Lost 1,000 rpm on a climb

[BackCountryBob]

04 REV-X-151, 9,000' trail gets 8,000 rpm but from 10-11,000' the rpm falls off to 7,000 on a steep untracked climb. Clutches cool, D^Js kit with no pin weight, stock ramps, white 160-320 spring, clicker on #5, secondary black.

It seems to back shift good but not enough. This was the first ride of the year and the engine ran flat down the trail for about 5 miles then was OK. Most of last years fuel was syphoned out. I have not checked compression yet but was heavy to the pull start.

The sled is tucked away in a 4 place so I haven't been able to get to it yet.
A broken primary spring comes first to my mind---any help would be appreciated,

Bob

Problem might be a worn sliding half bushing, compession OK, rollers OK, DPM OK

 

[Boondock]

Would for sure check compression ASAP.

Buddy has a doo 1000 that acted pretty similar and it was only making 85lbs Needless to say he ended up with a new top end.

 

[blksumit]

This should be interesting! Usually happens in 1 1/2 to 3 or 4 feet of powder. Usually on long pulls. I've seen it with new Doo's, RK Tek and SHR motors, I don't think it's a motor issue! I've also seen it happen with Team sec., stock Doo sec. and Doo sec. with DJ's kit. Kinda makes you think it's not in the secondary either. Also only notice it at 10,000ft. plus, but that is also the elevation we ride at in Colo. Be interesting to hear what others have to say. JMO

Dave

 

[sledhead05]

How does the engine sound when you cant pull RPM? How are the carb boots dooin?

 

[blksumit]

How does the engine sound when you cant pull RPM? How are the carb boots dooin?

I can only speak for my motor. It runs hard on the flats and hard on any hill that the snow is setup (or only 1ft. of powder). What it sounds like is the motor(primary)is loaded way to heavy. How ever, I see BackCountryBob was running hollow pins. My thoughts were the primary is overshifting. It seems more pronounced with the Team, which makes some sense because it's a roller clutch and way more sensitive than a button clutch. My carb boots seem to be in good shape, sprayed with carb cleaner and no rpm increase. Visually they check out also.

Dave

 

[BackCountryBob]

My engine will hold the 7,000 but it is definately loaded-heavy exhaust sound. I will check the DPM hoses Saturday--almost too rich of a sound. Also I ran out of gas at 40 miles---I usually get 60 miles with mixed riding.

I had to poach an XP to get on top---300 miles with the original belt.

 

[BackCountryBob]

It appears that the slliding half bushing is going south--any one know if it can be replaced or if I have to buy a new one?