Author Topic: IMD Pistons  (Read 990 times)

Offline paulmbsa

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IMD Pistons
« on: 16.12. 2018 20:44 »
Hi all

anyone used these please
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Online AdrianJ

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Re: IMD Pistons
« Reply #1 on: 24.12. 2018 09:54 »
I’m just about to fit a pair, but I guess that doesn’t help!
Everybody I’ve spoken to says they are better than the modern versions of the original equipment.
Adrian
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Re: IMD Pistons
« Reply #2 on: 28.12. 2018 08:40 »
Some information here Paul,
I am also interested to hear feedback from anyone who has bought them.

https://www.a7a10.net/forum/index.php?topic=13797.0

Cheers
Colin
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Colsbeeza
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Re: IMD Pistons
« Reply #3 on: 28.12. 2018 12:27 »
Cought in a bit of a loop there Col!
Cheers
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Re: IMD Pistons
« Reply #4 on: 28.12. 2018 22:20 »
OOPS - right there Muskrat *red*. I now cannot find the reference I found yesterday.
Colin
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Offline Steve.Carter

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Re: IMD Pistons
« Reply #5 on: 29.12. 2018 07:45 »
I've had a pair fitted in my Ariel Huntmaster, won't now fit anything else now. I had terrible problems trying to cure a smokey engine only finally fixed by IMD pistons. I can now do 2000 miles between oil changes without even having to top up the oil tank. 
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Offline Scott and Jay

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Re: IMD Pistons
« Reply #6 on: 06.01. 2019 21:01 »
Oh yes, I can contribute to this. I have posted before about the quality of IMD Pistons. I was going to chip in during the last "pistons" topic - because IMD wasn't mentioned. I have just checked and IMD are coming out with new A10 stock soon (they weren't advertising them the last time I looked). They only do flat-top up to +40. Adrian Wright, the proprietor was very helpful, though - and supplied me with the flanged liners that our reconditioner insisted on. There's 2 others in our club that have followed my lead now, and sleeved back to std - by this.

I have done about 3k miles since I fitted them. I put them in dry (with light oil on the skirt only). I ran them in using the "stationery" method described by Klaus, a while back. They appeared to bed in instantly, then. I hopped the performance up by a bit of skimming (some was unavoidable, I shortened the pushrods correspondingly).  This has raised the compression to about 8.1:1 (by my calculations). I fitted a 1 5/32 new Amal Premier carb. Since then, the bike has performed with a lot more power and burns no oil.

Our supreme guru local engineer was very impressed with them. He is very hot on piston quality (dislikes JPs). The other thing to mention is Adrian said "don't gap them - no need to". So, I didn't. The rings appear "modern" - thinner and deeper. The 3 piece oil ring is a big factor, I think. The pistons are light, too..
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Online groily

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Re: IMD Pistons
« Reply #7 on: 14.10. 2020 17:42 »
Well, on the basis of what you guys say here, plus some other positive comments, I've just ordered a pair too. Very nice people to deal with, was my initial thought - great sense of humour!

So, yup, a bit of top-end wear to deal with hereabouts, after 50,000+  miles in 13 years in my hands and I don't know how many before.

I was expecting gross bore wear as well as worn-out pistons. Was even worrying, as you do, whether when I got there the bores would come clean at +60 or have to be sleeved  . . .  I knew from when I had the engine open a few years back the one and only time  (crank endfloat job) that the time was coming for some top-end investment. But, wanting to get every last mile out of the 67-1421 BSA +1mm parts, I just put some rings in, new shells and D/side main down below just because it was apart, and some ex valves & guides  . . . and kept on going. Which she did, with hardly a hiccough. (The t/side bush had 1.5 thou clearance at that point, which also pleased me mightily.)

But to my delight several years on, bore wear max is 4 thou tops, and in most places is between 2.5 and 3 thou. Very hard to believe frankly, or maybe I'm just too pessimistic with these things! But -  the pistons are up to 8 thou undersize  most places below the rings. Not scored, not damaged, just tired, with signs of blow-by on the side faces of both pistons, and that golden-brown sticky colour on the top ends of the con-rods where oily stuff has happened. So the pistons took  the hit, and the bores have remained clean. Nice.  Wasn't smoking at all, but was using a drop, and had become noisy.

