Eric Gorr Big Bore Kit

[Jeepboy]

A friend of mine just recently got a cr144 kit from Eric Gorr. The powervalve was already assembled in the cylinder when he recieved it. We went ahead and reassembled the engine. Now I'm wondering if we should have checked to make sure the powervalve parts were greased and torqued. I thought I would ask here first instead of call since Gorr is busy this time of year. Does anyone who's had Gorr work on their cylinder/powervalve know if he greased and torqued it, or did he just assemble it to check for fit after the modifications were complete?
Thanks

 

[Rich Rohrich]

Eric assembles the powervalve to be ready to run.

 

[Jeepboy]

OK, I thought he would...thanks Rich

 

[bclapham]

bolt it up, and get ready to hang on!:thumb:

 

[TNUTT]

JEEP BOY,

Let me know what you think of the 144 cr. I am thinking about doing that kit. How did you have it ported mo' better power everywhere?

 

[Jeepboy]

Tnutt,
We had it ported for low to mid. My friend is a begineer rider, but heavy for a 125, so thought the 144 kit would help him out on tighter tracks. I'll post when we ride it....although the way its raining here it might be a few days.

 

[MikeeeP]

I found a cool little thing to do with the big bore kits is a compression test. Unfortunately I have no clue what the numbers were, or even if they work with other bikes of the same model - you've got a fresh engine, you can pick up an inexpensive compression guage for about 20-25 bucks at the autoparts store.

Check it new and fresh and get a baseline number. Then you can check it again in the future to see when it has dropped off 5%, 10% etc, in compression...

This might be cheating, but when you're riding a bike a lot, you don't really notice the power slowly starting to slip away... the big bore kits run GREAT, but they go through rings pretty regularly. I've had Eric do a KTM125 (144cc), RM125 (144cc), CR125 (133cc) and all ran really well - but ring life is pretty slim as he mentions on his site.

I just would check the numbers from time to time (compression) and that would give me an idea of sorts about when I might need rings.

No joke, my pistons lasted FOREVER in the bikes though. I think I changed one in the KTM once, just because... well just because. It mic'd out okay though.

Have fun with the jetting. All the bikes I've had done, were a nightmare to get done. I live at 1300 feet which didn't help and it's winter time and they are selling us crappy gas... the nearest race fuel was 2.5 hours away so we had to try and figure out a setting that would allow for decent everything - they always spooged with the crappy gas though.

You'll dig the engine.
MP

 

[MikeeeP]

When I said check the compression, I'm of course talking about seeing how many PSI of pressure you have.

MP

 

[Jeepboy]

How many sizes up on the main did most of the big bore kits require?

 

[GMX]

Originally posted by MikeeeP
... the big bore kits run GREAT, but they go through rings pretty regularly...

What year of RM125 did you get punched to a 144? And also what is regularly? Life expectancy cut in half? Im the jetting king so no worries about that :D

 

[Chili]

Originally posted by GMX
Im the jetting king so no worries about that :D

If that's the case would you mind sharing what your running in your 03 RM125 and what part of Canada your running it in? We are just starting to work on dialing in my son's for next season.

 

[GMX]

Right now I can't even remember what Im running for jets, but all I know is that I had to lean it out a whole lot. Its jetted for 2500ft, race fuel, aftermarket exhaust, and boyesen rad valve. I will be tearing my bike apart today (race on weekend) so I'll tell you what I have in it now, and will probably remember what I had it for a bit closer to stock. Im pretty sure im running a 420 main (560 stock) I need to run a leaner pilot but its not to bad (37.5, 40 stock) and im pretty close to the to of the needle for the clip.

 

[raceready99]

i have a 134 kit in my YZ. i ran a 400 main on mine before and after i went to a 410 cause it was starving for fuel and it would over heat. i had the motor done in may and i am just now rebuilding it. bout 40 hours on it. i would recommend putting a ring in them about 30 hours but i run harescrambles so its not wind open all the time.

 

[endurohero]

When eric did the big bore did he bore it off center to avoid having to modify the power valves? The reason why I ask is a local company offers a big bore and plate job for about 400 bucks canadian and a local moto guy got it done for his son's 02cr and the nightmare began.First, they didnt correct the port timing or change total area of any ports.Second they didnt correct the head for volume or squish clearance they just turned it off center aswell.(The deck of the cylinder was never changed from stock.)When the top end was reassembled and ran up it didnt seem to have much zip.After re jetting(dont ask what they came up with because that day they had almost perfect air/density)pipes reeds ignitions they where not happy so they struggled along until it threw a rod, rebuilt it and threw it again and then again then sold it for parts.Iwas wondering if anybody has heard of this problem with boreing off center.