Forged M.A.P- Pistons

The clearance they ask for is:
0,0035" - 0,005" for cast- iron cylinders and 0,002" - 0,004" for aluminium cylinders with cast- iron liners, measured at 0,200" above bottom of piston skirt. Temperature should be 74 degrees Fahrenheit.
If you wish I can send you the installation instructions given with the pistons.

Hi Klaus, thank you for that , but I think the young guy I am helping to build the engine will buy a pair of 850 as soon as his pockets will be full of cash ....he is the one with a 750 crank (good shape and std mains) but he had 850 case and barrels /head, so either we fit 850 crank (but he is cheap)or he buy 850 MAP pistons which are same weight than 750 stock one , and such respecting the balance as I had found that the static balance will be near 40% with 750 crank and 850 stock pistons ..............!

Hello,
The problem was found: It was a loose exhaust nut. After a quick test- ride (appr. 120 miles) to the river Rhein, i nearly lost the right header on the Autobahn. After i tightend the nut, the "mechanical" noise was gone.

In any case the spare big valve head (42/36mm) and the cylinder barrel with the new billet- pistons is on its way.

How fast did it go?

Hello,
I always stop reving after I reach about 110- 115 mph. I have the feeling that it could be faster, but I'm not racing. It's just for fun. I, as most of us will do, prefer the acceleration out of corners, certainly, after all it's a Norton.

Hello, still happy with your MAP pistons?

Klaus Monning said:

Hello,
I always stop reving after I reach about 110- 115 mph. I have the feeling that it could be faster, but I'm not racing. It's just for fun. I, as most of us will do, prefer the acceleration out of corners, certainly, after all it's a Norton.

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If you are racing, you usually make a choice about where you will be faster - in and coming out of the corners, or at the ends of the straights. With a Commando engine, faster in the corners is usually better.

NKN said:

Hello, still happy with your MAP pistons?

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Hello,
Yes, I am still happy with those pistons. Only thing is, that I didn't do much riding this year.
First, I broke my shoulder (falling out of my bed, a funny story). My cheeky brother said that my (Russian) wife kicked me out of it.
Second, I broke my right leg (just below the knee), when trying to kick- start the bike. No, there was no kick- back from the engine, but a slide- through from the clutch (wrongly adjusted).
That gave me the opportunity to fit another alternator.
Reason for this:
I have a Nourish- crank fitted with 91mm stroke but no facility for fitting the standard Lucas- rotor. The cylindrical part wasn't machined to hhe crank.
So a lot of designing, machining and working was necessary to fit a DUCATI- (Nippon Denso) alternator incl. rectifier. Well, an awful job, but it's done now. Let's see what happens.
By the way before that I had one fitted that only gave me 90 Watts, the new one should give me more than 250 Watts.
Best Regards and good night
Klaus

Klaus Monning said:

Hello,
Yes, I am still happy with those pistons. Only thing is, that I didn't do much riding this year.
First, I broke my shoulder (falling out of my bed, a funny story). My cheeky brother said that my (Russian) wife kicked me out of it.
Second, I broke my right leg (just below the knee), when trying to kick- start the bike. No, there was no kick- back from the engine, but a slide- through from the clutch (wrongly adjusted).
That gave me the opportunity to fit another alternator.
Reason for this:
I have a Nourish- crank fitted with 91mm stroke but no facility for fitting the standard Lucas- rotor. The cylindrical part wasn't machined to hhe crank.
So a lot of designing, machining and working was necessary to fit a DUCATI- (Nippon Denso) alternator incl. rectifier. Well, an awful job, but it's done now. Let's see what happens.
By the way before that I had one fitted that only gave me 90 Watts, the new one should give me more than 250 Watts.
Best Regards and good night
Klaus

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Cracked my leg bone just below the knee too. Rain had made everything wet and my kick effort slid off the kicker rubber and I hit the pavement hard with my foot. 2 months in a cast , season over. Enjoy.

Klaus Monning said:

Hello,
Yes, I am still happy with those pistons. Only thing is, that I didn't do much riding this year.
First, I broke my shoulder (falling out of my bed, a funny story). My cheeky brother said that my (Russian) wife kicked me out of it.
Second, I broke my right leg (just below the knee), when trying to kick- start the bike. No, there was no kick- back from the engine, but a slide- through from the clutch (wrongly adjusted).
That gave me the opportunity to fit another alternator.
Reason for this:
I have a Nourish- crank fitted with 91mm stroke but no facility for fitting the standard Lucas- rotor. The cylindrical part wasn't machined to hhe crank.
So a lot of designing, machining and working was necessary to fit a DUCATI- (Nippon Denso) alternator incl. rectifier. Well, an awful job, but it's done now. Let's see what happens.
By the way before that I had one fitted that only gave me 90 Watts, the new one should give me more than 250 Watts.
Best Regards and good night
Klaus

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Danke schön Klaus

Hope both of you will feel better soon.

