OzVMX Forum
Marketplace => eBay Finds => Topic started by: firko on November 07, 2011, 04:55:50 pm
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As is usual with Arizona Mikes's bikes, there are a lot of unverified claims made about the bike but all that aside, it's pretty damn trick anyway. You'd never get it past pre '75 scrutineering but it might squeeze into pre '78. That's if you're prepared to pay nearly 10 K for it!
http://www.ebay.com/itm/74-R-D-RACING-Suzuki-TM-RN-400-Vintage-MX-MotoCross-Moto-X-John-DeSoto-AWESOME-/260882399098?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item3cbdcd7f7a#ht_3594wt_786 (http://www.ebay.com/itm/74-R-D-RACING-Suzuki-TM-RN-400-Vintage-MX-MotoCross-Moto-X-John-DeSoto-AWESOME-/260882399098?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item3cbdcd7f7a#ht_3594wt_786)
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i am not into it, looks like a lash up to turn left over TM400 in TM400S, bent engine fins may hint at the quality of the workmanship. 10K USD is having a lend.
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I'll bet it will handle like an expensive, fast, pogo stick. With the shocks at this angle they have decreasing mechanical advantage (becoming easier to compress) and you never get the dampening or spring right - either being to stiff initially (compliance over small bumps) or too soft for the big hits.
(http://i323.photobucket.com/albums/nn458/mx250syd/OzVMX/KGrHqNl8E6P8-nwfDBOq1GgEmQ60_3.jpg)
Whatcha reckon - a $3000 bike :P.
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I'll bet it will handle like an expensive, fast, pogo stick. With the shocks at this angle they have decreasing mechanical advantage (becoming easier to compress) and you never get the dampening or spring right - either being to stiff initially (compliance over small bumps) or too soft for the big hits.
Sorry MX, but I think you have that arse about.
Inclined [laid down] shocks have a rising rate, not falling as you say.
When a shock is at 90° to the swingarm [assuming that the shock is in line with the axle] then 1mm of axle movement results in 1mm of shock travel.
When the shocks are inclined at a 45° angle 1mm of axle movement results in 0.5mm of shock travel [that ratio is from memory, and I can't be bothered to get the calc to check it, so sorry if it is not absolutely correct].
So on a bike with laid down shocks the biggest difference in mechanical advantage is achieved if the shock ends up at 90° to the swingarm at the end of the shocks travel. Eyeballing this one, that wouldn't happen so the ratio would be less, but it is definitely still a rising rate.
It could as you say be a 'Pogo Stick' but that would be more likely from having to run a much heavier spring rate to compensate for the increase mechanical advantage due to the extreme shock angle - vs. the primitive damping provided by the shocks. It would be more likely to top-out due to the springs overpowering the rebound damping.
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10K thats just taking the piss
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I like it!
I agree with VMX re the rising rate of the shocks BUT THAT ASIDE the SR500's of Williams & Gunter had falling-rate rear suspension; did it slow them down? Anyway I don't agree with rising or falling rate, whether it's MX or roadracing,straight rate is where it's at.
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I like it!
I agree with VMX re the rising rate of the shocks BUT THAT ASIDE the SR500's of Williams & Gunter had falling-rate rear suspension; did it slow them down? Anyway I don't agree with rising or falling rate, whether it's MX or roadracing,straight rate is where it's at.
Sorry mate but a straight rate on a motocross bike doesn't work.. everything you buy now has a rising rate, even KTM built the equivilent of a rising rate into their linkless PDS shock.
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I like it!
I agree with VMX re the rising rate of the shocks BUT THAT ASIDE the SR500's of Williams & Gunter had falling-rate rear suspension; did it slow them down? Anyway I don't agree with rising or falling rate, whether it's MX or roadracing,straight rate is where it's at.
Sorry mate but a straight rate on a motocross bike doesn't work.. everything you buy now has a rising rate, even KTM built the equivilent of a rising rate into their linkless PDS shock.
The PDS has a relatively straight mechanical advantage and then the compliance is tuned with spring rate and hydraulics isn't it?
Which is the whole point - it's easier to work with two variables rather than three.
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I like it!
I agree with VMX re the rising rate of the shocks BUT THAT ASIDE the SR500's of Williams & Gunter had falling-rate rear suspension; did it slow them down? Anyway I don't agree with rising or falling rate, whether it's MX or roadracing,straight rate is where it's at.
Sorry mate but a straight rate on a motocross bike doesn't work.. everything you buy now has a rising rate, even KTM built the equivilent of a rising rate into their linkless PDS shock.
The PDS has a relatively straight mechanical advantage and then the compliance is tuned with spring rate and hydraulics isn't it?
Which is the whole point - it's easier to work with two variables rather than three.
Yes basically, it stiffens up toward the end of it's stroke.
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It looks way overpriced and dodgy to me..
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haha - I'd have to look at some better photos to be sure...
But they look like IT400C forks!!
It even looks to have Yamaha fork gators (the brass vent type), and that's definitely a Yamaha '75/'76 fork gator clamp that the brake cable's running through.. ::)
Not the best photos, and we were discussing another matter - but check this out and tell me they don't look the same...
http://www.yamahait.com.au/forum/index.php/topic,10046.0.html
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The $10,000 question is 'does the seller know it's not as represented' or is he just overselling it like a good used car salesman :P.
My money says 'a bit of both' ;). Buyer beware!!!
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Welds look a tad fresh around that reed block, header of the pipe looks to be standard with cones tacked on afterwards. Would cost about $1000 to do yourself
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I'd have tho't thats as highly suspect as his protoype Kaw (bighorn).
IIRC Desoto was long gone from Suz by then.
I'd have said they were IT400C forks too (but w shortened forktubes), which would be circa 76
No decent/reputable R&D would have used lengthened stock 400 swingarm. It'd be about as flex-resistant as soggy speghetti.
In general, rear shocks inclined to about 30deg from vert are rising rate (eg 77 & later huskies). From 30 to about 40/45deg it starts rising rate then goes falling rate part way thro the stroke (eg 75/6 huskies). Beyond about 45deg they're falling rate pretty much right thro the stroke (eg GP2 Phantom, VA Monties)
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As for suspension this set up would R&D really have popped for a set of RM shocks given they had the damping sophistication of a flywire door closer...... I take that back most flywires have adjustable compression damping.
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The shocks are Konis and he had them listed for sale way over priced for a long time with no buyers, so i guess he decided to put them on the suzuki as no one was interested in them at that price. They are pretty good shocks though for their time.
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I'd have said they were IT400C forks too (but w shortened forktubes), which would be circa 76
Yeah, I doubt they've been shortened too much though - take too much off and you wouldn't have all that gap between the front wheel and mudguard.
I'd guess they've been pushed through the triples about 30 or 40mm compared to standard IT400C location, and then the excess cut off at the top of the triples..
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FUNNY, R&D ARE STILL IN BUSINESS http://www.r1dean.com/ . SHOULD ASK THEM IF THEY BUILT THIS JUNK.