Mr Paul Nicklin

[Paul Nicklin]

Owned a 1990 yamaha 535 for a month or two, no issues, went on a road trip to Bath from Stafford used motorway and A roads, sed for fuel in Bath and bike refused to start unless i jump started it in gear. The bike once started was not running right and so i called RAC who came out to it and diagnosed a faulty generator, got it home, replaced generator charged battery and bike restarted but is now bogging down it doesnt run as responsive as it used too, generator is pumping out voltage and battery is fine. Is it coincedence another problem may have cropped up, plugs look good tan colour, it revs smoothly no mis fire, any suggestions will be greatly recieved i am at the end of my tether as what to do next.

[Simon Davey]

Hi Paul, welcome to the forum.

Could be that those carb's need a clean. Get the jets out and replace or clean them.

Before you do that though, disconnect the fuel line from the tank, turn the fuel tap to reserve and check there isn't a load of crap coming out.

Edited June 18, 2024 by Simon Davey

[Nick the wanderer]

Hi, seems a bit odd it all started with the fuel stop. If running lumpy it could be a dodgy batch of fuel, it has been heard of. So maybe start there. Good luck.

[bonio]

...but "revs smoothly no misfire" suggest that the fuel is good and carbs are ok.

Not sure what the problem could be, though.

[Mississippi Bullfrog]

Somewhere I read recently of a similar issue and it turned out to be the plugs even though they looked fine. It was something to do with low voltage causing the plugs to glaze, or something similar along those lines. 

 

The guy changed the plugs and all was well. 

 

It happened after battery failure and he'd bump started the bike. Then it just wouldn't run right. 

 

It was the only time I've ever heard of this so it may just have been coincidence but someone posted explaining the science behind it and jn his case it sorted things out. 

 

No promises....

[Phil1]

Did you put E5 or E10 fuel in? Another potential avenue as E10 probably isn't suitable for a bike of this age. 

[brotorbike]

Welcome to the forum, Paul!

[RideWithStyles]

Welcome, a picture of all the plugs and order in the cylinder (shows the colour of tanning and condition) may help.

 

Phils suggestion isn’t too far from the realms of possibility but still a very off chance. e5 and e10 have different burn characteristics but for your bike with old rubbers id be putting e5 just for the old timers sake.

 

Personally id be checking the stator and rectifier.