Pro-X Cylinder life

[rustyATV]

I just got hold of an engine with a 330 Pro-X cylinder. It's at 76.5mm and needs to be bored again.

I see there are only four overbore sizes for the 330, so I was curious what the useful life of this cylinder is. Do you get four bores and that's it, or does the liner in the Pro-X cylinders let you run more than one piston on it between bores?

[Aceman]

Originally posted by rustyATV
does the liner in the Pro-X cylinders let you run more than one piston on it between bores?

I haven't needed to do it yet but I bet it's very possible you may be able run two sets of rings on the same bore. It'd be easy to take it into a machine shop and have them mic the cylinder and piston and see if it's a candidate for a simple hone/re-ring job.

I'm not sure if you're aware or not, but they can press the old sleeve out and install a new one, letting you start back over at square one again when you run out of bores.

[rustyATV]

Originally posted by Aceman
I'm not sure if you're aware or not, but they can press the old sleeve out and install a new one, letting you start back over at square one again when you run out of bores.

I'm aware that you can, but I also know that can be a little hit and miss. Sometimes those sleeves don't seal up right and give you problems. The stock cylinders do, anyway, maybe the Pro-X jugs are better about that.

[2-330s]

there are 2 sleeves a thin 1 and a thick 1 i think the thin 1 you can only go to 77 and the thick i think 79 i don't remember anymore but the thick ones are what they make into the 350 motors

[derby]

Originally posted by 2-330s
there are 2 sleeves a thin 1 and a thick 1 i think the thin 1 you can only go to 77 and the thick i think 79 i don't remember anymore but the thick ones are what they make into the 350 motors

I hope you don't have the thick one. Those were the worst about cracking. Basically a 350 cylinder with a sleeve and the first bore was 76mm and the sleeve was very weak.

[2-330s]

you must know something i don't? most people look for the thick sleeve! what size sleeve are you running?

[derby]

Originally posted by 2-330s
you must know something i don't? most people look for the thick sleeve! what size sleeve are you running?

I am not sure what the deal was but it cracked in several places. I have only seen 2 of the thick sleeve 330's and both were cracked.

[fulltiltrider]

Originally posted by Aceman
I haven't needed to do it yet but I bet it's very possible you may be able run two sets of rings on the same bore. It'd be easy to take it into a machine shop and have them mic the cylinder and piston and see if it's a candidate for a simple hone/re-ring job.

I'm not sure if you're aware or not, but they can press the old sleeve out and install a new one, letting you start back over at square one again when you run out of bores.

If you change your piston before the clearance gets out of hand, you should get alot of time out of a bore. I mean like 30hrs max on a piston. Sounds expensive but when you are talking about a 1k dollar cylinder, its worth it. The bore only really wears when you get the piston rocking in the bore. Think about it, if its nice and tight whats gonna wear, the iron liner or an aluminum piston. Now add a little space for that piston to be forced against the intake side and add a angle to it (small but, it deffinatley will angle slightly) and you have a cheese grater going over the bore.

[derby]

Originally posted by fulltiltrider
If you change your piston before the clearance gets out of hand, you should get alot of time out of a bore. I mean like 30hrs max on a piston. Sounds expensive but when you are talking about a 1k dollar cylinder, its worth it. The bore only really wears when you get the piston rocking in the bore. Think about it, if its nice and tight whats gonna wear, the iron liner or an aluminum piston. Now add a little space for that piston to be forced against the intake side and add a angle to it (small but, it deffinatley will angle slightly) and you have a cheese grater going over the bore.

I understand what you are saying but that can be true for any cylinder... not the case on this one. This is not one of the 1st generation castings just to clear things up before something is said.

You can see cracks in the exhaust bridge, aux ex ports, and even the transfers which I would not expect to see if it was a clearance problem.

http://i32.tinypic.com/b98yhf.jpg

http://i27.tinypic.com/149s3fd.jpg

[fulltiltrider]

Its been awhile since I seen anything like that. How thick is the bridge, and the distance between the aux and main. You need to keep at least 4mm in those areas or problems like that can occur. This is one of the reasons big numbers for drag ports is hard to get out of a prox jug. My statement wasnt about the cracked cylinder, it was just a statement of bore life in general

[Honda 250r 001]

So if i would run a cast piston at .002 and replace it at .005 say it would make the bore last longer than a forged running .003 and replacging at ..006?

[fulltiltrider]

Originally posted by Honda 250r 001
So if i would run a cast piston at .002 and replace it at .005 say it would make the bore last longer than a forged running .003 and replacging at ..006?


