1:11

[@blakesmotovlogs449]

Excellent video. Very well done sir.

[@UpAllNight91]

Thanks!

[@jfish6925]

About to do my GG 125 top end and found your video. Nicely done and I always hand tighten my cylinder bolts by hand as well once you get the feel of it. I would disagree in going with a one ring piston. That’s a super short lived item for racing only. The reason the Austrian bikes go so long on top ends is because of the two rings.

[@UpAllNight91]

Thanks! And I understand on the single ring. If the piston is expected to run a long life, for sure run a 2 ring piston. I do on my YZ250. However if the bike is being raced or mainly track riden and pistons will be changed out in shorter intervals then a single ring will last good enough. For me whats more important is using a forged piston. I find cast pistons if ran too long will break or crack before the compression fades away from ring wear.

[@bryanlacasse3257]

Nice vidéo for top end rebuilt

[@UpAllNight91]

Thanks!

[@dragoslavpetrovic3616]

Beautiful bike, I need one 150, for starting dirt biking.

[@jcody_parker]

Should just wrap a rag around the powervalve rod so the clip cant fall inside if it slips

[@UpAllNight91]

Yup, that surely works

[@minime5380]

Good vid 👍🇬🇧

[@UpAllNight91]

Thanks!

[@Multitrash100]

hey, at 42:00 you push power valve and it comes back by himself?

[@UpAllNight91]

Hello. My right hand that was just off camera was opening it. There is no spring on the cylinder to open it back up.

[@Multitrash100]

Okay, I just did my first 2t top end thanks to yours videos!

[@UpAllNight91]

@@Multitrash100 Right on! Good job

[@alesmikulencak9007]

Thanks It helped

[@craighills2382]

Hi, I like your content , you say two strokes need lead, Is valve saver ? is this a lead ? or what product would I use please, Regards Craig

[@UpAllNight91]

Well. I don't know off hand a lead additive, but there could be one out there. It needs lead to raise the octane up and control the burn. I use leaded race fuel to get the lead I need. Doesnt take much, can even be mixed 50/50 race fuel and pump fuel to get enough lead ,depending on the motors mods... mainly the head profile.

[@UpAllNight91]

Thats not a bad price though. PC has got the magic thats for sure. Any time I work on a PC motor im impressed with the level of tune. When you say 2:3 c12 do you mean 2 gallon of c12 to 3 gallons of pump?

[@shanemacfarlane1607]

Cool vid. what did you use to clean up with after porting? air?

[@UpAllNight91]

I used wd40 and air to clean most of the parts. Sometime I will also just dip them in old gas .

[@shanemacfarlane1607]

@@UpAllNight91 thanks for that. Greetings from sunny Melbourne 😁

[@UpAllNight91]

@@shanemacfarlane1607 Yes sir, Melbourne Florida?

[@shanemacfarlane1607]

@@UpAllNight91 Melbourne Australia. live on the bay.

[@UpAllNight91]

@@shanemacfarlane1607 Ahh Nice!🤙

[@JackMacdonald-ih3ht]

What does exhaust porting do will it change jetting ?

[@UpAllNight91]

It doesnt change jetting anything I can tell at least. The pipe works better with a polished exhaust port, the port is the engines window to the pipe .

[@JackMacdonald-ih3ht]

@@UpAllNight91 how do exausts and port heigh change jetting? And all parts?

[@JackMacdonald-ih3ht]

@@UpAllNight91 wdym the pipe works better?

[@UpAllNight91]

@@JackMacdonald-ih3ht The exhaust port is the window to the pipe.

[@masje1106]

do you need to find the tdc with a vhm head when changing the piston?

[@UpAllNight91]

You mean find the correct gasket thickness so the piston crown matches the top of the cylinder at TDC. I would guess yes. Its safe the assume they cut the VHM head to bolt on a motor as is.

