The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: paulmbsa on 16.12. 2018 20:44

Title: IMD Pistons
Post by: paulmbsa on 16.12. 2018 20:44
Hi all

anyone used these please
Title: Re: IMD Pistons
Post by: AdrianJ 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
Title: Re: IMD Pistons
Post by: Colsbeeza 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
Title: Re: IMD Pistons
Post by: muskrat on 28.12. 2018 12:27
Cought in a bit of a loop there Col!
Cheers
Title: Re: IMD Pistons
Post by: Colsbeeza on 28.12. 2018 22:20
OOPS - right there Muskrat *red*. I now cannot find the reference I found yesterday.
Colin
Title: Re: IMD Pistons
Post by: Steve.Carter 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. 
Title: Re: IMD Pistons
Post by: Scott and Jay 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..
Title: Re: IMD Pistons
Post by: groily 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!
Title: Re: IMD Pistons
Post by: groily 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
Title: Re: IMD Pistons
Post by: bsa-bill 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 (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
Title: Re: IMD Pistons
Post by: Truckedup 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.
Title: Re: IMD Pistons
Post by: Swarfcut 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.

Title: Re: IMD Pistons
Post by: groily 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  . . . .
Title: Re: IMD Pistons
Post by: Truckedup 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
 
Title: Re: IMD Pistons
Post by: RDfella 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.
Title: Re: IMD Pistons
Post by: Swarfcut on 15.10. 2020 19:27
  AE introduced a three piece oil control ring in the 1970's, under the APEX brand. Just two thin rings top and bottom of the groove and a spring loaded central spacer. The rings were like spring steel, flexy and easy to fit. They would transform a worn smoker and brought many a condemned engine back to useful life without the expense of a rebore and pistons. Easy to fit, not at all fragile like the original single piece cast iron oil rings.

 Just wondering if these IMD Pistons have different thickness of rings, using a more modern style of ring technology and presumably  more widely available sources of supply than the good old 62, 66 or 70mm X 1/16" cast iron compression rings of yesteryear.

 Swarfy.
Title: Re: IMD Pistons
Post by: groily on 17.10. 2020 15:00
And here is one, just out of its box.
Yes, thin modern-style compression rings and multi-part oil control, yes, all pre-fitted, and I think quite handsome looking things. Seem quite light too, but haven't weighed to compare with the BSA ones.
Says they want a bore clearance of 4 thou greater than the width of the skirts (measured at a point part-way up from the bottom) at 90° to the pin. Well, I'll have that plus a tad and we'll see how they do.
Just waiting for an inlet valve or two and a handful of gaskets from Draganfly, and she should be running next week if I have the time.

D'ya remember those Cord rings from way back Swarfy? My old Dad used to fit them when he couldn't get from A to B on a sumpful, or his car wouldn't go up a certain hill any more - all smoke and no go! Never a shortage of urgent projects at weekends half a century and more ago  . . .
Title: Re: IMD Pistons
Post by: RDfella on 17.10. 2020 15:27
Yup, remember Cord rings. Fitted them to old engines with worn bores when a rebore wasn't convenient or affordable. If I recall they were dished rather like a diaphragm clutch spring, and you fitted as many as you could get into the groove.
Title: Re: IMD Pistons
Post by: Swarfcut on 17.10. 2020 16:36
Sure I remember them, and they are still trading. The AE APEX oil rings were a very similar to the Cord three part ring, might even have been supplied by them raw and repacked in AE Livery.

 Way back Dad had an ex Hanger Motors (Birmingham UK) FordE93A  Van, the old sit up and beg type with a longstroke side valve engine, well known in motoring circles as a natural burner even from new.  Times were tough, and this wreck used as much oil as petrol. Father saw an advert in the paper, and as an ex RAF engine fitter had no problem fitting a set, which true to the advertising puff transformed it into a reliable runner and it was used as a stop gap for several years. He traded it for a Morris Oxford  series MO, leather seats, 4 speed box AND a heater. Yes folks, that's how it used to be in the 1950's.....heaters were an optional extra!

