Hello I have an 2007 Rancher 420. I have noticed that it backfires two of three times in about one hour of riding(depending on the speed I am going) Is this normal it happens when I am riding it higher speeds around 20 - 30 MPH. I don't know if this matters or not I have ran 93 octane in it every tank of gas I put it in it except the last I used 89. It happened with both types of gas.

Thanks Mike

 

I may also add that it does it on Deceleration when letting off at higher speeds/RPMs.

 

Mine does the same thing .

 

Mine did it four or five times, when it was very new. Has not done it since. Have you reached the 20 hour valve adjustment yet???

Deceleration backfire is a symptom of a lean condition. Honda no doubt has this engine leaned out to meet environmental requirements, just like all the manufacturers have to do.

 

Twin420s Have you adjusted your valves lately? I did and not sure if that has something to do with it.

 

Yes the 20 hr valve adjustment has been done. They were done a few hrs early my brother and I did them. He has been doing valve adjustments for many years so he knew what he is doing.

How do you richen the engine up? Is there anything special I need to know since its fuel injected?

Thanks Mike

 

I haven't adjusted the valves yet, I haven't put enough time on it yet.

 

Have you done any modifications to the air box? Air filter? or muffler?

 

Most likely the cause is either ethenol in the gas, which leans the mixtures too much...in which case, try a tank of pure gasoline (no ethenol)..and if that doesnt cure the back fire, go a 1/4 turn richer on the mixture screw. Valve adjustment and octane wont effect the backfire at all.

 

Uh, this machine is FI. Now I'm not sure, but I don't think FI has a "mixture screw".

Give it time. No doubt we will all be remapping these, but there just isn't that much available yet. Dynojet is all I know of right now....