Help!!! Major engine bog!!!

[Minndave13]

I have a 2010 Dragon 800. I rebuilt the engine and everything was running good. I have 200 to 300 since rebuilding. I was out the other day and about two miles from home the sled developed a major engine bog. I limped it back home and have been working on it tonight. I happen to have another parts sled so I thought it might be the exhaust sensor, so I replaced the exhaust pipe (slp pipe, it already had a sensor in it and I didnt want to mess up the sensor by taking it out and they were both SLP pipes). I also drained some gas into a clear plastic bottle looking for water, I did not find any water. The sled still runs the same. I even tried replacing the computer and the coils. I also pulled one of the power valves and made sure it was not sticking. The sled will run above idle but nothing at idle and dies. I am almost thinking its bad gas but I get my gas (91 octane) from only one source and thats all the sled has only been run on. I should also note that I had a RK Tek head on the engine and I put a power commander 5 on the sled (running with what the commander came with). I put the original head back on, and took off the power commander, hoping it would have started running right again. Nope. I should also note that I tried swapping the Voltage Regulator with the other one I have (I do not know the condition of that voltage regulator but would assume it was good).

 

[Sheer]

Man it just seems like your thorwing parts at it... do some testing... i cant say off hand for the 900 but most manuals have runability diagnostic trees in them... typically bog is fuel pump, reeds or choked out somehow...very few times have i ever seen bad gas causing a prob... just a few ideas.. but the best way is to find a prob is to do step by step diag... in the end itll save u lots of time and cash...

 

[Sheer]

Im guessing since u switched heads already u checked the plugs but maby all it is is a bad plug... kiss rule... try new plugs maby too

 

[Minndave13]

Your right, I am throwing parts at it! Usually I hate doing that and if it were someone else's, I would do the testing. But in my case I just happen to have another sled with every part I need already off and sitting in a box. I did not think about the reeds,( I was originally thinking clogged fuel filter, but I just put a brand new one on when I rebuilt the motor). I should note that snowmobile came with V Force reeds and I put those back in. I have the originals sitting in a box so i think I'll start by checking the reeds first. I think I remember somewhere that the V Force reeds were a problem on these 800's.

I also want to say that yesterday I went out and purchased a 2014 Pro RMK. I told the son that there is a ride this next weekend and if I can get the Dragon running good he could ride it. Otherwise it could sit for a few weeks for what I care. So ya, I'm throwing parts at it and hoping I find the problem.