At random times, usually at startup, but while riding too, my RPM's jump up about 500rpm's, and the exhaust gets quieter at the same time. The valves also sound different when this happens. Sometimes, if I rev it up, or when I decel from high speed, it will kick back down and exhaust gets louder again. I gotta keep messin' with the idle speed screw. Does this sound like a cam chain randomly jumping, and if so, how is that possible? I just put in the Verslavy about 800 miles ago. I'm also starting to hear a rapping noise up in the cylinder/head area.(Left side) Not to mention the whining gear-like noise, only when clutch is engaged, also on the left side of motor. I got a bad feeling that something is seriously out of whack from the large-rock-in-the-road incedent. Or, does this sound like another carb problem? I really don't want to rip it all apart again. I'm thinkin' of just riding it to death and call it a summer. Maybe I'll win the lottery and just buy a new one??

                   

Yes, got the plastic out.

20,800 miles on motor.
Verslavy installed at 20,000 miles.

700 miles since running over the rock.  (Remember I punched a hole in the front right side of crankcase. Fixed with JB Weld)

Humor me and think if this could be the problem. 1994 Mazda 626 in good condition would whine and kick down auto trans, but lose nearly all power. Mass Airflow sensor just dirty. 1999 Dodge 1500 with 318 cu in. Nearly same problem...stopped up converter. 2- stroke engines do similar when air intake is impeded. Just wondering if you're getting enough air in/through/out? ihth jar your thought process. That's all I got.  

before we get to that, check for an intake leak.
to simulate the leak take off the vac line.
if you have the stock petcock, turn it to prime.

What are we using to track down leaks now?  used to be wd40

check around the intake boot too.

If so, that would be about the first Savage one ever .... we are blessed with reliable electrics on the Savage anyway (not like a Yamaha !!).  

Still, Yamaha folks arrange an alternate ground strap for both engine and frame to the main ECU unit to PREVENT a poor ground from causing their electronics to crap out early as their black box isn't available any more on most of their 10-15 year old bikes.


While you were in there last, did you check your cam journal bearing slop?

Sloppy journal clearance can make a knock sound on the left side, and worn out rockers can make a persistent loud tapping sound (I got that coming on on my hot rodded bike so I know what that sounds like).

Both can be fixed, but are expensive in time & effort (and replacement parts).

Your timing sensor is under your alternator cover -- if the screws were loose you could get some movement/variation.  Ditto if your rotor was loose on the bolt/taper/keyway.    
Neither are very likely and the same cover removal checks both.

I think that may be where I'm headed. This morning I went out to fire it up after changing the oil. Did the same thing. Jumped to high idle by itself. No vacuum or intake leaks that I could see or hear. I did however, tightly cover the exhaust with some old rags--Idle dropped down and stayed there until I removed the rags and revved it up some. Then it went back up. After warmup it quit doing that, but still was running high. I then revved it up and it came down. I didn't ride out at all, but yesterday, while on the road, it would be doing it intermittantly. Up down up down.
And still, when idling high, exhaust is quieter than when idling slow. Noticeably. Strange. Almost sounds OE, and it's a HD torpedo with baffle out. (Virtually a straight pipe)

OF--I wasn't personally in there. I had the head gasket rechecked and fixed at the dealer. (There was a broken head bolt, dating back to the "blown head because of no oil" incedent)

I was thinking that too, but not sure how that would so drastically change the sound of the exhaust.