Yes, for both forged and cast. The problem is most people go off of static compression #'s to check the health of the piston. If you wait that long chances are the bore has worn from a loose piston, not so much that the rings are wore. Rings wear evenly as long as the piston is tight. When the piston starts to rock, thats wear you will see compression #'s drop. This probably happens well past the .005-.006 wear limits

[86 Quad R]

this is true. to prevent this very thing from happening i will take a cranking compression reading after the break in and note it. as part of maintanance i'll check it and if it gets below a 10% reading i'll re-ring. :cool:

[Ruf Racing]

Originally posted by 86 Quad R
this is true. to prevent this very thing from happening i will take a cranking compression reading after the break in and note it. as part of maintanance i'll check it and if it gets below a 10% reading i'll re-ring. :cool:

That's a excellent piece of maintance. Always learning.:)

[C-LEIGH RACING]

Derby,
How big of a shot were you spraying.
If you would, run a hone through that bore just a bit & then put some more pics up.

Rusty,
About the thickness of the sleeves on the Pro-x cylinders. If that is an older model, not the old type casting that was prone for cracking, but say mid 90s, you probably have the thicker sleeve in that cylinder.

Its not been so long ago, say maybe within the past 5 years, LA Sleeve changed the machining on their sleeves & the OD is smaller than the older model cylinder sleeves.

Far as one being better than the other, thick one or the thin one, shouldnt be any difference. All the iron sleeves LA Sleeve produce are spun cast iron sleeves & unless something would have went wrong in the material makeup of the sleeves all would be the same.
You can have a bad batch of anything that is made by man & far as the cylinder Derby has, those cracks in the sleeve, I've only seen one like that before since I been messing with the Pro-x cylinders & was caused by the aluminum casting cracking first & on into the iron sleeve from hormonics.

A 330 cylinder that has been bored straight every time, you can bore in up to a 77.50mm, but at that size keep in mind the o ring groove at the top is getting mighty thin between the groove & the bore.
I tryed to do a 78mm bore in a 330 jug a good while back, little thin pieces of the sleeve broke off between the bore & the o ring groove because of it being so thin, but the 77.50 lasted a while.

I heard for many years people saying the Pro-x cylinders were junk & you couldnt get very much run time out of them. Some complained about the bore being sloppie, pistons cracking, some even had cracked jugs.
So, what I did, took it on myself to do a test with one, just so happen to be a 330.
I built a 330 TT engine in 2004, we ran it locally & nationally ATVA sanctioned events untill 2007.
Within those years, we were running 10 nationals & anywhere from 21 to 26 local events per season, so that engine was beat up pretty good.
The only thing that was done to that engine during all that time, was a head dome replaced because it had spit the plug out & I cross threaded the plug putting one back in.
Because of how the ESR CR ignition adapter plate is made, I had the ignition timming set somewhere around 20* advance & the engine was spark knocking, but my daughter never told me, she didnt know & thought it was suppose to sound like that, so it ended up spitting the plug out.

At one of the national races in 07, one of the youth guys running a blaster with the CT cylinder kit on it, his reed cage cracked & we were through with all our races, so I just took the Rad Valve out of my daughters R for him to use.
Once we were done with his repair & I had time to look at the R engine over, I found a hair line crack in the back of the piston around the intake window.
After getting home I pulled the top end off to closer check it out, found 5 cracks in the Wiseco piston.
Checking the wear on the bore, was less than 0.005 & realy could have just put in another piston & go, but didnt.
When that engine was built, bore was set up a tight 0.003 as could be & was broke in with just about a tank of gas before it was ever rode any.

From what I learned from that test, to make one live, set it up tight piston to cylinder, good long break in time getting it good & hot each cycle, get it good & hot before you ride or race it, try to always run the carb close to rich as you can & keep the air filter clean.
If you deside to use a K&N air filter if you build one like this, forget all of the above because none of it will make any difference if you do, no 2 stroke likes dirt to rub parts together with.
Neil

[Rich250RRacer]

If you're worried about running out of bores, just send the cylinder to US Chrome and have it Nikasiled (yes, they can coat over the cast iron sleeve). I had one of my favorite cylinders done because I was running out of bores, it would have had to go to .080 over to clean up, now it's running at .050 with no issues.

[Honda 250r 001]

Originally posted by Rich250RRacer
If you're worried about running out of bores, just send the cylinder to US Chrome and have it Nikasiled (yes, they can coat over the cast iron sleeve). I had one of my favorite cylinders done because I was running out of bores, it would have had to go to .080 over to clean up, now it's running at .050 with no issues.

ive always thought about doing this before i get too far with bores. This is pretty expensive though correct? couple hundred bucks?

[C-LEIGH RACING]

Theres a company ( Bore Tech ) that offers carbide lacing of the iron bores as well to make them real hard.
Seen some of those take a beating.
Neil

[rustyATV]

I've used Boretech on my stock cylinders.

I just wanted to know because I picked up a Craigslist special 250R for under $1000 that I'm probably going to part out. The only really good thing on it is the CT 330 kit, which is on it's second bore and needs another.

[Rich250RRacer]

Originally posted by Honda 250r 001
ive always thought about doing this before i get too far with bores. This is pretty expensive though correct? couple hundred bucks?

It's about $200 to Nikasil over cast iron because of the prep work involved.