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Discussion Starter · #1 ·
Hey guys, just picked up my own Pocket bike engine. Used from a friend, I will need a bike eventually, but as of now I have this engine which has some things done to it and others not. But a failed project. Not mine obviously. It was sort of payment for helping him out. So the short of it is, it has a 44mm cylinder with bigger fins with a little bit of transfer port work, a piston that was smooth and polished as far as I can tell, stock case, looks like a PBU triple reed, A Full Circle crank, Stock carburetor and intake. I pretty much have all the hardware and all the stuff. And a race lightened flywheel. Brand new clutch.
I honestly think I should put a stack fly wheel on with the full circle crank and stock clutch.Then I am thinking of putting on a tin reed for now and working on the carburetor and reed stopper. But I think I might really work a lot on those transfer ports. They look rough and need a lot of cleaning up. I thought I would shoot for a high compression as well and a rocket key. I honestly don’t wanna spend a ton of money, it has brand new gasket kit and a Chinese spark plug. So I might get a nicer plug eventually, the crank seals are toast and possibly bearings,so I know I’m already looking at $20-$30 plus lots of my time.Honestly just want to get it running as cheap as possible and hopefully find a cheap pocket bike to throw it in. I’ve done tons of rebuilds and a few bolt on mods. So I think I might attempt some blueprint and polishing.
 

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Nice!! That will be a great start. I like your ideas, i think it will turn out nice.
 

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Hell yes, lets build this little monster. Going to need a lot of cyld porting, and .690" wide upper port and get rid of them fingers there for a stock engine, Then make the main transfer ports bigger and re-shape them for flow around the ffc. Do you have a 2 pc cyld you can use and alum head. I have a new alum round finned head here I put a compression relief valve, never got to try it, it would be perfect for this engine. You seen a chainsaw valve before, they use them on big engines to make it easier to pull start, it closes on the compression and it says that way running.
 

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Looks like somebody started to do the port work and didn't realize how much time and patience it takes then gave up on it.
The port work looks okay you're going to want to take your Dremel and start grinding away at the high spots slowly and gently after you get it the best you can with the Dremel then go at it with the needle files once I get it to about the point ( pictured ) then I start hot glueing small rectangle pieces of sandpaper to the needle file and go at it with 60 grit then 220 then 400 then I go at it with bits of red scrubby then green then finish it off with a high grit polish and call it good. Take your time and do it right and you will be rewarded with a nice boost in power...
 

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Discussion Starter · #5 ·
I’ll definitely work on making it better. I work long hours 6 days a week BUT I will move forward and thanks for the help guys!!!
I’ll like the superglue the sandpaper to files idea. I always wrapped the paper around any tool that would fit. Haha
It’s a one piece cylinder. I am not opposed to a 2 pc. I would like to keep the cost down (wouldn’t all of us) but the open top cylinder isn’t that bad in terms of cost.
 

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I put a 4 flute 1/2" end mill in my drill press chuck and either my X, Y vise hold and move it as needed. I have a very small like Bridgeport type table also. The end mill makes it so easy. the other is my piston port and reed port engine stand for testing
 

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Francis40, you ever get a chance to work on that engine? My engines are waiting for break in, the weather has been crazy here. And busy on the nice days. Hopefully I can get a short video of one of them running and riding.
 

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Discussion Starter · #8 ·
Soon, work has been busy. I am thinking of chopping a cylinder and doing a 2 piece. Maybe some mild massaging of the case.
 

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Need high carbon cutters to make it easy, spent $35 eBay for a set of 10 different shaped cutters. Why better than the China crap wood cutters, they don't do much to metal, even alum.
 

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Discussion Starter · #10 ·
All right guys, sorry for being an absentee. But with talking with a few people, I decided to go with a two piece cylinder head, so I picked one up and just got it in.
Among other things I will do to the engine, I’m going to start on the cylinder head. Again my time is limited so it’ll be working here and there on it and hopefully have it done for summer.
 

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Discussion Starter · #11 ·
It’s definitely a good starting point. Like I said I will do other things to complement the cylinder head
 

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Looking good now just start smoothing it out I use the little grinding bits for smoothing and some WD-40 helps keep the little grinding Stone from clogging with aluminum but you have to use light pressure then I use needle files from harbor freight they come in shapes and sizes lastly I finish up with some sandpaper.
 

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I like the WD40 trick I will have to try that. H/F tools is the Place, lol. jewelers file is what I use too, for little tight places. I keep 100 thru 800 grit wet dry sand paper, there is a grit for everything there. 600 & 800 are for polishing. I got 2 clone Dremel's before $18 each with case and a bunch of junk to wear out, lol,
 

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Nice. Yeah, small files are great. I have small sand paper rolls on my dremel. Saves a little time.
 
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