How to Easily Resize a Nitro Engine Piston & Sleeve 

The lathe chuck definitely seems like the way to go in my opinion. Seems way more precise and consistent than this method, but this is definitely a cheap and quick way to do the job. Good for if you need a quick pinch at the track or something like that. I watched EB Mod’s video on his repinch tool and I’m pretty sure it used a lathe chuck that he custom machined to his design for the tool. I found and priced out the parts I’d need to make my own and been meaning to buy them for a while now but haven’t yet 😅

Happy to hear the success you've had using this. It is a quite effective method at a low cost.

@@moralesrcdesigns3784 absolutely mate, it only cost me £9.50 to, it's a no brainer. And let's face it, if a sleeve has gone that bad that it needs re plating, we'd be better off just buying either a new engine or piston and sleeve. And depending on what engine it is, some of them cost about as much for a brand new engine anyway. I'll put a video up on my channel soon showing you the one I use, it only has 1 bolt, and I use different shims for size.

Thank you! Glad I was able to help 😃

👍🏼

I got mine from Ace Hardware but you can find them on Amazon too

You can but it’s not necessary. The main instance where heat and sleeve repinch is related for me is if I accidentally repinch a sleeve too tight. I make sure to preheat the engine up to 240°-260° for break in and I let it idle 4-5 tanks straight without stopping the engine. Doing this allows the pinch to loosen up without having the stress of starting the engine again after each tank. Little tip. I have an electric screwdriver with a clutch setting that I use to test the tightness of my repinch. If you have one, take an engine that is running good and has good compression and try turn it over with the screwdriver (using the clutch screw) until you get to a clutch setting where the screwdriver can turn the engine over. Now you have a reference to about how tight you should make your pinch

@@moralesrcdesigns3784 excellent advice m8, I'll take note of that for sure. I appreciate that. And thanks for he link for the tool, I was finding it difficult to fins the proper tool and was using 2 jubilee clips, uno old school site lol. I'm uk but was able to find the proper tool thanks to you. 👍👊

What part of the process would you suggest using oil on? I’m willing to test it and see if I get better or more consistent results

I got mine from a local hardware store. You can check your local hardware or plumbing store and if they don’t have it, look for 3/4” inner diameter copper pipe on amazon

I haven’t thought to check the measurements, but when done correctly it’s probably no more than a .1 or .2 mm difference. These tiny engines have such tight tolerances that it doesn’t take a whole lot to get a good repinch

i have not, but i know it pretty popular to do so for diy sleeve pinching. the theory behind doing it makes sense, but i haven’t found myself in a situation where i’ve needed to do it

i have an amazon link to the exact clamp i use in the description of the video

From my experience, that’s what the os engines do, they actually use quite soft metals, but the piston doesn’t go as high in an os sleeve so even though you move the piston down, the clamp actually compresses more of where the headbutton sits rather than around top dead center. I’ve found that pinching an os like this actually works quite well because the pinch isn’t crazy tight, but it holds its pinch better when it gets hot. If you’re still having trouble, try move the clamp itself lower down on the sleeve about 2-4mm and try again. It’ll be a bit harder to keep the clamp straight, but by doing that, you’ll compress more around where top dead center is and you should be able to fee more pinch. Always start with a little and then go tighter if you need to. It’s easier to tighten the pinch a little more than fix over tightening it

What did you use to make it fit?

@@timovangennip just keep tightening the bike seat post adjustment and one part I forgot to leave out is that you need to make sure the bike is owned by someone you dislike because it will damage the seat post holder

I got a little copper pipe from ace hardware and cut it to make a 4-5mm ring. Any copper pipe that’s 3/4” inner diameter 7/8” outer diameter (or something close to that) shoulder work

@@moralesrcdesigns3784 perfect thanks

No. As far as I know, that wouldn’t do anything. The only reason I did it a second time is because I didn’t want to tighten it too much the first time and then be stuck with an engine that’s way too tight. It’s much easier to make it a little tighter if you need to than try to break in the engine while it’s unnecessarily tight. The engine runs phenomenally with the pinch that I gave it in this video. Idles for ever, runs extremely consistent, and has plenty of power. I think the common mistake for most people is that they tighten down the clamp too tight and then the engine can’t run efficiently/properly because the sleeve is likely warped and misshaped

@@moralesrcdesigns3784 and as I understand every time you tighten you turn it and tighten again to make sure everything is round all around. Awesome vid. Thank you

It should but I think the con rod length for the trackstar is shorter. Definitely something worth trying though. I’ll try it when I get new bearings for the sirio

I mainly use that one, but some engines are different and either start their pinch lower down or higher up and I have a slightly think and slightly thinner piece depending on the engine.

@@MyZxcvb12 i’d say just copy and paste the name of the clamp that i have linked in my description and put it into your web browser and see what pops up. if you find the same thing on a website that ships to you, there you go

3/4” is what I use

@@moralesrcdesigns3784 very cool! If I paid you to do it via eBay, what is the turn around time generally? I'm also considering your rebuild service. It's for an o.s. max .12 cv with a bottom end fuel leak and poor compression

@@thomdoers3222 if it’s just a repinch, I can have the repinch done the day it comes in and send it out the next day. If it’s a full rebuild, it should be within a week depending on how long bearings and stuff take to come in

I used a 3/4” inner diameter copper from ace pipe and I cut it to be 4mm wide. This works for just about every .21 engine, but I’ve found that some .21s have a lower point where the pinch starts so you need to use a 5-6mm ring. Cut a few with different thicknesses and see what works with each engine starting with the thinnest and working your way up until the pinch starts where it’s supposed to

Thanks alot bud👍

It’s in the description :)

Nice!

A 3/4” clamp will probably work, but just to make sure, measure the outer diameter of the sleeve and get a clamp 1/8” bigger

@@moralesrcdesigns3784 Awesome ;)

A mildly warped sleeve can be fixed, but it takes a bit of work and patience. If it’s super badly warped, then there’s a 99% chance it’s not repairable

Can you make a quick video on how it can be done?

@@godsun358 Sorry for the late reply. I'm not super active on this account. I will definitely consider making a video on it!

@@moralesrcdesigns3784appreciate you sharing your experience bruh

for 21, i have done buy 7/8 clamping collar

@@felixharyanto8773 .21 engines use a 7/8 inch clamp with a 3/4 inch inner diameter ring. Sorry for the late response. Hope this helps

For 1/10 or 1/8

@@sharudinhjsudin1696 link is in the description. Get the 3/4” size for .12 size engines and 7/8” size for .21 size engines

Are you still offering this service?

@@thomdoers3222 No. I had to many people tell me that they were gonna send in engines to get rebuilt or repinched and then never did. I got tired of that and now i just do it for the guys at my local track

@@moralesrcdesigns3784 sorry to hear that. There aren't enough people doing this for people.