 Used Cord rings myself on a selection of ex fleet cars of the 1980's, Cavaliers, Cortina, Sierra, Crossflow and CVH Fords. The rings would seal at the first turn of the key, the secret being to use cheapo Supermarket Oil with non of the anti wear additives as a first fill. As well as a good radial pressure against the bore, the dished feature on compression rings compensated to a degree for worn piston ring grooves, often overlooked when re using old pistons, any  up and down movement of the rings in the grooves will pump oil  up into the combustion chamber. The back to back spring loaded individual parts of the ring compensated for this wear.

 Sparing no expense on oil with your new A10 Bore and Pistons could be why some rings don't seal, the anti wear lubricating properties of all singing and dancing modern oils are just too good for traditional metallurgy.

 Swarfy.
Title: Re: IMD Pistons
Post by: groily on 18.10. 2020 10:09
The AE APEX oil rings were a very similar to the Cord three part ring, might even have been supplied by them raw and repacked in AE Livery.

That's what made me think of them.
Early A series BMC engines is what we practised on, the old 803cc jobs that would just about pull a maggot off a slice of rotten liver - when new. Bit like an E93A then! Heater?? Wow, luxury! The cold winter of '62/'63 I well remember our annual pilgrimage at Xmas to visit one lot of grandparents, 200 miles in an early, unheated, Morrie Minor van, me and my brother sitting on cushions in the back. Mum and Dad were OK cos (as ever) 'there was a pub they knew' about half way where they stayed for ages warming up while we froze half to death in the car park  . . . Very character building. There has been progress!
Title: Re: IMD Pistons
Post by: edboy on 19.10. 2020 00:11
my old a65  had a set of cord rings. although they seat very quick and cut oil consumption they also wear our your iron barrel quick as cord rings are steel rings.
Title: Re: IMD Pistons
Post by: Colsbeeza on 24.10. 2020 08:37
I fitted my new pair of IMD pistons today.
The circlips which came with the pistons were so stiff that I could not get them in without brute force. Slipping them in with light finger pressure?? - Forget it!!
Anyway I found a relatively easy method and got them in today. If anyone is having the same trouble, I will explain.
I weighed mine months ago. Will post the details later.
Col
Title: Re: IMD Pistons
Post by: groily on 24.10. 2020 08:40
Quite agree about the circlips. An unexpected disappointment! Have said something quite forceful to that effect on the feedback I was asked for via Trustpilot.
Title: Re: IMD Pistons
Post by: Scott and Jay on 25.10. 2020 00:18
I have posted before about my IMD piston-and-ring set. They were often overlooked in "pistons" topics, on the forum. The modern rings, including 3-piece oil ring - really sorted my A10. I did the "Klaus" method of "static" running in. They appeared to bed in instantly, still running great - no smoke. The pistons are a high-quality product, and light. The reconditioner followed the "boring" (they were quite dull reading) instructions, supplied - that was because the barrels required sleeving (already 60 plus). But the great things was that Adrian Wright, IMD's proprietor - sourced the sleeves. I would otherwise have had to get some made, here in NZ - at great cost. Adrian said "they just need to be cut shorter" - which was easy...
Title: Re: IMD Pistons
Post by: Miker on 25.10. 2020 00:38
I have just ordered a set of IMD Pistons. I would be very interested in your method of installing the circlips.
Title: Re: IMD Pistons
Post by: Jules on 25.10. 2020 01:02
just info. at this time, but these Hepolites are on Ebay and a bit cheaper than IMD's and are boasting about modern ring packs, but I notice that Wassell now own the brand - I always though Hepolites were the "original and the best", has IMD now got that banner for BSA's then??
https://www.ebay.co.uk/itm/BSA-A10-NEW-HEPOLITE-7-25-1-STD-20-40-60-PISTONS-FOR-1950-TO-1962-MODELS/272225606385?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20131231084308%26meid%3D213e8c638af849ba8223b96de526def2%26pid%3D100010%26rk%3D2%26rkt%3D12%26mehot%3Dpp%26sd%3D153712381275%26itm%3D272225606385%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganic&_trksid=p2047675.c100010.m2109
Title: Re: IMD Pistons
Post by: JulianS on 25.10. 2020 08:54
Same problem with poor quaity very difficult almost impossible to fit circlips - solution is to throw them away and buy a better quaity set which can be fitted.
Title: Re: IMD Pistons
Post by: Triton Thrasher on 25.10. 2020 13:42
just info. at this time, but these Hepolites are on Ebay and a bit cheaper than IMD's and are boasting about modern ring packs, but I notice that Wassell now own the brand - I always though Hepolites were the "original and the best", has IMD now got that banner for BSA's then??
https://www.ebay.co.uk/itm/BSA-A10-NEW-HEPOLITE-7-25-1-STD-20-40-60-PISTONS-FOR-1950-TO-1962-MODELS/272225606385?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20131231084308%26meid%3D213e8c638af849ba8223b96de526def2%26pid%3D100010%26rk%3D2%26rkt%3D12%26mehot%3Dpp%26sd%3D153712381275%26itm%3D272225606385%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganic&_trksid=p2047675.c100010.m2109

