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Hey guy's , one of my best bud's ( Wardy ) is getting ready to tear down his 14' KTM SX150. He asked me if I knew of a way to get a tad bit more over rev out of it , without sacrificing to much bottom and mid. His motor is bone stock , except for a bill's pipe and silencer. For a 150 , she has good grunt through the bottom and mid , and he's looking to add a little over-rev. Any suggestion's?
I know some guy's have played around with base gasket height , milling the head and so forth. I told him to call Boyesen and ask about a different set of reed pedal's ( stiffer or softer than stock? ) Obviously porting , or carb mods something similar may help? Just wondering where it might be a good place to start?
I know some guy's have played around with base gasket height , milling the head and so forth. I told him to call Boyesen and ask about a different set of reed pedal's ( stiffer or softer than stock? ) Obviously porting , or carb mods something similar may help? Just wondering where it might be a good place to start?
The Shop
I heard that some guys are running 125 SXS ignition control units in their 150's in search of more over rev but I think it might make 150sx tendency to detonate even worse https://www.ktm-parts.com/SXS15125390.html
Has he adjusted his power valve setting?
Putting a thinner base gasket with stock head improved low end and pull into midrange as well, with minimal change in top end and over rev. With stock gasket setup, lower RPM range isn't quite as clean running but does rev out slightly better. The thinner base gasket makes it easier to ride.
Recently, I added a STIC metering block to the carburetor. Definitely added more top end and over rev. Low end feels similar to stock and mid range is stronger but jetting is not optimized yet.
I also have tested the SXS 125 ignition. Feels like a very racy 125 with that setup, but wasn't the feel I was looking for. Will sell the ignition for $75 shipped if your buddy is interested.
On gearing, the stock 48 tooth gives it the broadest spread of gearing. Have tried 48, 49, 50, and 51. All the larger sprockets meant was more shifting and less drive as it revs through RPM range too fast.
And a safety note: I roasted my stock cylinder when the stupid check valve ball in the gas cap stuck causing an extreme (but intermittent) lean condition. Would highly recommend taking that POS out.
Read the Article from the MXA 150SX Four Stroke Fighter with the Lynks Racing Tuning
Have a 2016 150 with Doma Pipe /VForce4 and
Cone Valve Fork.
Think about switch to FMF Exhaust
Which Setup do you run in your Keihin Carburator?
Pit Row
Stock- Baseline power
Shorty- More bottom end, less over rev then stock
Bud Racing- Simaler to stock/Could argue a little less or little more power. It was bought used so maybe new packing could help
PowerCore-Simaler to stock/Could argue a little less or little more power. It was bought used so maybe new packing could help
Turbinecore- has Spark arrestor. Less bottom end, power feels less but smoother overall then stock, call me crazy but I feel like it revs farther.
Problem here is that the bike needs to go on a dyno to test all this stuff out properly.
Post a reply to: KTM SX 150....searching for more over rev.