Huffy Cranbrook with Tanaka in frame

R

recumbentbill

New Member
My Honda gxh stage 111 grubee trans died. Decided to see if I could mount my Tanaka 40cc . I'm a novice when it comes to fabricating and welding metal. I managed to make a motor mount that mounts on top of the sick bike parts motormount. The trans is a Tanaka paveracer gokart trans. I was concerened about the #25 chain that these karts use but figured if grown men can race these little karts then the chain might work on my bike. I still dont have the gearing worked out. The trans is 3 to 1. The jackshaft drive side sprocket is way to big [super granny] but it does work. I would like to quite the engine via a china girl type exhaust/muffler--any recommendations?
I rode the bike for about a hour tonight and it works.Just need to dial every thing in . Any comments and or recommendations are welcome
 

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Excellent!

I have always wanted to see a Tanaka engine mid-frame mounted with shift kit! I have a center-framed Tanaka 47R engine. Your install looks cleaner, but that HUGE #25 sprocket looks like a meat grinder.

What size are your sprockets? I can help calculate gear ratios for you. The lower the better, since pedal-assisting isn't too helpful.

I'd recommend 100:1 engine oil. You'd have that much less oil spray on you and your bike.
 
Thanks 5 7 for the gearing offer
The trans is 3.1:1 Trans sprocket is 18t the rear jackshaft drive side sprocket is 70t [5.72" diameter]. Chains and sprockets get me really corn fused. Mc master carr is my sprocket source.here is a link to the avail sprockets . Right side is 9t to a 48t [4stroke SBP shift kit]

McMaster-Carr
Click #25 5/8 bore sprocket
 
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Brother, you've got super-low gears!

If you had a 36t bicycle chainring sprocket and 11t/32t, first gear is 55.3:1 and eighth gear is 19:1!

I thought I had granny gear. My first is 46.32:1 and eighth gear is 15:1. This works EXTREMELY well for me in street driving.

You could use a MUCH smaller gear to replace that 72t. If you tell me what your bicycle cassette and rear cassette gears are, I can finalize your gearing.

What size are your tires? That figures into your gearing too.
 
5 7
3 to 1:1 ratio trans with a 18t driving a 70t on the jack shaft. Other end of jack shaft [right side ] is a 9t to the out board bottom bracket 48t chain ring .The inner bottombracket 24t chain ring drives the rear 22t sprocket on a sturmey archer internal geared 3 speed hub. 26 x 1.95 tires. The 3 speed sturmey to me is rocket science and i have no clue except 1st is over drive 2cd does not use internal gear and 3rd is ???. My original set up with the honda the stage 111 3 to 1 trans had a 10t that drove a 17t jackshaft sprocket on the left side.The right side is unchanged. I do have a 22t #25 jackshaft sprocket that is laying on the bench that i could try. I'll get this setup working eventually
 
Nice bike, that left side sprocket is HUGE. I'd say you need to calculate your gears to use something smaller, or make a shield of some sort. Maybe it's just me but that looks dangerous. :) either way good job with build
 
F_Rod81 said:
Nice bike, that left side sprocket is HUGE. I'd say you need to calculate your gears to use something smaller, or make a shield of some sort. Maybe it's just me but that looks dangerous. :) either way good job with build
Click to expand...

Yep it does look dangerous but keep in mind the bike is not finished. A chain guard /shield is in the plans as well as the gearing problem. Photos are a documentation of progress
 
If you replaced the 70t with that 24t AND changed the drive sprocket from 18t to 17t your gearing would be 27.52:1 in 1.33:1, 20.69:1 in second and 15.52:1 in overdrive.

Unsure if SA hub gears are 1.33:1 low, 1:1 and .75:1
 
Change the 70t to 40t and your gearing would be 32.57:1 in low, 24.49:1 in second and 18.37 in high gear.

Just changing that 70t gear to 40t will make your bike very responsive.
 
I applaud your effort, the question gets asked quite a bit about using certain utility engines in-frame but I haven't seen many tries at it. I particularly appreciate the overhead pic showing how wide the install is and how it will effect pedaling. To me that's critical and generally why I prefer they be mounted somewhere behind the seat post.

Quieting these 2 stroke utility engines has been a major concern for me. I cannot speak about how a stock China HT muffler would do but I assume it would knock down some of the ping. What it would do to performance I can't say. Depending on budget, there are expansion pipes available that can be fitted with a silencer. The question would remain if they fit into the geometry and just how much noise they reduce for their price. One thing I have found perhaps worth mentioning is that once you are successful in quieting the exhaust down a bit, it makes it apparent that half the noise come from the intake side.
 
Actually, you can replace your 70t with your spare 22t, but gearing would be too high. First would be 23.84:1, second be 17.92:1 and 13.44:1 for highway gear.

Lemme check more.

Okay, if you replace your 70t sprocket with a 28t sprocket, your gears would be 30.34:1 in first, 22.81:1 in second and 17.07:1 in overdrive. The large 5.72" blade would be replaced with a sprocket having 2.37" diameter.

BTW, I bolted the SBP happy Time expansion pipe directly onto my 2.8hp Tanaka 47R engine.
There was a GROSS mismatch at the exhaust port. One would imagine that there'd be a hp loss. Unbelieving, there was quite a power increase with the setup. The engine also quieted down much better than the OEM muffler.

I also bolted the same SBP pipe onto my 4.25hp GP460 engine. Another major port mismatch, but not as bad as with the Tanaka engine. Again, there was a large power increase, but I never revved the engine past 10,000rpm(11K max).

The 460 engine became so absolutely quiet at i8dle that I swear I could hear the internal noise(ring, piston,rod, bearings). All rpm speeds were very acceptable.

I would recommend the SBP expansion pipe for non-China girl engines.
 
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Try using an 18t/32t combination.

this will give you excellent response from a standing start, strong second and final gear. Ratios are 34.67:1 first, 26.07 second and final drive of 19.55:1

Your engine should peak around 30mph; cruising @ 25-30mph should be pleasant. It's a good first start. If the engine winds too much, drop down to an 18t/30t combination. Switch the 32t to a 30t sprocket. Ratios there would be 32.51:1, 24.44:1 and 18.33:1 respectively.

Good luck. With the Tanaka engine's reliability, it'll be a sweet ride.
 
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