125-200cc Crankshaft failure, Pro-x rod kit.

I'm really just looking for a vote of confidence on the quality of the Pro-x rod kit for Husky CR125-144, part# 03.6217 http://www.pro-x.com/connectingrods.asp

I'm interested in any opinions even if the Pro-x experience was with another brand of bike.

They sell for a very reasonable $75 to $100 usd. The OEM crank is over $500. The OEM rod kit is like $267 dollars. I generally believe that OEM is best, but I can't justify the price difference of the OEM, for a setup that lasted 41 whole hours.

Also interested in any rebuild tips on clearances, etc. Probably more of a Wallybean or Tinken question but fishing for any tips relevant to this particular model.

How about any high-dollar titanium options?

Thanks! MM

I ran a Pro-X rod in a heavily modified 2008 KTM 200 XCW. Seemed just as good as OEM to me. No issues.

When I was doing the prep for a stroker 177, I got one of each and compared them. The pro-x kit visually was on par with the oem kit. I went with the oem kit but wouldn't have been detracted from using the pro-x kit if that was what I had. It certainly appears to be a quality piece.

The oem cylinder lining is very good and I would probably be surprised if you had any measurable wear. If you are using a quality oil and don't have any significant events that would effect wear then I would expect you to get ~200 hours out of the oem coating given WOT track use. Probably much more using it for endure/hare scramble/trail riding. Typical events affecting this would be seizure, over heating, passing dirt, etc. If you can't see or feel any wear lines at the top and bottom of the ring travel you are probably good but I would still check your piston gap with a new piston. Needs to be .002". If you are using the oem coated piston then it is going to be very slightly less than .002". The oem coating is ~.0001-.0002" thick. Another way to see if you have measurable wear is to measure the end gap on a ring placed above the ring travel and when it is in place ~1/2" down from the top deck. .001" of difference in end gap ~ = .00016" of wear on the lining. This is pretty minimal and you probably can't feel it but is what I would expect to see after ~100 hours of use with a good running motor using a good oil. It is certainly within tolerances and wouldn't call for a re-lining but I would expect to re-nikasil at the next rebuild. All these figures are given your 144 bore of 58.00 mm.

I have seen guys just slap a new ring/piston into bores that are far more worn than that and get by for what would seem far to long with no catastrophic issues. Not my choice of maintenance but doable. I am interested to see pics of your bore/piston and what kind of measurements you get.

I would also opt for having the crank balanced too which will need to be done with your new piston kit/top end bearing.

I am also assuming that you will replace the mains/seals while you have the cases split. Interesting that right after I made this post the crank folks called me to let me know that my stroker crank was done and balanced. They told me it took a little over 2 oz's of heavy metal weight to get it balanced. Glad I had it balanced. I would expect that your 144 would be closer than that but still worth doing.

It only took 2 months to get my crank done. It would probably make sense to have someone that does a lot of work with a crank rebuilder handle the process so you get a better place in line. Believe me when I say that a business that does 10-20K in business a year with them is ahead of joe shmoe like me. Especially during the peak rebuild season.

Thanks for the answers guys, I ordered the pro-x rod $73 shipped. I like that it is a Japanese piece.

Thanks Walt I will certainly be doing new main bearings and seals. Amazingly the cylinder is untouched and shows insignificant wear. Two very minor dings in head that I will smooth and live with. Bike got a new piston/ring at 17 hours when my cylinder/head came back from pro-circuit. Piston got scuffed enough that I will scrap it or save it for an emergency, but it took the cage not the cylinder. The big-end bearing seized to the pin, then the rod ate itself sloppy. My riding partner heard the rattle on his hour of an endurance icerace and shut it down quickly and likely saved my cylinder. Thanks Stew!

Oil was Klotz R50 mixed at 32:1 with straight VP C12 with winter-safe jetting. Nothing else shows wear and plug BR10eg looks great, so I think I just lost the parts lottery and got the weak crank of the bunch. We also flog it mercilessly at high RPM and use the generous overrev into corners when it doesn't pay to shift for that split second. I'm still surprised that it failed at 41 hours, I've never had a crank fail in such short order I generally don't start to sweat until 80 hours.

Walt do you feel having the crank balanced can improve it's durability, or is it more for smoothness and less vibes? Would you recommend anyone over anyone else? I'm considering having that done (never have in the past). Is the crank in balance from the factory as a 125 and it is a factor of the larger piston of the 144? Thanks a bunch for your time, as always!

Marc,

I think anything you do to make the crank operation smoother will extend its life. I doubt that your crank would be anywhere near as far out of balance as my stroked crank with the bigger 62.00mm piston. But as you say you will be running it at far greater rpms for extended periods and in unloaded situations. The cost to balance was not a huge add on to the total crank re-build. This is the first crank I have had to rebuild personally in many years so I couldn't recommend one place over another. I would contact pro-circuit who did your engine mods and get their opinion. I have to believe they could give you much better recommendations than I can. I also have read on here of a number of members that have experience building cranks and could help you with recommendations. I think Dirt Dame has done a lot of this work and now sends her work out to be done. I would PM her and get her opinion. I also know that Ron at RB Designs does excellent work and does crank rebuilding too. It might be worth a new thread asking for member experiences and advice.

Sorry to hear that you had the crank failure. You probably did get the one Monday crank in the hole husky tiddler world.

I run a pro-x and its running fine
Robert-Jan

Thanks for the answers and info. Does anyone have specifics on crankshaft specs? I'm going to use my local guy who has done many cranks for me over the years, mostly for convenience but also he's never failed me and his prices are as good as his work. I wasn't budgeting for this so the balancing will have to wait. If I can't get any specifics, I was going to go with a rod side-clearance of .020" and just have him set it up to it's existing width. Of course he will true it carefully. Sound good?

it all sounds good to me the pro-x in my kdx 292 feels an sounds happy you musta got a bad one and balancing makes everything better hell look at imbalanced people lol

Pro X pistons for Japanese bikes are made by ART who also makes OEM for big four. Good reputation.