Eastern pistons

[Brian]

This is more a information topic which may help some in trying to decide what brand of pistons to buy when needed.

I bought a pair of pistons from British Only Austria, mainly because the current exchange rate makes the OZ dollar strong against the Euro. They cost me Aus $150 (104 Euro) landed in Oz.

The pistons are Taiwanese, Fuh Juinn brand. They are 7.25 - 1 (flat top). As you can imagine I was very reluctant to buy these due to the poor reputation of a lot of Eastern products but they assured me the quality was good and they have sold lots without problems.

I am very happy with them. They are a cast piston and very well machined. They have a .005" grind (ovality) which is the same as a Hepolite. The thing that I hope does give them a advantage is their weight, they weigh the same as a Hepolite. This is one area that can be a problem with GPM and JP pistons, they are usually quite a bit heavier than originals. I have given them .004" clearance in the bores.

Time will tell how they will wear and perform when hot etc but they look good and I am confident they will be ok. I guess the thing is dont dismiss eastern made stuff without checking it out first.

[cus]

G'day Brian,
I have a good contact in Vic. that sets your pistons up with a 3 peice oil ring,
he did my pistons,...great job, let me know if you're interested,

Cus

[muskrat]

G'day Brian,
                will be interested to see how they perform. Weight is important as is the ovality.
Do cast pistons expand more or less than forged ? I thought 4 thou is a bit much.
Was it you that spoke of the Total Seal gapless second ring ? I'd like to try that.
Shame the pistons had such a long journey Taiwan/Austria/Australia. if we could get them direct it would shave another $50 off the price.
Do you know if anyone does forged pistons for our bikes anymore ?
Cheers

[MG]

Hello to all!

I also would like to hear how they perform. Let us know!

muskrat,
cast pistons expand slightly less than the forging alloys, but the latter offer higher material strength and therefore are better suited for high power/high temp. applications.
4 thou imho is okay, that's what JP recommends too.
Ref the long journey of the parts: If everything was sold to you guys down there directly, BOA would soon be broke and I'd loose my local supplier. So just keep ordering here, PLEASE!!!  

Cheers, Markus

[muskrat]

G'day Marcus,
                   No worries mate. Just had a look at their site and bookmarked it. Very good.
Good suppliers of BSA stuff down here are few and far between. I often think how lucky you lot in Europe are with the number of suppliers.
Cheers

[Brian]

G'Day Muskrat,
                   I always give my pistons .004" clearance. BSA recommends .003"-.0045" for solid skirt A10 pistons. I dont run my engines in carefully like some so like the clearance to be adequate.

I doubt that you would find forged pistons anywhere for BSA's, or most other makes even. As for rings I just use the standard rings, I've never bothered with any of the alternatives and havent had any problems yet. As Cus suggests you can get the three piece oil rings. I have always believed that a well assembled standard engine will do everything that is asked of it.

I have not long discovered British Only in Austria and the pistons are the first thing I have bought although I have just ordered a set of cam followers from them. So far I cant fault them, everything on their site is priced so no nasty surprises and its easy to order from them. They use paypal so payment is easy. While the exchange rate stays good I will probably get more stuff from them. Like you say reliable suppliers of stuff for our bikes are hard to find.

[muskrat]

Thanks Brian,
 Yes I just had a good look at their site and will be ordering a few bits. just bent an inlet valve !!!
I used to give my race motors 4 1/2 thou but did 3 on the cafe. Run in, wots that ? 500 miles tops. LOL.
I have a set of forged 10.5:1 in at moment and another +20 set as spares. JB brand from the US with an offset pin, but haven't been able to find any more.
You are right in that a std motor is good for what they are made for but I tend to ride a little harder than most classic riders and tend to soop up anything I get my hands on (even this old nerd box). I know most will say I'm a fool, but I have fun.
Oh, beer o'clock
Cheers

[MG]

Brian,

I mentioned that several times on the forum already, but once again especially for you: 
Forged Wiseco pistons for the A10 in 9:1 are available from Cake Street Classics (CEO Roger Shirman) in the UK. Great stuff!

Cheers, Markus

[Brian]

Thanks Markus, I will keep that in mind. I cant see myself using 9-1 though, I use 7.25-1 in all my engines except my 61' Flash which has 8-1 in it.
9-1 would be good if you were chasing performance but I have found 7.25-1 with a 356 cam gives a very nice engine. Nice and smooth and tractable but still with good performance.
I suppose living in Austria you are able to visit BOA and peruse their goods, lucky devil !

[MG]

I suppose living in Austria you are able to visit BOA and peruse their goods, lucky devil !

Yep 

[A10Boy]

With the quality of modern "petrol" 7.25 is plenty high enough, especially with an iron headed engine.

[Brian]

I fitted the pistons today and discovered one problem, the rings. They had way too much end gap, .020". I had a set of Hepolite rings so I used them. Now I have a spare set for a STD or +.010" engine. Otherwise it all looks good.

[muskrat]

Lucky you had spares mate. Having to wait for rings would be a bugga. Why is quality so hard to get with parts made elsewhere (China, Taiwan, India etc) ? Lucky it was the rings and not the slugs that were wrong.
Cheers

[Brian]

I try to keep a few spares that might be needed.

I'm not sure if the rings are made with too much gap or maybe the wrong ones were put in with the pistons.

The pistons look good and the pins are the correct size etc so maybe they did put the wrong rings in the boxes.

[muskrat]

Could be the case.
When I bought two sets of pistons from US, one set had no clips, the other no pins.
Cheers

[MG]

Brian,
anything worth reporting about the pistons already?

[Brian]

They are in the engine Markus but I probably wont have this one finished for at least 6 months. Its another plunger A10 I'm building.

While we are on the subject of pistons, a friend recently bought a pair of GPM's for his A10 so we weighed them bare, exactly the same as a set of genuine BSA ones. There seems to be a lot of different opinion of GPM pistons, I havent used any in a A but I have used them in B series BSA's without any problem. I had a good look at them and we measured the ovality etc and I would have to say it all looked good.

[chaterlea25]

Hi All,
Brian,
I had the same problem withe the ring gaps on the set I fitted recently
gaps were 25-30 thou???
Had to wait a week or more for a replacement set!!

Regards
John O R

[a10gf]

Totally off topic comment, sorry:

Brian, I admired the very good quality of your 003 photo above, and the exif info identified it as an old canon A410. Good to see one does not need the latest megagigabyte cam to get great photos. And great looking engine btw

[Brian]

I got rid of the old HP Erling and have been using the other halfs A410, I still havent bought another camera, I'll get round to it oneday. (like a lot of other things)