"High-end" racing engine mods

[GPracer2500]

I'm curious if anyone has invested in any of the more "high-end" engine building services such as undercut transmission dogs, cryogenic metal treatment, blueprinting, or any other "special" build features? I'm calling them "high-end" because I'm not sure how else to categorize that type of machine work.

I imagine factory supported MX bikes get some of this massaging but what about top level racing quads?

Why aren't some of these mods more popular for quads? Why don't some of the more predominant engine builders advertise these services? Is it simply a price issue or is there another reason? Is it that the very best builders guard their techniques/methods for competitive reasons?

Are undercut tranny dogs even appropriate for off-road machines? Do their power and traction characteristics make staight cut dogs better for some reason? Just wondering...:confused:... Seems like the race oriented quads and bikes would have this as an OEM feature if it was appropriate. I know some streetbikes get undercut dogs off the showroom floor.

Is blueprinting a mostly outdated practice because of modern production techniques and tolerances? Is there really much to gain in a single cylinder application?

Who has a price-is-no-object-best-of-everything engine? Show off your commitment to ULTIMATE performance!!



ETA: I've left porting out my comments because I figure that part of performance engine building deserves a stand-alone discussion. I'm wondering about all the rest...

[ryanh250ex]

i cant speak from first hand experience, but i will say this....


cryogenic freezing is a surprisingly cheap way to get weak parts to hold up. Whenever i rebuild my 250ex, i'll obviously use a new piston, and prior to installing it i think i'll send the piston, rings, etc etc etc to the folks at percryo.com to be frozen. I'm considering a home-fabbed turbo setup, and due to the lack of parts- pistons specifically- that dont have sky-high compression and fit a 250ex, i shall use a cast piston. it should hold up once cryo-frozen.


i know alot of the banshee drag racers get their gears straight cut or use lockup clutches.

as far as the top MX dirtbikes getting this stuff and the pro quad guys not going to this level, i cant explain it. however, from everything i have heard, dirtbike trannies are not quite as strong as those found in quads, because the dirtbikes typically have less traction than a 4 wheeler does so it doesnt see the jarring impact of a clutch dump and still get traction.

[GPracer2500]

I'm with ya on the potential value of cryo treating. With all the discussion on rod and crank strength in hopped up recreational engines I wonder if our market is being underserved by cryogentic treatments. :confused:

Regarding undercut gear dogs: I probably shouldn't have used the term "straight-cut" in my comments above. Straight-cut transmission gears vs. helical cut gears are a different deal than undercut gear dogs vs. traditional gear dogs.

Stright-cut and helical refer to how the transmission gear teeth are shaped. Undercutting the transmission dogs changes the shape of the gear's dogs. The dogs are the little nubs that link one gear to another on the same shaft. This pic shows an undercut gear dog. The undercut dog is the circled part:

http://www.aperaceparts.com/resources/transmissions/undercut.gif

Undercutting involves beveling the dogs. The dog is wider at the end an then tapers down slightly where it connects to its gear (think wedge-shaped). The effect is that when undercut dogs meet the dogs of another gear the taper "draws" the two sets of gear dogs together. You only have to get an undercut dog to just barely engage another set of dogs and they will "snap" together on their own. This creates a very possitive feeling shift. Undercut dogs are also less prone to inadvertently disengaging.

Next time you get a chance, swing a leg over a Yamaha R6 (or CBR100RR or ??) and toe the shift lever around. You only have to barely engage a gear and it "slips" in the rest of the way on its own.

[EXevan91]

lol as u can see no one has these complicated mods done because most have no idea what these mods are and iam sure some of the pro teams have that kind of time and money into their very expensive/sponsered motors.

[300ex mxracer]

i know yoshimura blueprints and polishes doug gusts engines.

[sixer3]

ya, i know for a fact yoshimura does it to their suzukis, that stuff isnt cheap, but i guess the blueprinting makes a pretty noticable difference, only heard that never got to try it myself :ermm: