86' VFR750F spluters at 5500 revs

Hey Guys,

I have an 86' VFR750F, she starts up fine and revs fine but when I ride it from pull off to 5500 revs, she goes well, from 5500 to 7000 she splutters like there's no tomorrow, 7000 up she goes well again. I've stripped of the carbs and given them a good clean, I also made sure the jets, float levels and sorts are right, nothing seems to help, when I run it without the air filter, she's not perfect but is 100 times better. I've tried adjusting the pilot screws but no luck. She's also running very rich. Please Help:frown:?

 

5500 to 6500 seems to be a natural flat spot for this bike stock but it shouldn't sputter.
You sure thge main jets are there and screwed in properly?
Are the proper sized main jets installed?

 

Does it or do you know if it has a jet kit installed?

 

You could have stock numbered jets, but some wanker prat migtht have drilled the holes larger.

Carefully clear out all the holes on the sides of the main jet carrier tubes using a thin wire.

You say it's rich at idle too, but if you can't kill any cylinder by adjusting the idle mixture screw clockwise on that cylinder, then maybe fuel level is too high cuz petrol is leaking past a float needle or the float's adjusted improperly .

That is, floats could be set correrctly, but fuel can still flow past and around a defective needle, raising fuel level too high in one or more cylinders, so check your plugs for one or more darker than the others.

Plugs need to look right: grey to Cadbury light milk chocolate tanish brown or creole/mulatto, if you prefer.

 

Thanx for the replies, the jets are stock, the right size. the bike used to run well, then like a wanker I let her stand for quite a while. I've made sure all jets and air holes are clear. I adjusted the float level and she ran much betterFloats are supposed to be 7mm but at 7 she was no good, at 12mm however (and I know it's a big jump), she runs much better.

 

I figured out the problem, which I found strange. My R/R is causing the splutter between 5500 and 7000 revs. How, I'm not sure but I have tried another R/R and the problem disappears. If someone can explain that to me, that would be cool. Question is, Can I use a gold wing R/R on my VFR, the plugs are different but the wiring (Colors) are the same.

 

try to sync the carbs you have to sync them if you take them apart and sounds like you did.

 

I sync'd the carbs and replaced the r/r. Charging system is perfect, bike still splutters. I tried turning the pilot screws all the way in, just to see what might happen, the bike runs so much better now, the question is, where is it getting air from if the pilot screws are all the way closed.