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Rocky_Motor

New Member
Nov 14, 2011
367
0
0
Fort Collins & Boulder
Do not mount it with rubber between the frame and engine mounts unless you engineer a standard automotive design.
Here's a few references:
http://motorbicycling.com/f6/rubber-not-27364.html
http://motorbicycling.com/f6/anti-vibe-mounts-34336.html
http://motorbicycling.com/f6/aftermarket-high-quality-mounts-34114.html

There are alot more if you do a search for them.
Aaah, good to know. Wish I didn't get that rubber now, it's actually rather expensive at 15 bucks a square foot. I'm sure I can find a use for it. The real reason I wanted to use rubber was to prevent the mounts from vibrating and slowly working the aluminum frame down till it brakes. Maybe that won't happen at all or not for a very long time. Talking with mdlee he warded me against aluminum frame because of that but there aren't many steel frame mountain bikes. Looks like most everyone else has not had a problem though so I'll just go for it. Especially if I use my older schwinn bike I'm not to worried about damages.

Very helpful information, thank you!


@rustycase- I agree that taking apart this motor is risky but it is also risky to not replace parts on it. Guess that just makes it a risky motor!..
I'm reading through this thread
http://motorbicycling.com/f4/bgf-t80-total-teardown-34793.html
Good info on taking it apart. However for my use I think I'm going to stick with replacing the bolts with the ones from SBP. I don't have head bolt replacements though as those are also 6mm or 8mm which I'm not sure which size is mine yet so I'll follow your advice and leave that alone for now.
 

rustycase

Gutter Rider
May 26, 2011
2,746
5
0
Left coast
Ditto... IMO 1/4" rubber mount will do you no good, and possibly create many probs from the power unit floating around in the frame!
Perhaps a swatch of 1/16" garlock where the engine bears against the downtube *might* not be a bad idea...

...inch lb torque wrench isn't gonna be of much value for auto maintenance...

I can guarantee you'll NOT get 2k miles without constant maintenance and at least minor repair. What we hope for is to avoid *major* repair for the longest period of time!
Some folks have done really well !

...if you wish to cart the mab in a vehicle, there should not be much smell.
Drain the tank and let the carb run dry... there will be less than an ounce left.
If you are sensitive, maybe wrap a towel around the motor unit before loading into the vehicle???

lol
sounds like you are having fun already!
rc
 

BarelyAWake

New Member
Jul 21, 2009
7,194
21
0
Maine
...The real reason I wanted to use rubber was to prevent the mounts from vibrating and slowly working the aluminum frame down till it brakes. Maybe that won't happen at all or not for a very long time. Talking with mdlee he warded me against aluminum frame because of that but there aren't many steel frame mountain bikes.
I've found the anti-aluminum bias to be completely unsubstantiated, I've yet to see an aluminum frame broken as a result of motorizing - what failures I have seen were a direct consequence of poor mounting/build technique, such as "rubber" mounting and/or improperly torqued/substandard fasteners, which would ofc be problematic regardless of what material the frame is made from.

Having said that, the frame's quality should be examined thoroughly - regardless of if it's steel or aluminum it should have quality, uniform welds & a good design... this doesn't mean "expensive" but just not shoddy like the very cheapest of the box store bikes, which while many have used w/success, they can't be assumed to be all constructed the same, which is why there's some that have failed and some that haven't - like the Cranbrook's upper chainstays *shrug* (steel bike BTW).

As an example, my Schwinn Aluminum Comp mountain bike. While not a "quality" bike by any serious bicyclist's standards and was a mere $200 - the frame's design is exemplary (strength/gussets etc) with simply gorgeous welds, which is why I bought it instead of a cheaper steel bike. While the other components are pretty much junk (derailleurs wheelset etc) - the frame itself has proven incredibly rugged, surviving over 10,000 miles, years of unrelenting abuse (rough roads @ stupid speeds) and even a major, "cartwheeling" crash (a friend & he's ok lol) without even a sign of fatigue or any damage at all to the frame - despite the fact it's aluminum.

As an example of something that should be examined no matter the material, here's my (yea, filthy) Schwinn's welds & gusset vs an inexpensive steel mountain bike's complete crap welds... and that isn't near as bad as I've seen on some o_O (click to view detail);


(I don't actually advise this bike as a candidate for motorizing, not because it's aluminum - but because the engine doesn't actually fit w/o a LOT of mount mod/fab that isn't worth the bother)





It's not the material it's made from, but how it's made.
 
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Rocky_Motor

New Member
Nov 14, 2011
367
0
0
Fort Collins & Boulder
Well that certainly makes me feel a lot better about using the aluminum frame! I won't use the rubber I have for sure then. I actually am going to use my current schwinn bike to mount the motor :D Hopefully it fits though. It barely makes the specs for that image dipicting 11" between the bottom of the top tube to the bottom of the down tube. If not I'll get another bike which isn't a problem. I would use this GT avalanche 2.0 I have but the downtube is not the regular circular tube, it is widens out to much more oval like as it goes down...... I'm trying to sell it, hopefully can get it gone soon I don't like it that much. Has a front disc brake and boy I tell you those brakes are wonderful!

I do have a thread on it though..http://motorbicycling.com/f6/flat-downtube-35553.html

I love the way your bike looks, rugged and strong. Takes on the elements!
 

Motorbikermark

New Member
Nov 16, 2011
100
4
0
Western N.C.
I had the same problem as many with the clutch handle that came with my kit , Crappy quality, didn't fit my bars etc, Decided to replace with old style front shimano 3spd shifter. Holds in fine and pops with just a flick of the thumb...Looks sort of vintage also, and clean no brake handle.
 

DawgBarber

New Member
Dec 16, 2011
22
1
0
Compton CA.
Question : I tightened motor chain after readjusting the motor..yesterday ..it has about an inch give...bur now after going 35 ...40 yesterday I seem to be topping out around 25...suggestion?
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
Chain is too loose. Go for 1/2 to 3/4 inch freeplay.
Also, how clean and lubed is the chain?

After readjusting your motor, is the carburetor sitting at an odd or different angle than it was before?
 

DawgBarber

New Member
Dec 16, 2011
22
1
0
Compton CA.
Its gonna be the chain...I rode it with a loose Chain about a mile...chain rubbed my white walls off thus leaving white rubber crap on my chain and left it really dry ...I didn't think that would mess thinks all up like. That....wow...
 

rustycase

Gutter Rider
May 26, 2011
2,746
5
0
Left coast
What carb do you have on the motor, DB?
probly a bit of crud passing through the jets????
rc

..I recently bought a can of Liquid Wrench brand chain lube... $4 at Autozone.
Kinda black and yukky to spray on, but when left overnight to set, does NOT sling off and my chain noise and pulse are MUCH improved.
 
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5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,661
240
63
In the pics, the skateboard tensioner is positioned on the right side of the chain, pushing outward. However, I have now relocated the tension wheel to the left side of the engine chain, pushing inward. The tensioner arm still pivots at the same place. For more throw, it has been shortened on the spring side to clear the underside of the engine block.