Stock or tampered carbs?

Last year I bought and went through a 90' VFR750F. When disassembling the carbs I noticed a shim on one jet. Would (factory) stock carburetors have one jet shim on a carb?

 

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I be guessin you mean a shim on the needle, not jet ??

Could be factory or added by PO.

Needle shims are usually used to smooth out any lean flat spots in 4500-6000 rpm range caused by aftermarket exhausts.

 

The needles have one washer under them from the factory.

 

Could my removal of that one shim affected the performance of the bike if I then synchronized the carbs afterward? I believe the owner before me cut up the airbox and ran the thing with the muffler off. I've returned everything to stock. When I rebuilt the carbs I pulled out the only shim I found and reassembled the carbs that way. Of course they were also synched.

 

Toecutter says they come stock with one shim on the needle. I would trust him on that.
The question is - do you know the difference between a jet and a needle in the slide?
If the shims are all missing it means that it could be running lean.
Put the shims back in and you will get more power out of it.

Make sure to measure the thickness of that remaining shim and make them all the same.
It would interest us if you told us how thick that shim is. That is if you know how to use a vernier caliper. How about a photo?

At least the slides are easy to get to.

BTW I would not use that word "tampered".

IT may have been modified. Everything I have in my life has been modified.
It does not mean those things are sub standard as long as the person doing the work is experienced and knowledgeable. Right????

 

Yes sir, I'm sure you're quite "modified"... Anyway, I don't claim to be any kind of motor guru. I just want to get the most out of my bike. If something was "modified" (i.e. F#$@'d with) I wish to return it to its previous, factory state. That is all. I love my bike, and love riding it. If I can make it perform better with a shim under something, then so be it.
I occasionally turn to you all for your willingness to help and share information... priceless information, and I thank you. I don't have anyone in my personal life who shares my love of riding and tinkering with bikes so its been a solo endeavor except for this online community. Thanks everyone... I'll be pulling carbs apart tonight.

 

You say you have no one to share your love of riding. What about the 20,000 members of this forum?
I understand you want a motor that has not been #$!%$with. Perfectly understandable.

What happened is that all motorcycle carbs used to have needles with 5 notches and a circlip so the carbs could be adjusted for different cities with different altitudes.

Then as the EPA tightened up emissions regulations and they did not want the carbs to be altered by the consumer.
So the needles that had notches were modified. However that did not mean that all bikes for all elevations would run best with only one needle and no adjustment grooves. It was less expensive for the factory to add a washer than to make a different tapered needle for each elevation.
And what if the owner of the motorcycle moved to another state? Shouldn't they be able to make adjustments?

I live near the ocean and the air is very dense. And the humidity must be taken into account also.
For aircraft engine testing they call this... "Standard Day Conditions" sea level and 29.92 inches mercury.
Engines at sea level need to be richer than engines in Colorado. See what I mean?

Good luck on your carb cleaning/rebuilding.
BTW Carb synching should be done after mounting them back on the engine.
The reason is that when you remove the carbs from the engine it slightly affects the syncronization.

You would need that special tool and the special bevel gear drive tool with socket mounted on it.

 

Yes sir, just purchased a set of carb synch gauges yesterday. I've wanted them for a while now. My problem may be in a synch issue as well... And yes, bench synching is nothing more than a start. Found that out last time I had them off. A quick synching at "Honda Bob's" and she purred like a kitten.

Thanks for all the info.

Oh yah, I'm not forgetting you 20,000 plus VFR guys... I was more referring to the people in my area.