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Discussion Starter · #1 ·
Hi, my SX 500 v-max that I bought to trail ride this season is acting up. Since my first ride on it, it seemed a little doggy, like slow throttle response. I thought it might have been bad gas, and kept riding it noticing it sometimes accelerates awesome, and sometimes plain old just dogs, not going fast 5500 rpm even at full throttle.. like almost like its fouled out. I thought it might be primary clutch, because it engages too soon.. at 3,000 rpm. But then I looked, and my plugs are looking like they are oil fouled, and they are BR9ES, so i switched to 8's today and they are the same.. what the hell is wrong? reed valves sticking? too much oil consumption? main jets too rich? I am stumped. It will run good half the time and its like hit and miss, when i go to hit it, sometiems its there sometimes its not, sometimes its slow responce.
please help!

thanks
 

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Check to make sure the enricheners (choke needles) aren't getting stuck in the carbs. happens to mine sometimes and it boggs like mad, makes the plugs foul.
 

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Make sure your secondary clutch spring is adjusted properly. If its set too loose it will upshift to soon.(High Gear) High gear low speed equals bog!!!!
 

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How many miles on the sled?

Check the surface of the primary weights and see if there are any waves/groves worn in the surface. The face of the weight can wear in a high mile sled and it prevents full shift.

Your engagement is also too low, I'd probably replace the primary spring.

Checking the twist on the secondary spring (like already stated is a good idea too).

You shouldn't run different plugs, stick with the BR9ES.

The oil pumps are real rich on these sleds. Set the idle speed, then the throttle cable free play, then adjust the oil pump. There are notches on the pump that you align to adjust the pump output, set it on the lean side of the notch.
 

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Almost sounds like maybe your CDI box is starting to go bad. That would explain why sometimes it runs great and other times it stumbles.
However, the fact that the clutch engages at 3,000 rpm really caught my attention. That just seems really low to me. Id replace the primary spring and see if that helps.
To me it sounds like an ignition issue, but Id rule out clutching as the culprit before I look at the ignition system.
Check the simple, cheap stuff before you go to the expensive, complicated stuff.
 

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Discussion Starter · #6 ·
well, I know for a FACT its nothing with the engine. Sorry for bringing up this post again, but my internet has been down. Anyway, last friday I the sled for about a 40 mile ride, and the motor is prime, nothing wrong with ignition or intake. My oil consumption was a tad too rich, but i took care of that. The sled has 8K on it, and it hasgood compression. Its really been babied for its life. The Yamaha shop I bought it from is rebuilding the clutches free of charge for labor. I can do it, but they are going to fine tune it. The primary needs a spring and the Secondary is not engaging to the best of its capabilaties, and its Sticking open, wich gives it that lag. If that makes sense.. These are basically my own predictions / observations. If i put the sled on a Jack stand, it will never have bog. See the reason why it bogs is because I will accelerate and get track spin, and when the sled regains its traction, the secondary is still open, and the RPMs naturally will stay like a 5500 rpm or somthing like that depending on my actual speed and gradually gain more rpm ones it gets up to a faster speed.

does that sound correct? I get my sled back monday. So I'm guessing that they have the problems figured out.
 

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I wouldnt go by what it does on a jack stand because there is no load on the motor. It does sound like a clutching issue though.
 

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Discussion Starter · #8 ·
Yes i know but what im getting at, is it only does it under load. So it really seems like it would most likely be clutching.. catch my drift?
 
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