Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board A65 Alloy barrel

So, your pistons have to fit the bore? I mean you don't hone the new barrel to fit piston?

Leon; I would expect one would need to specify the exact size needed when ordering.

It does raise the question of how to deal with the next set of pistons once the first set wears out or comes to grief.

Gordo

Hi Gordo

That's right, if you have a set of GOOD pistons, then a new set of rings is all you need. The barrel will then be made to suit your pistons.
Note: Good pistons, I wont do it for pistons that are scuffed, have pick-up marks and generally wore out.

Hi Leon

I have already stated that I don't supply the pistons. I think my reply's above explain that.

regards

John

Hi Leon

I have already stated that I don't supply the pistons. I think my reply's above explain that.

regards

John [/quote]

Yeah, I didn't phrase that well. I meant MY pistons have to fit the bore. So a buyer sends you his pistons? Or the measurements?

Hi Leon

Yes, the preferred way is you send a piston and the coating company measure the piston and make the bore to suit the piston for the correct clearance and best result.
With you being on the other side of the pond, then the other way is for you to send me an accurate size of your piston measured at 90 degrees to the gudgon pin to the third decimal place at its widest point.

regards

John

To make stock and big bore versions, you really only need two bore sizes, as a damaged bore would be restored by replating. It might be worth telling people what you are using when you test and recommending what you know works at what clearance. Pistons vary quite a bit in material, design and skirt taper and rings employed. The B44 Ed V forged pistons I've been using are good value and quality. I've just had my cyl replated to give .002" clearance, about 150miles so far and it seems good.

Using total seal rings with the Ed V (JE pistons) you can get real tight clearances when using a nikasil lined bore (I think the .002" as Mark mentions is what they quote from memory) Not sure about the Standard rings for the JE pistons, but as they use a modern ring design, I imagine it won't be much different.

Hi Allan

What JE quote on their information sheet for these pistons is "Important clearance information guidelines only, set clearance at o.oo3 thou". Although they do also state they have run them at 0.0025 thou clearance without problem.

Hi Mark

Good to know your running at 0.002 thou clearance without any issue. While that Ok for you or me to play around with and accept responsibility for should things go wrong.

If sell a barrel to anyone using these make of pistons, then I need to set the clearance at the manufactures stated clearance, unless the buyer requests a tighter clearance. Then they accept responsibility for any possible issues.

regards

John

I emailed the guy at JE when I first ran these pistons a few years ago asking him about use in a nicasil plated alloy block(B44 has a liner) and he recommended not going tighter than .002". So this time I'm experimenting with .002" and just thought it might be interesting info for you. I need to do more miles and run it a bit harder to be sure it's ok, but I expect it is. You will probably have people race with your cylinders and get feed back on things like that.

Hi Mark

That's good information, as I was only going with what was on the sheet they sent out with my pistons(same JE 80mm as yours). I should think you'll be Ok having got 150 miles in. At this time of the year your a little warmer than its ever going to get in the UK, but as you say you need to give it a hard run to be sure.
But good to know for anyone racing, that they can probably go down to 0.002 thou clearance with these pistons.

regards

John

Will the JE pistons have the modern very narrow rings or maybe the old type as on Hepolite?
I have been using JE pistons with narrow rings in my 80mm bore Laverda triple and I amongst others found the oil consumption to be too much.Dealers reports the same and blame the rings (The spring behind the oil ring broke on some also). I now use Ross pistons with old type rings and the oil consumption is very much lower. The Ross pistons is, by the way,a bit heavier than the JE..so JE`s with old type rings would maybe be better?

I believe the JE pistons with current narrow rings would work very well with Mark's nikasil bores, not so well with older iron cylinders, where softer iron rings would be better.
It was a common problems for Triumph / BSA triples when they arrived with 3 piece steel piston rings.

Adam. I'm using JE pistons with total seal rings in my iron barrel at 060".

If they are bedded in using a good oil ( running in oil makes a big difference) and not disturbed on the rings or hone they seal quite quickly and nicely.

