? on Eric Gorr Big bore kits

[Gary Drake]

I blew up my 99 RM 250 last weekend and am thinking about Eric's big bore kit and was wondering about the pros and cons and what kind of time frame it takes to get it done? Are there over heating problems and is there a lot of jetting changes? I mostly ride woods/trails. I would call him but my work hours make it impossible. Thanks, Drako

 

[Senior KX Rider]

My KX has been a 310 for 2 years and I have had no reliability issues at all. The pros: much more power and Eric will put it wherever you want the power. Cant say as I can post any cons. I am completely satisified. As for turnaround time you would have to call eric about that.

 

[bscottr]

Gary,
I asked Eric for a 265 kit for my KX and I'm very pleased with it. You'll need to deal with jetting just as you do now, no significant changes to that. From what I understand Eric doesn't "take it to the limits" as some other folks do, so overheating shouldn't be a problem.
As Senior said, more power and where you want it. For what it's worth I went with the Mo Better porting for the very smooth power delivery in the woods. Ask Eric for the best options for your bike.

 

[kev_rm]

how did you blow up your rm250? has it ever had the top-end replaced?

 

[bigred455]

I had the 2mm overbore on my 00 kx 250 with eric's porting mid -top.The kx flattens out sooner than other brands stock,but it has great bottom.With the overbore and porting,It felt even flatter.The roll on was excellent coming out of the corners better than stock for sure, hardly touched the clutch,but I did sacrifice some pull up top.I told him I did not like it and I am getting another stock cylinder.He found a customer for my cylinder and he set it up I told him what I wanted for the cylinder. He told me it was worth more than what I was asking .I just wanted to get rid of it,he send me a check for 50.00 dollars more than what I was asking not bad .I am one of the very few who wasn't totally satisfied I am pretty dam fussy.I believe I should have repalted my cylinder back to standard size and had eric ported then.For 1 reason I like oem pistons,and another I love kawa's head gaskets.I have a 00 kx 250 and I am waiting on the 03,I am going to send him 1 of them and just let him port it.I just don't think the overbore was for me.I do believe I will like his porting though.

 

[afm_722]

I've run my 310 for 2 years and have been very pleased. The big bore on pump gas with the stock pipe, pretty much made the bike into a diesel and I rode it accordingly, kept the stock gearing, and had a lot of fun and success on it.

Check this out, I recently made the jump to an FMF Gnarly (recommended pipe for Eric's 310 combo), a longer silencer, race gas (and corresponding leaner jetting), and Eric's recent porting updates for his 310 cylinder. In a nutshell, the engine is unbelievable. I had adapted my riding style to a very effectice low-mid motor before, but with this new version it's "hold on" time. The pickup in the mid-range and top end was absolutely incredible. For trailrding weekends, I'll probably mix 50/50 for the gas change a few jets and just have a blast.

Eric has come through everytime with anything I have worked with him on. He recently cleaned up the head and did some porting on my friend's CRF450 and he is very very pleased. The only problem Eric might have is turn around time (but that's a nice problem to have!!) :). There's certain slowtimes that he can advise you of or he might also offer a cylinder exchange program to speed up the process.

Bottomline is you get more than what you pay for and it's definitely worth the wait!

 

[Senior KX Rider]

Originally posted by afm_722
but with this new version it's "hold on" time. The pickup in the mid-range and top end was absolutely incredible.



Bottomline is you get more than what you pay for and it's definitely worth the wait!

Couldn't have said it any better myself :)

 

[Canadian Dave]

Eric did a 275 big bore on my 99 YZ250 and I love it. I wanted the power to be as smooth as possible for woods riding and some unintimidating fun on the MX track. I’m very happy with the results. The power is very smooth and friendly and definitely works to my advantage on and off the track.

Give Eric a call and talk to him about your options. He’ll supply honest and accurate feedback on your wish list and you can make your decision from there.

David

 

[whyz]

We have a EG/CR100

Yesterday I looped it (in fact it looped me)and ghost ridden off the track while I was in the dirt. I dont think it likes me riding it. Awesome! :confused:

One false move on that bike and Aloha ay!
Had a blast!

The YZ seized yesterday so its goin in this week. Hopefully its not too bad.
See Ya...

 

[BSWIFT]

Big bore, big power. If you like bottom end pull with smother mid to high you can't go wrong. 310 kit = big :).

 

[splatt]

I just called Eric on Thursday and he said turn around is about ten days right now. My 94 YZ250 top end is gettin sent out this week for the Mo Better treatment. and from what I`ve heard from alot of you guys I can`t wait til my first ride with it.

Steve

 

[whyz]

My son and I just crated the YZ motor last nite to be flown.
Wanted to see what was inside :| Piston particles everywhere.
Just to be safe,I'll be having the bottom end done also.
Could a motor seize because of reving down or up alot? :silly:

Thanks..

