heh guys

I just went out this weekend trail riding ie (speeding) and when I come down out of the throttle or pull the clutch it will back fire after beening run hard. this doesn't happen very often. But man it feels like a bomb!!! I readed the other posts on this subject. I tend to think it is too rich and it loads up. I haven't done a plug reading yet!! Any ideas??? thanks

2001 bombardier ds-650
2002 rancher es 4x4
1970 jeepster
1997 ford f-150

 

What are your mods? Has it ever been altered, or is it stock. If you still have stock pipe and it hasn't been rejetted, then the jetting shouldn't be rich. The idle mixture screw may be out of wack though - if it is it will cause a lot of popping and a little backfiring after letting off the throttle.
Turn the idle mixture screw inward until the motor begins to bog down. Then turn it outward, counting every half turn, until the motor begins to bog again. Set the screw half way between the two points of bogging. This will be the correct setting. Then see if it pops, it shouldn't.

Valve clearance can decrease over time - if your valves have never been adjusted and there is a lot of hours on the motor, intake clearance may be gone, and an intake valve may not be fully seated, causing the backfire. Others on this forum have had this issue. If this is the case, valves would need adjusted before any damage results. Not trying to scare or anything, but they should be checked if they haven't been, and adjsuted if needed.

 

Heh thanks

I just bought it and really dont know what the total time is but it was my friends and by what he said its between 10-20 hours. I'm going to check the idle mix like you said. How long and what parts are needed to check the valve clearance?? I have the service manuel and it mentions adjusting plates is there a set you can buy or are they bought seperatly.
I think what I mit do is try the idle mix first and then take a plug reading and see if that fixs the problem if not then I'll go to the valves!! what do ya think??

no mods at all as off yet. it was set up and sold above 6000 feet in laramie,wy but my friend said he doesnt think that the dealer change anything like the jets.
northjeepster

 

<< it was set up and sold above 6000 feet in laramie,wy >>



Really? I wasn't aware there was a dealer in Laramie. Thats cool if there is though. I just moved to UT and there is about a 3000 ft difference between here and Wyoming. I had to move up from a 170 to a 185. The air is thinner there than what peope think. Just ask anyone who comes to ply a ball game. Anyways if it was rejetted then there is a very good chance you are indeed very lean. Try choking your filter by applying duct tap to it and see if your back firing stops. If it gets worse then your rich.

 

The alt. is like 7900 feet really. the dealer there in laramie is ok but not top of the line you know. when they jeted my honda 2002 rancher es they jeted 2 sizes smaller than the book said for alt and i had to change it.

 

It's 7900 ft in Milwauke? Or in Laramie?

 

maybe in a airplane here in milwaukee.lol no really in laramie. I work as a traveling temp radiology tech and i travel all over the state and I take my atvs with me. I just got back from a trip to yellow stone. I talked my wife into going to st antony's sand dunes cool huh!

 

That is cool. I cant beleive your in WY that much. Let me know when your going to be in the WY/UT area!!

 

sure I'll be head out that way in sept. dont know where yet but ill email ya when i find out