[@KaiMiller]

How do you get a torque wrench to fit in between the cylinder bolts to tighten it. Is there a special wrench for that

[@UpAllNight91]

They sell little wrench extentions that connect to a standard torque wrench. They include a little card with the math needed because the extension extends from the wrench and changes the accuracy of the reading.

[@cnc.moto_factory]

That unburned piece of toilet paper seems fishy... Its not burnt from the cylinder pressure and heat? also, that piston looks a little TOO clean for having just a perfect fuel mixture. Did this motor really need rebuilt?

[@UpAllNight91]

Hello. The paper was in the water jacket area so I'm thinking a previous mechanic maybe had paper in the radiator cap area to keep trash out and just put the cap back on and forgot it. Juat a guess, I don't know though. The motor didn't really need a rebuild but the owner was about to start a race series and just wanted me be sure everything was good and healthy for a full season.

[@Seth-s5n]

How many hours were on bottom end ?

[@UpAllNight91]

This had about 80 hours on it. It had a hard life though.

[@Seth-s5n]

@ why would you expect a 2 stroke bottom end to go anywhere from 75-350 but a 250f one to be normally right on 200

[@UpAllNight91]

@@Seth-s5n The 4 strokes can snap a rod at some point. They can check out perfectly fine with a good rod bearing and all but after so many hours of usage and if ran to hard to long they just snap the rod out of no where with no warning. If its just a trail bike or riden easy then they can go over 200 hours easy but if used on the track by more skilled riders then every 200 hours a new crank should be installed to keep things safe. On the other hand on a 2 stroke they dont break rods on their own unless something else goes out first like a lower rod bearing. But otherwise they dont break rods. So if the lower rod bearing is in good shape and the left and right play measure out good and there is no up and down play its safe to keep running them no matter the hours.

[@Seth-s5n]

@ ohhh but on ones that don’t break rods they could also last 350 hours ??

[@Seth-s5n]

The 4 strokes

[@burkleythompson1855]

what website can be used to order the whole set up for The Ktm 150Sx Piston & Cylinder ?

[@UpAllNight91]

For the cylinder, motosport.com or www.rockymountainatvmc.com/ and also partzilla.com. for the piston, if its just a standard, any of them 3 will carry it. But if its the wiseco race piston, some have it, some don't. But wisecos web page sell them and can always be found there

[@burkleythompson1855]

appreciate it Much love from the 🇧🇸🇧🇸

[@henning_8246]

My burning chamber spins when tightening the spark plug, do you have any advice? I have cylinder head at 18Nm

[@UpAllNight91]

Hmm. I would surely take the head off and see whats going on. It could be just bolted down to lightly. But I would pull it off and make sure it hasn't been vibrating around for too long and cause wear of the surfaces

[@henning_8246]

@@UpAllNight91 thanks, I already tried changing the o rings to KTM original spare parts so I guess buying a new chamber is my last option..

[@UpAllNight91]

@@henning_8246 yeah might be

[@jangoreo]

You weighed the piston without the wrist pin clips. Maybe next time

[@UpAllNight91]

Yes, I should have. Next time for sure

[@jojokarli]

I bought a shock spring from eBay for my 05 yz125 they said it was 2010 but in pen I can see slightly it says 4.9 I was hoping for a 5.3 so is there any other way to help 4.9 be ok for my weight 170/180lbs and I was looking at a .44 fork springs is about right or can I make them stiffer with more oil

[@UpAllNight91]

Hello. A 4.9 on a 125 on the rear will be ok for you at your weight. It will be on the softer side but surely within range for you on a 125. Up front the .44 will be right on for that rear 4.9. Good balance. Balance is very important with springs and that is a good balance. You can add more oil on the outer chamber to help control bottoming but thats really all it does. You won't feel the extra stiffness of the extra oil till the forks reach almost the bottom. I try to only put in as much as is needed to control bottoming and no more than that, so it also retains smoothness

[@jojokarli]

Ok cheers mate 🤙🏻