4-stroke engine fit on mountain bike...

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I'm not recommending this kit, know nothing about it. It's FYI and there's a bunch of them for sale on ebay. These might be rev limited unlike Grubee's 144f's, dunno.
 
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Lewiebike, So I've been measuring the space between the tubes on my two mtb and I found that my old early 2000s genesis 26 bike has more space than my new 29 tornado (both Steel, it looks to me the welding on my genesis is much better than my New 29er) .The genesis has 26 wheels, no disc brakes and no suspension. What are the downsides of having 32 rear wheel spokes? I'm 156 lbs btw

darwin, the HS 53cc I found costs around 200$ and more, is that normal? The mitsubishi would cost me 150$ brand new( I actually don't know where they are made, could be chinese too).

Some pictures from today(the measure is not perfectly aligned cause I had to take the pics) :
Mitsubishi lower end engines are made in china, some are in Thailand.

also thats 150 JUST for the engine, nothing else. you need a mount, throttle, airfilter, tank, transmission, wider cranks, and a bunch of tiny other things. the hs144 and the hs142 has everything included. my 142 is a bit rarer (has a 5/8 straight shaft vs the normal taper shaft) the 144 is basicly the same thing. but before you by anything, measure the frame triangle to see if you can even fit it.
 
The biggest issue with having a 32 spoke wheel is, when you try to mount the drive gear one of the spokes is going to be in the way of the mounting screw. Because most kits come with 9 screws, it's better to have 36 spokes, one screw every 4 spokes.
 
35 mph on 26 inch wheels with a 20:1 reduction, how do you keep from blowing the engine doing 9050 rpm? Unless you were talking about down hill speed.

Most of the small 4 strokes max horsepower is at 7000 rpm. A small person could do 35 mph at 7000 rpm with a 15.46:1 reduction on 26 inch wheels.
Yes, I do rev out my engine to over 9000 rpm from time to time. Not sure how it hasn't thrown the conrod yet :p. I've been a bit nicer to it since installing the shift kit.
 
Lewie, what in the world made you count the spokes on his rim? OCD maybe? Come to think of it I don't know how many spokes my wheels have. See what you've started, now I feel a need to count them!
I'm a bicycle mechanic by trade. and worked for a year and a half production building wheels for bike trailers for Burley.

After about your 8,000-enth wheel build, you get a little preoccupied with wheel quality, strength and proper useage.

The number of holes in the typical rag-joint spoke mount sprocket is 9. Which will cause all sorts of f#ckery with a wheel spoked with 32 spokes. Less spokes also means less strength, and on top of this being a online purchased, cheapish looking MTB, who knows what kind of quality the rear wheel is built with. Are the spokes even quality made, stainless steel true 14 gauge spokes?

How about the rear wheel hub? Is it a cheap, stamped steel, swedged 3 piece, loose ball bearing hub with barely any grease packed in it? These things matter greatly when you elect to start running a few horsepower through them.
 
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Lewiebike, So I've been measuring the space between the tubes on my two mtb and I found that my old early 2000s genesis 26 bike has more space than my new 29 tornado (both Steel, it looks to me the welding on my genesis is much better than my New 29er) .The genesis has 26 wheels, no disc brakes and no suspension. What are the downsides of having 32 rear wheel spokes? I'm 156 lbs btw

darwin, the HS 53cc I found costs around 200$ and more, is that normal? The mitsubishi would cost me 150$ brand new( I actually don't know where they are made, could be chinese too).

Some pictures from today(the measure is not perfectly aligned cause I had to take the pics) :

Plamb, the main advantage is that your older bike is it's frame is a lot more close to matching the "V" angle used in your engine's mounting seats, the areas contacting between the seat and down tube parts of your two bike frames.

What this means is when you bolt your engine up to the frame, you can use your stock bolt mounts on both the seat and down tube. When I bought my HT engine, I had a bike already chosen out, that I had a good idea that the seat tube and down tube would be within a degree or less of ideally matching the clamping area of the bike engine's frame mounts. More precise sitting and less chance the engine will creep out of alignment.

