Tensioner issue solved for $5 and a hacksaw

East82

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Oct 17, 2011
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After toying with my first engine and now on my second, here are some observations that will help the noob (i.e. people like me who own just a few tools and aren't machinists).

~ Start with the sprocket, because it is the most tedious if done right. Get all the hardware set as perfectly as possible tightened just enough so it does not move. Flip your bike upside down, put the wheel in the holder and spin. Look good? Remove it and in a sort of north south east west pattern, tighten each a little in turn until it's good to go.

~ Put the wheel on and tighten it just enough to hold it in place.

~ Next flip the bike over and mount the engine tight enough so you can wiggle it left to right and put the chain on. Move the engine to a point that, when the chain length is eyeballed from the rear of the bike it's as straight as it can be. tighten engine mounts, trying to maintain this position. These two steps are your starting point.

~ Add the factory shipped tensioner, but don't tighten it all the way, maybe 60%.

~ Prior to all this you'd have gone to the home depot hardware section and purchased a 4 ft piece of pre-drilled flat steel and cut off an appropriate length. Add this from your rear wheel to your roller mount (I took out the bike wheel washer and used this as the new washer).

~ Tighten the wheel. Strange, but it makes a big difference; Tighten the the nut on the right side (Bike chain side) and then the left.

~ Finally, tighten the tensioner.

Thanks so muck to Bikeguy Joe and Norm for their insights.

hth
 

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decoherence

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Aug 23, 2010
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sebring,fl
i hope that steel is thick enough to have no flex.
if it flexes slightly, the idler will have the opportunity to pivot on the chain stay.
2 pivot points perpendicular is only slightly more stable than a single pivot point.

i personally say idlers are evil & should thrown away.
 

East82

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Oct 17, 2011
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@ decoherence - I did look at all of the threads you point out and there are some really fantastic solutions, but I wanted something that was fast and effective, not to mention cheap. I believe you are correct about the 2-point system being the best.

With my solution there is some flex, but just a little. I did an experiment for only like 50ft, where I loosened the tensioner bolts a little and it held. At this point, I've only put about 15 miles on my rig and all looks good.

My biggest concern, and I should have stated this in my original post, is that over time the engine torque and tensioner will win out. Regular PMCS (Preventive Maintenance Checks and Service) should catch this beforehand.

