K Piston Rings

Brothers,
are K and WL pistons exactly the same, my rings have never been great since my rebuild, they smoke, I'm over it, no power loss just a little stinky down the highway... can I save a few bucks and just buy W model pistons? AND What are the best rings to use in a smokey world like mine, might I just change the rings only, the bike has done only 2,000 miles since the rebuild and the jugs were bang on spec 2.75 or whatever they are meant to be...
Best, old smokey pants, Nick.

Hi Nick,

I have a 55 KH, and have had problems with it eating rings and oil for 20 years, actually a little more than 20.... We have tried all the recommendations, with still no results. The best rings I have found are Hastings with three Piece oil rings. The W models after 1952 used the same ring sizes as the KH and K models, but many of the after market pistons available for K models now are set up for the earlier W models with wider compression, or top two rings and thinner one piece oil ring. Well, the K models had a thicker one piece oil ring, but I prefer the three piece Hastings rings. The K model rings and pistons are much better than the others, that were cut to be cheep, as there is a plethera of those older style rings around.

Anyway, my motor had been rebuilt before I got it in 1986, and we kept the same pinion shaft. This is what runs the power from the fly wheels to the oil pump and the cams. It also controls the flow of oil from the pump, down the center of the pinion shaft, into a hole in the right fly wheel and feeds the oil through the crank pin between the fly wheels and the oil ends up feeding the lower bearings on the piston rods. Then the oil is splashed into the lower end, and oils the right side main bearing via splash along with the pistons and upper wrist pin bearings in the rods. It is kind of a long way to describe it, but that is how it is supposed to work. There are also side oilers on K models that spray oil on to the pistons, from a hole in the side of the cylinders. Hoping to reduce my oiling problems I plugged these up. It did not help.

We have now heard from an old school mechanic in the area that the flow down the pinion shaft is too excessive, and he came up with a left hand threaded Philips Head screw that threads backwards into the end of the shaft. We drilled a .090 hole in the screw, right in the middle of the Philips head slots. This he says will reduce the amount of oil building up in the lower end, as when ever I dip it or drain it, it is always about two to three inches down there, and that is about the height of the return slot to the oil pump. There is supposed to be much less, and feel that because the KH needs less oil than the OHV Sportster, the hole was smaller thought the pinion shaft. We checked on a later 1000cc Sportster fly wheel, and low and behold it was filled and drilled from the factory with about a .10 hole. The one in my shaft was about .18, so taking it down to .090 is a lot, but I have not run it yet, and it may just blow the thing to bits. I don't know, but will have it back together in the next couple of weeks. Just got the trans back in from, pulling the whole engine down, and splitting the cases to check the scraper clearances, which were just fine.

This time we also used a later 1000cc model breather with larger window in the breather valve shaft to get as much breath and oil out that is possible, something I learned from The French Owl. Anyway, still working hard to put it back together. Just a few days left, but will let you know. Last time I got it running, after torque plates being made for straight boring, and using total seal rings, it got a good 30 miles to a quart. Not too good!

Will let you know how it turns out. If yours is smoking, and is wet up top, do a search on my posts on "Wet up top", and learn the saga....

Best Regards,
Barry55KH

Thanks Barry,
We both have 55KHs that were rebuilt 20 years ago! What are the chances of that. Sounds like I'm in for more heartache... I'm pretty sure mine is running stock WLA pistons and rings? Where is the best (cheapest) pace to buy the ones you recommend online do you think? 45" Parts Depot? They have these listed (below) I think it's what you mean? What's the best piston clearance for them, my WL manual recommends 1 to 2 thou which is tight by my standards...
–Late style piston complete
–Size +.010" (69,92 mm)
–Modern 3 piece oil control ring
–Used on: 1956 to 1973––45 models
–Includes Hastings rings, 1/16" compression, 3 piece oil control rings
–Sold as a PAIR –Note: recommended for 45 models 1929 to 1973

Thanks again for your advice, Best, Nick.

They are a good outfit, but make sure you get the pistons with the 1/16 in compresion rings.

Here is the chart from Hastings.

1950-65 45, 55 cu. in. Engs. Side Valve G, GE, K, KH, KHK 2.745 2 4244 4 - 1/16 2 - 3/16 These come in oversizes to .070

1937-55 45 Eng. Side Valve D Ser. G, GA, W Ser. 2.745 2 5044 4 - 3/32 2 - 1/8

The 4244 is the stock number, and the 2 in front of it is the number of pistons it fits. The 4 - 1/16 is the number of compression rings in the set and the size of them... etc....

I got my last pistons from Sporty Specialties in California. Nice guys, and easy to deal with for phone orders. They do have a web site, do a search, but I like to talk to them when I order...

