It looks like I am going to have to get a new piston for the M20. On-line searches come up with JP or GPM brands for the +60 I need.
If I can't find a NOS piston which of these new ones should I opt for or are they of equal quality?
I use a lot of JP pisons & have no problems with the, provided you shot the rings away and fit proper Cast Iron rings.
he ones they supply are way too hard and take forever to bed in
email (option): bsansw1@tpg.com.au
If you are reusing old rings that are ok don't use oil on the bore but just use WD40. It seems to work and bed the rings in well. It may work with these JP rings Im not sure.
Has the excessive piston weight issue been resolved with either of these manufacturers?...Ian
email (option): ian@wright52.plus.com
Not AFAIK
The problem is JP have about 2 dozen patterns so they get cast thick so they can be machined down to fit as many different models as possible
The bigger the oversize the heavier the pistons get
The Std B50 piston was a little lighter than what was in there when I got the bike .
email (option): bsansw1@tpg.com.au
What kind of life are you experiencing with pistons and bores?
I prefer the GPM over JP, but the prices are getting too high for a cheaply made piston in my opinion.
email (option): pes.sales@btconnect.com
What is the current price and what makes you say they are 'cheaply made'?....Ian
email (option): ian@wright52.plus.com
Where stock is available I can do M21 piston kits for £52.00 + vat if it applies.
The M20 piston kits are now £120.00 + vat for the same quality piston and rings.
I expect the new stock M21's will be this price too.
For my M20 I will have some forged pistons made with a modern ring pack that should retail at £200.00 + vat.
Maybe not the best prices, but sustainable.
Reboring service too.
email (option): pes.sales@btconnect.com
Are these prices that you sell pistons at?...Are they GPN, JP or another make...?...
Also could you expand on your comments regarding the quality of the pistons..?...
Finally, what make would the forged pistons be if you were to get them made?....Ian
email (option): ian@wright52.plus.com
The prices I quoted for the cast pistons were gpm.
They are not the worst I've seen, copies of the old hepolite in many cases.
It's the ring pack that lets them down, but then I'm used to using better.
I believe you can get better rings for them, but then the price increases.
I have used gpm for racing and they do seem intolerant of that. Not surprizing really.
The forged pistons would be my make, as I send drawings and specifications to the subcontractor.
The rings I like to use were originally Japanese, but claimed to be US made now.
I have used a few piston subcontractors over the years, generally sacking them for not doing as they are told.
The reason I was asking about Piston/Bore problems, is that if they are good for high mileage it might change my approach.
email (option): pes.sales@btconnect.com
I've used JE Pistons (USA) and CP Pistons (USA, part of the Carrillo group) for forged pistons with good results, though I have a preference for JE Pistons to be honest...I've always had problems getting past first base with Omega, much as I would like to use a British company...
For aftermarket products I've generally found the Americans to be good, helpful and prompt with good products...MAP Cycles, CP/Carrillo, JE Pistons and Manley valves spring immediately to mind....
It's definitely the case that forged pistons are becoming a realistic option now as the prices of (particularly) NOS and aftermarket pistons are rising quickly...There is also the question of availability..NOS 'Long Rod' B33 pistons, for example, are very hard to find and NOS M21 pistons are even thinner on the ground these days...
The only drawback with forged is how much investment has to be put in 'up front' and the decision on which size to go for...Ian
email (option): ian@wright52.plus.com
I don't expect you know much about us Ian, (Performance Engineering Services) (new website under construction)
We make all sorts of engine and gearbox components.
Most stuff is made is house, but some is subbed out as long as quality and price are maintained.
We don't charge much for a custom piston design and that's a one off price. Repeat orders don't incur that cost.
There are lots of piston manufacturers now, all with the same kit. It's just about how fussy and honest they are.
They will design an manufacture any piston for you, but they are generally horrible as they don't know about engines let alone specific models. Hence we design our own.
Rings are harder as there are few good manufacturers.
The price I quoted was based on us commissioning four pistons of one size. There are some price breaks but not much.
I have another company that would be better price once you get over 50 pistons.
Over 100 and I'd be looking at having tooling made and going back to a cast piston, but with modern techniques.
I originally went down the uk route and wasn't happy. In fact they stole my piston design and still sell it.
A similar thing happened with camshafts. They changed my spec on materials, and I ended up rebuild engines for free after the cams destroyed them. They now brag about using my specifications for material and treatments.
We're in the slow process of tooling up for camshaft manufacture, hoping to go live this year.
There are risks in making parts.
email (option): pes.sales@btconnect.com
A motorcycle shop in Melbourne Australia is currently selling on Ebay original ex army pistons complete 20 thou oversize for $145. Seeing that Ebay charge to sell I would say you could buy cheaper direct off him. Ebay name is 1150brough He has lots of ex army parts.
email (option): ukcarbsathotmail.com
Hi Mark...I am aware of your business...I have looked at your website previously....Are you linked in some way to CCM?..or is it just that you make CCM parts?...
I'm primarily into the heavyweight BSA singles and am usually after upgraded parts for those..I'm now retired but have a few projects on the go..I ran a business servicing those models for 18 years or so after I left the engineering game, mainly engine and gearbox refurbishment and quite a bit of tuning...I've had many parts manufactured over the years and it can be an unforgiving task...On the other hand it's good to walk round an event and see bikes that have your parts fitted..
I recently had a one off forged piston made by CP Pistons and it was pretty expensive...I've used JE Pistons most for batch work, usually 10-20 units....Ian
email (option): ian@wright52.plus.com
Absolutely nothing to do with any of the clews family.
In my stupidity I adopted looking after the 70's bikes and proving they could have been good.
One of the many downsides is that people thought I did nothing else. Due to a lack of respect for what I was doing I'm dropping that work unless commercially viable.
The moto of the company was "if you think it doesn't exist, it's because you never asked us to make it"
I started looking at a M20 project over 15 years ago, and I should have bought one when the prices were better. It seems now I'm a bit late to the party.
It looks like all of the tin ware will be Indian. I think the forks will come that way too. I just hope they will be better than claimed.
As usual washers, brackets and fasteners seem to be in short supply. So if I can't find any I'll make them. If I make one, they'll be half a dozen or so. If they sell I'll make more. Most of the bits we make stared that way. If someone want's to commission something it will be there's and we'll respect that.
Sorry to the original poster for taking this off topic.
email (option): pes.sales@btconnect.com