viper not reving up!! any help appreciated

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catt_tracker

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I have a 2004 mnt. viper that ran perfect last year. This summer I had yamaha dealer replace throttle/oil cable. I put psi pies on and it would only rev up to 7000 rpm. I fought with them for a couple weeks and put everything back to stock. It still only goes up to 7000 then drops to 6500. I checked the power valve servo and it is working I am stumped. I've changed the secondary around a bunch doesn't change anything. Thanks, Ben
 
Check your primary if your having rpm probs, don't mess with the secondary to correct rpm's. You changed your jetting back to stock when you took the pipes off I presume? When's the last time you cleaned your power valves? You can could have a sticking valve(s) even though the servo's working.
 
catt_tracker said:
I have a 2004 mnt. viper that ran perfect last year. This summer I had yamaha dealer replace throttle/oil cable.
Click to expand...

Did you have the throttle/oil cable replaced with an OEM cable or did you have an aftermarket cable put on?

I'm rebuilding an engine right now because of an aftermarket cable. That's why I ask. My machine had good compression, good leakdown tests and my cable was adjusted correctly, well at least using the Yamaha manual which works prefectly for the OEM cables and in theory should work for any cable. Another thing I noticed was I kept smelling coolant. I had a power bog, and wasn't developing rpm on the topend.

The end result was that the cable wasn't correct and it wasn't getting enough oil from the pump. The pistons were scored on the intake and exhaust sides below the rings. The plugs lost their cinnamon color and progressed to dark (but not wet), and eventually I was seeing the "ash" color on the plugs. Comonly known as "death ash." Looking back at it, the 2smoke also changed color from the blue to a darker more ash color. I believe the reason why I would smell coolant was that the coolant was boiling out the overflow which I found to be wet after I pulled the engine.

If you don't figure out some other reason. I would take off your pipe, and exhaust manifold and look at your pistons thru the exhaust ports. If they're scored up (vertical lines) you know what's happening.

I would checkout other possibilities first then try this. My engine problem had me baffeled for a while and didn't make sense to me after checking reed valves, powe valves, compression checks, and leakdown tests. It also started consistantly well and ran well. I hope your problem is something else. Either way best of luck.
 
Air breather could be clogged..fuel filter the possibilities are endless it's a step by step process on these babies
 
Track or drive cog issue can cause rpm loss ! Track tension ! Seized bearing! My idea is to check idle rpm 1700 to 1800 ! Power vales should be adjusted from a low 1k idle or something dumb saw it in the repair guide :rulez: :homework: :homework: :homework:
 
This is worth a quick look. Check to see that the T fitting that connects your carb airlines (look like hoses) to the airbox is plugged into the airbox. Sounds small but this has messed up some people.

Pull the cover off your PV solenoid and look for it to move right after startup, then idle it down to 600 or a little less and look for it to move then also. Put the idle back to 1600 - 1800.

I would verify that throttle and oil cables are properly set. You may have them incorrectly adjusted and your carbs may not be opening up all the way. To verify this:

Pull the airbox off
Verify you have 1mm of free play in the throttle cable. When this is correct you will notice that when you push on the throttle lever the gap between the throttle lever and the plastic case is 1 mm before the throttle cable starts to pull the carbs. Now while moving the throttle lever with one hand use your other hand to verify the slides in the carbs are moving up and out of the way giving you full throttle.

Put the airbox back on.

Once that is done, verify the oil cable adjustment is correct. You can do this by pulling up on the oil cable just blow the 'Y" or "junction." You'll see the upper oil cable housing separate from the lower cable housing and you'll see the actual cable exposed. Measure from the lower end of the upper cable housing to the upper end of the lower cable housing while pulling on the upper oil cable housing. It should be 20.5 + - 1mm. Then let it back down allowing it to seat back in the recess of the lower cable housing. This is with an OEM cable. If you measure less then the above this means more oil is provided by the oil pump. If the gap you measure is greater then above, it means less oil is being prvided by the oil pump. This is very important that this is correct because there's little room for error on "too much gap" side.

If this oil cable adjustment is out of specs on the "too much gap" side. What I said in my past post may have happened and I would consider pulling the pipes and checking the pistons thu the exhaust ports.

If you do the above, I wouldn't make any adjustments so you can tell the shop you haven't worked on it. Just verify things are correct. Then work from there.
 
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If none of these pan out then it maybe the stator is getting weak. Turn down/off the warmers unplugged headlight basically turn of or unplug unnecessary electric and take it for a rip. If your able to hit 75-8000 and hold it there the stator may not be putting out enough juice to keep up with the higher RPM.
 
Says to set the cable with a block of wood to set the thumb throttle play
 
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