ends and installed old leads with better contact and the bike runs perfectly now, bike shop also sells mowers and they sold me a set of mower HT leads ....

Good luck

Dan