I just rebuilt my entire engine three years ago, and then have gone through 4 sets of pistons and 6 sets of rings trying to get it right. Made some mistakes on one bore, like leaving one of the wrist pin keepers out, and scoring the cylinder to the needed next bore size. Much farther and I am going to need sleaves. Setting up wall clearance will depend on the piston manufacture, but most aftermarket ones I have used worked good at 3 to 4 thou. but I have run them with no problem up to 6 or 7. Eat just as much oil, until it ruins the rings and clogs the exhaust valves you loose compression. I will let you know if the restrictor works...

Best Regards,
Barry55KH

Hi all,

K/KH pistons are taller than WL pistons, you'll have "negative pop up" if you fit WL ones in a K/KH!!!

A good place for K pistons is Dixie under their brand name Superior. If you manage to find a shop that's not too greedy on their mark up, you're in for a surprise, they're only about $ 20.00 a pair, "dealer list price", complete with rings, pins and circlips keepers. Last time I bought some, 4 pairs + 4 extra sets of rings + dealer mark up + postage to UK + some UK taxes, about $ 150.00 in all...

As all other, I guess they're made in Taiwan or such far away place BUT I never had any problems with them... I also bore to much less clearence, only 1.5 thou, bed them in fast, less than 200 miles, I can feel when the engine's happy and willing to go... About 3000 miles on the KHK since the 2006 rebuilt mostly at full throttle. Yes it drinks a lot more oil than any of my early iron Sportsters, but sparks are a nice shade of brown...

Patrick

Thanks Patrick,
you are the single most valuable member of this site, if you kick the bucket we are all done for! I can't find Superior brand pistons supplied by Dixie anywhere online? And what's on ebay only offer one piece oil rings; you didn't mention the oil ring concern? Digression: Did you read the latest post on "56KH Project"? I've got a busted foot from my KH: the starter got me at the top of the kick and has really done some damage. Bad kick back – the worst I've had in 20 years... I never retarded the motor for starting but now I'll have to! What's your thinking on this?

Best, busted, Nick.

"$ 20.00 a pair, "dealer list price", complete with rings, pins and circlips keepers."

That was a long, long time ago.

I've never worried too much about side-valve engines burning a bit of oil, on the basis that if they are burning it, it has to get there first.. same as leaky rocker boxes on Triumphs and BSAs!

Seriously though, I wouldn't dispute what Patrick says, because I'm sure he is speaking from experience, but I use 0.004" clearance on WL engines and that seems a happy medium between the various alternatives ( seizing, smoking, oil consumption ) for a mixture of town and open road use

Nick55KH, I have sent you a PM, please check.

Anyone got a link to a lead to the pistons Patrick is pushing? What else are my options???
Best, Nick.

Nick,

Anyone got a link to a lead to the pistons Patrick is pushing? What else are my options???

I have had real good luck with Antique Cycle Supply. Three running K's with the pistons he supplies. Some have been "Superior" brand and some have been "Eastern MC Parts". He will work with you if you have a preference. I usually phone in my order and discuss what is best or available.

http://www.antiquecyclesupply.com/default.htm

His on-line catalog makes it easy.

Good Luck,
Cody

Thanks Cody,
it's a good looking site, never seen it before! Do the Superior pistons have 3 piece oil rings? Do you find 3 piece oil rings are the way to go?
Best,
Nick.

The Superior pistons as supplied come with a cast one piece oil ring. The Eastern pistons are 3/32 compression.
Didn't note your location but the source is Dixie Distributing Co. in Ohio, but they are wholesale only.
Most any shop that deals in vintage is probably set up with them.
Not all sizes are available anymore.

http://www.hastingsmfg.com

You can go here to find the correct rings, and then order them through your local auto machine shop. Use the part number and then quote the over size and they will send them out. You can also order them in 1/2 oversize and then cut the end gaps to fit. My cyclinders have been honed out a bit fromt the last two sets of rings, but the standard oversize was just over end gap tolorance, so I am going to run them.

I have heard a lot of talk over the years about "bad oil pump timing, and bad rings. "The Oil up top syndrom" I should have mine running with the ristrictor in the pinion shaft in the next few weeks. Just finding the time to hang all the parts is tough. Mine has always eaten through rings in a short period of time. I will run her for 1000 miles or so, if she is not smoking, and then pull the front head to check for oil. I will write a report then.

Barry55KH

Panic:

"$ 20.00 a pair, "dealer list price", complete with rings, pins and circlips keepers.

That was a long, long time ago."

T'was in 2006...

As I said, find a not too greedy intermediate!!!

