Huffy Cranbrook with Tanaka in frame

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recumbentbill

New Member
Jul 5, 2009
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millington tn
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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5-7HEAVEN

Well-Known Member
Aug 2, 2008
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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.
 

recumbentbill

New Member
Jul 5, 2009
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millington tn
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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5-7HEAVEN

Well-Known Member
Aug 2, 2008
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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.
 

recumbentbill

New Member
Jul 5, 2009
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millington tn
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
 

F_Rod81

Dealer
Jan 1, 2011
1,031
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Denver, CO
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
 

recumbentbill

New Member
Jul 5, 2009
87
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millington tn
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
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
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
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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
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
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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.
 

happyvalley

New Member
Jul 24, 2008
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upper Pioneer Valley
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.
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
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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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5-7HEAVEN

Well-Known Member
Aug 2, 2008
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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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