Modern Hepolites are made in Taiwan by JCC.  They are good pistons.

They are also marketed as JCC, Harris and EMGO.

I’ve had no trouble with the rings supplied by Wassell/Hepolite or Harris, in a Triumph 650.

I did not fit the circlips supplied with them though.  Look at them!

(https://i.postimg.cc/cH835ccT/0-EED1-FF6-10-D1-4294-91-C0-87811-B120-E1-A.png)
(https://i.postimg.cc/MTDYY5Z4/0048-D2-FF-0782-4718-95-A6-DD3-E47-B92-C10.jpg)
Title: Re: IMD Pistons
Post by: RDfella on 25.10. 2020 15:41
Never liked split-skirt pistons. They're quieter because they can run with less clearance, but they can break, too. Allright for an old car or for pottering around, but definitely not my choice if one is prone to give it a handful now and then.
Title: Re: IMD Pistons
Post by: groily on 25.10. 2020 17:21
You DEFINITELY wouldn't like the wire-wound one on the left then RD!
The only solids I have hereabouts are Notruns - and the A10
Title: Re: IMD Pistons
Post by: muskrat on 25.10. 2020 18:44
G'day Fellas.
This is the type of split skirt pistons I used on the first rebuild of the A7 plunger back in the early 80's. They nipped up but didn't brake after an hour sitting on 70mph  *eek*. I used the recommended 1,1/2 thou clearance.
Cheers
Title: Re: IMD Pistons
Post by: Triton Thrasher on 25.10. 2020 19:06
G'day Fellas.
This is the type of split skirt pistons I used on the first rebuild of the A7 plunger back in the early 80's. They nipped up but didn't brake after an hour sitting on 70mph  *eek*. I used the recommended 1,1/2 thou clearance.
Cheers

0.0015” wasn’t enough that day.

Gratuitous chamber of horrors photo:

(https://i.postimg.cc/VvV7dZ0j/91165147-BE5-B-4926-80-A9-C77090495-AC5.jpg)
Title: Re: IMD Pistons
Post by: Colsbeeza on 26.10. 2020 11:04
Hi Miker,
I have written out the method of getting the IMD circlips fitted which worked for me.
Scott & Jay - Can you steer me to Klaus's method of bedding the rings?  Is that a "dry" method ?
Col
Title: Re: IMD Pistons
Post by: Greybeard on 26.10. 2020 18:15
Hi Miker,
I have written out the method of getting the IMD circlips fitted which worked for me.
Scott & Jay - Can you steer me to Klaus's method of bedding the rings?  Is that a "dry" method ?
Col
You forgot to add the bit about finding the clip after it went on a trip of the darkest corners of your workshop!   ;)
Title: Re: IMD Pistons
Post by: Triton Thrasher on 26.10. 2020 22:07
Quote from: Greybeard
You forgot to add the bit about finding the clip after it went on a trip of the darkest corners of your workshop!   ;)