I too have the Map cycle billet pistons and their standard length steel rods in my 74 850 ,i`m also more than happy with them.
Very nice kit for the price.(and the bike runs like a rocket)
But as always, time will tell.

Klaus Monning said:

Hello,
Yes, I am still happy with those pistons. Only thing is, that I didn't do much riding this year.
First, I broke my shoulder (falling out of my bed, a funny story). My cheeky brother said that my (Russian) wife kicked me out of it.
Second, I broke my right leg (just below the knee), when trying to kick- start the bike. No, there was no kick- back from the engine, but a slide- through from the clutch (wrongly adjusted).
That gave me the opportunity to fit another alternator.
Reason for this:
I have a Nourish- crank fitted with 91mm stroke but no facility for fitting the standard Lucas- rotor. The cylindrical part wasn't machined to hhe crank.
So a lot of designing, machining and working was necessary to fit a DUCATI- (Nippon Denso) alternator incl. rectifier. Well, an awful job, but it's done now. Let's see what happens.
By the way before that I had one fitted that only gave me 90 Watts, the new one should give me more than 250 Watts.
Best Regards and good night
Klaus

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It was an awkward job. Awful usually means it ended being a bad job.

jan nelder said:

It was an awkward job. Awful usually means it ended being a bad job.

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Another interpretation. I took Klaus’ words to mean that the undertaking, not the final result was awful, i.e., he likely had better things to do than redesign the mount/system, make drawings, build custom fixtures, perform custom machine work, etc, but in the end, it met his usual high standards of German engineering. The end result was likely superb but it was an awful job getting to that result (and possibly awkward too).

Hello All,

My experience with their billet- machined pistons and their older aluminium rods was very good. No issues at all and super- light pistons in comparison to all the ones I know on the market. After mounting them I had the impression that my engine had instantly more power.

This good experience led me to the purchase of their long- rod conversion with their steel rods. And here I did have a lot of issues:

The problems could be seen below. As new, they look really beautiful, and I think, that the pure machining job M.A.P gets done, is really next to perfect. Unfortunately, according to my experience, the stiffness (or the guide- length?) of the piston skirt is not up to the job.

Here the issues:
After about 500km I heard a rattling noise between idle and appr. 3500 RPM. I ignored it first because the engine had to be run in and any R.P.Ms higher than 4000 were avoided. The rattle became louder and louder and also, I could see some blue smoke leaving the exhaust pipes.

After 1600Miles I decided to open the engine and found the following:

I marked out three zones which were identical to both pistons. The “NEW”- Dimensions were 76,91mm (Zone 3). The cylinder was bored and honed with a 0,09mm clearance, which is recommended to be the lowest running clearance. This rather small clearance was chosen because the pistons are a lot shorter at thier skirts and so the guide length of the piston is rather disadvantageous.

The diameters are:
Zone 1, directly under the oil scraper ring(s): 76,71mm
Zone 2, in the middle between the lowest part of the skirt and zone 1: 76,77mm
Zone 3, the lowest part of the skirt: 76,61mm

So, the piston skirt is distorted by nearly 0,3mm, which is the reason for the rattle.

Now my own analyses:
I ordered a set of WISECO pistons from Jim Schmidt and compared them to the M.A.P- Pistons:

• The WISECO- skirts are approximately 3mm longer in comparison to the M.A.P- skirts.
• The weight of one bare M.A.P- piston is 183 grams, the weight of a bare WISECO-piston is 200grams. But the M.A.P- wrist pin is slightly longer and therefore also slightly heavier. The weight of a complete WISECO- piston (incl. rings and pin) is still about 10grams heavier then the M.A.P- piston.
• The WISECO- skirt’s lowest thickness is 2.5mm expanding to nearly 3.0mm towards the wrist- pin boss. The M.A.P- skirt is 2,2mm expanding to 2,5mm towards the wristpin- boss.

This shows to me that the WISECO is a lot stiffer, and also has a longer guide length. The only problem is, that the WISECOs have an 18mm wristpin and the M.A.Ps are the original Norton- diameter of 17,5mm. So, I will have to get the diameters of the bronze- bushes adapted to the new wrist pins.

All in all, I cannot recommend the M.A.P- long- rod- pistons. They need to be stiffened somehow (by forging and also the skirt needs to be longer and thicker).

I suspect that due to the rather short guide- length, the long- rod piston tends to canter very easily and after a while the skirt gets distorted. The rather thin skirt (good enough for the standard- length rod) starts distorting. I think that WISECO knows very well what they are doing and so:
1.) The pistons are forged and
2.) they are also a lot stiffer with more material at the most sensible places.

I was in contact with Marino from M.A.P for a while and suddenly he stopped answering my questions and suggestions.

All this and a lot more was also communicated to M.A.P and I did get some answers but no suggestion how to deal with the problem, which is a pity because otherwise I could say that the quality of other parts I received from them was very good indeed.