A trial fit of a 71mm brand new STD B31 piston (why the heck have I got one of them sitting around???), just to see if I could believe my measurements, gave me skirt clearances of 4 - 4.5 thou, and the 71mm rings supplied with that piston gapped at 11 thou. Not definitive of course, but a useful indication. So I have forced myself to believe the evidence of my eyes and measuring sticks.

And am  more impressed than I have ever been with the hardiness of these motors.  With any luck these IMD bits will see me through  the next 50K or to the grave, whichever comes first!
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Online groily

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Re: IMD Pistons
« Reply #8 on: 15.10. 2020 10:43 »
I don't know if the attached is of any use to people (or maybe you've all got the info anyway - or maybe it's all on the site somewhere and I haven't spotted it, in which case, apologies!)  . . . but I found this helpful in deciding where I was with my pistons and bores. Obviously it's Hepolite data and not necessarily 100% accurate for other makes, but a handy starting point I thought.
http://www.barnstormers.co.nz/barnstormers/wp-content/uploads/2020/08/Hepolite-Piston.pdf
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Bill

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Re: IMD Pistons
« Reply #9 on: 15.10. 2020 11:09 »
available on Ebay
https://www.ebay.co.uk/itm/BSA-A10-650-1950-1962-PISTON-KITS-2-Standard-size-STD/153712381275?hash=item23c9f8cd5b

On a bit of a tangent - I've corrently got 8.5 in my alloy headed A10, my intention is to refit the cast head - will it run with the persent pistons or will there be some problem/s
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All the best - Bill
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Re: IMD Pistons
« Reply #10 on: 15.10. 2020 11:28 »
 I just bought a set for the A10 SR project....Not installed yet..Nicely finished..The rings came installed on pistons..I suppose at recomended clearance end gap checks aren't  necessary?  The rings are thin like what  use on my Triumph race bikes...Top ring appears faced with chrome or some other treatment.
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Offline Swarfcut

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Re: IMD Pistons
« Reply #11 on: 15.10. 2020 11:55 »
Reckon that useful Pistons/Rings link from Groily is well worth inclusion in the Forum Literature section. Don't think it is already as I was forced use Drag's hide and seek site.

 Swarfy.

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Online groily

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Re: IMD Pistons
« Reply #12 on: 15.10. 2020 13:25 »
I just bought a set for the A10 SR project....Not installed yet..Nicely finished..The rings came installed on pistons..I suppose at recomended clearance end gap checks aren't  necessary?  The rings are thin like what  use on my Triumph race bikes...Top ring appears faced with chrome or some other treatment.

The bloke I was talking to at IMD said 'no need to play with gaps, just fit them' and said they were putting something up on their websit on the topic. I also heard from another user that gaps weren't an issue - he had been told the same - so he fitted them and was happy; He added that they bedded in in no time, no smoke no oil consumption. Here's hoping!. Three piece oil rings, so it will be nice if they do come pre-fitted 'cos I always worry about busting one or other bit on them  . . . .
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Bill

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Re: IMD Pistons
« Reply #13 on: 15.10. 2020 13:56 »
I just bought a set for the A10 SR project....Not installed yet..Nicely finished..The rings came installed on pistons..I suppose at recomended clearance end gap checks aren't  necessary?  The rings are thin like what  use on my Triumph race bikes...Top ring appears faced with chrome or some other treatment.

The bloke I was talking to at IMD said 'no need to play with gaps, just fit them' and said they were putting something up on their websit on the topic. I also heard from another user that gaps weren't an issue - he had been told the same - so he fitted them and was happy; He added that they bedded in in no time, no smoke no oil consumption. Here's hoping!. Three piece oil rings, so it will be nice if they do come pre-fitted 'cos I always worry about busting one or other bit on them  . . . .
  A Wright  from IMD responded to my questions and said the top ring is chrome plated and a narrow modern ring package.
  Some on the Brit Bike forum have complained about chrome rings not seating. My experience is if the cylinders are prepped correctly, cylinders installed  properly , proper oil and break in, any type ring seats quickly, as in no smoke from the moment of first start up
 
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Re: IMD Pistons
« Reply #14 on: 15.10. 2020 18:20 »
Most of the engines I've built over the years had chrome compression rings. Never a problem - indeed they are my favourite. Just don't use them in a chrome bore.
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