DIY Shift Kit Project--'The Shifty Beast'

The piston ported pocket bike engines for midibikes rated at 47-52cc are pretty good too. I really like the one on my BMX because it has been a reliable runner and revs the higher than my Cag will with the same gearing. I guess its a Mitsubishi TL/TLE clone, some are sold by Predator for their post hole drill as in my case, some are sold as well for ice augers marketed by Viper, up to 71cc, the cylinder kit from which I'd like to try, since their transmission mounting pattern is different from the auger tranny as well as pocket bike gearboxes. The case looks the same so I'm assuming it uses a larger diameter piston.
 
If you got that engine off of ebay with a guy that was debating using it or a Tanaka 47r you got a sweet deal. I was negotiating with him when his price was at $260.

I've used the Harbor Freight 52cc engines they sold on there water pumps. I'm looking for a more reliable engine. Thanks
 
AV,
Thats the one!
He didnt take my offer for $220 when he 1st listed it but after a bunch of no-sales, He listed it for $220 & I snatched it up.
Yeah, stick with Japanese if you want reliability.
I've gone thru 4 cag engines and am done with them.
-Low-
 
Cag engines need long head bolts or studs with nuts inside the case to make sure the head bolts don't come loose and trash the top end. Other than that they are a good engine for performance, although for outright reliability right out of the box the non-reeded upright TL clones for x1, x2, x3, x6, augers, etc. are hard to beat. The pumper carb on them and the lack of case induction makes them easy to start, tune and keep running right. The Dellorto rep carburator needs more fine tuning and doesn't offer the response that a pumper does.
 
Today I spent some time working on both '2High' & 'The Shifty Beast'.
On '2High' I removed the std china girl muffler & added a pocket bike expansion chamber with some flex pipe and rubber donuts at all hanger mounting points. I still need to wrap it with header tape but not today.
On 'The Shify Beast' I removed the straight pipe and replaced it with the original drop & curved pipe. I get more leg clearance with the dropped pipe & am planning on revising the chain management for more pedaling. I cut a groove in 2 skateboard wheels for the chain to ride in. I'm going to use these on a 'scissor like' spring loaded chain tensioner.
-Low-
 

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I had 15' of 2" black header wrap that I bought awhile ago & never opened.
I decided to give The Shifty Beast a pipe makeover & re-wrap it in black.
Here's how it looks today.
-Lowracer-
 

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I swapped engines last night to see how it perform with the new Tanaka 40cc I bought for a different project.
How did it ride?
The 47r all broken in & teamed up with a tuned pipe & with a shift-kit & is an amazing engine both reliable & powerful.
The new 40cc isnt broken in yet and is definitely more sluggish than two previous 40's I've owned. I'll probably re-install the 47r cause once smitten by its powerband makes it hard to step back down.
-Low-
 
Lowracer,

Does the stock clutch for the Tanaka PF-4000 fit the 5:1 pocket bike tranny or did you have to put on a new/different clutch? My clutch is engaged on my Tanaka PF-4000 at idle speed. The sprocket continuously turns. You have any idea what the problem might be? Thanks
 
AV,
I had to add 1 small washer between the engine and 5:1 tranny on the PF4000, which I didnt need to do on the 47r or the TC47. Make sure your 4 tranny bolts don't go too deep into the engine or they'll hit the flywheel.
-Low-
 
Lowracer,

Thanks that was it. 2 might have been better because I can not crank down on the 4 bolts or it gets stiff again. Right now the transmission is also making a squeeky/creeky noise it never made with the GX35 and also it is throwing the chain. I do not understand why just changing engines would make it throw the engine chain. It might be that when I put on the throttle it causes the bell drum to shift outward.

If you have any ideas or opinions I'm all ears because right now I'm thinking about throwing back on the Honda GX35 on the shifter and getting a GEBE kit for the Tanaka 40. Thanks
 
I'd check the alignment of the drive sprocket in relation to the driven sprocket (vice grip a piece of angle iron to both sprockets to see if tere are perfectly lined up). Make sure your bearings are tight. None of my pocket bike trannys shift outward when the throttle is applied?
Might as well either install another washer or get the 4 correct spacers from a hardware store.
I'm planning on mounting two carved out skateboard wheels (chain guide) on a spring loaded bit of metal to route the chain under tension to ork better for when I pedal.
Cheers,
-Low-
 
AV,
Let me know how the Zenoah performs for you once you get it nice and broken in.
At this point, I'm sticking with either Tanaka or Zenoah (Japanese engines).
-Low-
 
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