 

[Unit74]

I sent my KTM 400 motor to him on Aug 12 from SoCal. Yep...All 85 lbs of it and I expect it back by the this coming Friday. I opted for the Mo Better treatment on kept it on stock compression to avoid the" I ain't got money for race gas " blues. I am very excited to see what it's gonna feel like.

 

[Unit74]

Still waiting..................Grrrrrrrr

 

[NO HAND]

Originally posted by Gary Drake
...is there a lot of jetting changes?...

According to my experience there was some jetting changes needed, mostly in the area where the power was increased. I have a mid-top ported cr 133 and had to richen all across the board. The low speed had to be a tad richer but the main needed a few sizes up. I hear some people have to lean out after a big bore kit. It's hard to predict, but it's worth it :cool:

 

[Rockey5000]

Originally posted by whyz
My son and I just crated the YZ motor last nite to be flown.
Wanted to see what was inside :| Piston particles everywhere.
Just to be safe,I'll be having the bottom end done also.
Could a motor seize because of reving down or up alot? :silly:

Thanks..

Did the skirt shatter? Thats usually too much piston slap, or too old a piston. If the piston shattered I think its usually because it got to hot or the piston is too old.
Is it stuck at the crank or at the top end?

 

[whyz]

I have'nt been informed yet on what had happened, except there was particles in the pipe and also the reeds,dont know if the crank was stuck.

All he said was that He was surprized that the cylinder wall was not that bad.
I'll let ya know when I find out.
The piston has been in there for a year and I should have changed it on a regular basis. My screw -up. :|
See Ya...
Just got back from the beach>> 75 deg. and clear>> oysters/crab/clams. :cool:

 

[Pantera]

I have never had motor work done without aggrivation of some sort EXCEPT the work I have had done by Eric gorr.Timley,exceptional price and relability.Hows that?

 

[woonga]

Well I have only raced my YZ125/144 for 1 race so far. Keep that oin mind. 1st off I noticed a big gain in low end, great for H/S , 2nd I noticed that Mid range pull is very smooth, deep sugar sand use to make me clutch to keep the revs up, now its just twist and you can feel it pull like a tractor.

I have a low end vibration that will really give your arms a work out in the real tight stuff. Other then the vibration everything is an A+, but yet if given the option to return back to stock or keep the EG kit with Vibration. I'll keep my kit.

Now I did do a tear down to see what the vibration may be after the race thinking rod bearing, but nope everything is good so slaped a new set of gaskets in her and she will be run again this weekend.

 

[whyz]

Doin some cycles tomorrow. :yeehaw:
Back order on sprockets :|
Got everything else serviced this weekend :cool: Lotta work :silly:

I was so excited that I forgot to ask EG what he thought
might have happened. I'll ask him the next time.

 

[Brian]

I rode KelvinKDX's KDX 225 and will have Eric work his magic on my KDX the second I can afford it. I couldn't believe it. Big :) s from me!

 

[whyz]

got it going today(using older sprockets and chain).
PJ went up 2 sizes from 25. Clip 3rd. and MJ-460-stock. 26:1
This is what I put in before the break-in cycles and is still in the bike.

We babied it for about 4-5 hours with cooling periods. Then> Ripped!

Throttle response is instant off idle.
No clutch work like it use to be. It just flat out pulls and pulls.
It seems the power is broader.
I rolled the throttle on, then wicked it, Holy Ka Moly. WOW!
I have to rejet later(well maybe) Just the PJ by dropping one.
One thing happened though (It backfired once) at starting
after riding for awhile,maybe to much gas or ?
Gonna check timing (maybe?) See how it goes tomorrow.
All in All>> This bike is much better than before :yeehaw:
It's really easy to ride compared to before. :cool:
meaning that it has MORE controllable Bigger POWER.
(133 kit with a MBE powerband.) :worship: Thanks Mr EG.

 

[whyz]

Forgot one thing>
Power stays to the ground.Very tractable.
Wheel spin is a non issue.

 

[splatt]

I just got mine back today and I`m about as exited as a kid in a candy store to get it up and running.

Steve

 

[KXaggerator]

Initially, when I got my 310 put together I was disappointed. After breaking in the bike for a few hours I got on the throttle and the bike felt like it lacked snap. My first ride was at dry and dusty Hollister Hills and I did not realize it at the time, but I was suffering from wheel spin on the dusty hard pack that is until I got onto the freshly watered TT track. Geez...I got big eyes out of the first big sweeper when the bike pulled a 4th gear wheelie out of the corner. On the straights I was king of the drag, none of the other 250's and one YZ400F could keep up. I then took it to a tight twisty hill climb and found that I could lug the motor in the tight places much like I do with my 500.

Horse power wise the increase was good, but for me the best gain was the added torque. My only regret with this bike is that I wish I could get a wide ratio transmission to take advantage of the power.