Okay, I have a 90 model recently purchased from a friend of mine who owns a bike shop and has gone through everything on this bike carbs, regulater, rectifier, valves...you get the idea. Bike only has 13k on it and around 5k RPM I get a lot of hesitation and also on WOT and hard acceleration it just kind of jumps like it is trying to find the get up and go. In 5th and 6th I can ease into WOT and it will accelerate fine kind of up to 115-120 then no more acceleration after that point. The chain does need to be replaced and I was thinking that this could contribute to the problem. Any suggestions would be greatly appreciated.

 

Hard to tell without experiencing it. Have the cams been out & put back a tooth out??? Check your plugs. They should give an indication as to carburation.

 

Check the air box for restrictions plus fuel lines, filter and pump for flow. Fuel pump will only work when engine is running.

 

How does one know when a chain or a sprocket need to be replaced?

 

Mine was doing something like this ( -91 model ) - I did all the same checks as you have done.

Only cured it by re-setting the float heights to the recommended 9mm setting.

One other thing - Has the bike been fitted with an aftermarket exhaust ? - it might need re-jetting to suit.

 

If you can pull the chain off the rear sprocket more than 50% of the height of the teeth.

But mostly I go by feel.

If u have a bad chain you will notice the fuel economy going down.

Also slow speed manovering and using small amount of throttle coming out of corners will be jerky.

Also you will feel odd vibrations or even clunks through the footpegs.

 

When a sprocket is worn it becomes "undercut". That is the side of the tooth that the chain roller pulls on wears in such a way that the roller cuts into the tooth. Some times people reverse the sprocket to get more life???? I have even seen them where the entire top of the tooth is missing & the chain literally rides over the teeth. When the chain is worn often the only sign is that the chain doesn't seat on the sprocket properly. By that I mean that you can pull the chain links away from the back of the sprocket as if its too long & doesn't quite fit into theteeth snugly. If in doubt have someone you trust show you. I hope you understand what I mean. 5am before work & brain a bit foggy yet.