Resizing a hole from 37mm to 39mm, how?

[spyug]

For all the machinists in the crowd. I may have to take a set of GS550 clipon bars with a 37mm hole in the riser for the fork tubes and adapt them for 39mm tubes.What would be the best method of doing this considering some degree of accuracy. I believe the risers are aluminum or an alloy of so should be fairly soft.

As many know, I am soon swapping my 550 for an FZ750. The FZ has low clipons that I think will cause me to stretch to reach. I will be hunkered forward and I will have strain on my wrists and shoulders that I don't think I can cope with. I've been thinking about the solution and I think the 5" rise on the 550 bars should do the trick.

I have never ridden an FZ and only sat on one once (Gatekeeper's project bike) but I'm pretty certain I will have to make a mod like this based on similar bikes I have sat on. I have seen a couple that were converted to standard handlebars and that would be easy enough but the bike does not look right and I'd like to have it look as similar to stock as possible.

If possible, I'd like to avoid the expense of a machine shop but would go that route if its the only way.

Thoughts ladies and gentlemen?

Thanks,
spyug

[rustybronco]

An adjustable king pin reamer should work nicely.

Or years ago the used to enlarge shotgun barrels by using a split cutter and adding layers of paper between the two halves when it stopped cutting. I suspect you could cut a hard wood dowel in half length wise and groove one half to accept a hardened piece of steel sharpened to act as a cutter and then screwing the two halves together with the paper between them. Just make sure the cutting edge is parallel to the opposite side.

[spyug]

Thanks. I have not heard of a king pin reemer nor the method you mention. I will look into both.

I was thinking of a rotary file or stone of some kind but finding anything that large is proving a bit difficult from my preliminary searches.

Cheers,
spyug

[rustybronco]

Similar to this... http://www.etoolcart.com/adjustable-...in-reamer.aspx

If you know someone who owns a small lathe you could also bolt it to a face plate and bore the hole larger with a cutting bit as well.

[Toasty]

It would probably be cheaper and come out better if you just buy the correct size.

[spyug]

It would probably be cheaper and come out better if you just buy the correct size.

Well the problem is kind of two fold. Clipons with risers are hard to find in 39mm and somewhat cost prohibitive if available. I've only found a custom set in Germany that would run around $300 before tax and shipping. I can get a set of GS 550 or 750 bars locally for around $40 shipped.

Some guys use FJ 1100 or 1200 bars for this conversion but I don't think they give enough of a rise, maybe 2" and they are also for 41mm tubes so would require shimming, something I would rather avoid.

Since starting this thread my good buddy and fellow FZ conspirator Gatekeeper has put me on to a machine shop about 5 minutes from me that may be able to it for me. It might all be unecessary anyway since I have yet to confirm my suspicions with a ride on the darn bike. Hopefully that will be remedied in the next week or two when we make the roadtrip to seal the deal. I might be worrying for nothing.

Thanks for all the input guys.
Spyug

[Toasty]

Normally I would recommend Woodcraft, they make a bunch of vintage bike sizes and risers but unfortunately not risers in 39mm.


I saw these though and they look nice, the price isn't too outlandish either.

http://www.drivenracing.com/content.cfm/go/storeproduct/id/1091/name/billet7075riserclipons-37mmclickforapps

Edit: arg, 37mm not 39.

[chuck hahn]

Got a compressor and a 1/4 inch die grinder? Go get a carbide BURR from Fastenal or the local supply house. jsut go round and round and make it whatever size you need. I recommend a single cut above the double cuts for removal of large amounts of materials.

[spyug]

I was thinking of a die grinder too but I'm concerned about accuracy. Hard to cut a concentric circle free hand. If worst comes to worst that is the way I would do it. I actually found a 37mm stone in my workshop that might work too.

The issue with store bought bars, apart from price, is that you can seldom get them with much more than an inch to 2 inches of rise which might not be enough. The GS bars are 5" which I think would be about optimal for the almost upright sitting position that I'm used to with the 550 and the 750 before it.

I really won't know if this is going to be necessary or even will work the way I hope until I get my hands on the bike.

I'll know better in a week or two.

Cheers all,
Spyug

[rustybronco]

I was thinking of a die grinder too but I'm concerned about accuracy. Hard to cut a concentric circle free hand.

Much less keeping the hole perpendicular to the surface.

If you could fixture the two parts so you could slide a 39mm rod into the 37mm hole then you could use lamp black the part identifying the high portions needing to be removed, but that's W A Y too much work involved.

[GateKeeper]

machine shop, with a boring head, and 20-30 bucks, and it will be done....

the shop I was thinking of can't do it, they are CNC based, no classical machines so his setup charge would be way too much and not cost effective.

I have a buddy at another shop, I will talk to him over the weekend

.

[Agemax]

this may sound silly but..........grind off enough to make it a sloppy fit on the 37mm fork tube, then wrap some emery cloth around the fork tube, slide the clip on over the top of it and spin it round and round until it smooths it out. nice and round and perpendicular to the fork

[spyug]

grind off enough to make it a sloppy fit on the 37mm fork tube, then wrap some emery cloth around the fork tube, slide the clip on over the top of it and spin it round and round until it smooths it out. nice and round and perpendicular to the fork

Good old British igenuity at its best. Well done that man!

Actually, as the son of a tool and die maker/production engineer/enginebuilder/flattrack racer and the dad of a mechanical engineer, I would prefer to have a machine shop do it for a kosher job. On the other hand, as a frugal Scot I'm keen on keeping the cash in my sporran. I'm somewhat conflicted

Well, as mentioned it may not be necessary.

Thanks for all the great input.

spyug

[Nessism]

An adjustable king pin reamer should work nicely.

Or years ago the used to enlarge shotgun barrels by using a split cutter and adding layers of paper between the two halves when it stopped cutting. I suspect you could cut a hard wood dowel in half length wise and groove one half to accept a hardened piece of steel sharpened to act as a cutter and then screwing the two halves together with the paper between them. Just make sure the cutting edge is parallel to the opposite side.

This would work as long as the blades doesn't catch on the slit in the round shape. The blades on these reamers are pretty sharp and angle forward so they may snag and hang up.

[spyug]

The blades on these reamers are pretty sharp and angle forward so they may snag and hang up.

Well at over way over $100 that is one tool I can't see investing in so I don't think I need to worry about breaking a blade or screwing up the hole.

Good pal Gatekeeper is still trying to source a fabricating shop to do the work. He has "connections".

I'll let you know how it turns out.

Cheers all,
spyug.