Tractor Pulling CR500?

[M.F.D.B.]

Ive been thinking, I ride the shnit out of my cr250 every weekend and never notice vibes when im riding. The bike vibes, Its just not enough to notice when you are jumping 60-80ft jumps. Im wondering if you can port a 500 for such low end torque that it basically "signs off" before the vibes get bad enough to notice, say 3000ish rpms? Basically get the power way above the 250, yet keep the revs low enough to keep the vibes similar or less than a 250.

Just an idea:

Real high comp ratio and proper dome (100 octane minimum of coarse)
Stock pipe or even a custom tuned (dimension wise) stocker or Gnarly
Advance the timing a bunch
Of coarse a lot of port timing mods all done for bottom end
36?mm PWK A/S

The main thing that keeps me from AF'n my steelie is I just cant stand the vibes and the motor is tits, no bad bearings or twisted crank, etc. I think a setup like this would make one bad ass Woods/Single track setup that wont numb your hands and feet...

[AlisoBob]

Building a good chassis is easier.

I've posted before about this simple fact.... go up a hill under power at 5,000 rpm and you will feel the " power impulses" of 65 hp. Go down the same hill at 5,000 rpm and the bike is way smoother..... less power impulse now that the motor is making 10 hp.

Balance has nothing to do with it...... unless its a Siezco in the bore.

[Gravel Scratcher]

Balance has nothing to do with it......

Huh !
If your talking about the engine, i totally disagree.
By there very design a single cylinder engine will be out of balance (vibration) unless they have a counter balance system. From my understanding when you "balance" a single cylinder engine all your doing is moving the vibes from 1 part of the rpm range to another to suit a particular riding style or application. If M.F.D.B is looking for a woods/ single track machine i would be looking for a crank balance with the vibes in the high rpm area of the engine and the opposite for a flat out desert racer. I don't see how the other stuff he wants to do will have a great effect on vibration.
I totally agree about getting a chassis /suspension set up, its the best money you can spend on making you quicker.

[M.F.D.B.]

Balance has nothing to do with it...... unless its a Siezco in the bore.

you will feel the " power impulses" of 65 hp.

I like this theory, but why would a counter ballanced motor making the same power be so much smoother?

[AlisoBob]

Cuz the counterbalancer acts like a big flywheel weight.

[M.F.D.B.]

So do you mean you feel that the counter balancer absorbs and then releases energy alternately from the crank hiding the "power pulse"?

I had a 16oz flywheel weight on the bike when I bought it, after removing it I didnt notice an increase in vibes?

[2strokeforever]

I think a setup like this would make one bad ass Woods/Single track setup that wont numb your hands and feet...

the only time my hands go numb is when im freezing
i dont see what the issue is if everything is right, my bike dosent numb my hands at any RPM(and i go on long rides all the time),even with a 1 sided headstay, sure i wouldnt mind less vibes, but there not bad
i did hear that crank balancing really tones it down tho
i notice the vibes most in neutral reving it???? but maybe i just ignore it while riding

From my understanding when you "balance" a single cylinder engine all your doing is moving the vibes from 1 part of the rpm range to another to suit a particular riding style or application

in theory, but they also fix hondas poor tolerances too, cant remember who but someone posted on this site about it and they had 5 grams removed from 1 side and 9 from the other or something like that, the point is they werent close from side to side
i think it was mick

[Gravel Scratcher]

balancing will refine on hondas tolerances but in general if it left the factory it was probably in tolerance. Loose tolerances are from shit quality control at the factory or the parts are worn, which is more likely. There is a whole lot more to balancing a crank than just making sure the weight is the same on each side. Balancing a crank is a real black art that very few can do, like i said it comes down to where do you want the vibes in the rpm range. Honda produce a product for the masses which is not a fine tuned race machine, if you want that you better stump up the $$.

[2strokeforever]

heres a link
http://cr500riders.com/cgi/yabb/YaBB.pl?num=1159539306

mick from the other site says

It's been years now since STR's work, and my bike feels no darn different than any smooth running 250

Surf 'N Turf Racing balanced crank $325
'94 CR250 ignition $90
Nuetech TuBliss core $100

That's the first $515 I should have spent...

[Gravel Scratcher]

you also forgot to quote

It has still got a spot that shakes a bit when going up and back down a particular spot in the power


I'll stand by my statement.
Balancing will help but unless you balance all of the spinning parts (crank, piston, rod, flywheel etc) as a whole i reckon your wasting your $$ Heres the kicker though as soon as you change something weight wise your back to square one.
MFDB if your gunna do it just be aware its not a one off thing that lasts forever.......sorry for hijacking your thread to I looked into this when i had my roadbikes done and while i'm no expert i did enlighten myself enough to make sure the shops were not taking me for a ride.[/quote]

[2strokeforever]

Balancing will help but unless you balance all of the spinning parts (crank, piston, rod, flywheel etc) as a whole i reckon your wasting your $$

they do all that except the flywheel... i guess thats a good point, ill get my flywheel balanced when i do my crank

MFDB if your gunna do it just be aware its not a one off thing that lasts forever

its suposed to make the balance point at a higher rpm as your piston gets heavier
but ill prolly get alu/nikasil bore so it should last forever