Gas motors

[model-a]

Any one ever put one of these gas motors on a bike,just curious I know there are kits you can buy I figure someone has seen it done or may have done one them selves. I guess you would need to use a 26 inch bike or maybe that don't even matter, I saw one at my local flea market for $500 got to be able to do it cheaper.

 

[outskirtscustoms]

I've helped build three of them and two of my own. They are fun but not nearly as reliable as I'd like. You're constantly wrenching on it, adjusting things, and the cheap China bolts they give with the kit I would throw away and go buy good grade 8 hardware. I have put them on 24 inch bikes and even one 20" Bratz Lowrider but it was TIGHT! Had to cut an access through the top tube for the throttle cable on that one. Also make sure your bearings have plenty of grease and are adjusted properly or it will not last a week. Even on new bikes the bearings can be dry. And lastly make sure you have good brakes and if using coaster brakes add hand brakes in case your chain comes off at 30 mph. Also a springer front end helps the ride tremendously but do not get a bent springer or it is squirrelly as ever.

 

[model-a]

Thank's guy's, about how long did you have in it start to finish. Any real trouble or did it go together pretty good.

 

[wheelbender6]

The easiest kits to install are the rear wheel friction kits. They have no belts or chains to line up and adjust.
Motorized bikes are not Hondas -they require simple, but frequent maintenance, in my opiniion. I used to commute on mine 20 miles round trip to the park and ride to catch the bus to work.
I have commuted 40 miles round trip at my previous job.
Some guys race their motorized bikes and some build them just to have fun customizing.
I think a motorized bike gives you a lot of fun for the money if you don't mind doing a little wrenching.
You can find "Bikes with motors" on this site under the "Builds" subforum in the board index.

 

[outskirtscustoms]

Thank's guy's, about how long did you have in it start to finish. Any real trouble or did it go together pretty good.

Mine normally took around two hours start to finish. Little more with the 20" or 24".

 

[DougC]

The gas engine kits mostly aren't very refined.

First thing you should do is find out if its legal in your area or not. Some people have built them only to find out from police that there's no way to legally ride it on public streets at all....

Second, the China 2-stroke engines are the cheapest, but also the worst in reliability. Look around on motoredbikes.com or motorbicycling.com forums to see the issues; it is not so bothersome if you know what to fix in advance (for one example, one engine had the problem of the head studs breaking within a few hours of use. They didn't cost much to replace with better studs, but it's not the kind of surprise you pleasantly recall). ...The name-brand engine kits using Tanaka, Honda or Robin-Subaru cost a lot more and don't look the same, but have much fewer engine issues. Often no engine issues at all.

I built one a few years back using a Golden Eagle motor kit. Fun for a while but the engine vibrated a lot and had no torque at all (couldn't run up hills much, or even get started rolling into a stiff headwind). I tried to do it vintage-style (using some real-actual dimensions of a vintage motorcycle) and it rode horribly.... I eventually junked most of that bike. I'd like to do another one but would probably use a China moped/gearbox setup & moped rear hub, just to get useful gearing. (Trying to run motor torque through any kind of bicycle multi-gear rear wheel will quickly grenade the wheel, it is way more torque than they are built for)

The best-functioning motorbikes use custom-welded frames and moped engines+transmissions, like the 4-speed 90cc and 110cc's sold here: http://www.hooperimports.com/dept.aspx?dept_id=02
You must use a MOPED rear hub + spokes with these though, because the low gears on these engines will generate WAY more torque than any bicycle hub + spokes can withstand for long.
The "bicycle" frame also needs to be built with full-suspension, and VERY heavy-duty..... Figure that a moped with these engines would weigh about 150 lbs, and the engines weigh ~50 lbs, so your 'bicycle' should make up the rest of that weight if you want it to be durable.

 

[meatwad1]

Mine took about two years to put together. There was no part of the kit that did not need to be massaged in some way in order to make it work properly. I think I probably could have wittled a motorcycle out of titanium with a butter knife in less time.

I think the decideing factor is whether or not one has health insurance.

 

[DougC]

... I think the decideing factor is whether or not one has health insurance.

Yea, this is one thing I noticed too.

Some people will spend hundreds of dollars for top-end MTB forks, rear shocks, wheels and so on, and build a REALLY capable-looking full-suspension bike, and I wouldn't hesitate to ride it 50 MPH if asked. It simply looks like it could take it.

Then other people,,,,,,, go to Wal-Mart and buy the cheapest aluminum-framed cruiser bicycle that they know the biggest engine kit will fit in, they drill a hole through the down-tube to mount the engine because they don't want to pay for the clamp-on engine mount { :shock: }. They go and put on a cheapo China beehive springer fork on so that they have "front-suspension".... and then they come back saying that they like that it goes nearly 50 mph, but they are complaining because the frame is developing cracks and the fork is getting bent. Gee, ya don't say??? :wink:

Bicycles are "built" for about 20 MPH. You can push them to maybe 30 MPH it you watch them carefully. Beyond speeds faster than that, hitting bumps puts HUGE amounts of stress on the entire bike--wheels and frame. The only bicycles that are arguably "built" for 50-MPH speeds are downhill mountain bikes, that typically cost $1500-$2000+.
You don't gotta spend that much, but starting with the cheapest parts you can find is rather.... optimistic. In a very-naive sort of way.

You can build them safe, and you can build them ridiculously fast (75+ MPH!) but you cannot build them safe, fast and cheap.

 

[model-a]

You are so right my friend, Don't know what I might do just checking it out.

 

[meatwad1]

Then other people,,,,,,, go to Wal-Mart and buy the cheapest aluminum-framed cruiser bicycle that they know the biggest engine kit will fit in, they drill a hole through the down-tube

I'm glad someone else thinks that is a bad idea. I suggested on one of the motored bike forums that I thought doing so was a bad idea and basically what I got back was " I did it and never had any problems."

Anyway I hope I didn't discourage the first poster but if somone is going to do it that they are quite confident about working on bikes. Some of those guys in the other forums seem to really know their way around engines but as far as bicycles and safety goes i'm just not sure.

 

[outskirtscustoms]

As they say...fast, safe, cheap...pick two.