Another method is to use a fine scotchbrite wheel on a drill motor.  It won't remove metal very easily and can really make quick work of the more stubborn gaskets.

Anyone know what this is? I'm about to put the head cover back on, and all of a sudden I see this piece laying on the floor.

justin_o_guy2 wrote on 10/15/22 at 13:00:13:

ding ding ding... I think we have a winner.

should be 46mm long give or take a 1mm.

You can mail me my Gold star.
I sent mine to Dave.

I used SAE30: 1.5l Briggs and Stratton stuff, and 0.5l SAE30 cheap O'Reilly's stuff. Just read the back of the O'Reilly's oil and it has friction modifiers  :'( Only ran 3 miles, but damage may already be done to clutch.

Two valves were dead on (0.005in exhaust, 0.004in intake), and two were only one-thousandth off. I adjusted the throttle cable; maybe that'll help with the "feel"/response.

Still hoping when the smoke clears, I'll notice a performance increase. I can't see how I wouldn't. Maybe it just needs more tuning.

verslagen1 wrote on 10/19/22 at 07:49:02:


I drained the 30W and put in T4 15w40. Seems to run fine. It doesn't "feel" much quicker or torqueier than before, but maybe after break-in it will?

verslagen1, thanks for the perspective; I think you're right. The "butt dyno," I imagine, might only detect a significant change (e.g., 20% increase in power), but will likely not register the 9.4% increase from the cam and piston (per DBM's data.

Below is a pic of a quickly made graph showing DBM's modifications in order, and the decrease in time (between a given gear and RPM) associated with each mod. I've edited out the head port and made some other changes to his data to closer replicate my bike's mods.

The long and short of it, is that going from stock to a pod filter, more open exhaust, and PWK38 gets you about a 50.2% increase in acceleration time (as measured by the sum of the 2nd, 3rd, 5th gear pulls between the various RPMs). Going from that to a cam and 94mm hi comp piston only gets you a 9.4% further increase in acceleration time.

In other words, cam and hi comp piston get you about a fifth of the performance increase that pod filter, exhaust, and bigger carb do. It's like an asymptotic exponential function (i.e. "diminishing returns").

Using DBM's dyno numbers, and doing more math, I estimate that I gained 0.6hp and 0.6tq (assuming that acceleration time and hp/tq are closely correlated). It makes sense I wouldn't register half a HP.