I revel in the luxury of spare circlips before I start fitting pistons, these days.
Title: Re: IMD Pistons
Post by: Colsbeeza on 27.10. 2020 00:51
Yes GB that was my greatest fear. I had no spares.
Sweating profusely until the last circlip was in.!
Col
Title: Re: IMD Pistons
Post by: Colsbeeza on 27.10. 2020 01:49
Attached Data from my Crank Balance in 2019 for the Golden Flash as promised. Sorry I had to save it in pdf format to get it to attach. My Spreadsheet is in xlxs format. How do I change this to an acceptable format?
IMD and Hepolite Piston weights are detailed. The IMD are considerably lighter, which suited me fine, as I already had too many holes drilled in the flywheel and Balance Factor with the Hepolites would have been higher than I wanted.
The IMD's gave me BF = 59.  (Note 54 for standard, 65+ for racing)
Note - mentioned are Priory Gudgeon Pins (from Priory Magnetos) with the Hepolite Pistons. I had purchased them in the hope that I could re-use the old Hepolites as the old Hepolite Gudgeons had been badly damaged by some ham-fisted operator, so calculated the BF with Priory Gudgeons - not used obviously.
The quality of the IMDs is impressive, and the clearances are spot-on. Hair Dryer used to get the gudgeons to slide into the pistons nicely - no go without heat. Even used the hair dryer to install the gudgeons in the small ends. They would go in without heat, but would have needed some light tapping.
Cheers
Col
Title: Re: IMD Pistons
Post by: groily on 27.10. 2020 07:34
That is great info, thanks. (Not that I am taking things apart to weigh it all or change the BF on mine. It will be what it is, and I'll avoid running in any rough patch caused by the change in piston weights, if there is one.)
I second your comments on clearances - my experience is the same.
Only gripe  . . . those circlips!
Title: Re: IMD Pistons
Post by: Triton Thrasher on 27.10. 2020 08:01
Quote from: Colsbeeza
Hair Dryer used to get the gudgeons to slide into the pistons nicely - no go without heat. Even used the hair dryer to install the gudgeons in the small ends. They would go in without heat, but would have needed some light tapping.

I’d be happier with small ends that are free to swivel on a cold morning.
Title: Re: IMD Pistons
Post by: Colsbeeza on 27.10. 2020 11:12
Yes TT, I decided to leave well enough alone, and hope the high spots will ease quickly. Besides, if it is that cold, I'll stay in bed. *lol*
Col
Title: Re: IMD Pistons
Post by: Jules on 27.10. 2020 11:39
couple of questions then...
1. whats wrong with the old style circlips with the wire tab? has anybody really ever experienced them letting go?
2. after fitting the new IMD circlips, I guess you never want to (try to) take them out again, lol.....
Title: Re: IMD Pistons
Post by: Triton Thrasher on 27.10. 2020 12:44
couple of questions then...
1. whats wrong with the old style circlips with the wire tab? has anybody really ever experienced them letting go?

Not me, but this stupid thing, not from IMD, isn’t even round. The flat bit next to the bend didn’t sit down in the groove.

(https://i.postimg.cc/MTDYY5Z4/0048-D2-FF-0782-4718-95-A6-DD3-E47-B92-C10.jpg)

Quote
2. after fitting the new IMD circlips, I guess you never want to (try to) take them out again, lol.....

Use a pointed tool to rotate the circlip, so it crosses the slot at the bottom.  Then use long-nosed pliers.
Title: Re: IMD Pistons
Post by: Colsbeeza on 27.10. 2020 22:02
I doubt that you could rotate the IMD circlip - they are so hard and very tight in the groove. The IMD circlip has thicker wire (1.38mm) than others. I did not want to use an alternative with thinner wire, as I was concerned that it may move about in the IMD groove and eventually come out.??
TT - In Scotland, you might be concerned that the gudgeons might tighten in the small end on cold mornings. Here in Oz, I doubt I'd be riding in under 15 deg C. And I've never seen snow here. More concerned about overheating in 40 Deg.
Anyway if it seizes I'll know why.! *roll*
Col
Title: Re: IMD Pistons
Post by: chaterlea25 on 27.10. 2020 22:16
Hi All,
In my opinion those circlips as posted by TT are crap  *ex* *ex*
Circlips like these were supplied with the new "Hepolite" pistons I got for a current build
I threw them away and use plain clips without the "ears"
The wire circlips in service should be pushed tighter into the groove by the little chamfer on the end of the gudgeon pin , the ear on the clip prevents this happening ..
Some time ago there were a lot of circlip failures on vintage Indian and HD engines where the clips with ears made a bid for freedom  *eek*

John



Title: Re: IMD Pistons
Post by: berger on 27.10. 2020 23:41
apart from 1001 things what does IMD stand for , as in the piston makers
Title: Re: IMD Pistons
Post by: RDfella on 28.10. 2020 13:18
Keith - it's where the circlips go when trying to fit them - 'in many directions'.
Title: Re: IMD Pistons
Post by: berger on 28.10. 2020 18:20
RD fella   *lol* *lol*