Yamaha Rhino 660 problems??

jjarvis0007 · 2008-02-19 21:36:26

A guy at our duck club purchased a Rhino in 2006. We drove it one weekend and it was doing about 53. Is that top end for a stock Rhino? The next weekend it would get up to around 35 and just start popping and backfiring. He brought it in today and it wouldnt even start. I took the plugs out and ran a compression test on it. It was about 110 on the gauge. It has spark and getting fuel. I cleaned the plug and put it back in. It started right up. When I gave it gas it would backfire and die. I put a brand new NGK in it. Fired right up. Took it for a spin. I got it to go 45 now before it started to backfire. It keeps fouling plugs. My only guess would be the valves need to be adjusted. Has anyone had this same problem. Is there anything else that I am missing. When I first took the center console out I found a rats nest in there with chewed up wires. 2 wires that went to the carb heater. Fixed them. Another wire that went to another sensor next to the valve cover to the right. Fixed it. Plugs just keep fouling. I am hoping that we just need to adjust the valves. Are there any special tools I will need to do it. I mainly work on 2 stroke outboards so I dont think I will have a special tool for Yamaha if needed. Thank you for your time!

baker01 · 2008-02-20 19:53:08

Well, the stock Rhino should see around 42 mph for a top end speed. the speed limiter then kicks in and will remove spark to the plug. two things come to mind. The fuel filter is plugged (crap in the tank from poor QA) and or the gas tank vent line being plugged or pinched. Both happened to me and caused backfire and shutdown problems. The tank vent only shows up after running for awhile. The other possible problem could be the manual choke is stuck.

Fasttrax · 2008-02-20 20:57:22

The stock fuel pump isn't to top notch either. If it is happening at exactly at I believe 25 or 35 I would check the speed sensor. Air cleaner good? dirty air filter will choke it too. :?:

jjarvis0007 · 2008-02-20 21:21:17

Air filter was dirty. Took it out and ran it without it for a sec and it only does 40 mph and then starts sputtering and then backfires and dies. I put a NGK DPR6EA-9 in there. Its a little bit hotter of a plug but it hasnt fouled out yet. Adjusted the valves according to the manual. Ran it again until 40 mph. We had it up to 52-53 on the road to the duck blind every morning. He hasnt had anything done to it. Until now. We have some high volume vacuum fuel pumps in the shop for outboards. Gonna try one of them and see if it works better. Something that kinda caught my attention was when I was test running it if I pulled out the choke it would run at higher rpms. Any suggestions? Thanks for all your help. This is a new project im trying to tackle. Where is the speed sensor and how do you go about checking it?

MR. KRYPTONITE · 2008-02-20 23:23:28

What I am trying to figure out is that if it is "stock" there is no way that it can hit 53 mph so I am wondering if there is something else in the mix that is messing with ya such as the cdi...

66cummins · 2008-02-21 11:30:25

Stock mine will only see about 39-40 mph.

Badley · 2008-02-21 17:11:42

I believe a backfire is a lean condition? I would not think it would result in a fouled plug. I have been through just about everything suggested here.

As baker01 and Fasttrax suggested - check fuel delivery, I ended up with a hi-vol Mikuni Fuel pump (stock pump is weak and unreliable). Another forum members have found plastic shavings in the tank - clogging fuel filter and possibly pick up line.

I will likely agree with Mr. Kryptonite - I wonder if your CDI is faulty. If you can go over 50mph you have an aftermarket CDI (stock limiter is set 42mph max - I believe). I have been told Dynotek is the only one to own (I have one - no problems).

FYI - opposite of lean condition, my choke was sticky also.I went from lean to rich condition and realized (after some frustration) choke was partially closed. Lubed it and have not had a problem.

baker01 · 2008-02-22 09:29:44

Maybe the speedo was set to kilometers per hour on that first trip.

jjarvis0007 · 2008-02-25 14:25:50

I was wondering on where to get the best deal on a carb kit and a new cdi for the rhino?

rhinoryder · 2008-04-10 12:57:17

I was wondering if anybody else has had a problem with there fuel filter, i have been threw two in the last two months. Now i keep a hollow pen in my glove box just in case, it fits perfect.

#1 2008-02-19 21:36:26

Re: Yamaha Rhino 660 problems??

#2 2008-02-20 19:53:08

Re: Yamaha Rhino 660 problems??

#3 2008-02-20 20:57:22

Re: Yamaha Rhino 660 problems??

#4 2008-02-20 21:21:17

Re: Yamaha Rhino 660 problems??

#5 2008-02-20 23:23:28

Re: Yamaha Rhino 660 problems??

#6 2008-02-21 11:30:25

Re: Yamaha Rhino 660 problems??

#7 2008-02-21 17:11:42

Re: Yamaha Rhino 660 problems??

#8 2008-02-22 09:29:44

Re: Yamaha Rhino 660 problems??

#9 2008-02-25 14:25:50

Re: Yamaha Rhino 660 problems??

#10 2008-04-10 12:57:17

Re: Yamaha Rhino 660 problems??

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