DragBikeMike wrote on 01/21/26 at 18:44:13:


I know that a 0.004" inch feeler gauge would fit between the cylinder and piston.....I don't remember trying a 0.005".

The Flat Top piston is supposed to have a minimum of 0.0025", and I figured I would try this piston and see what it would do.  I don't like the way it appears to be rockin' in the bore - the wear pattern on the bottom of the skirt is pretty significant for only 50 miles.

I am going over to a friends house this morning so he can measure the cylinder with a bore gauge and the piston with a micrometer to see what we are working with.  Line2Line coatings would prefer having actual measurement and not just a feeler gauge test.

badwolf wrote on 01/21/26 at 17:10:52:



Here is your comparison photo.  The pistons have a lot in common...the photo is misleading - the Wiseco piston on the left side actually comes up higher in the bore at TDC.  The Wiseco piston is a bit shorter in height than the stock piston.

This is what the machined piece looks like - it is made from a 10mm bolt.

The piece on the right is the original one turned upside down from how it would be installed.

The one on the left is partially machined.

The once in the center is completed.

Here is what it looks like fully seated and epoxied in place.

An 8mm stud will be inserted from underneath, and the large top on the machined insert prevent the threads from being pulled in the aluminum head.

Dave, Thanks for the photo, the holes on the Wisco are fewer, but larger. Next time Ihave mine apart I will open those holes up some.

badwolf

Envelopes get crushed  , torn or simply disappear in shipping. I’ve had several empty envelopes delivered , never received an empty box. I box everything I ship and maybe he wanted his customer to receive his product. So your running oil thru that tiny rubber hose , external to cylinder head ?

I did not like the fact that the oil being bled off served no purpose - I was pumping oil and not doing anything with it.

I wanted to get that oil up into the head to help lubricate the cam, rockers and valves and also provide some additional cooling for the head.

I wanted to do it in a manner that looked nice and not too industrial.

Since the oil flow is restricted by the #120 jet, the diameter of the hole is approximately 0.0465 inches.  The small 90 degree fitting that I would like to use has a ID approximately the same as a #44 drill with a decimal of 0.086" - which is 45% larger than the jet.  The 1/8" rubber hose will be more than 5 times the diameter of the jet....so it appears the jet will still be the controlling factor in how much oil flows through the bypass circuit.  If it turns out the #120 jet, 90 fitting and rubber hose is not providing sufficient bypass and my oil pressure is too high - I can drill out the jet until it is working properly.

This is about what the clutch cover will look like with the small 90 fitting and 1/8" hose....although the house is vacuum tubing in the photo and is a little larger diameter than the braided hose will be.

The small 90 degree fitting for the 1/8" tubing was just a bit too small for me to use the 5mm jet.  Instead I used a 4mm x 0.7 hex head screw and I cut the head down the head diameter a bit - and I drilled a hole with a #56 drill to be equivalent to the #120 jet.

My lathe is pretty big, and doing small work on it requires some creativity.  My 3 jaw chuck has jaws that were too wide to hold the 90 degree fitting - so I had to use a drill chuck in my tailstock.  The 3 jaw chuck won't go small enough to hole the #30 drill I needed to use to tap the fitting for a 4mm screw - so I had to install a drill chuck into the 3 jaw chuck!