Post subject: 3MA GP Tribute Build; V4 or Big-Bore Twin?
Posted: Wed May 02, 2012 10:48 am
Joined: Fri Mar 19, 2010 1:29 am Posts: 228 Location: Seattle, WA - USA
So, they say that it takes a village to raise an idiot! No, wait a minute - somewhere in South Africa there's a village missing an idiot...? However the story goes, here's what I am contemplating!
A group-influenced build of either a V4 or a big-bore parallel-twin installed in a 3MA frame. Final specifications & finishes TBD! The idea then that those interested would track the development, make open forum suggestions, lend ideas, share resources and take part in the creation of a baby which at the end of the day would represent the global knowledge of this bulletin board!
What I have to start with: 1989 3MA TZR250R reversed-cylinder frame & side stand 1999 4TW4 TZ250L Banana Swing-arm & pivot bolt NC30 VFR400 tank in reasonable shape (a few minor dings to attend to!) Squared-rear YZR Airtech tail section (kinda hate it!) Complete YPVS RZ350 motor (no carbs, or electronics!)
I'm not married to any of it, but I think that it forms the basis for the right direction. Think about any of the recent and ongoing custom / replica / specials on this forum and you guys get the picture! The big question is; do we keep the 350 twin and do a big-bore conversion, or do I sell it and get a V4 to build some sort of Johnny Bravo Uber Mass power-plant for it...?
It will be a gradual build and slow-going at first, but the idea is that I am open and the general direction will be set by forum consensus. I would naturally reserve final veto, but truly want to see what can be achieved with as much full participation and consensus as possible! Initial thoughts?
For inspiration -
_________________ Anything with an engine in it...
Last edited by JungleJustice on Sun Jul 20, 2014 7:52 pm, edited 9 times in total.
Joined: Sun Nov 05, 2006 6:10 pm Posts: 947 Location: Essex, England
Initial thoughts ....... dont do it
500 engine makes more sense, from a resale point of view
Really like what alexander has done to his frame
Swingarm depends on look / year youre creating
Power output expected/wanted?
Joined: Wed Dec 29, 2010 8:38 am Posts: 142 Location: MD
Yeah, the RZ idea requires uber work. Like cutting out the back end of the enginecase/kickstarter, even then you need to fab mounts. You would be better off throwing that RZ350 in an R6R frame as it would fit. I too have the same parts you have and plan to do an RZ500 in there as they fit, RGVSteve can do the swap, and it is popular to the Japanese as all this stuff is from them.
I say do a 3MA, but stay away from the RZ350, even a RG500 or RG400 in there would fit, not a RZ350, too wide and long
Joined: Sun Jul 19, 2009 8:51 am Posts: 62 Location: Liverpool UK.
I have built a TZR535 a few years back
Its very good fun & the power to weight ratio imho would be better than the V4.
As Alex says the 350 Engine fitment is much easier than the V4
However it all depends on what you want the bike for, track days, road bike?
The TZR even though its got a 535 motor fitted and is very fast ect.
It still just looks like a 250! and thats the problem.
If I were you, build a V4, its a bit more work but worth it in the end & it will look much better.
I started this a while ago with the intention of putting a 500 in it;
I've got a spare 350 engine and thought I could get the same power to weight ratio with a big bore 350 and end up with a lighter simpler bike. You can't beat the V4 for cool, but the speed my projects progress at simpler is better. Maybe you will help me decide, I'll be following with interest.
Joined: Sun Jan 21, 2007 4:09 am Posts: 89 Location: Calif,the only state that matters!
I've viewed a few of the NSR/RS even TZ conversions over the years@Willow Springs...all really sweet! As far as a true performace bike/track bike the 350 is a better choice/alternative than a V-4. IMO the 350 twin easily outpeforms the 500 when even moderatly tuned and the weight savings of the 350 based twin is another major reality.
A 350 based engine ,with just basic mods can deliver 70h.p with the correct pipes..and with the stroker kits avail now..its really just a choice of how fast and how much $ you want to spend.
6-7 k for a total "stock" 500 rebuild yields what 80-90ish h.p.? A proper built stroker 350 is easily on par on a basic stroker build and can easily exceed deep into the 100.h.p range,but done right there not cheap either, But IMO would be the far better track performer.
I would do a conservative 350 based stroker build looking for 80ish h.p,you'd need the basics
1.) stroker crank
2.) o-ringed head or aftermarket
3.) programmable Zeeltronic ign
4.) proper designed pipes..(this is where the power can be found and directed!)
All of which are avail from guys/vendors/members here. Example Wicked motorsports,makes billet 0-ringed heads and quality made is USA cranks,Slinger makes "stroker" tuned pipes and also does engine/port design and If I recall he has built and raced this very concept in a TZR based trackbike, His was relly nice but also had the potential to be taken much further when money allows.
The reason I'd do this setup is reliability and lower costs..you have a lightweight,great handling,fast BUT RELIABLE motor completley racetrack ready without the need to replace cranks and pistions on the scale of say a RS or TZ.....and you can still utilize the YPVS head and keep costs down. actually WAY DOWN from what a total cylinder conversion"Cheeta/Cub" etc.. would cost. By this IMO again you gain reliabilty,lower costs and retain a better spread of power,obviouslly there would be some debate and prefferances over retaining the YPVS for all out track use,but I'd keep it,even though you could probably lose another 10-lbs of elec and hardware from the project,The YPVS has always impressed me with its power spread so I'd run it on my machine until proved wrong.
But a v-4 would also be fun and interesting as well as trick,but I belive as far as performace was concerned the charactheristics of the 350 based combo would almost definatley peform better. But if the goal is just somthing really cool,or even a track based bike,built for fun! not winning your class..theres nothing wrong at all with the 500 based setup except the cost will certainly be higher. Either way its all good fun
NICE BUILD Peddrotzr! Funny, I thought that I was going to have a unique naming - what with the TZR535... What front-end and swing-arm is that?
Good start RuZty! Ditto question for you! What swing-arm and forks?
The swinger is RGV250 with a Brembo caliper from a Monster, RGVSteve merged an Aprilia RSV1000 caliper bracket with the RGV one to make it work with the Katana wheel and GSXR disc. The front is R6 and again Steve shortened the stem and made new steering stops to work with the 3MA frame. Front wheel is a GSXR item to match the rear, and the rotor size and spacing is same as the R6. Tank is TZR125, but I've got a 3MA tank as well. I haven't done anything to the frame yet other than fitting the bearings to take the R6 forks. The suspension is currently on a modded 350 frame that might actually get on the road this year and then I need to buy a TIG welder and get back to putting an engine in this one.
Well, Jungle Justice, I guess I'm just going to have to disagree with all these twin lovers. First off, you didn't give us a price range to keep this build in, and I sure enjoy spending someone else's money. So, I suggest going for YZR500 performance levels in a much more reliable and streetable package. The only way to do that is cheat on displacement. I suggest you contact this guy:
And see if he'll make you a V-4 crankcase for counter rotating RZ350 cranks, cylinders, and tranny. If that's not big enough you'll have all of the aftermarket support for the 350 to choose from. Not to mention lots of pro's that know how to make power out of the 350's. Just look at what these twin lovers are claiming for horse power- THEN DOUBLE IT!!!
PS, I hope none of you twin lovers take offense from this. They are damn good motors, they just come up a pair short on a 500 GP-Replica forum.
PPS, If Mattoon Machine says no just offer more money until they change thier mind!!!
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