Best Regards

Klaus Monning

Thank you very much, Klaus. Your R&D and detailed experience will save many of us from learning things like this the hard way.
Jaydee

I had been thinking about Jim Schmidt's light pistons and longer rods. They seem like a very good idea. However my concern would be about finding an alternative supplier, if Jim went out of business and I buggered a piston. With MAP, their customer base might be larger and they might carry more stock. My preference in pistons is always Mahle, but how can you buy them ?

As I have said before - My pistons and rods will always be available. If I am not around then the part numbers will be posted on my website so you can order them directly from the manufacturer - Carrillo rods and Wiseco pistons will be instructed to make them available to the public so anyone can order them.

Klaus - can you show us photos of your threaded collars for the re-angled guides? And what is the name of the 1100 deg temp fastening liquid similar to loctite?

acotrel said:

I had been thinking about Jim Schmidt's light pistons and longer rods. They seem like a very good idea. However my concern would be about finding an alternative supplier, if Jim went out of business and I buggered a piston. With MAP, their customer base might be larger and they might carry more stock. My preference in pistons is always Mahle, but how can you buy them ?

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Hello,
here I can definately help you. The company to contact is:

Wahl Spezialkolben GmbH
Siemensstrasse 18
DE 71691 Freiburg am Neckar
E- Mail info@wahl-spezialkolben. de
phone: 0049 71419134500
website: www.wahl-spezialkolben.de

Before I bought Jim's WISECO- Pistons I also intended to buy Wahl- pistons. This company had been manufacturing pistons since at least 1968 (maybe a lot ealier). The father in law (Helmut) gave it over to his son in law about one or 2 years ago.

Dieter Busch, BMW RS- Speciallist always bought his pistons. Dieter was responsible for all 6 World- Championships of Klaus Enders - Ralf Engelhardt with their BMW RS sidecar- racer. Later he was also responsible for the Rolf Steinhausen's Worldchampionship with his KÖNIG (yes, a 2- stroke) sidecar racer. So, not only Wahl, but also Dieter Busch was a genius himself.

I was informed that Wahl only uses this special MAHLE alloy blank, that needs a clearance as low as 0,05 to 0,06mm for pistons in cast iron cylinders. So, it has next to zero thermal expansion. The disadvantage of this alloy is, that it must be very hard to machine. That's why MAHLE themselves like to give orders for this alloy to Wahl for manufacturing.
Wahl manufactures according to drawings or samples.

As could be imagined the price for a set of 2 pistons could be rather high. I suspect that we are talking about approximately 800,00- 1.000,00EUR for a set of 2, which was one reason for the purchase of Jim's pistons.

I did have the same thoughts as you have about Jim's activities. But I'm pretty sure that, in case if he gives up his business he will give WISECO or JE the permission to sell the NORTON- pistons. So, I guess with Jim you'll be on the safe side for spare- pistons.

I'm also pretty sure that worldwide you won't be able to get pistons like the one's from Wahl, because there is one more advantage. You can finish- bore and hone your cylinder what ever the dimension will be. You give this dimension to Wahl and he will manufacture the pistons exactly to the dimensions you need. So, there is no standard, 1st., 2nd., or 3rd oversize. You'll have multiple oversizes.
One more advantage is that they manufacture any quantity of pistons that you ever like to have, from only one to complete sets of 2, 3, 4, or what ever. All made from this special alloy.

For me there were 2 reasons why I went for Jim's pistons:
1.) I already mentioned the spare situation. I guess, even if Jim gives up I could still buy WISECOs or JEs from the company itself and
2.) the price. Jim's pistons cost half of Wahl's pistons and being a pensioner, money is always short, unless somebody gives me a NORTON cylinder head for a big- valve conversion.

Coming back to the supject: It is not so easy to suitable bore the small end eye to Jim's 18mm wrist pins. The bore in M.A.P's conrod small- end is very precisely 19,05mm (3/4" and very precise indeed). If I bored this bush to 18mm I end up having a small end bush- wall of just 0,5mm, which is way to small. So, I will have to bore the conrod small- end to 19,5mm.

This is a special- job for a company with special equipment for holding the necessary tolerances. We are talking about microns here. So, I left it to a company called: Motorenteilebearbeitung (www.motorenteilebearbeitung.de) in Belgium. He is an old friend mine and knows what he is doing. I myself am not well enough equipped for this kind of a job.

Ok, that's enough for now.
Good night and good luck and keep healthy
Best Regards
Klaus

jseng1 said:

As I have said before - My pistons and rods will always be available. If I am not around then the part numbers will be posted on my website so you can order them directly from the manufacturer - Carrillo rods and Wiseco pistons will be instructed to make them available to the public so anyone can order them.

Klaus - can you show us photos of your threaded collars for the re-angled guides? And what is the name of the 1100 deg temp fastening liquid similar to loctite?

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Sorry Jim, I have no photos, because the collars are installed in my cylinder head. But I sent you a drawing. Just insert it into this forum, because I'm not intelligent enough (well, no VIP- Member) for doing it..
Good night.

Klaus asked me to post this photo of the high temp locker for guides etc.