John, you are unite right about the quoting of the 003", I could be too sure from memory but I knew it was less than stock.

On the TS rings, you can run tighter ring gaps according to the literature, I won't quote any figures.

However with my honed barrel have slightly more clearance than a freshly bored one, the ring gaps didn't require any filing etc to get them right.

Hi

I've just ordered another batch, witch should be ready for delivery end of March based on present schedules. At the moment I have four of the second batch with no names against them.

The earlier photo's shows a 79mm bore version (not yet Nikasil coated), but can be bored to suit your requirements as with the stroke. The original weighed in at 9.3kg, this one is 3.5kg.
It comes complete with a set of 12.9 grade bolt and studs which are 3/8 UNF top thread.

The price is 700 GBP plus P/P (no VAT), half the price when ordering and the rest prior to delivery.

regards

John

contact me on [email protected] for further information.

Hi Nick

Not sure why you would want to go with steel liners, which are going to mean the liners are either thin to get them inside the stud pattern, or really thick and you use the top flange to tap the stud pattern into! Plus you end-up requiring greater piston/liner clearance than with the Nikasil.

As I've had question about distortion before and ran tests to check this. Assuming the worst case between bore and stud clearance, which is the two rear out board studs. We set-up the test pieces with 3/8 UNC 16TPI drilled and tapped holes to represent the clearance between thread OD and 80mm bore clearance which is approximately 0.05mm between the thread OD and what would be the bore. Our test piece on the above clearance had six bored and tapped hole, with the test bolts torqued down to 25 ft lbs.

Test results gave a material displacement of between 0.0003 and 0.0005 thousands of an inch. Although when I talked to the engineer at the Nikasil coater, he said that in 30 years he's not had issues with distortion using the same material.

My barrel uses 5/16" UNC threads into the barrel on the big bore versions, as I feel this gives a greater head gasket sealing area between the bore and stud pattern.

Hope the above information is helpful.

John

Hi Nick

Yes, years ago I had a friend with a set of ARE barrels, head bolts used to come loose, UNF threads in alloy is not a good idea. Once we re-tapped them with a Whitworth thread (think it was the only one that would fit, no more problems after that.

If you can get 85+ BHP out of a A65, you should appreciate the benefits of not only dropping 6kg of engine weight, but also the better cooling and tighter piston/bore clearance.

Times have moved on and Nikasil and the other variations of the process have now been used successfully for years.

Regards

John

I tried thin iron liners in the first alloy cyl I made, they were straight and stopped from moving down by butting against a lip at the bottom, one of them turned a bit and cracked, the nicasil cyl I run now seals better and being all one piece is stronger, I think it's a much better solution for big bores.

Hi

I have two barrels in the second batch without names against them if anyone is interested, then drop me an e-mail [email protected]

regards

John

Hi

Only one barrel left on the second batch without a name against it. If anyone is interested, then drop me an e-mail [email protected]

regards

John

You still have my name against one John? I am expecting the pistons very soon.

Many thanks

Hi Allan

Yes one has your name against it. I'll send you an e-mail.

regards

John

Hi

I now have two barrels of the second batch available, due to a lad dropping out at the last minute.

Should anyone be interested drop me an e-mail [email protected] for information or details.

regards

John

email on the way with lots of questions...

Hi

Back to one barrel available in the second batch.

FYI

If your looking for a big bore street bike, you can use B40 pistons which means you can keep the standard pushrods.
Where using the shorter B44 piston means you need a set of shorter pushrods to go with the shorter barrel height.

My contact address is [email protected]

regards

John

Hi

Been a while since I made an update. My 650 test bike has now done close on 500 miles without any problems.
As it only had 5/16" base studs and I didn't want to completely strip the motor to change them out to 3/8" studs for the big bore version, I had one done to 75mm bore to replace the standard barrel.

http://s1314.photobucket.com/user/ecosse_lynx/media/A65_zps771f1ddb.jpg.html

E-mail me on [email protected] if you want any further information. I'll try and post a couple of photo's later.

regards

John