Here's my bike, which is a 1958 J.C. Higgins 3 speed frame built by Steyr in Austria..

DSC00055.JPG DSC00056.JPG

Notice that I used some PVC black irrigation pipe to fill in the gap of the clamping part of the bike. When I first test fitted this engine into this frame it dropped right in without any misalignment, but the clamp diameter was a 1/8" or so too big.

Which isn't surprising as these engines were made to fit Chinese built, 28" wheel size, rod brake fitted Flying Pigeon single speeds, all based on the old Raleigh 28" Roadster. The engine clamp angle hasn't changed on any of these engines, ever since they were first made. Flying Pigeon has made a billion or more of these bikes. All based on the 1930's standard English designed Raleigh roadster.

So finding a bike frame that fits properly isn't easy, but most really old MTB from the 1980's and some 1990's bikes are going to be better fits than any cruiser or more modern MTB with more acute angles between the seat and down tube.

In an ideal world, you would buy a Flying Pigeon bike with all quality aluminum bits, indexed gears and decent wheels. But your 2000 Genesis is a good match. If the rear wheel is sound and in recent overhauled condition and has been recently looked over by a competent wheel builder/bike mechanic. The rest of the bike's condition matters also. Is the bike in recent overhauled condition, especially the brake pads new and the brake cables and cantilevers tuned up?
 
Wow, I really should have made this thread before purchasing the bike. So many things I didn't take into account. You guys really know your stuff.
Oh well, I can still return it.
The only things I've changed on the Genesis, since I bought it 20 years ago were the tires, the seat and the brake pads and that was 2 years ago. Had no problems with it all these years, no rattling sounds or something breaking but I don't plan to motorize it.
Maybe I should return the new bike and start searching for something that will actually work.
 
Wow, I really should have made this thread before purchasing the bike. So many things I didn't take into account. You guys really know your stuff.
Oh well, I can still return it.
The only things I've changed on the Genesis, since I bought it 20 years ago were the tires, the seat and the brake pads and that was 2 years ago. Had no problems with it all these years, no rattling sounds or something breaking but I don't plan to motorize it.
Maybe I should return the new bike and start searching for something that will actually work.
That would be your best bet, id look for a old diamondback or a giant, both can be had for around 20$ on craiglist (i paid 10$ for the diamondback and i paid 25$ for the gaint) first things first, you NEED to regrease everything (seat post, front and rear hubs, head set) and make sure the wheels are somewhat true (doesent have to be perfect, you can get a park tool spoke wrench for about 8$ and do it yourself) for your safely id upgrade the cantilever brakes to shimano V brakes (they stop much better than those old ones)

This should be a good start on your bike.
 
Hey, thanks for the responses.
darwin, thanks, btw the engine is 4 stroke not 2, I personally don't like 2 strokes for many reasons but here is the picture (below),
mark20, if I remove the factory exhaust, air filter and fuel tank, the size and dimensions between the hs and the mitsubishi look kinda similiar, do you think it will work, or it's wishful thinking?
Specs from the site: http://www.mhiet.co.jp/en/products/engine/engine/gasoline/four_cycle_engine_gb_series/gt.html
Picture of the engine:
Def won't fit ....I can't fit an hs142 in a 26 inch mountain bike. The engine won't even fit without aircleaner, engine plate and chock cut in half much less with the engine plate so I'd say unless you have a large mountain bike with at the very least a 21" top tube then maybe it's possible
 
Def won't fit ....I can't fit an hs142 in a 26 inch mountain bike. The engine won't even fit without aircleaner, engine plate and chock cut in half much less with the engine plate so I'd say unless you have a large mountain bike with at the very least a 21" top tube then maybe it's possible
What you obviously don't have is a 26" frame mountian bike unless you're very tall. What you have is a mountian bike with 26" tires. Most department store mountian bikes generally only come in 1 frame size. Bicycle shops have mountian bikes in different frame sizes but you're going to pay $500+ for one.
 
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