I'd like to jet my carb. It's a Keihn CVK (it's all stock for an 05 Vinson 500 Quadmatic).

I'd read that the stock main jet is too small & should be a #38. That's my real motivation for a change.

Underlying all that, my Vinson has no top end power so I'm trying everything.

This is what I've done so far.
*Adjusted valve clearances
*Cleaned muffler & spark arrestor
*Rebuilt carb
*Adjusted float height & mixture
*Cleaned both driven & drive faces, belt, and sheeve
-im ordering a new belt, though mine doesn't show signs of slipping, but I noticed manually advancing it from the driven face creates slack & slippage, but III wondered if it's because I was advancing the driven face instead of drive face.


I'm out of ideas for the power loss. On flat ground I'm lucky to break 22mph but I'm hearing other guys with the same machine - all stock - get 50+mph and can pull wheelies.

What else can I troubleshoot? ....I'm no technician, just learning on the fly. Thanks.

 

My 2002 Vinson manual shows 128 for the main jet and 35 for the pilot jet. Where does your 38 number come from? If you are in the US, your pilot screw is probably capped. You have to remove cap to adjust screw or clean out the passage.

Do you have manual? PDFs are not expensive.

 

I'm sorry... I miss-quoted what I meant. I'd read that one of the Jets (maybe the fuel jet) comes stock as a #35 (my carb says 35 on one of the Jets) and should be bumped to a #38 for better performance.

I've got a copy of the service manual now too.

Just wondered if there's a jet kit I should look for, or if I can just purchase/replace a single jet.

The carb. itself is in rough shape I think... Diaphragm just seems worn, as well as the one on the accelerator pump, but an OEM carb is $600!!

Anyone have a recommendation for an aftermarket replacement?

 

The OEM KeiHin is going to be much better than any aftermarket you are likely to find, esp those from China. You can buy a selection of various sizes of aftermarket KeiHin jets for less than the cost of one jet from the dealer. That way you can try different sizes, plus and minus. The only reason to give up on the OEM carb is if you can't get the pilot screw out, if you broke off the support towers for the float pivot, or other corrosion/damge makes it unrepairable.

I get my jet kits and carb parts off eBay, but there are other sources.