How To - Rebuild a KTM TBI Top End 

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Hello: I use Gunk spray on the engine.

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Thank you. I still prefer the wood over plastic.

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Glad to help.

Hello Kyle: When your cylinder bore specs become out of tolerance, go back to the A piston size.

Hello Tom: I think it's possible. I unplugged it and had no negative consequences.

The KTM manual is vague and says .40mm or less. Vertex has a tighter tolerance recommendation. I treat the .40mm as a absolute out of spec threshold.

@@The_Snowbike_Channel I was worried but been riding the piss out of it and it's been the great. Crazy bottom end with a tsp medium head, IRK, tune, and Z set to zero with some C12/90 mix. So much bottom end I had to tune it back down a bit it's almost unruly.

Hello: I said to set it at .012" to .014". Those are thousandths of an inch, not metric.

Hello: From the factory they have a zero deck, but I often change that spec for increased low-end torque.

Hello: I removed mine to eliminate a possible failure point. slavensracing.com/shop/tpi-tbi-oil-filler-removal-kit-for-ktm-hqv-gg/

Hello Old Vet: I did not service my PVs because the engine has low hours and I use Amsoil Saber @ 100:1 and it does not leave much carbon. If you like to constantly over-rev like many MXers, 40-50 hours is a good service interval. If you run it at low and mid RPMs you could extend the service intervals to 75-100 hours. For MX applications (high revving) we recommend the Wossner forged piston. slavensracing.com/shop/wossner-top-end-rebuild-kit-for-ktm-hqv-gg-250-300-tbi/

Yes, it should be done on you XC.

Don't do it.

If ya don't mess with the PV, you MAY be OK, but just check/reset anyways...take 2 mins. It's easier than filling the tank. Braaap!

​@@hoosk125-wm5bp What if i dont reset the power valve

​@@hoosk125-wm5bp What if i dont reset the power valve

Hello Mark: Yes, stay tuned please.

@@slaverace1good, my 2023 300xc with 28 hr is bogging bad.

Hello: If you have an O.E.M. head the squish is approximately .080", which gives you plenty of room to make changes. Mine has an aftermarket head insert but still had room for improvement for the high elevation I ride.

Hello: Usually if you need a C piston for correct clearance, you need to have it replated.

Hello: Sorry, I have not yet made that video and probably won't until winter. What are you calling "faulty cylinder issues"? We have not encountered any issues.

@@slaverace1 Jeff, cracked cylinders. There are many people on 250’s and 300’s with the issue and elko cylinders. There’s an entire fb group that has many people with the problem. Some have been lucky enough to get a good faith warranty. Ktm/husqvarna denied replacing mine twice. Bike has been eating coolant since the first 5-10 hours. Only has 40 now. Ktm claims on the 23+ models they won’t even consider helping you unless you change your top end at the “new” intervals of every 15 hours which is insanity. I am happy to send you photos of what I am talking about as well as proof from many others. I personally know a shop owner here in Denver/littleton area that had the same exact problem. Our cylinders are cracked in almost identical along with everyone else. The water jack ports get hairline cracks causing back pressure in the coolant system and coolant goes out the overflow. It doesn’t get past the first inner oring under the head so bike still runs fine. I documented everything in addition to fay Myers here where I bought it brand new. They still told me and the dealer to pound sand.

​@@Freestylematt139I have a 23 TX300 with a cracked cylinder. Where did you source your new cylinder from?

Hello: The oil injection has nothing to do with performance.

Not necessarily. Both have their strengths and weaknesses. I have a video in the queue about forged and cast pistons. Please stay tuned.

If ya make a drastic change to the "envelope"? Always test it and verify it. Read the plug, yank the pipe, check the Ex side of the piston. Trail ride? Motul 710 50:1, Full race? Motul 800 32-45:1. More oil = leaner AF ratio. Test n tune. Verify it. It's up to YOU. Braaaaaap!

Ok. I’m a little confused. If I’m running 60:1 which is more oil than 50:1 it’s running leaner instead of rich. I thought more oil was ok as long as it’s not pouring out the back of the pipe. How does he run 100:1 wouldn’t that be a bunch of oil? I use to run my old carbureted 2 stokes 40:1.

Sorry I got that backwards 50:1 is more oil. My bad.

@@motofamily461 no worries. The dif between 50 and 60:1 is minor unless one is on the very cusp of lean. If my bikes are a bit fuel rich, but running spot on otherwise with no mechanical issues, I'll add more oil to the mix to get the plug color where I want it (fine point tuning) and re-test 3 times to verify. Amsoil is one of a couple if not the only oil maker recomending100:1 for small engines (chain saws etc) and super slow use trail bikes. I would not use that ratio for anything other than first gear all day HE stuff. I use Motul 710 for trail/HE or 800 for fast/race exclusively. Never scuffed a piston or bore with it. Super clean and super slick stuff. Regardless- Just read the plug, ignore the spooge, do what works for your engine/riding conditions, not someone else's. Unless you are track or wfo XC racing, trail riding will usually result in some spooge when the pipe/crank case loads up then gets cleaned out wfo. Re-packing your muffler often helps control it. Spooge is simply a fact of life on most 2T's if one is not wfo on the pipe all the time. If your setup is clean and the plug reads good/safe, you got it right...Enjoy! Braaaap!

Thanks for the help.

Hello: Copper draws heat away from the base metal it is clad to.

Hello: Slotted rods (for more lubrication) have been used for many years on many brands without negative consequences.