Power loss in 2005 rhino 660 - Yamaha Rhino Forums - Yamaha UTV Forum
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post #1 of 6 (permalink) Old 10-08-2010, 05:01 PM Thread Starter
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Exclamation Power loss in 2005 rhino 660

I have a rhino 660 with a few mods. I added a BRPcdi about a year ago, and just added AC racing dual exhaust, CFM cold air intake box, and K&N airfilter. Also I replaced the oem belt with epi severe duty belt. With these mods I thought that I would have more low end torque and better overall performance. But instead it seems to have less power than a stock rhino. I put a 175 main jet made by dynojet in the carb. Do I need a larger jet or could there be another problem. Thanks
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post #2 of 6 (permalink) Old 11-20-2010, 11:01 PM
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I think a 170 should be plenty. An A/F gauge will really help tunin.
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post #3 of 6 (permalink) Old 11-24-2010, 11:17 PM
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I had the same thing happen to me. I have a 2006 rhino. It is basically stock. I don't have a CDI box, it only increases the rev limiter so you can get more top end speed but not anymore torque. I did place a Fuel gauge, volt meter, water temp and oil pressure. I like knowing the water temp especially. Back to the loss of power. I did build a custom snorkle on mine w/ 2" ID PVC with a secondary filter at the top. I didn't do anything to the stock air box, just placed a plummer rubber coupler to tie in the PVC to air box. I went down the road and it didn't seem to anything to the acceleration or top end speed. I went to the mountains a month later and it had horrible torque and was running hot. When the rhino is under alittle load or going up hills is when I noticed the torque was horrible. Of course I didn't change the jetting. I read alot of forums and they explained about running the engine after changing the jetting and reading the spark plug and/or waiting for a hard or soft stumble on acceleration, etc. I did everything from changing the slow jet, main jet and adding washers to needle jet. Basically I wanted low end torque. This is what I did.

I changed the slow jet to a 45, added 1 washer to the needle jet. When the rhino is under heavy load that is when you can tell if you have the right jet. I tied my rhino up to a tree and had it on my driveway. Each time I went up on the jet I tried to spin the tires on both 2 wheel drive and 4 wheel drive. I think I went up to a 175 main jet on mine. All 4 wheels spun on my driveway while tied up to a tree. If you go too small or too big on the jet it will lose power and of course won't spin the wheels. I didn't punch the gas, I just slowly gave it gas until the wheels started to spin. This should help.

To increase torgue you can add one washer between the sheave so the belt rides lower in the sheave to increase torque. Your top end speed will decrease about 4 mph.
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post #4 of 6 (permalink) Old 11-24-2010, 11:21 PM
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You may need a larger jet because the more air you take in the air/fuel ratio will change. Especially with a K&N filter you may need to go with a lager jet. A fuel/air ratio gauge will definetly help like JSilva mentioned but if you don't want ot spend money on a gauge then tie you rhino up to a tree.
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post #5 of 6 (permalink) Old 12-05-2010, 08:12 PM
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Join Date: Jul 2008
Location: Norco,CA
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I have about the same mods and I run a 210 dynajet
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post #6 of 6 (permalink) Old 03-23-2011, 06:04 PM
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Join Date: Aug 2009
Location: hughesville,pa
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I have been running into similar problems.. The last time i was out riding the one side of the mnt had over a foot of snow! and When you going wide open for several 100 yards it acts like it runs out of power and shuts off...No temp light on nothing.. So today i brought a box of jets home from work(love working in the power-sports industry) and changed the main jet from 145 to a 155.. test rode in the snow.. seems to be better but still had a rather annoying pop out of the exhaust and it only shut down once.. So i went to a 150 main with a washer under the needle and test road again.. made several passes and not one pop and seemed to run really well.. Would not shut off.. So i left it alone.. I am headed to snow shoe this weekend and hopefully i will be able to tell is this is the fix.. I have two rhinos and there a year apart and acted the same way in the snow under a load! ... I only have changed the jetting in the two seater..
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