Pan head With Flathead Flywheels

[diablo]

Way back when--The trick was to put a set of Flathead flywheels in a Panhead with cylinder base spacers and go really fast--or maybe not. Then comes up the subject of the oil scraper. It makes sense that the scraper should be extended closer to the flywheel, however, I have a friend that did nothing to the scraper and the bike did not appear to make excessive smoke. Does anyone have any actual knowledge of bikes that had nothing done to the oil scraper verses bikes that did?

[Chris Haynes]

The scraper is to remove excess oil from the flywheels which create drag and rob the engine of power.

[diablo]

So you think the real issue is power loss and not excess oil thrown into the cylinders causing excess smoke? I picked up an old Pan engine that was set up that way--no modification on the scraper--and would like to run it that way. Just curious as what experience other people have had with no change to the scraper. Thanks

[Chris Haynes]

A scraper extension can be made from a piece of steel flat stock. Mill it to the thickness needed. Drill two countersunk holes into it and the scraper body and install it. Don't forget to use Locktite red. When you go back to original size wheels simply remove it.

[pan620]

Great ideal Chris, I just spent some time on the Bridgeport milling out some welded in scrapers that were very crudely made, welded in.

[Rubone]

Working in a custom shop in the early '70s we always bolted in scrapers, however we only used aluminum so there were no issues if a flywheel ever touched them. (cranks don't stay very round under load). I always set my own strokers up at 1/16 clearance on the scraper but made sure it had a knife edge to shear as much as possible.And modify Breather timing too. Oil drag becomes an issue at RPM, the reason H-D did sumps on all the post '72 XRs. I like RPMs so every trick to get there. Regularly hit 7000 RPM on my Pan/Shovel combos.

[billpedalino]

My experiences with built-up scrapers mirror Robbie's. I installed a set of ULH flywheels in a panhead motor in the early 1970's. The young customer had the flywheels and cylinder plates (probably left over from a 1940's motor build) and not enough money for a set of S&S flywheels. We built up the scrapers using flat aluminum stock with milled knife edges and installed them using countersunk screws. We used locktite on the screws and also staked them in place. It worked fine.

I used the scraper build-up because a couple of years earlier, my boss at the Harley dealership where I worked decided to increase the stroke in his Sportster from 4-5/8" to 5". The 5" S&S flywheels were of a smaller diameter than the 4-5/8" wheels to allow for a slightly longer piston skirt. He decided not to address the scrapers and paid the price. The bike smoked like mad. We disassembled the cases, welded up the scrapers, had them machined down and the motor ran fine afterward. Lesson learned!