Nice trick with the marked piston for depth measurement. I used my calliper extended at 15mm. Will correct to 20mm. It’s possible that the nicasil coating may not be consistent through out, ie thickness of nicasil My 21 TE 250, at 182 hrs showed (.6 to .55mm) on both rings. The higher end was the bottom ring. New proX ring shows .50mm. Thanks for the excellent vid.
I was pretty excited when I found KTM has free service manuals on their site. But man are they terrible. Their maintenance chart say that all the engine bearings need to be replaced after 40hrs!! What a bunch of BS! Thanks for making these videos. They are much more useful than the service manual.
There is some misleading information out there. I am right now changing the piston on my Beta RR300 and the Vertex piston says in it's manual to use .006 - .009 inches minimum ring gap per inch of bore, what in 72mm would translate to a 0,43 - 0,65mm gap. Beta, same as KTM, says in the workshop manual that the maximum gap is 0,40 mm. I measured both new rings and they are at about 0,25 - 0,28 mm new, if I file them as recommended by Vertex I would be out of spec for Beta.
For my 300 boys, ring end gap min spec is 0.28mm. Max spec (worn out rings) is 0.40mm. Vertex 300 rings should come at 0.28mm from the factory, "trust but verify" ;)
8:28 : where did you find this spec for Vertex? The instructions that shipped with my Vertex piston call for 0.42-0.65mm (newly replated 72mm bore on '15 Husky 300). My rings are at 0.28mm out of the box, so I'd love for your spec to be right! :)
Mikhail - My thoughts are that the OEM ring tolerances are controlled tightly so that for a new OEM kit you’d be extremely unlikely to experience rings with too little gap. And so long as you perform regular top end overhauls (100-200H depending on how hard you ride) you should be fine. Also compression testing will show whether the rings have excessive wear.
The piston skirt wears and will eventually fail, causing catastrophic damage to the cylinder. My recommendation is to change the piston and rings every 100-200H depending on how hard you ride.
From the 2017 repair manual: Cylinder Bore Size 1: min=66.400mm, max=66.412mm; Piston Diameter Size 1: min=66.340mm, max=66.350mm. From these specs you can calculate the minimum cylinder to piston clearance=0.05mm, maximum clearance=0.072mm
Hey, maybe you read a comment on a that old video^^ I have the same markings on my cylinder from the bottom to the top every few cm, you know how that happens or if it is a problem? And can you maybe make a video for Ktm 250 to set the X-dimension? That would be awesome. best regarts
Yes, every cylinder I've seen has had the same marks, even zero hour take offs. The marks should not be deep though and you shouldn't be able to feel them with your finger nail. If they were deep it would be an issue... Yes, good idea regarding the x-dimension video. I'll be working on an engine soon so will be making some new videos soon and will be sure to make an x-dimension measurement and adjustment video.
MrShaniqua42 - When you tried what method did you use? I’ve reverse bled my clutch (to replace the fluid). The method is the same as shown in this front brake bleeding video: m.ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6UCNWfA7dVs.html
hi mate my manual says end gap 0.3-0.4 , ktm 250/300 , I just got a new mikita piston kit ktm300exc 2007, new rings gap measures .25 mm is that too small or can I still put them in at that thanks
Your ring end gap is a little tight. Wiseco provide a minimum ring end gap formula which is 0.04" per inch of bore. For a 300 this gives a minimum ring end gap of 0.288mm. My recommendation is to open up the gap to 0.3mm. This Wiseco document provides some advice regarding filing rings. Great care should be taken to keep the ring end square, with no burrs, or damage. Only file one end of the ring. www.wiseco.com/PDFs/Manuals/RingEndGap.pdf
Hello how i can select right ring end gap? ,when i buy new piston kit from ebay ,lets say for used cylinder like 200h on it, i know how to messure cylinder to piston clearance to select right piston, but piston ring end gap to get correct i dont understand it can be to small gap or to big gap, only thing i dont know is gap size !! ,yes if i see that piston in shop then i can do like you in video to messure gap ,but my piston comes from ebay...
The ring end gap needs to be measured in the cylinder you will be using (as shown in the video). If using a KTM OEM piston kit no adjustment should be required.
Currently my carb model (Keihin 38mm Air Striker Short + STIC) is performing better than the TPI, so I’d keep the the carb model. It will be interesting to see how much better the TPI performs when I change the ECU to PowerCDI (when it becomes available.
Tnx for the answer :) I'll consider changing my carb to Keihin + STIC combination (not a cheap upgrade for me) instead of upgrading to TPI (even though I'll love to stop mixing oil and fuel haha)
The feeler gauges I have are made by RSK (Riken Sokuhan) which is a Japanese brand. The part number is 100MZ. It includes these thicknesses: 0.03、0.04、0.05、0.06、0.07、0.08、0.09、0.10、0.11、0.12、0.13、0.14、0.15、0.20、0.25、0.30、0.35、0.40、0.45、0.50、0.60、0.70、0.80、0.90、1.00mm. I could start selling them on the Tokyo Offroad webshop if there is some interest.
Hey man I was just wondering if you can let me know how I can learn how to mess we with everything on a 2 stroke dirtbike, I dont want to rely on shops and I would rather work on my own bike but where can I learn all of this?? I know you have a degree for engineering or something like that and thats why I'm asking, thank you
The ring gaps are offset by about 4mm and positioned at the intake. I think this is done as the intake is the coolest part. I previously made a video which shows the ring gaps passing over the intake port which you might find interesting: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-K6gzvgV8uIs.html
Tokyo Offroad emailed Vertex and this is his reply “Thank you for your excellent question. When talking about ring end gap placement in most 2-strokes you have to consider the intake, exhaust and transfer port locations in the cylinder. The ring end gap needs to stay on bridges of the ports or else the rings may stick out into the port and get caught and then bad things happen. If you have any more questions just let me know.” Didn’t answer my question really
Tokyo Offroad also just checked pictures of my cylinder and piston orientation...and the ring gaps are directly over, and in the middle of, one of the intake ports...not even close to one of the port bridges. Pretty much goes against his reply
