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Discussion Starter · #1 ·
So picked up a couple pocket bikes and one used engine. I installed my 'mild modified engine' on one frame and the other is a Lucky 7 frame!!! Excited, but it was missing alot of stuff. No big deal, I have read enough to know what to do, where to go for parts, and how to do it. I will sorta show the frame that has the mild modified engine in that thread, but the lucky 7 and motor rebuild will be here.
 

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Discussion Starter · #3 ·
Measured out to a 44mm with 12mm wrist pin. The case says 40-6 and the rod is unclear. But should be a 44mm with the 12mm wrist pin.
Considering I have parts available, and my thoughts are RAISE COMPRESSION, ROCKET KEY, MODIFIED REED STOPPER, AND SLIGHTLY TAPPERED & REJETTED CARB.
 

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Discussion Starter · #4 ·
With that HEAVY duty steel clutch with stock springs, I will NOT lighten the flywheel. Again, a budget USED engine rebuild. Gaskets, spark plug, and rocket key will.be the only outside cost.
I will clean and reuse the Chinese crank bearings from the last engine. They were in decent shape and roll WAY better than the current used ones. Clutch side is binding, even though they dont look old or rusty.
Dirty crank case, pieces of grass or something. The piston looks ok, might reuse. The carb is interesting....
 

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Discussion Starter · #6 ·
Already taper bored the carb and took 0.200" off the reed stopper.
Did all this in a few hours after pickup.
The nice thing about used engines is the flywheel and clutch come off easy.
I used a puller for the flywheel which was already drilled and tapped for removal. The clutch after I pulled the bolt, I hand threaded it back in five threads and tapped on that both with a hammer while I used a big flat head screwdriver to pry up on the clutch. FOUR hits and it popped off.
Next is reuse the crank seals, as they look new, and install those new Chinese crank bearings, I will also do a light blueprint on the case and bottom transfer ports. (Originally didn't mention that)
Should be enough of a power boost to make this worth it.
I have a cylinder that I had already worked the transfer port base, unfortunately the modded piston is a 10mm wrist pin. But I have a 12mm, just need to mod it. The.exhaust port was extremely low on this head, so I will taper the piston on the exhaust port side so BDC is even with the lower port.
More to come this week. Stay turned.....
 

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Discussion Starter · #8 ·
Pretty excited that I found one. And only a two-hour round-trip. There's another one triple the price has a snake pipe on it that's about a five-hour round-trip. Even has the Plastics. But I'll just go with this one. The frame is in good condition. And I know most of the rest can be filled in with A2 parts.
 

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Discussion Starter · #9 ·
Baked the engine cases at 350 degrees for about 25 minutes, the bearings were in the freezer for about an hour. Of course, 1 bearing dropped right in and the other took a beating. Just like my last engine. But they are both in. I did a little blue printing on the case, might as well well, it's apart and bearings are out.
The cylinder had a little bit of transfer Port base work to match the blue printed case. That's the only light things I'll do to the bottom end. Otherwise it's the other things I had listed previously. Hoping now at this point to be close to double the horsepower.
Tomorrow I should be able to get the seals in and case back together and probably the piston and cylinder on. The piston has been polished and lightened up a little bit. I will post that info tomorrow.
I know I'm moving fast on this engine but I have had a little bit extra time unlike the last engine where I had very little time. And that previous engine will be ridden this week for break in. Then this one.
 

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Discussion Starter · #11 ·
Well, slow down a bit, got busy helping some friends with some mini bikes. But I got a little bit further on the engine.
The case bolts for dirty so I clean them up with some dies. I taper bored the carburetor a little bit and doing the petcock mod right now.
Just need to permanently Mount the cylinder head and carburetor and then get the flywheel and clutch installed. Not sure I will get to it this weekend but definitely next week. I want to get it finished up and take both engines to a parking lot for break in. Of course this engine will need its heat cycles first.
 

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Discussion Starter · #12 ·
Well, I sped up a little bit and didn't take a whole lot of pictures but I have a few, the carburetor held me back waiting for the epoxy to dry Andre drill and make sure that the main jet was drilled out a little bit which I couldn't remember so I had to go back and make sure. A lot of redo's.
Almost done, and I will work on breaking this one in after the other one.
I also had to wait for some new O-rings for the bottom of the petcock on the carburetor. Amazon purchase. See how they work.
 

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Discussion Starter · #13 ·
So this one has higher compression than the other engine. The squish measured out at 0.040". So I definitely got to run at least a 95 octane. So higher compression, the Reed stopper mod, taper bored carb, a little bit of case Blueprinting and base transfer port modification. That's pretty much all on this engine, we'll see how she runs.
 

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Hey my friend, that plastic starter is not going to last long, lol, with .40 Squish, you can watch it twist when pull the rope. It should run pretty good now.
 

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I have a few new ones here I replaced, most engines now have the alum now. The newer starters are much better and have way more leverage than stock, lol.
 
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