welding the engine to frame?

brydonb

Member
Joined
Jun 6, 2008
Messages
75
I have now broken both my front and rear engine mounting brackets and am getting kinda frustrated by them. Has anyone done or heard of just welding the engine to the actual bike frame? Does it sound like it would work? I have the 80cc chinese engine.
 
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GasKicker

Member
Joined
May 28, 2008
Messages
72
I don't think the casing of the engine could stand up to welding temperatures. If the weld fails you would have a useless engine. The engine vibration alone would eventually cause stress failure.
I had engine mount failures with my first build on a mountain bike. There just wasn't enough room in the frame to put the engine mounts squarely against the frame tubes. I eventually abandoned that project and put the engine on a more suitable Beach Cruiser frame. I haven't lost any engine mounts on my cruisers.
 
J

JemmaUK

Guest
A really really bad idea for alot of reasons.

Firstly even a common or garden mounting gives a little protection from vibration and such, a insulated mount is better still. welding the thing to the frame looses you all that and means *all* the vibration goes into the frame.. which is not what you want.

Secondly - heating any metal will weaken it and in many cases a normal bike frame is borderline for stress and vibration as it is - hence several people have had stress fractures of frame components. failure at two points on the frame at speed is the quick way to the ER.

Thirdly - you would have to adjust everything to the mm while holding everything together and welding it all as well. I dont know anyone with 7 pairs of hands lol

Finally. There is a reason why even pre-builds and car companies dont weld an engine to a vehicle of any sort - because there will come a time when it has to be removed for maintinence and replacement - impossible when its been welded.

Maybe you could post some pictures of the offending setup and people here can try and suggest fixes

Jemma xx
 

loquin

Active Member
Joined
Jan 11, 2008
Messages
2,210
And, FYI. There's no such thing as an 80cc chinese bike engine. Despite the EBay ads. They're actually a little less than 70 cc.

Plus, moved this thread to the frame mount forum. It shouldn't be in the bicycle mod forum.
 
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fastboy9

Member
Joined
Jan 22, 2008
Messages
584
PLus the engines are made from aluminium so would be very difficult to get welded. A better solution would be to weld up a better mount, perhaps some form of mounting plate, from there you would then have the possibility of fitting a much better engine. try searching custom engine mounts.
Heres an interesting solution: http://www.motoredbikes.com/showthread.php?t=11027&highlight=custom+front+mount

Or if you are good with a welder then why not try fabbing a front mount plate like this? http://www.motoredbikes.com/attachment.php?attachmentid=4291&d=1202736406

This plus much stronger mounting studs and a couple of pints of loctite should do the trick!
 
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