Reduced power VF500 F2

Hi folks I'm new here and could do with some info please.

I have a 1987 vf500 F2. The bike will not do more than 55-60mph. Could this be due to the fact that it has been restricted for "learner legal?" If this is likely then how would I de-restrict it?

If it is not restricted then any ideas as to why it is so down on power? Apart from this the bike is in good condition and only done 30,000 miles.

Thanks for any info.

Bob51

 

Check Compression?

How are the Plugs?

 

Thanks slowbird. The plugs are fine put new set in a few miles ago, and the compression is good. Apart from the fact that it will only do 60mph it runs really well.
Any more suggestions gratefully recieved.

Thanks.

 

from what I've read there might be a restrictor plate on the carbs/ intake, but that would reduce power not set speed limit.
Japan bikes have some kind of speed restriction that is hooked up to the speedo.

 

Plugged exhaust?

Yeah! Good idea.
Count the teeth front and back.

 

stuck slides in the carbs? open up the air box and look into the top of the carbs. the slides are the first thing in line, try to move them in and out with a lint free rag with a screw driver. if one or more wont open all the way then that would be a big problem.

Only reason I say it could be that is if tehy open part way fine the low speed wouldn't be hurt as your reporting but it would hurt open throttle a lot...

 

I'd suspect that one or two cylinders were not firing and look for a carb or electrical problem.

 

Learning the hard way about a V4 and loving it so far

:crazy: Sounds like the carbs are sticking, taken them apart on my bike and i can see how they would case loads of problems as they get very hot in a v4. Seem prone to sticking or gunking up.

 

If the carbs were the problem I think you would feel bad surging or other major misbehavior of the bike. I'd say there is something else going on. The restrictor thing is a possibility, though I've only ever heard of that for larger (1000cc+) bikes.

Let us know what you find!