125-200cc 166 hour 165 piston/ring

I just tore down my top end to get ready for winter trips. It has been 14 months since I mounted this top end on my '12 WR165 and haven't pulled it down until now. 166 hours on the ring and piston. Ring end gap was a bit large at .022" but there still weren't any sharp edges. Piston had a tight .0025" clearance. My compression was down ~5 psi. This is now ~280 hours on the cylinder bore and it is in great shape. Here are some pics of the piston. All I have done is wipe the oil film off.
https://picasaweb.google.com/103632705395230046313/165CustomPiston#5934364427334134770
https://picasaweb.google.com/103632705395230046313/165CustomPiston#5934364712241372674
https://picasaweb.google.com/103632705395230046313/165CustomPiston#5934364839522162082

Rookie...







Later,

Very impressive Walt.
What was the piston clearance and compression to begin with?

Piston clearance was .002" and compression started at 195. Was a tick under 190 before tear down.

Very nice!

In reality I could have just run this piston/ring the rest of the winter. It still ran great, I just wanted to pull it down and check it after doing a whole bunch of WOT mile long runs in 6th checking different pipe combinations for top end. The winner was the DEP 200 SX pipe. Pulled 73 MPH, 2 more than any other pipe. For clarity here were the numbers. 200 fatty: 67 mph, 200 SX stock pipe(the swallowed wombat pipe): 70 mph, HGS 200 SX pipe: 71 mph, Dep: 73 mph. All these pipes pulled to 62/63 mph very quickly but the DEP pulled really hard to almost 70mph.

So to what do you attribute to the lack of wear, and longevity? And how long do you think the stock 125/144 piston and ring are good for?

Walt can you post what gearing you used for your tests please
That piston looks identical to mine at around 180 + hours and mine will pull 76mph with the dep on 14/51

First is that the 165 depending on pipe pulls hard to 10.5 Krpm-11Krpm and then you should shift as it gains slowly from there. Now the 165 makes piles more bottom/mid than the 125/144 so keeping the engine stirring from 6-10K rpm is where the hay is located. That adds up to a whole lot fewer revs / mile on average for the 165. Also the short stroke of the tiddlers doesn't yield the same kind of piston speeds of the average 250 that you are screaming.

One of the great things about the husky tiddler motor is that the bottom end is very robust. Also the husky design of having an exhaust port bridge extends ring/piston life. Husky has also produced really top notch internal parts for the engines in these tiddlers. I know there have been quite a few guys that get very long service life out of the stock 125/144.

I am running 13x48 gearing which is slightly lower but the biggest difference is that all my tests are done at just a touch below 4000' elevation. That's ~10% less power than sea level. The wind resistance isn't the limiting factor it is the lack of 3+ HP at the top.

Hey Wally,

What about the Scalvini pipe?

Thanks!

I tried to get one to test but the deal fell through. They are really spendy and probably not the best application for them unless they built one purpose built.

At the risk of hi-jacking the thread, I am going to pipe my son's 2012 CR144 this winter and am considering the Lectron and as one might surmise, I am looking for the most versatile pipe option.

Assuming there is a good chance I will be eventually moving to the 165, shall I run the DEP pipe and if so, which model and silencer do I purchase and where do I get it?

Thanks in advance -

Riders that have the DEP pipe really like it. Makes great mid to top for the 125/144. I don't have enough experience with the Dep myself to make a recommendation. I think any of the 125/144 pipes are going to hold the 165 back. I sent the 200 SX Dep to another rider who can test it better than I can as my riding is pretty much done for the year without travelling. I should know more in the next week. JohnnyBoy a 165 rider in the UK first talked about the 200 Dep pipe and he really likes it. Best mid to top pipe for the 165 in his testing.

All this 165 talk is killing me. I have the 165 sitting in my garage with modified KTM 200 pipe thanks to Walt & Kelly. I've been playing with the 144 and trying to get a good feel for it before doing the 165 kit. I want to make sure I notice the difference. Right now I'm having a slight issue with getting my Lectron setup right so until I resolve that I'm not messing with the 165 kit.

I'm glad to see the piston/ring life you all are getting out of these things that is promising. I'm loving the bike it handles Great.

Sounds familiar. I didn't want to swap out my fresh 144 top end for the 165, but I finally did and never looked back. 165, FMF 200 pipe and Lectron made this bike as fun as humanly possible!

What can you do on the 165 that you can't on the 144?

Probably nothing Curt. It just does it easier in most situations for a lot of us. You get used to the bottom/mid of the 165 and the 144 just seems lacking/requires more attention to the throttle/clutch. The nice thing about the 165 is that it does it all so easily but doesn't have so much it wears you out or gets away from you. JMO

I'd really like to ride a 165 some time to feel the difference,I'm starting to get tired having to finesse things constantly.