View Full Version : Possible shop tips while making starting rollers for a competition motorcycle.

08-04-2011, 01:35 AM
Hi Everyone,

I just wanted to pass along a few tips that I have learned through the years. Sorry if they have been covered already.

A friend of mine is coming over from England to run his bike at Bonneville Speed Week in a little over a week. The bike is already here & he’ll be here in 2 days.

I have become his pit crew and janitor & I just finished rebuilding the transmission in my Pathfinder (our chase vehicle) this morning.


So much to do, so little time! Gee, rather catchy phrase don’t ya think?

I needed to make a set of starter rollers & looking for the quick & dirty way out I used regular black pipe for the rollers. I had to fit stub axles in the ends for the 1 inch pillow blocks I had on hand.

Trick #1:

The tool plate I made years ago is just for when I need as rigid a tool mount as possible. It is about 1 inch thick, cast iron and as you can see it covers the width of the compound. The tee nut is steel and is just as wide.

This smokey photo shows me roughing 2 inch diameter steel to 1.400 in one pass at 185 RPM (highest speed in back gear) on my 16 inch South Bend.


Next came the corner radius - inch w/no chatter.



No way would I try this w/any standard tool post, turret, kwik change holder etc.

Trick #2:

If you have worked w/water pipe you will know that wall thickness & concentricity it is not very accurate. Even though the pillow blocks are self-aligning, I didn’t want the bearings to wiggle wildly in the cast iron mounts.

Not having a lathe long enough to bore the ends for concentricity I welded up spots on the 2 inch bar stock so that I could turn the welds between centers at the same time finishing the 1 inch stubs. This would average the pipe’s errors to some degree when I drove them in before welding. I also had to make up .080 diameter difference too.


Continued next post…………….

08-04-2011, 01:36 AM
Trick #3:

This is one of my favorite tricks I picked up when I worked in a racing department & had to cut & re-weld engine rocker arms.

Using the center holes, insert a ball bearing on each end and put tension on the balls. If the shaft is short enough you can do this in a vice.


Even though you can put quite a lot of tension on the balls, the shaft will still turn rather easily allowing you to turn it as you are welding. No arcing, no sticking, just a smooth turn w/the amperage flowing just fine.


Because I am not an octopus & I only do TIG inside the shop, I couldn’t turn the shaft, hold the torch & feed the weld rod all at the same time. Even having to stop & start several times, you can see by the heat band that the weld is quite even. W/MIG or stick you can get welds that look like they were done on automatic machines.



Because my shop is quite crowded, I only do the TIG inside because of the lack of spatter.

So, that’s my story & I’m sticking to it!

If you’re interested, my friend started an online build diary last October. The finished bike (as if there is such a thing) is on page 13 here:


08-04-2011, 02:09 AM
Cool project, but why are the rollers built so wide?

Many starters I've seen have used go-kart rear wheels for a roller. A quick & dirty frame, small engine or large motor for driving the wheel.

08-04-2011, 02:17 AM
Hi Peter,

Don't know!

I wanted them to fit w/in my trailer, so I actually narrowed them a bit from what he suggested.

These will be driven from the rear wheel(s) of my Pathfinder.

It does allow plenty of 'elbow' room for the bike though.

08-04-2011, 02:28 AM
Aah right, you have to fit your truck wheel on as well as the bike - that would make a lot of sense then.

Have you ever crewed at Bonneville before? I was going to do it a couple of years ago but it fell through. I know a guy who had trouble reading the speedometer on his bike whilst doing his licensing runs because of the bright sun - he couldn't see the digital readout.

08-04-2011, 02:34 AM
Nope, this will be my first trip there.

Always thought it would be great to go, but life kinda got in the way.

So, when this chance came up, I jumped at it.

I remember reading about Burt Monroe in the magazines during the 60s when he was coming here. Still have some of them & his work was truly inspiring!

I did a lot of drag racing in the 60s though so the competition thing is in my blood I guess.

Just noticed that you are in the U.K. - must be 5:30 AM there!

08-04-2011, 02:43 AM
hahaha jumpstarting from a car, I love it.

that 2lb for the kickstart is just too much eh? :)

And I guess pushing it up to speed gets old..

08-04-2011, 02:49 AM
Hi Black_Moons,

I suspect that it is not only the weight of the kick start assembly. The cases are certainly machined for it.

I think that w/the long intake tract & supercharger that he has, plus magnetos w/o impulse devices this would be a bear to start w/a kicker.

He even mentioned that a chassis dyno that he tried wouldn't get beyond backfires!

Yow Ling
08-04-2011, 03:01 AM
Has your Pathfinder got a Limited slip Diff ?
I have a similar set of rollers but they work best on a car with a simple differential.

Sometimes we just use some other race bike to power the rollers

A kickstart is a waste of time on many race bikes, mine is a onda XR500 motor bored to 640 with no flywheel, its almost impossible to push start, thats if you can find anyone that would want to push, a kicker would most likely damage your leg

08-04-2011, 03:15 AM
Yeah you don't want to be kick-starting a high-compression race engine. Even electric-start engines can struggle to get going at 13+:1 compression. Hayabusas are famous for kicking back and smashing the engine cases (2k for new ones) so many people put a second battery in series and run the starter with 24V. If it can knock a chunk out of a fairly strong casing think what it could do to your hip joint.

08-04-2011, 03:16 AM
Hi Yow Ling,

Yep the Pathfinder has limited slip, so I intend to keep the other wheel off the ground while running the rollers.

I hope it doesn't slip off the stand or I might set my own record.:D

08-04-2011, 03:20 AM
Got your CB Radio fitted and working? As I understand, it's a requirement.

08-04-2011, 03:25 AM
High compression race engine?

The Harley 750cc KR racing flathead was 6:1.

I think that his version is in the same ball park, but the supercharger will add to the compression pressure - just not to the ratio.

If you try to raise the compression, you shroud the valves too much cutting the flow.

These engines present some cool challenges to squeezing HP out them.

Can't raise the compression much & can't rely on intake ram effect (inertia). Too many right angle bends.

Good thing I already lost most of my hair - I'd be tearing it out about now!:D

08-04-2011, 03:28 AM
CB radio - tomorrow's to do list.

Have the radio - but had to replace countershaft bearings in the trans first.

Felt it might be a good idea to be able to drive the chase vehicle rather than tow it w/the bike.:D

08-04-2011, 03:54 AM
I have to get going off to bed now. The next few days are going to be quite intense.

Not only w/the bike.

I promised my wife that I would help her shovel out the house to make room for our guests.

I’ll do my best to get back here as much as possible;)