I was wandering if I could get some help with this. I've got aV-FORCE and when I get on the throttle and let out of it there is some bad back fire with a blue flame coming out the back. I installed a hmf slip-on exhaust and jetted to their specs . I was wandering if I might need to adjust the air mixture screw and if so how many turns. if thats not it does anyone have any other suggestions. thanks.

 

Turn the Air screws out 2 to 3 turns out see what that does.

 

Also might want to check for any exhaust leaks. When quickly snapping off the throttle, an exhaust leak will introduce oxygen into the exhaust, igniting any unburned fuel...backfire.

 

thanks vnasty i'll go try that . kliff the only exhast leak i can find is where the pipes go in the scilencer how can i fix that i have the clamps plenty tight enough thanks

 

vnasty that did work for the backfire but now it wants to sputer when i open it up or if i ride awheelie and go in &out of the throtle it seems to me like it's getting to much gas & trying to flood out or something.could i be jetted alittle to high i am not sure what size the jets are but it is what hmf called for .

 

Here is the right way to adjust the air mixture screws.

Step 1 - Put the bike in nuetral Turn them both air mixture screws out 1.5 turns. This is your starting point.

Step 2 - After the bike warms up turn in the front carb air mixture screw until it seats (don't tighten the screw or you will damage it) you will notice the bike begining to idle roughly.... once seated turn the srew out 1/8 to 1/4 turn at a time until the bike runs smooth and idles nice.

Step 3 - Basicly repeat step 2 for the Back carb. Turn in the Back carb air mixture screw until it seats you will notice the bike begining to idle roughly.... once seated turn the srew out 1/8 to 1/4 turn at a time until the bike runs smooth and idles nice.

Step 4 - once both air mixture screws are adjusted go back to the front carb and slightly micro adjust the air mixture screw turn it slightly to the left or right to see if it runs better. Repeat for the back carb also.

The air mixture screws are what regulates your lower throttle, once done put tap the throttle to about 1500-2000 rpm. THe bike should not backfire or hesitate. This is the best way to adjust the air mixture screws without using a mercury gauge.

My setting on my stock Vfornce are approximately 1.75 turns out on the front carb and 1.25 turns out on rear. I bet yours will be 2-3 turns out. Good luck let me know how you made out.






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Just for clarification, backfires come out of the intake - what you are experiencing is what is called an afterfire. Naturally aspirated engines will backfire if running too lean, afterfire if running to rich, usually.

 

thanks badboy iwill try to get my mixture srews adjusted tommorrow. i have to go to church tonight. we have a ride planned for logan wv this weekend and i want my v to be running good for it. my dealer said to bring it by tommorrow and he would see if the carbs were syncroed right. thanks to all for the help.