As for 3 pieces or one piece oil ring, I've used both in the past, always found 3 pieces is a pain to fit, don't have any preferences...

As for piston assembly play, It's hard to find good info from the factory, BUT, they do say in the race catalogues to put more clearence in the KR, 4 to 5 thou, my guess is the K/KH factory play would be around what I fit. Too much play to start with only hinder the heat transfer from pistons to cylinders, so too little is bad, but too much is worse as piston will run hotter, use more oil etc... Despite the way I use my KHK, never had a piston seized on me for lack of play...

All the best from Patrick

Hi Nick,

I have a 55 KH, and have had problems with it eating rings and oil for 20 years, actually a little more than 20.... We have tried all the recommendations, with still no results. The best rings I have found are Hastings with three Piece oil rings. The W models after 1952 used the same ring sizes as the KH and K models, but many of the after market pistons available for K models now are set up for the earlier W models with wider compression, or top two rings and thinner one piece oil ring. Well, the K models had a thicker one piece oil ring, but I prefer the three piece Hastings rings. The K model rings and pistons are much better than the others, that were cut to be cheep, as there is a plethera of those older style rings around.

Anyway, my motor had been rebuilt before I got it in 1986, and we kept the same pinion shaft. This is what runs the power from the fly wheels to the oil pump and the cams. It also controls the flow of oil from the pump, down the center of the pinion shaft, into a hole in the right fly wheel and feeds the oil through the crank pin between the fly wheels and the oil ends up feeding the lower bearings on the piston rods. Then the oil is splashed into the lower end, and oils the right side main bearing via splash along with the pistons and upper wrist pin bearings in the rods. It is kind of a long way to describe it, but that is how it is supposed to work. There are also side oilers on K models that spray oil on to the pistons, from a hole in the side of the cylinders. Hoping to reduce my oiling problems I plugged these up. It did not help.

We have now heard from an old school mechanic in the area that the flow down the pinion shaft is too excessive, and he came up with a left hand threaded Philips Head screw that threads backwards into the end of the shaft. We drilled a .090 hole in the screw, right in the middle of the Philips head slots. This he says will reduce the amount of oil building up in the lower end, as when ever I dip it or drain it, it is always about two to three inches down there, and that is about the height of the return slot to the oil pump. There is supposed to be much less, and feel that because the KH needs less oil than the OHV Sportster, the hole was smaller thought the pinion shaft. We checked on a later 1000cc Sportster fly wheel, and low and behold it was filled and drilled from the factory with about a .10 hole. The one in my shaft was about .18, so taking it down to .090 is a lot, but I have not run it yet, and it may just blow the thing to bits. I don't know, but will have it back together in the next couple of weeks. Just got the trans back in from, pulling the whole engine down, and splitting the cases to check the scraper clearances, which were just fine.

This time we also used a later 1000cc model breather with larger window in the breather valve shaft to get as much breath and oil out that is possible, something I learned from The French Owl. Anyway, still working hard to put it back together. Just a few days left, but will let you know. Last time I got it running, after torque plates being made for straight boring, and using total seal rings, it got a good 30 miles to a quart. Not too good!

Will let you know how it turns out. If yours is smoking, and is wet up top, do a search on my posts on "Wet up top", and learn the saga....

Best Regards,
Barry55KH

Barry
It was common practice to run a .060 restrictor plug in the cam cover on "R" motors. When I first built our KR race motor I had a sumping problem during races. Next time it was apart I took the time to build up the scrapers an get them closer to the flywheels, got the breather timing spot on and installed the restrictor in the cam cover. Fixed the problem. I use 15-40 DELO 400 oil. This is a high rpm motor so the .090 may be closer to what you need. Another thing that I have been using is a breather off of the rear of the camcover with a one way check valve. With this you end up with a slight negative pressure which calms the crankcase and helps ring seal.
Mike

Thanks Mike,

Reaferms what we have been told about the K Models. Lots are burning lots of oil, as the stock shafts had smaller pinion shaft holes.

We shall see, as I put mine back together and run it!

Thanks for your help Mike!

Barry

Barry

I notice Deves lists rings for the Ks. Anyone tried them?

Hello folks,

What is the measure of the "negative pop-up" experienced when running WL pistons in K or KH application? I would like it to be -8mm, please.

Can I run WL pistons in a motor with KHK bottom end and KR cylinders, negate the stroke difference, and forego the spacer plates? I would be happy with a slight pop-up.

Thank you all for this thread, I've reread it about 40 time so far and am ready to buy my slugs. However, as I was jotting down the Dixie info to get to my not so greedy intermediary, I kept repeating in my head - negative pop-up...stroker plate...negative pop-up...strok....hmmmmm....

richie