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Old 02-10-2013, 07:56 PM
bwader bwader is offline
Motorized Bicycle Member
Join Date: Feb 2013
Location: hampton roads VA
Posts: 21
Default Roadmaster Mtn bike 49cc bike

Hi, I'll say I started with a 49cc bike kit from BGF/LEB luckyearlybird about 2 years ago. Got it all put together and only got it to run for 30 sec. I ended up turning a head bolt a little too much and it stripped. I tried my darndest retapping a new hole and using a HELICOIL like brand thread saver in the spot and didn't work.

After watching a lot of youtube videos and some forums I have bought a new chain (I cut it too short and destroyed the remainder of it with a hammer and flathead.
New carb. and now a new "speed carb". Haven't tried the speed carb. yet.
another CDI coil checked connections to magneto seemed ok. Got spark turning the engine.
Fresh premium gas and mixed 16-1.
Tried different spark plugs still spark with each so led me to the conclusion after making sure the intake and carb. connections are sealed.

So now I got a New 49cc engine from LEB. Checked it , it was a little rusty inside the clutch gear though it had red grease in between the gears, made the clutch work how I want it.

So now after all this rambling about stuff I've done over the past years. The part I have trouble now is IF this new engine works like it should. I just need to get it mounted to the frame good. The quick and easy answer I know is just get a beach cruiser bike or larger frame.

But I'm making this work on my Huffy Roadmaster. I got a slanted head for the spark plug which gives me more room to work with than before.

Anybody know the size of 49cc mounting studs, they are too short to go around the frame and the U bolt won't work. The studs make it about half way around the frame. So if I had a female stud extender I could have a working front mount. Right now I can make the rear mounting bolts secure.

Sorry no pictures I don't have a camera or it would be sooo much easier.

Also I use an off-set intake for the carb to be able to fit the frame.

Last edited by bwader; 02-21-2013 at 11:53 AM.
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Old 02-10-2013, 08:04 PM
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2door 2door is offline
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Join Date: Sep 2008
Location: Littleton, Colorado
Posts: 16,219
Default Re: Roadmaster Mtn bike 49cc bike

The "female stud extender" you want is called a 'threaded rod coupling'. Check with Ace hardware in their metric fastener section. You'll want 6mm x 1 thread. Good luck.

Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"
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Old 02-11-2013, 08:03 PM
bwader bwader is offline
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Join Date: Feb 2013
Location: hampton roads VA
Posts: 21
Default Re: Roadmaster Mtn bike 49cc bike

I found that searching 6mm x 1.0 I found a british site.
Then remembered M6 x 1.0 threaded coupling worked out.
I went with Fastenal

I'll update when I get them in and try it out.l

OK. I didn't realize I didn't have enough room for them to screw onto the front mount bolts. Imagine each bolt goes around the down tube, not much clearance. But at least now I have wide 6mm nuts that I see could come in handy later.

Last edited by bwader; 02-21-2013 at 11:57 AM.
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Old 02-21-2013, 11:44 AM
bwader bwader is offline
Motorized Bicycle Member
Join Date: Feb 2013
Location: hampton roads VA
Posts: 21
Smile Update! Roadmaster Mtn bike 49cc bike

So I swapped out the new 49cc engine with speed carb. And I got it to RUN!
This is a first for me! I have been tinkering with this damn kit for 2 years now (a few hours a week).

I found this parts site and bought a stronger hardware kit for 10 bucks, mixmizer 2 stroke easy mixer and a couple NGK spark plugs. Just a cold weather one -40 to 80F and a hot weather 80F to 110F plug. There are "better" ones but they warn of piston hitting if clearance is close. I got my kit finally running so I'm not in a hurry to mess it up!

I looked at the Large and small front engine mount kits. I thought this will solve my problem! But after looking at my bike. The 49cc engine fits tight to the bottom tube where the water bottle holes were. I have a small V-frame so I'm happy just to get it to work. Though it would be awesome to put on a SHIFT KIT!

I just noticed I can use the REAR MOUNT BOLTS on the FRONT! So I got the old engine ones off and now I got to take the factory short ones off the new engine.

All I needed was LONGER BOLTS! I just thought it wasn't a possibility(didn't want to break it taking it out). Now I should be able to mount it no problem now. Just got to loosen the rear mounts and move it to the side. Remove one front bolt then the other and loctite and screw the longer ones in.

Lastly I ordered a spring tensioner off this guy on ebay after shopping around. Current problems are loose chain and the stock tensioner doesn't really cut it for me. I move it and it slides back(Probably stripped). I don't feel like removing more links, its a pain even with a chain breaker.

Spring tensioner I ordered:

Once I get a good chain tension and get my engine mounted well I can actually ride it(and not worry its going to break off, being held by the rear mount only). I ride start it then keep the clutch in. No load break-in just let it run for 15-20 mins then shut off.....wait to cool and try again.

Last edited by bwader; 02-21-2013 at 12:04 PM.
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