133 Kit in a KTM 125 SX??

Joined
Jan 8, 2001
Messages
23
Likes
0
#1
Has anyone had any experiences with the 133 kits in the KTM 125's? I've read threads here, and spoken to racers about their results with the kits in the Japanese bikes,, but haven't heard or read a thing of the kitted KTM's. What were your results,,power spread,, where were the most gains,,, what pipe recommendations,,reliability????
 
Joined
Feb 24, 2001
Messages
132
Likes
0
#2
why do you need a bigger bore on 125? especially since if it is a newer ktm it has a nickasil bore, and that would require a sleeve. if more power is what you need get a 200 or 250.
 

HiG4s

Subscriber
Joined
Mar 7, 2001
Messages
1,308
Likes
0
#3
Actually Eric Gorr does the big bore kits and they are plated not sleeved.
 
Joined
Jan 8, 2001
Messages
23
Likes
0
#4
Let me clear the air a little. My son races motocross on a 01 125 SX. 133 kits are legal in the modified class for the Loretta Lynns Amateur Motocross Nationals. We competed there in '99 on a stock bore RM, and got out motored BIG TIME!!!! After learning that most of the bikes in the mod class were running the 133 kits, we decided that to be competitive there, that was the modifications we needed.
As this year progresses, 133 kits are showing up in more and more bikes even at the local level, and as the saying goes,,,"YOU GOT TO PAY TO PLAY"
I just want to get feedback from others who have the kits in their KTM's, before we make the PLUNGE!!
Oh Yeah,,,,as for getting a bigger bike with more power,,,he rides my 300 KTM when he really wants to sling some dirt!!
 

Reon

Member
Joined
Apr 11, 2000
Messages
101
Likes
1
#5
The 125 KTM probably puts out the most HP of any 125 out there. Have you considered other reed valves, a Doma pipe & silencer maybe and a bit of porting ? Then offcourse its probably 80% rider & 20% bike, so maybe some lessons from a expert might enhance things too.

It's not the amount of HP that counts but what you do with it.... :)
 
Joined
Jan 12, 2001
Messages
196
Likes
0
#6
Reon,

What your forgeting is that the 133 kit is ama legal. So when you say that the ktm 125 is the fastest 125, you are probably right. But its not the fastest 133!

There is no replacement for displacement!!!

Mark
 
Joined
Jan 12, 2001
Messages
196
Likes
0
#7
motowrench, i would just call eric gorr. He seems to be the man in this area and I don't think I have ever seen any negative comments about his work. Good luck
 
Joined
Dec 5, 2000
Messages
139
Likes
0
#8
I have an '01 125 SX with an EG 144 kit installed. What a difference. The stock 125 is very fast, but a little hard to ride if you are coming off of a bike with a broad spread of power. The 144 kit was based on a '00 125 cylinder and includes porting and head mods. The 144 has decent bottom (for a 125), unbelievable midrange and really strong top end power. It may have a shade less top end than stock, but then again the bottom and mid are now so much stronger that the top end may not appear as strong any more. I bought the kit used so I didn't get to specify the type of power I wanted. If you call Eric, he can port it to produce the kind of power you desire. As for reliability, I don't know yet. I have done 3 GNCC races and countless rides in the last two months and haven't had a problem yet. One thing to note is that the top end will make a lot more noise with the big bore kit and I'm told this is normal. Just for reference, I rode an '00 200 mxc the previous season and loved the bike, so I was a little reluctant to go with the 125. Even though the 200 had a better spread of power, the 125 just handles much better. Most people are surprised about this, but it's true and the difference isn't small. With the punched out motor, the SX kicks butt in the woods. It's a lot easier to ride than a typical 125 and screaming fast when you are on the pipe. Plus the light weight and quick handling of the 125 chassis make it an easy ride for endurance events. I think I know of someone that is selling a used 133 kit if you are interested.
 
Last edited:

Reon

Member
Joined
Apr 11, 2000
Messages
101
Likes
1
#9
Mark, point taken. So if you went to 133cc it would probably be the fastest 133 in that class ?
 
Joined
Jan 12, 2001
Messages
196
Likes
0
#10
not necessarily, but if as racers we would look for every possible advantage possible and the rules allow for an overbore, wouldn't you do it. Tell me that you would race a 125 in a class were 133's were allowed. By the time you get done with pipe/silencer/reed cage and porting it would be the same cost as Gorr doing a 133 kit and personally i would think you'd be further ahead. I'd just personally not want to give up cc's. If you look at this one particular case of motowrench i know alot of people who do the Loretta Lynns Amateur Motocross Nationals and the kids who race there are scarey fast i would take every advantage possible and most of these parents do for the kids.
 

lawman

Lifetime Sponsor
Joined
Sep 20, 1999
Messages
764
Likes
0
#11
if i were seriously racing mx in the 125 class, against 133's & particularly the yz250f, i'd get the big bore kit & THEN put all the other aftermarket goodies on it. eric ported my 200; the service was great, the price was right (& then some) & it rocks. the 125 does feel lighter & quicker-handling, i guess due to the lower power & reduced gyro effect (prob minimal). the 1 i rode was an exc, so the difference wasn't the lack of enduro stuff.
 
Joined
Jan 8, 2001
Messages
23
Likes
0
#12
Thanks for all the info fellow KTM'ers!! I appreciate your opinions and insight on the 133 kits.
BUDMAN,,,,Is the used kit you know of for sale stateside,,,,or from across the pond???
I also just learned of of a complete 133 Top End Kit for sale,,,but it's in Europe.
Yeah,,,You guys are right,,, There is only ONE place to go for Big Bore Kits,,,
ERIC GORR!!!!
 
Joined
Dec 5, 2000
Messages
139
Likes
0
#13
Motowrench, it's probably the same one you know of....out of the UK. I bought mine from a guy in the UK and it wasn't much of a problem. I just went to the bank and wire transferred the money and they sent the parts through UPS. If the price is right, go for it. You wont be disappointed!