Posts
38
Joined
10/27/2017
Location
Granbury, TX
US
Edited Date/Time
2/15/2021 12:56am
Hi All,
I have searched and can't find my specific answer. So don't kill me if it's in here. I have a 2019 KTM 125SX that I got a few months ago. Absolutely love this little bike, so light. Not too much power. Bought it for my son but he doesn't want it. I let him have my 2016 350SXF. I also have an '18 450SXF that I bought for MX. I do mostly offroad racing in north Texas which is pretty wide open. Very little slow technical but we do get into the woods. I set up my 350SXF as my woods racer and did double duty when I did Vet MX. Was getting beat on the 350 (too lazy to shift) so I got the 450. Only had a couple of rides on the 450 and I am only a little faster on it. I am thinking of converting the 125 to an offroad racer for our tighter woods tracks. My question comes down to would a high compression head and maybe pipe/silencer increase the power equivalent to the KTM 150 kit? Wonder if anyone has done that and can answer. I know I will be giving up some torque down low but you gotta scream the 125 anyway. I have only had a few chances to ride with my friends in the woods and on the track. Seems like I am just a tad slower on the 125 but man when it comes to tight corners, whew what fun. Also, I am jumping more easily as this bike feels like I can do almost anything and not get too out of control. I don't have the same feeling on the 450.
Thoughts?
Anyone put an XC tank on a '19SX? The body is different for 19 but I know it can be done for 16-18.
Many thanks
I have searched and can't find my specific answer. So don't kill me if it's in here. I have a 2019 KTM 125SX that I got a few months ago. Absolutely love this little bike, so light. Not too much power. Bought it for my son but he doesn't want it. I let him have my 2016 350SXF. I also have an '18 450SXF that I bought for MX. I do mostly offroad racing in north Texas which is pretty wide open. Very little slow technical but we do get into the woods. I set up my 350SXF as my woods racer and did double duty when I did Vet MX. Was getting beat on the 350 (too lazy to shift) so I got the 450. Only had a couple of rides on the 450 and I am only a little faster on it. I am thinking of converting the 125 to an offroad racer for our tighter woods tracks. My question comes down to would a high compression head and maybe pipe/silencer increase the power equivalent to the KTM 150 kit? Wonder if anyone has done that and can answer. I know I will be giving up some torque down low but you gotta scream the 125 anyway. I have only had a few chances to ride with my friends in the woods and on the track. Seems like I am just a tad slower on the 125 but man when it comes to tight corners, whew what fun. Also, I am jumping more easily as this bike feels like I can do almost anything and not get too out of control. I don't have the same feeling on the 450.
Thoughts?
Anyone put an XC tank on a '19SX? The body is different for 19 but I know it can be done for 16-18.
Many thanks
I ended up dropping in because I have so many part for the bike. When I got it done, I only street tested the 150 and it’s got wayyy more juice than my 125 that was ported + VHM high comp head. My 125 was really good and would scream up top but tough to ride is tight situations.
To convert the bike, I did a OEM 150 kit with the RK Tech high comp head insert. 9oz flywheel weight, 18in rear wheel and XC tank. basically the only difference I have from stock XC is the transmission ratio. But I went up a tooth in the rear to help lug in tight spots. I’m also working with different power valve springs to see which is best.
I’m going to trail text next week and can give you a better comparison.
This is when I had it set up for track riding but was using it offroad (Not sure why all the photos load sideways now)
Rebuilding here:
The small bores will never lug like a 300 but this set up is pretty impressive so far!
The Shop
I am probably no where near your skill level. I race Over 52 Amateur offroad, sometimes Over 45 to race with friends. I will have the opportunity to race it stock in a couple of weeks, hopefully. Our first race back was rained out yesterday, bummer.
I did all the Jarvis mods - drain bolt holes, drilled out baffle holes, crimped over flow tube and filed slide. We are at elevation 4000 - 7000 ft. The Mikuni at elevation on the 150 is a very finicky carb. On the days its running well I believe it makes more power than the Keihin ( which we have run a 36mm ) if you want a set it and forget carb just put a Keihin on it.
Pit Row
Sick looking pipe, for some reason not many people know about it.
Anyone with experience like this please let me know
I ran Smart on rm144, and lectron onnsx150 and prefer a regular carb.
Silencer is important on sx150, most aftermarket ones are slower because the outlet is too narrow
https://www.ktm-parts.com/50405907000.html
https://www.ktm-parts.com/51605907500.html
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