Finally get to post success with first build!!!

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soccerrj88

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Sep 30, 2009
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Well after having to post questions, and browse old threads for hours looking for the best way to make a chain tensioner, mount to a big frame, and other misc things I finally got it workin... for now. Before it was too unreliable for me to trust it for a mile or less, but now that i got it fairly well replaced with custom made parts, it feels pretty sturdy. Here's my ideas for big motor mounts and chain tensioner if anybody is looking for a tip.

P.S. I couldn't find the spring tensioner at tractor supply that everyone is talking about... but instead I got a piece of 3/15" flat stock with holes already drilled into it. and extended the stock tensioner to hang from the top chainstay and it's long enough with out cutting it so that if it does get kicked in, it will hit the tire before it rips the spokes out.


Overall pic. It's a Pacific Elite 3.5 Aluminum frame with front suspension.


Pain in the butt to build! everything was too big and needed fabricated. Luckily i hate a long strip of 2" aluminum flat stock... And muffler clamps


The muffler clamp that i screwed into the water bottle holder screw..


Any suggestions or questions are welcome. Especially from the more seasoned MBer's. This is my first China build that i hope lasts a while for the work I had to do...
dnut

Also there is a lot of excess oil coming out. I only have 30miles on it so I'm still breakin it in so thats a good thing but it seams like a lot. Im at a 16:1 ratio like the "instructions" said for break in... Im not using synthetic tho... Does that matter. I haven't really found any here.
 
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silverbear

silverbear

The Boy Who Never Grew Up
Jul 9, 2009
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Congratulations for getting so far along in your build. Regarding the mix, it may be a little rich. If regular 2 stroke oil others here recommend 24 to one. I use either synthetic Amsoil or Opti-2 so the mix ratios for those are different. Mostly I'd like to comment on the tensioner. I would find a way to secure the lower end of that extension you made so that it can's pivot, which I think it is going to want to do. It shouldn't take much.. a conduit clamp or piece of plumbers strapping should do it.
Silverbear
 
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starrunner

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May 12, 2008
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george_n_texas said:
Is there any reason you couldn't mount the tensioner like I did in this pic?
Click to expand...
So you're talking about two bikes, right? One, you modified the tensioner and the other one you didn't? Regardless, people generally drill a small hole through it and secure it to the frame. This prevents it from the dastardly deeds you mentioned earlier. Otherwise, no matter how tight you get it, it will still move with the force of the chain on it.
 
2door

2door

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Sep 15, 2008
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george_n_texas said:
Is there any reason you couldn't mount the tensioner like I did in this pic?
Click to expand...
George,
Your tensioner mounting is correct as far as the kit instructions go but If I may suggest one improvement; secure the tensioner to the bike frame with a small bolt to assure that it can not loosen and rotate into your spokes. That particular failure is not only one of the most common but also dangerous and expensive. Drilling a 3/16 or even a 1/8" hole through the bracket and frame WILL NOT compromise the strength of the frame and will keep your tensioner in place.
Tom
 

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2door

2door

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Sep 15, 2008
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Soccerr,
Silver Bear speaks true. Secure the lower end of your bracket to the chainstay. Almost anything will work; but don't rely on it hitting the tire as a way to keep it out of the spokes. Secure that puppy and you've got a winner.
Tom
 
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starrunner

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May 12, 2008
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2door said:
George,
Your tensioner mounting is correct as far as the kit instructions go but If I may suggest one improvement; secure the tensioner to the bike frame with a small bolt to assure that it can not loosen and rotate into your spokes. That particular failure is not only one of the most common but also dangerous and expensive. Drilling a 3/16 or even a 1/8" hole through the bracket and frame WILL NOT compromise the strength of the frame and will keep your tensioner in place.
Tom
Click to expand...
Yeah, I believe that's what I said.
 
BarelyAWake

BarelyAWake

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Jul 21, 2009
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A few thoughts...

Folks may or may not have noticed you have an aluminum frame, not to worry - I too have one lol but I did want to say that while it seems like a great idea, lining the motor mounts with rubber can actually increase the amount your engine vibrates - although you will feel it less as its dampened a bit between the motor and frame.

On a steel bike... *shrug* perhaps people can get away with it tho I had fuel frothing problems - the big problem is that with using exhaust clamps as motor mounts you stand a good chance of crushing your frame tubes if you torque them down on a aluminum frame, add to this the problem of cutting/wearing through the rubber due to vibration & time and the chafe of the steel on aluminum and you might have some cutting issues...

Yet exhaust clamps make great mounts! Somewhere on the forum someone made a perfect and cheap mod that alleviated the above problems - but bedanged if I can find the pics... It was easy enough tho - they simply took flat stock prolly 1/16" - 1/8" thick, cut 1 - 1 1/2" strips outa it and bent them into U-shaped plates to go between the clamp and the frame and welded them to the U-bolt to keep 'em in place.

This spread out the clamp's compression, allowing the clamp to be tightened enough to stop the motor's wiggling (and the chafe prob) without risk of kinking the aluminum frame.

Aluminum bikes are awesome and I like yer build - but be so very careful about drilling holes and any movement at all, I've had some chafe/cut issues with mine, even a rattling chain guard had nefarious thoughts, keep an eye on yer bike and all should be well though ;)

Some additional tensioner ideas;
http://motorbicycling.com/f11/chain-tensioner-suggestions-11815.html
 
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soccerrj88

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Sep 30, 2009
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Florida
Thank you all and yes it feels great to get a job, especially of this undertaking, completed. It looked simple enough in all the pics but once I started it def took some work for oversized frames!
It's all one bike. i put it together the first time the way it was supposed to just to see it run then I read a whole bunch on here and started fixing things I felt necassary especially the chain tensioner due to the horror stories on the forum and the lack of money i wanted to spend on this project... Plus my dad said this couldn't be done... so i hade to prove him wrong. lol
As it was said the reason i didn't drill the chainstay is b/c it is aluminum and i didn't want to weaken it even more after drilling the other hole to mount the engine. (I took the bolt out and went to the muffler clamp idea... thats why you cant see the hole...)
And FYI if you do drill a hole in your bike make sure you measure 2 and drill once so your bottom hole is aligned with your top hole... DOH!!! lol I though the drill was straight but the alignment of the motor proved me wrong! oh well live and learn and then ride!
 
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