Running like crap!!

Tore down my carb completely cleaned and reassembled. New plug, new fuel filter, new fuel pump but still running like crap!


I can't get a hold of this issue. I tried my stock CDI and still have the same result. Runs, starts and idles smooth but as soon as I take it down the road and hit about 38-40mph it starts spiting and sputtering and then backfires.

Is there a possibility of hitting the rev limiter because of a dirty clutch?
If it was starved for fuel I can see it spitting and sputtering but the backfiring issue?? 
Perhaps the fuel flow is fine at low revs but once it gets high it's starving. Is the fuel filter full?
Maybe worth it to take the carb back out and check everything over again,check the slide

Nope definitely not hitting the limiter. Positive it's not a carb issue...could be a jetting issue but I'm leaning towards not firing correctly or the timing...It's getting too much fuel not going lean

Wonder if the new fuel pump is delivering too much!? Is it Oem?

The reason I changed the fuel pump is because of this issue so I've ruled that out as well...but yes it's OEM

how do you know it's too rich?  sounds like it's lean to me.  could be a float level issue.  these things are super picky with float levels.

pretty rare to have a too rich mixture at almost wide open throttle... these engines will burn almost anything once they're wound up.

Pull your plug, check the color of the porcelain, if its white its lean, if its black its rich, if its brown its right on

FLOGROWN wrote:

Pull your plug, check the color of the porcelain, if its white its lean, if its black its rich, if its brown its right on

 he's right.  however, since yours starts, idles and runs generally okay, you need to check the plug exactly when your problem is occuring.

run it up to whatever speed it's having a problem at, then turn the key off and coast to a stop.  then check your plug.  
it'll be a rough stop, and the plug will be wet, but the color will tell you where you're at.

I know it was rich because I could smell the fuel. Pretty sure that the problem was due to the timing being off and not firing at the right point at high RPMs. Yesterday she shit the bed! I think I either broke a timing chain or the tensioner. Need to also check compression. Things just don't sound right when she died and when I turn it over. Either way...solved this problem...hahaha

Pokahpolice wrote:

I know it was rich because I could smell the fuel. Pretty sure that the problem was due to the timing being off and not firing at the right point at high RPMs. Yesterday she shit the bed! I think I either broke a timing chain or the tensioner. Need to also check compression. Things just don't sound right when she died and when I turn it over. Either way...solved this problem...hahaha

 Awww man that sucks.  Hope it's not grenaded and you can be back on the trails fast!

That makes me think... does the Rhino have an auto decompressor?  My raptor, which I thought had a similar motor... did.  When doing a regular compression check I would only get like 100psi when the book said it should be around 180psi.  I could never figure out how to test it properly, without opening it up and somehow disabling the auto decompressor.

Pokahpolice wrote:

I know it was rich because I could smell the fuel. Pretty sure that the problem was due to the timing being off and not firing at the right point at high RPMs. Yesterday she shit the bed! I think I either broke a timing chain or the tensioner. Need to also check compression. Things just don't sound right when she died and when I turn it over. Either way...solved this problem...hahaha

Did you ever check the key on the flywheel ?? A few of us left James' place , and ole boy 's 660 was doin the same shit you're describing. Him and James fooled with the carb till it finnally quit runnin all together...and it was doin that backfiring crap too. Anyway , it ended up being the key was sheared on the flywheel. I'd check there first

I spoke to James and he said the same thing a few weeks ago. I didn't feel like diving into the motor so I just ran it. If I kept the RPMs down it ran alright just had to be easy on the pedal. Now something broke...I can hear it in the motor. I'm going to start on that side of the motor after I check compression. I first need to get the ambition to tear into it, I usually like working on it but pulling the gas tank and flywheel just isn't going to be a good time. From what I've read these flywheels can be a nightmare.