I've got this single cylinder engine that's had an overhead valve conversion done to it. I believe the engine was part of a university supermileage competition vehicle. I'd like to get it running again for a motorized vintage bicycle, but what is the base engine? Briggs and scrap iron? It'd be nice to know what it started out as so I can try to find a few parts I need.
No numbers on the block whatsoever. The OHV conversion is definately a custom piece. It's been milled out of a piece of billet. Rockers are also custom milled. Compression feels like it's through the roof, almost can't turn it past TDC by hand.
The gasket for a flathead Briggs isn't going to be much help on one that has been converted to OHV. The Plymouth and Dodge bros. engines i converted to OHV I made my own gaskets from .041 half hard Copper and them annealed the finished piece
If you're able to remove the head gasket intact,..see if a Briggs parts shop can either match it up, or direct you to what you need. 4TTRUK
Thats pretty cool. It reminds me of a replica board track engine on youtube called the dixie flyer. Dont know how to add a link but the guy used a honda single cylinder. It was a nice build. Is that your plan or more of a bicycle with a motor like the wizzer?
Come on guys. Have you ever noticed how a flathead combustion chamber and gasket is open from the cylinder to outside the valves? Now if you convert a flatmotor to OHV what goes where the flathead valves were? The pushrods of course. Now if you use the same gasket where will the compression go? That's right. Down the pushrod holes into the lifter chamber. No compression in the combustion chamber. just lots of air and gas being pumped into the crankcase. You don't want that, do you? Go back to my previous post, get some copper and go for it. Or take the head to a Briggs dealer and see if they have a gasket that will work on an OHV. Check with lawn mower shops and like that. Seriously guys. If you don't understand why you can't use a stock Briggs head gasket on an engine that has been converted to OHV, please put down the wrench. Back slowly away from the engine. Go into the house. Sit down. turn on the TV.
Briggs donates the base engines for those competitions. This project http://www.calvin.edu/academic/engineering/2010-11-team5/PPFS_Final.pdf says "Briggs & Stratton 3.5 horsepower flathead engine (Model 091202 Type 1016E1A1001)" Also mentions "Dana™ Fire-Ring Head Gasket" They usually run lots of compression, and high running temps for maximum efficiency. I've seen one engine with all the cooling fins machined off for maximum heat retention. Often, they downsize the engine so they can run full throttle with minimal acceleration.
RS, that's some pretty interesting stuff. Given the fuel the engine was built to run on and the modifications I'd say the OP has a nifty display piece. Probably impractical for a motorized bike.
Gear reduction? Probably trying to save some size and weight in the overall gearing by using the half speed shaft of the engine.
Appears to be a JR Dragster type Briggs Clone. Put it on your motorized beer can smasher or make a lamp out of it. They typically have a lot of problems.
In the twentys Brigs made an engine with single overhead exhaust valve and poppet intake. Early ones has fins cast at an angle to cylinder later ones had typical horsizontal fins.
Im into vintage mini bikes and karts, I also like to build odd engines I even have a small foundry for my oddfukitry of building things... If you ever ponder the thought of setting that thing free let me know, I would love to have that in my collection... A switch port
Did a little more looking around online, definately is a briggs 3.5 HP as the base engine. I pulled the head off last night to see what I had and it's got a sleeve in it. With rough measurements it's right around 75cc. Yes, the clutch is run off of the cam but there is also a bicycle freewheel on the flywheel side. Not sure what to run at this time. Head gasket looks like it's regular old gasket material. It's definately run like this as there is carbon on the valves and the gasket is starting to get burnt around the piston area. had a brain fart yesterday, should've been obvious that the stock head gasket won't work. Will have to look into making my own copper one. I want to use the engine as a build for something like the Dixie Flyer menioned earlier. Even if it isn't ideal it sould look wicked. I'll have to measure the compression but it's super high - could be cool running on alky! What's the detail with the switch port??
Those are both Tecumseh side poppers basically they were used with edgers they are not popular in the vintage mini bike field (exhaust blows on leg) so I decided to build a couple showing the potential of beeing cool. The lower one is with a cast header I decided to build and cast, the switch port is a side popper with HS50 Tecumseh internals so now the old exhaust port is the intake port, I have a build up on them but verry OT for here. Carry On....
More than likely for the reverse rotation. They use the extended camshaft for the reverse in roto-tiller applications. Len
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