long rod 125 motors

I read something about them but I'll wait till I find it again before I put up the info in here.

sage...long time no hear!:)

check this out

http://www.dirtrider.net/forums3/showthread.php?threadid=53548

changing the topic slightly, i wonder how long it will be before people start selling stroker cranks ready to go. at $180 the complete wiseco crank is not far off the price of a new rod and the labor to fit it!

Sage, the rod length on a KTM is 110mm, 5-6mm longer than Jap OEM rods. They're changing the rod to stroke ratio, which enables the piston to dwell at TDC longer so as to produce a higher pressure rise before the piston starts on the downstroke, which should raise the overall BMEP.
Not exactly a new development, back in the mid-1980s we were buying up old Honda NSR 250 cranks and stripping them down for the 110 mm rods so we could fit them to CR125s. Over the past 20 years rod ratios have gone from 2.01:1 to 1.77:1, and now they're moving back closer to 2 again.
Theres a lot of other factors to consider when installing a long rod kit, spacer plates for the base and modifications in port timing are needed.
One common myth is that a long rod changes the displacement of the cylinder, but it actually it increases the crankcase volume. Some tuners like the guys at Honda stuff the crankcases with epoxy to compensate for the volume added by the longer rod.
Its not for everybody and it takes a lot of planning to implement a long rod kit effectively.

92 Husqvarna had 110 mm rod , just try to find one . ProX used to make and sell at LA Sleeve but-NLA- .

They are considered amateur even in the Pro class so you are allowed an .80 over bore or stroke - there is your hp that you are looking for.

Of course, a couple seasons ago all the women were running (ahem) 167 kits which were totally illegal so... then again they out of respect for one another never tore each other down.

I know Stefy was running 125s though because she had to run the same engine for WML racing and for AMA racing when she tried to qualify for the AMA Pro class (not WML Pro).

With that said, think about the big bore .80 over kits. They put you out to 133cc and are totally legal in the womens classes.

MP

EricGorr said:

Theres a lot of other factors to consider when installing a long rod kit, spacer plates for the base and modifications in port timing are needed.
One common myth is that a long rod changes the displacement of the cylinder, but it actually it increases the crankcase volume. Some tuners like the guys at Honda stuff the crankcases with epoxy to compensate for the volume added by the longer rod.
Its not for everybody and it takes a lot of planning to implement a long rod kit effectively.

Click to expand...

OK, i am not going to stop until ive driven Eric insane with my questions, and if evenone else knows then chip in!!!

Eric, on the site you are talking about the long rod retro fit on the RMs. Since the cylinder has already been ported to your MoBetter 144 specs, does it need additional porting to work with the long rod setup? does the increase of additional crank case volume create a big isse with this kit?

thanks