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I ran a compression test last night to eliminate low compression from my rough running condition diagnosis and came up with something at the opposite end of the curve. 190psi compression verified on two different gauges. This is an 00’ with an EG225 kit. I asked him to do the mo better porting favoring low end and that I’d like to stay on 91. Seems at this pressure I may be in need of higher octane fuel? Also, this was on a dead cold engine probably 42DegF so the number would likely be higher if it were at operating temp. Manual says usable range is 95-151psi

What numbers have others gotten for compression on rebuilds? The motor is relatively fresh just over 6hrs on the rebuild.

Did you do it with the throttle fully open?

The OEM manual pressure range is for an OEM head, not a modified head. 190 is fine. Is it harder to kick over than before you got it modified?

Yes throttle was wide open. EG did work on the head I guess I didn't know it was so different than stock.

I got the bike as a basket case and did the 225 as part of my original rebuild. Having never ridden a stock KDX I guess I don't have a good frame of reference for kicking effort. I'll say that I split the sole on a pair of sneakers firing it up to load on the truck. I make a point to at least have my work boots on now when starting.

I talked to EG today and he said 190 isn't uncommon for that build and would be reduced when the power valves are active. I'm thinking less that fuel octane is the issue and more that my carb is just worn out.

Still curious what others see with RB head mod and stock rebuilds. Just to know how far if any the 190 is from average.

169 psi on my 220 with RB head. Before RB the piston was fresh (10 hours) and had 142 psi.

I’m done trying to mess with 20 year old PWK’s. If it has a worn slide or oblong shaped needle jet, it’s a waste of time trying to tune.

People really like to underestimate just how worn their carbs are.

Ditto.....Ditto....!

decluk13 wrote: 06:07 pm Feb 25 2020 Yes throttle was wide open. EG did work on the head I guess I didn't know it was so different than stock.

I got the bike as a basket case and did the 225 as part of my original rebuild. Having never ridden a stock KDX I guess I don't have a good frame of reference for kicking effort. I'll say that I split the sole on a pair of sneakers firing it up to load on the truck. I make a point to at least have my work boots on now when starting.

I talked to EG today and he said 190 isn't uncommon for that build and would be reduced when the power valves are active. I'm thinking less that fuel octane is the issue and more that my carb is just worn out.

Yes, sneaker starts and 190 is not a good combination.