OzVMX Forum
Clubroom => Tech Talk => Topic started by: mick25 on February 01, 2014, 06:24:50 pm
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A mate of mine needs a set of 40mm triples bored out to 43mm to take Yamaha forks.
Anyone on here know any mobs that can do this work.
happy to post to the right place, my mate lives near Newcastle NSW.
Thanks for any help ;)
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3 or 4 in Newcastle can do it
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Tell me more GB , can you name these places ;) thanks for the info so far
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This doesnt sound like a clever idea.
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I have been wanting to do the same thing with a set of Husky 40mm triples, to fit a set of YZ465H forks, but just haven't got around to it. The Husky triples have plenty of meat in them, so should be able to be bored out to that easily and still be safe. I was also thinking of getting a set of 35mm Husky triples bored out to 38mm, to take '77 YZ400 forks.
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I've bored my 490 maico triples to take 43mm forks, just about any machine shop can do it no problem..
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Yeah...sounds ok, but the existing triples have a set amount of meat around them for a reason... if things go wrong off a fast, high jump, you won't even have time to form the "f" of your first reaction... :o
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If there was not much meat on the bone I would stay clear from doing this mod.
but that's not the case , some triples have more meat around them than others ,thanks for the advice ;)
its taking 1and half mm off each side of the hole on the triple , and theres still enough meat there to be safe , they are husky triples.
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1st call to Dave Hall at Classic Motorcycle Machining
Seaham st Holmesville
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If there was not much meat on the bone I would stay clear from doing this mod.
theres still enough meat there to be safe , they are husky triples.
All good, mate. 8)
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Be carefull taking that much out!
Maico are 41.7mm so to 43mm is not such a big deal.
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Be carefull taking that much out!
Maico are 41.7mm so to 43mm is not such a big deal.
I may have jumped the gate a bit on this one :o I should of done some more home work on it ;)I guested maico ones were 40mm not so , I have measured a few different triples I have laying around for alloy wall size ,they are within a couple of mm some have a wider wall at the bottom triple say 3mm than the top one.
The top husky triple once taken out to 43mm will match the wall size as a Yamaha top triple I have, but the Yamaha lower triple has 3mm more wall size around it , the husky lower triple has the same size alloy wall as the top so the lower husky triple will be less than the Yamaha one .
So I am going to ditch the idea its not my bike so I don't want to take the risk. (BETTER SAFE THAN SORRY )
if i had a set of 36mm triples and wanted to take them out to 38mm maybe not so much.
sorry to waste time on here with this subject.
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I have done it to the Husky triples on my 510. there is still 6mm+ of material after boring in the middle of the triple castings. So it was a risk I was willing to take.
The offset on the 40mm husky triples (of the twinshock variety) is less than most other forks (18-20mm ish from memory) so I chose to go this way rather than swap for 43mm triples, and increasing fork offset is not ideal for husky steering!
Your decision at the end of the day though, but for sure a set of custom billet triples would be the best solution!
Its not a big job so should not cost too much, requiring a mandrell to centre the mill head over the 40mm hole, then the boring process (x4 is pretty quick.
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I have done it to the Husky triples on my 510. there is still 6mm+ of material after boring in the middle of the triple castings. So it was a risk I was willing to take.
The offset on the 40mm husky triples (of the twinshock variety) is less than most other forks (18-20mm ish from memory) so I chose to go this way rather than swap for 43mm triples, and increasing fork offset is not ideal for husky steering!
Your decision at the end of the day though, but for sure a set of custom billet triples would be the best solution!
Its not a big job so should not cost too much, requiring a mandrell to centre the mill head, then the boring process X4 is pretty quick.
Thats one of the reasons I told my mate to use the husky triples it has a good off set ,the pre85 yz triples have about the same off set as the husky but they are not evo legal, thanks for your advice I am a bit 50/50 on this and its not my bike.
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yes ,
Its a different call when not your bike. I was a bit 50/50 ish about it too, but did it anyway, so far so good.
but I will keep an eye on them, and the 510 is not exactly a jumping machine, so it stays low with me astride it !
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I realise it's a different set of circumstances but I've bored a set of 32mm Arces/Ceriani triple clamps out to 35mm with no problems whatsoever. I'm pretty certain the 32mm clamps are the exact same casting as the 35mm version, the only difference being the machined bore.
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Mark, that seems to be the case with the clamps from the Yamaha MX175 and the MX250/360 forks -- same casting, different bore sizes.
More than one set of Moto Guzzi 35mm clamps have been bored to 38mm for road use.
cheers,
Michael
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A mate of mine needs a set of 40mm triples bored out to 43mm to take Yamaha forks.
Anyone on here know any mobs that can do this work.
happy to post to the right place, my mate lives near Newcastle NSW.
Thanks for any help ;)
A nice little machining job, here's how I would do it rather than bore it on a mill, I would machine a plug from scrap the same size as the new fork leg, get some shims to put between the slit on the clamps and adjust the shims so with the slightest pressure you can hold the plug. That will ensure the clamp bore is round when tightened against the shims. I would then attach to a faceplate on the lathe using the centre in the plug for alignment via a dead centre in the tailstock. 2 cuts and one slow with fine feed on to finish, make sure not to cut back away from the chuck. Rinse repeat for the other hole. Any competent machinist should be able to do it.
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as an amen to this,
my husky triples bored from 40mm out to 43 survived the Toowoomba track with me flat landing, beating up myself with 120kg of bike behind it over the step up jumps. I wasn't good enough to clear them (but then not many were!)
I cant remember in 10 odd years of vmx such consistent hard landings, so I didn't do it all the time as the body/ wrists couldn't take it..
So either the husky triples can take being bored out, or now they are stressed to the point of breaking on the next ride!!