Has anyone jetted their vinson yet? I'm doing some airbox mods and filter. it seems to be bogging in the mid range right now and popping when I get off the gas. does 92 oct. make a difference when jetting? right now it seems to run better on 87 but still is missing power. I pulled the plug and it looked black but not wet. maybe a hotter plug? if I take the lid off it really gets bad no power at all.

 

The reason it runs bad with the lid off is because it's getting to much air.Have you added a pipe or anything?Instead of re-jetting you may be able to play with the air-fuel screw to get the right set up..I added a Uni Filter and drilled a 3/4" hole in the snorkel on my Vinson and adjusted the air-fuel and it runs like a champ!

 

I'm adding a k&n Filter and a pipe with the air box mods.

 

Have you already purchased your pipe?If not I got a HMF with 1 ride on it I'll sell ya..

 

I've rejetted both of my Vinsons, and have added the Dial-A-Jet to one of them. I'll try to reply to the symptoms you describe -

bogging in mid-range = too rich - try moving the e-clip on your carb needle to up one slot

popping when you let off the gas = too lean - turn the air/fuel mixture screw 1/4 -1/2 out OR it coulde be an exhaust leak. These two things cause backfire conditions during decceleration If you mess with the air/fuel mixture screw, you may have to reset the idle speed once you're done. Changing the idle speed doesn't affect the air/fuel mixture.

plug looked black = too rich - the electrode should be tan to dark tan

92 octane gas won't make it run better. High octane gas burns faster.

My best advice - try solving one problem at a time.

In general, there are three main circuits in a carb. Which circuit feeds the carb fuel depends upon the throttle opening. 0-1/3 open primarily uses the idle circuit. This can be tuned with the air/fuel mixture screw. 1/3-2/3 throttle opening primarily uses the needle circuit. You control the needle air/fuel mixture by the position of the needle. 2/3 - wide open is the main jet. Changing the main jet has the most effect with this throttle opening.

Keep in mind that as you continuously open the throttle, two carb circuits overlap which means the carb gets gas from both circuits until the throttle is opened wide enough that one circuit stops feeding fuel and the other takes over. For example as you open the throttle past 1/3 open, the idle circuit feeds less fuel and the needle circuit starts to take over.

Hope this helps. Good luck
Mark

 

Thanks for the info I'm waiting for the parts to come in and I'll try like you said. where abouts is the air/fuel mixture screw at? I haven't taken a good look at the carb yet.

Woody what don't you like about the slip on? how loud is it compared to stock?

I'm looking at the supertrapp slip on

 

The idle mixture screw is underneath the carb in the center. You'll need to remove the black fuel tank plastic to access it.

Mark

 

OK thanks

 

Elk,I loved the HMF,but I'm selling the bike is the reason I wanna get rid of the HMF..It's alot louder than stock.If you are looking at a SuperTrapp you have made a wise choice..I've had 3 different Trapp's in tha past and liked each 1..

 

whats your airbox mods? ive been looking on forums for peoples air box mod suggestions but nobody has had anything to say,