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Author Topic: 900cc HAINST pistons in my K5  (Read 3260 times)

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Offline BIKE

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900cc HAINST pistons in my K5
« on: January 27, 2009, 04:55:13 PM »
Well, I thought something was strange about the bike when I bought it i the fall and noticed the double row drive chain.
But since it was leaking oil so badly, I decided to take it apart and do a top end gasket/HD head studs.
While I was at it I started measuring...and tada....

What I noticed is that the bore is 66.8mm (2.63 inches).  Yes, way over the 61mm stock spec I have in my Shop Manual.  I pulled the pistons, cleaned them up and looked them over.  Here's what's marked inside:

HAINST
900CC

There's also an "SK" marked in an oak leaf looking thing.

Shockingly the bike is pretty clean.  The pistons measure out at 66.6mm.  The rings and pistons actually look really nice besides some carbon buildup on the top of the pistons.

Anybody want to offer anything up to me?
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Offline UnCrash

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Re: 900cc HAINST pistons in my K5
« Reply #1 on: January 27, 2009, 05:04:09 PM »
Congratulations?
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Offline BIKE

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Re: 900cc HAINST pistons in my K5
« Reply #2 on: January 27, 2009, 05:13:15 PM »
Quote from: UnCrash on January 27, 2009, 05:04:09 PM
Congratulations?


I just wanted to know if there is anything else I should look for. 
Ring clearance...etc.
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Offline Old Scrambler

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Re: 900cc HAINST pistons in my K5
« Reply #3 on: January 27, 2009, 05:32:45 PM »
Is the cam stock?  Is the cam-chain an endless unit?  Where the valves modified?  Any intake porting?  What size carbs and jets?  Needle setting?  Stock air-cleaners or???  Standard ignition (points) or something special?
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 900cc HAINST pistons in my K5
« Reply #4 on: January 27, 2009, 08:42:10 PM »
Henry Abe made 2 different 900 kits and also used 1 piece oil rings and 3 piece oil rings. One of our members, Axl aka Satanic Mechanic, has info posted on his web site so that's the easiest way to get info. Also search our gallery for info. The clearance on those pistons as suggested by Henry Abe is rather loose so if you find that do not be alarmed. I should be sending Big Jay my NOS HA kit and my jugs soon to get set up. I plan on having the pistons cut for/fitted for 3 piece oil rings. I'd sure like to find rings that fit without cutting.   
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Offline Big Jay

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Re: 900cc HAINST pistons in my K5
« Reply #5 on: January 27, 2009, 11:24:30 PM »
Quote from: Jerry Griffin aka Rxman on January 27, 2009, 08:42:10 PM
I should be sending Big Jay my NOS HA kit and my jugs soon to get set up. I plan on having the pistons cut for/fitted for 3 piece oil rings. I'd sure like to find rings that fit without cutting.   

Honda CB360 twin??
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 900cc HAINST pistons in my K5
« Reply #6 on: January 27, 2009, 11:54:41 PM »
Quote from: Big Jay on January 27, 2009, 11:24:30 PM
Quote from: Jerry Griffin aka Rxman on January 27, 2009, 08:42:10 PM
I should be sending Big Jay my NOS HA kit and my jugs soon to get set up. I plan on having the pistons cut for/fitted for 3 piece oil rings. I'd sure like to find rings that fit without cutting.   

Honda CB360 twin??

The 350 twin is a definite fit for my Yosh 812 pistons. That should eliminate the 360 I'd think. Do you or anyone know the size of the 450 pistons?
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Offline Terry in Australia

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Re: 900cc HAINST pistons in my K5
« Reply #7 on: January 28, 2009, 12:10:52 AM »
I really can't understand what the problem is running one piece oil rings. Sure, with many, many miles up you might get a little oil blow-by once the ring gaps start to open up a bit, but so what?

Modern oils are so good the rings aren't gonna wear nearly as quickly as they did back in the day, so as long as your cylinders have been bored correctly with .001 - .0015 "piston to bore" clearances, the ring gaps are spot on, and providing that you run the engine in properly, you won't notice any difference, for many thousands of miles.

It worries me somewhat that some of the more inexperienced guys here are being convinced that it is absolutely essential to (expensively) convert their NOS big bore kit pistons to accept 3 piece oil rings, just because 3 piece oil rings are an evolutionary improvement that was developed by OEM manufacturers to increase mileage between rebuilds.

