Any Friction Rollers Larger Than 1.5"?

[5-7HEAVEN]

I'm looking for large friction rollers, something bigger than 1.5" spindles. I have two Mitsubishi TLE 43cc with friction drive and 1.5" rollers.

I ride "The dragon Lady" down the middle of a three-mile highway. Top speed is 40 mph; engine speed is 10,100RPM.

With 1.65" roller, same speed has 9200rpm.

With 1.75" roller, engine speed is 8700rpm.

Thinking about finding larger-diameter rollers, or modifying the ones I have. Larger spindles will decrease engine rpm. I am WAYYY over redline at 40mph and that's the reason for concern.

Strangely, the engines don't seem to be protesting at that rpm.

Low end torque will suffer but hey, I have two engines and therefore TWICE as much power anyway.

Dimension Edge has 1.75" friction rollers, but they are not interchangeable with Staton or BMP friction drives.

I've looked but cannot locate friction rollers larger than what I have.

Is there some way of bonding layers of material onto the existing spindle?

 

[DetonatorTuning]

5-7,

my shifter testing showed that the same thinking on my part was in error.

the strength of all these 2 strokes is in their rpm derived HP and they WANT to run near and above their power peak.

with nearly 5HP i can do 55mph @13,500rpm and have reasonable accel.

this at 19.09:1 ratio, but hills need to be approached with savy and headwinds will knock it down fairly quick.

at 40mph you are getting a very good return out of the power you have available. i fyou go to larger rollers you willl go slower and begin to struggle to maintian what speed you get.

if you proceed, the easiest way might be to press fit sleeves oner the 1.5" rollers and add some set screws as insurance.

good luck,

steve

 

[5-7HEAVEN]

Thanks for your input, Steve.

Top speed is right where I want it. I'll be installing two Walbro WYK-58 carbs to suppress a lean condition. Speed might increase but 40mph is my self-imposed limit.

Maybe the increased carburetion would compensate for the higher gear ratio.

Twin engines will soften the blow of slower acceleration and less torque from larger-diameter friction rollers.

Basically I want to relieve engine strain at that speed.

The engines should be closer to their redline and have more power.

I'll look into those sleeves. Do they exist, or do they have to be machined to fit?

If I DO experiment with larger sleeves, I'll use 1.25" spindles. That way the rollers fit thru the 1.375" bearing holes, and the drum and roller slip out as an assembly.

The 1.5" spindles are a MAJOR pain to remove and replace. Clutch drum must be removed (a bear!) and both bearings needs to be PRESSED or POUNDED out. The spindle will then drop out from below. It is too large to pass thru the 1.375" bearing holes in the housing.

My next trick will be to machine the housings for the bearings to be SLIP-FIT.

 

[DetonatorTuning]

1.5" pipe ,plumbing type is measured I.D. if it has 1/8"walls it should be very close to 1.75" O.D.

you can always turn the outside down if needed and you would probably want to crosshatch it anyway.

1.25" I.D. pipe might be slightly harder to find, i'm not sure. you may have to find a piece of solid stock and have it bored for a slip fit on the 1.25" spindles (locked on with bolts or set screws) and machine the O.D. to suit.

if you go THIS way you can simply loosen the locks and pull the 1.25" spindle out, the sleeve drops out into your hand.

so you're saying that at 39.7mph you are running above redline, i believe you've mentioned that before and it got past me.

in that case you WILL drop unwanted strain off the engines but i'm not at all sure you'll have more power to work with. you MAY however not have much less, down to the rated power peak atleast.

perform and document change, test and document result, perform and document change, test and document result..............................................................

story of my life in one unending run-on sentence,

steve

 

[5-7HEAVEN]

Steve, thanks for more information. That plumbing pipe just might work! And I'd want the sleeve to fall out like you mentioned.

Yeah, at 39.7mph, engine speeds are about 10,000rpm. It's WAYYY over redline so less hp is pushing the bike.

A 1.75" roller would drop engine speed to 8700rpm, which is MUCH MUCH closer to the Mitsubishi engines' maximum hp range.

In order to compensate for the rollers' higher gearing, I might retire this single-speed girlie cruiser and transfer all equipment onto a 21-speed full-suspension bike.

 

[5-7HEAVEN]

I found this and the price is right:

http://www.mcmaster.com/#44665k261/=1w0nbt

WAYY cheaper than standard friction rollers or custom machine work.

After experimenting with cheaper aluminum, then upgrade to brass or stainless when the correct size is determined...when the aluminum fitting wears out.

 

[DetonatorTuning]

5-7,

i think you will find that the threads on that are going to be pretty rough on a tire even if you crosshatch them.

maybe you can find a coupling in that stuff, the threads will be inside where it doesn't matter and you can rough up the outside as needed.

steve

 

[5-7HEAVEN]

Steve,

yes, I know that pipe threads are sharp and will tear up the tire if not filed down.

First I'll crosshatch the pattern onto the fittings. Then, since the outer diameter is 1.9", the fittings must be machined to 1.65" OD or 1.75" OD. Hopefully that should smooth its surfaces enough, so as not to destroy the tire tread.

This is the 1.5" rubber drive roller from bikemotorparts.com I will use for my experiments:

http://www.bikemotorparts.com/parts.html

I asked if this rubber roller was available in larger-diameter size. Sadly, they are not.

Since this spindle takes a .5" driveshaft, some BMP parts will need to be retrofitted to the Staton friction drive.