I have a 2004 Yamaha rhino that i bought used for my family. The previous owner had put a HMF exhaust on and had the carborator rejetted by a Yamaha dealer. After purchasing i found that the machine will stall after idling from 10 to 15 minutes. The engine sounds great, no leaks, everything appears to work as specified, however, the engine stalls only when idling, not when moving. I changed the oil, fuel filter, air filter, tried to adjust the idle screw to see if that makes a difference, I change the spark plug and even tried a spark plug that will burn more fuel as the plug originally was mildly black and cleaned all the terminals for the coil and contacts. I plan to remove the HMF exhaust and rejet the carborator back to the OEM specifications. I was wondering if anyone has encounter a similiar problem with the stalling. I'm also thinking that the coil or CDI box maybe in the process of failing, that may cause this problem, as well. Any suggestions or ideas that can solve this problem from someone else would be very helpful before I spend another $400 or so in parts I may not need. I appreciate anyone ideas and input. I'm also looking to sell the HMF exhaust, if anyone is interested as it is only 6 months old. thx in advace for your consideration and potential help. Vince

stalls after 10-15 minutes of just sitting?

first question, why would you leave it running that long..

and it sounds like its loading up(too much unburnt fuel), not electrical.. the black plug and stalling at idle would give me this impression.

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TONYMRECO@YAHOO.COM 480 612 2715

Thank you for replying to my post. I would not normally leave it running for more that 5 to 10 minutes but the point is that it should idle until it runs out of gas. Any time before this point is not really relevant and thus we are facing a problem either fuel, air or electrical. I tried changing the spark plug to one that runs at one and two levels hotter to burn off the fuel. With the one level hotter running spark plug the Rhino now now runs until it stalls at 10 minutes. Prior to that it stalled at 4 minutes. It is my assumption that the previous owner changed the CDI, put on a HMF high performance exhaust and rejected the carborator. It is also my assumption that they did not do the job right. According to the previous owner a Yamaha dealer did the work but when i called they were not interested in discussing it. Thus, I'm going to go back to a stock CDI, exhaust and jets. I'm curious do you agree with my assumptions? Also, this machine tops out at about 50 MPH, when i go back to stock what is the maximum speed I should expect.

Again, I appreciate any help and look forward to more input to validate what I think is the solution.

mine does this to after sitting all summer the battery was week so i was trying to let it idle for a while to get the bat charged back up but it would stall after a few minutes it is also jetted for a pipe do you have to choke the hell out of it to get it to start afterwards

thanks for your reply. The battery on mine is new. I don't have to choke it at all to get it started up again. It just stalls like someone shut off the ignition switch or like a gust of wind blowing out a candle. Once started again it will run for another like 8 to 10 minutes.

i would only change one thing at time.. starting with the jetting.. go back to a standard plug, find out what main jet you have and go down one or two.. run it, then check the plug.

if you search rhinoforums.net , you will find a section on plug color.. follow that section on how to check it..

it doesnt sound like anything electrical at all, otherwise it would generally be sparatic. start with the jetting..

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TONYMRECO@YAHOO.COM 480 612 2715

I agree with your recommendation. I plan to rejet the carborator to the OEM standards and go back to the OEM provided exhaust system. The Rhino was upgraded to a Procomp black blox CDI to allow for the machine to rev up to 1000 RPM more for top speed. Do you think if I go back to the stock jets and exhaust I could keep the procomp CDI or will I need to go back to the stock CDI?

Thx again for your quick response.

if you change the exhaust, you will also need to change the jets for that too.. also an air filter too..

you can run a cdi solo.. Im not sure if you need to change jets from stock it just for a cdi though.

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TONYMRECO@YAHOO.COM 480 612 2715

well as you indicated, I think I will change the exhaust back to the OEM and the Jets back to stock specification. If that does not change the stalling when idliing issue, i will change the CDI from a Procomp back to the OEM CDI. At that point, we would have covered all the bases, I think. You mention that the airfilter would need to be changed in your last response. Can you expand on that? The airfilter that I currently have is stock. Should that have been upgraded with the exhaust, Jets and CDI? Would that cause the stalling from lack of intake? thx

no, i ment if you had an aftermarket intake, generally you would run a bigger jet size.. so you would have had to compensate for that if you had one..

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TONYMRECO@YAHOO.COM 480 612 2715