My K0 came out of the factory with 1 piece oil rings, and, as much as I suppose I should now be petrified with fear that it will explode with the force of an atomic bomb at any moment, 39 years down the track, it still doesn't blow smoke, and still goes like the clappers! I know all the advice here is well intended, but I still can't help but think that this is just another case of "a fool and his money, are soon parted".

Just my 2 cents of course, sorry for the interruption, please return to your regular programming.............  ;D    
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Offline BIKE

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Re: 900cc HAINST pistons in my K5
« Reply #8 on: January 28, 2009, 03:45:20 AM »
Quote from: Jerry Griffin aka Rxman on January 27, 2009, 08:42:10 PM
The clearance on those pistons as suggested by Henry Abe is rather loose so if you find that do not be alarmed.

Thank!

I'm glad to read that as they were a bit "looser" than the Honda manual shows they should be.
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Offline 754

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Re: 900cc HAINST pistons in my K5
« Reply #9 on: January 28, 2009, 07:38:19 AM »
They said they were set up on  the loose, which can mean they wear out quickly..

 At any rate measure your bores and pistons and let us know what you got.. it may be usable.. or maybe not..
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Offline BIKE

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Re: 900cc HAINST pistons in my K5
« Reply #10 on: January 28, 2009, 08:09:42 AM »
Bore on # 2 measures out at 66.8 and piston #2 measures out at 66.62.

That seems within spec on Satanic Mechanic's website. 

I didn't measure the ring gap though.  I'll do that tonight.
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Offline 754

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Re: 900cc HAINST pistons in my K5
« Reply #11 on: January 28, 2009, 08:18:34 AM »
.1 mm sounds like a lot, you got almost 2.. (1.8)
.1 is near .004 thou

You also should measure for taper and out of round, having pistons & sleeves is only 1/2 of a good bore job, then the work starts. Some are bored carefully, some are not.
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73 836cc.. Green, had it for 3 decades!!
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 900cc HAINST pistons in my K5
« Reply #12 on: January 28, 2009, 09:02:52 AM »
Henry Abe's instructions are to bore to .001 - .0015 PER INCH OF PISTON. That works out to approximately .003 to .0045. This is one of the reasons I do not like 1 piece oil rings. To me it just makes more sense to not have an open gap for oil to get through. I just feel that the 3 piece design will control oil better, use less oil, smoke less, and keep fresher plugs in our immuno compromised ignition/electrical systems. I'll be glad to post the instruction sheet if anyone can't find it at Axl's site. 
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Offline BIKE

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Re: 900cc HAINST pistons in my K5
« Reply #13 on: January 28, 2009, 09:13:07 AM »
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Offline NitroHunter

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Re: 900cc HAINST pistons in my K5
« Reply #14 on: January 28, 2009, 09:44:47 AM »
Check your bores at the center of the stroke, you may find the bore is barrel shaped. A shop I worked in had a contract to rebuild the Police Kawi's and found this regularly, even on some pretty low milage engines. The piston speed is highest at this point and the rings wear more here. Also keep this in mind when you hone, your dial bore gauge will show you that the top and bottom of the bore are smaller, a power hone will show this as well on the ammeter. Double stroke these spots.
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Offline BIKE

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Re: 900cc HAINST pistons in my K5
« Reply #15 on: January 28, 2009, 02:19:39 PM »
One last question.  Is there an issue installing the head and jug with standard Honda gaskets?

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Offline NitroHunter

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Re: 900cc HAINST pistons in my K5
« Reply #16 on: January 28, 2009, 02:29:31 PM »
Stock sleeves, no problem. If the sleeve OD is larger than stock, you can carefully trim the gasket with scissors. The head gasket should match the bore size.
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Offline Terry in Australia

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Re: 900cc HAINST pistons in my K5
« Reply #17 on: January 29, 2009, 12:16:26 AM »
You'll need a bigger bore head gasket mate. ;)
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline BIKE

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Re: 900cc HAINST pistons in my K5
« Reply #18 on: January 29, 2009, 03:45:35 AM »
Just ordered one.  I went to line up the head gasket, just to seen and no way would it work.
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