PDA

View Full Version : CR 250R engine in a TRX 250R


Jared Cole
02-13-2010, 09:03 PM
I'm new to 2 stroke quads and just recently purchased an 86 TRX 250R. I was wondering if a CR 250R engine would fit in a TRX 250R frame and if it would is it even worth doing???
86 Quad R
02-13-2010, 10:21 PM
do a search. should find plenty of info on the subject. most of which is that it isnt worth it.
LT80
02-14-2010, 11:49 AM
It'll vibrate the frame apart.
That's why the TRX motor has a counterbalancer.
rooster300ex
02-14-2010, 11:55 AM
Does service honda put a counterbalancer in the engine they use?
smokinwrench
02-14-2010, 11:58 AM
I wonder how service honda gets by with it on there cr powered 400ex hydrid? I would guess that if it was a total pice of junk they wouldn't build one.
LT80
02-14-2010, 01:05 PM
I've wondered about the SH Hybrid myself.
destey
02-15-2010, 07:09 AM
Probably has been asked a zillion times, but why is there no counterbalancer in the cr250 or 500? just to save money?
rooster300ex
02-15-2010, 12:09 PM
Originally posted by destey
Probably has been asked a zillion times, but why is there no counterbalancer in the cr250 or 500? just to save money?
Naw not to save money
mohler
02-15-2010, 07:27 PM
less rotating mass= more power
destey
02-16-2010, 05:05 AM
moves at 2x crank, so at 8k rpms, counterbalancer is moving 16krpms.

Maybe 1/2 a hp to spin something that fast?

So by removing a counterbalancer you gain 1/2 hp and get a motor that vibrates uncontrollably?
86 Quad R
02-16-2010, 05:57 AM
Originally posted by destey
moves at 2x crank, so at 8k rpms, counterbalancer is moving 16krpms.

Maybe 1/2 a hp to spin something that fast?

So by removing a counterbalancer you gain 1/2 hp and get a motor that vibrates uncontrollably?

are you cornfusing this to the 4 poke cam shaft versus crank? my counter balancer is same revs as crank. :confused:
destey
02-16-2010, 08:31 AM
I don't have one of those motors so I was going off this wikipedia (http://en.wikipedia.org/wiki/Engine_balance) article.

"The second of these is the main consideration for secondary balance. There are two main control mechanisms for secondary balance—matching the phasing of pistons along the crank, so that their second order contributions cancel, and the use of Lanchester balance shafts, which run at twice engine speed, and so can provide a counteracting force."

can someone confirm the counterbalance gear is the same size (not half) as the primary?