Revolution Racing frame mods + my engine build

[Jscobey]

well ive got things all set up with a local racing engine builder out here in So Cal. they do alot of MX and superbike building for local club racers all the way up to AMA and professional racers. the build quality and the work that comes out of there is insane and it just so happens that the owner/head builder is a good friend of one of my really good buddys as well as a VTR owner and is really excited about the project.

im bringing my engine in to have the JE pistons put in as well as either a hone or a resleeve because he wants to see less than 5% on a leakdown, a set of hard weld cams (similar specs as STG 1 Mori's), polished new OEM valves as well as guide seals, new main and big end bearings as well as a look through the gear box and make sure everything looks good and possibly do new gearbox selector forks and shafts, as well as gearbox bearings, Port and flowed heads, a balanced crank, new seals and gaskets all around, a larger oil cooler, and a few other odds and ends. after everything is done and built, they are gonna dyno and tune, as well as a go through of the carbies, to get the most out of everything.

im actually very happy with the price they quoted me including all parts. because the owner is a close friend of my friend, and also loves VTR's they are only charging me their cost for parts so no up-charge and a minimum hourly rate for the labor. plus they said i can hang around during the build to learn a thing or two or five.

anyways while i have my motor pulled, ive been taking to my buddy that owns a fabrication shop and who also did my swinger brace about doing the Roger D. style frame bracing which includes the 3rd spars on each side, bracing at the head stock, as well as plating in the diamond section at the rear of the frame.

my questions regard the specifics of this process for anyone who has done it. what thickness and type of alum was used in each area? Im also wondering, for those that have done it, how did you like the effects on the chassis dynamics? considering my build will land me somewhere around the 120 - 125 bhp mark based on builds ive seen with similar specs and what the engine builder doing my work has concluded, is this enough output to require such bracing? maybe some but not all? i dont want to go to stiff per my power output and loose "feel" sorta speak. just looking for any experience from those of you that have done this kind of build before and what your thoughts are.

in regards to the chassis im also considering swapping an SP2 swing arm on because its much lighter than a stock VTR swinger, let alone a braced VTR swinger, and i feel that it would net better performance, as well as looking pretty sweet! although im sort of leaning towards waiting until a later point as i dont want to make to many changes all at once plus im not sure if i want a longer wheelbase that the SP2 swinger gives.

glad to come across these photos from gl_s_r's build so i have more references for my fabricator.




i will be posting pictures and updates here once we get underway. I'm open to advice, criticism, and experience from everyone! really excited to finally see this project materialize!

[tony.mon]

Sounds like a plan!

The bracing on a VTR swingarm weighs next to nothing if cut from a Blade SA, and these bikes are already long and lazy in the turns, but more stable as a result. Fitting a longer SA will only make that worse.
But there's another concern; the SA is mounted onto the back of the gearbox casting and tuning the engine too much can result in the casting/mounting points fatiguing and possibly cracking- failures have been known.
A longer SA will increase the leverage and exacerbate the issue.

Stiffening the frame and then stiffening the SA as well might make it too rigid- I'd be tempted to do the frame work and then see how it rides.

[Jscobey]

interesting point on the SP2 swinger causing added stress to the casing. tweety is running an SP2 swinger with a much higher output engine. i beleive hes got a 130bhp and another 150bhp engine IIRC. he hasnt done anything to reinforce the area where the swinger bolts to the engine either i beleive.

i think you are spot on tony. the storm is already pretty long and i think any longer and your doing more harm than good... at least from a performance standpoint

[VTRDark]

Good to hear you finally going to get them high comps in . That will be one super duper VTR by the time it's finished. I look forward to so,me progress pics, especially of the engine being built.

As for the frame, quote from Roger

Exactly so. The headstock area is plated with heavier gauge plate than the rear side sections. the 3rd pillar is correct. It is important not to make a "V" twin too stiff because of the torque otherwise the handling goes to pot and all feel is lost.

http://www.vtr1000.org/phpBB3/viewtopic ... 45#p243744

You should go through that complete thread as there are some interesting snippets in there. If you have any questions about the frame stiffening or anything else VTR related for that matter, shoot Roger an email, he's very approachable and extremely helpful and of course his knowledge, well... you wont find any better.

(:-})

[8541Hawk]

Well I hope reinventing the wheel goes well.

Just saying that as it seems you missed Honda USA also built a racing VTR with input from Moriwaki and all those folks (except for 2....one up north and one passed....RIP Bob H.) are still around.
So if you know who to ask, Moriwaki and HRC connections are plentiful here.

The VTR is a bit different than other bikes and has its own set of issue...... which I guess you'll find out.

Though one last parting tip..... You do know that your Ohlins shock will no longer work if you swap the swingarm..... and that is just one of the easy traps on this bike.