Any other advice you can provide is welcomed. After all, I am a noob

cvlt1
 

decoherence

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Aug 23, 2010
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sebring,fl
the advice i like to give is to get rid of the idler pulley.
if you have nothing getting in direct line of the chain you will have less problems.
it took me some time & several times remounting till i found the perfect position to get both chains tensioned well.
it may take a half link on the pedal side. you will mostly focus on shimming the rear motor mount.if you have horizontal rear drop outs, adjusters can help keep the wheel strait while setting up & using.
they can be picked up @ any bike shop.
i have had the idler go through my spokes & the chain break & get snagged. just like i have read from other people.
i got rid of the idler & used 415 roller chain. i have not had one problem since.
i still have not run across someone that wrote about how they removed the idler & somehow it reappeared in their spokes. lol


~~~~~edit

that flat iron would make perfect shims if they are cut into several peices. & you have bolts that are long enough.
 
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wayne z

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Dec 5, 2010
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Here's my easy fix.
DSC_1393.JPG

Some haso have adjusted the motor chain tight without the idler then installed the idler on the pedal chain. I've had to use the idler on the motor chain on all my bikes to keep the chain from rubbing the frame.
 

East82

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Oct 17, 2011
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Here's my easy fix.
View attachment 41208

Some haso have adjusted the motor chain tight without the idler then installed the idler on the pedal chain. I've had to use the idler on the motor chain on all my bikes to keep the chain from rubbing the frame.
By the marks on the rear tire, looks like your idler leaned in causing the chain to rub. Solution looks good, although I can't make out the materials and anchor hardware used.

Could you describe why you decided on this fix and how you implemented it? It seems that the idler ruins most newbies' motor bicycling experience and any insight would help.

When your idler careens into your spokes its gotta be like buying a brand new car and getting T-boned just as you pull off the lot!

BTW - I've been using the word 'tensioner' vs 'idler. Which is the correct term and why?

:-||
 

wayne z

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Dec 5, 2010
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Hey East, The marks are on my tire from when the rear sprocket was on dish side in. The idler isn't meant to fix chain alignment to keep the chain off the tire.

Can you make the pic go full screen or much larger than the thumbnail pic? It is easy to see how simple this mod is with a large pic.

I drilled a hole in one corner of my idler bracket and bolted a piece of 1" Hdw. store aluminum angle there, and zip ties at small holes on the ends keep it positioned against the frame.
I used several flat washers on the 1/4" bolt between the angle aluminum and the idler bracket to keep the bracket where it needed to be with the aluminum against the frame.
I fixed it this way because it was very easy and didn't require drilling the frame for a screw.

I now use a different method with good results. I use better quality bolts on the clamp and put 2 pieces of screen mesh sanding media in the joint then clamp it down hard. Be sure and bend a little twist into the bracket to make the idler wheel perfectly parrallel with the chain . This requires taking the idler wheel off and using a large crescent wrench to induce a slight twist into the bracket, just below the adjustment slot. This may require assembly/dissasembly several times .
Be sure chain alicnment is right, then align and adjust idler wheel to the chain.
 
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decoherence

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Aug 23, 2010
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sebring,fl
technically it is an idler. a tensioner pushes against the chain. imagine you were adjusting the rear wheel & slid it closer to the engine. a tensioner would continue to tension the chain while it would normally go slack.
it really shouldn't bother anybody if one term is used or the other except the semantic police.


Does anyone make an aftermarket tensioner/idler that works better than the stock one?
check the link i made earlier in the thread. it has a lot of good info if you want to use an idler.
 

wayne z

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Dec 5, 2010
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Tensioner, idler, adjuster. Tomato tomahto LOL, a rose is still a rose no matter what you call it as long as those involved know what yer talkin about. :~)
 

East82

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Oct 17, 2011
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So, today I had the opportunity to fix a guy's bike (bad carb and fried mag). Thing is he had no idler, just a shortened chain. I'm building a second bike and might try this. Where can I buy a chain break tool; standard bike chain tools don't work.

Also, this is a standard chain included with the kit; How do I know what the size is and is there a decent guide to chains?

brnot
 
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decoherence

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Aug 23, 2010
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sebring,fl
east82, if you take the time to shim the engine & get it fitted well, you will wounder why you ever used one.

i was bothered that my chain break tool wouldn't fit a 415 chain.
i refuse to pay 35$ for a chain beaker. there probably cheaper ones.
i was thinking of making one out of bolts & angle iron.
right now i am using a master link & have not had a single problem.
 

East82

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Oct 17, 2011
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OK, now my ignorance is apparent. I know what a shim is, but what does it mean to "shim" the engine?
 

Mozenrath

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Jan 13, 2011
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I bought this chain breaker from a local bike shop for $35(yeah I know). It works with the 415 chain and normal bike chains. Although it doesn't fit the 415 chain perfectly, so when you re-attach a chain to itself the point where you reattached might be a little tight. Just grease it up and move it to let it loosen up a little. I haven't had a problem using this tool with the chain on my bike.

Park Tool Co. CT-7 : Screw Type Chain Tool : Chain

You can get them on ebay starting at $24.25 with free shipping. I know that seems a lot for a tool you'll hardly use, but it's good quality compared to the $4 Bull chain tools from Wall-Mart, and you'll be getting it cheaper on ebay than you would at an LBS. I don't know of any cheaper tool that will do the same thing. I've seen people on youtube use an awl and a hammer, but honestly I've tried that many times and I've never gotten that to work.
 

decoherence

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Aug 23, 2010
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sebring,fl
OK, now my ignorance is apparent. I know what a shim is, but what does it mean to "shim" the engine?
try using pieces of flat iron in between the rear mount where it meats the engine. running the bolts through the shims.

what i did was use both of the aluminum blocks that came w/the kit.
but i split one of them in half w/a dremel.

if you hold on i will see if my camera & flash can pick up what i did.
i will post a pic in about 15 min