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More Le Mans 850 piston questions

Sahms

Sahms

Cruisin' Guzzisti
GT Contributor
Joined
Oct 27, 2008
Messages
116
Location
Knoxvegas, TN
1: I am looking at some new Le Mans pistons, but I am used to seeing them manufactured by Mondial, and these have "ASSO" cast in them underneath. Has anyone seen this maker's name before?

2: Le Mans I bikes were almost all iron cylinders, but some late Le Mans II bikes had Nigusil. Are the pistons the same? I'd like to take the pistons I am looking at and send them with some flaky T3 cylinders to have Nigusil plated, but need to know if the "grow rate" on the pistons is the same or if the pistons intended for Nigusil are different from the pistons intended for iron (I know the rings are).

TIA!
 
Asso were another supplier used sometimes Fred. Pistons are, I believe, identical for cast Fe. and Nicasil. Only difference being the piston/bore clearance used. This would presumably be dealt with by the plater/applier of the finish.

Pete
 
Wot Pete said and nigusil require pain old cast rings - they don't like moly coated ones. So gapless rings are out.

The advantage of nigusil is that you can use an aluminum liner with an aluminum piston which results in much closer tolerances. Plating a cast iron liner will give you longer life but not the life span of proper nikasil nor the improved blowby. If you can find them always go with the Gilardoni kit. It is the best performance improvement you can make on the guzzi - even if you have to source the pistons separately from the cylinders and throw away the pistons.

Asso are a standard OEM manufacturer - they did the pistons for the 3 1/2 Moto Morini as well. Nothing wrong with them.

And Pete, hope you are well - have you been operated on? Am still peeved you didn't visit me in Toronto. Next time I will come gunning for you.

Ta,

Chris
 
Chris R said:
Wot Pete said and nigusil require pain old cast rings - they don't like moly coated ones. So gapless rings are out.

The advantage of nigusil is that you can use an aluminum liner with an aluminum piston which results in much closer tolerances. Plating a cast iron liner will give you longer life but not the life span of proper nikasil nor the improved blowby. If you can find them always go with the Gilardoni kit. It is the best performance improvement you can make on the guzzi - even if you have to source the pistons separately from the cylinders and throw away the pistons.

Asso are a standard OEM manufacturer - they did the pistons for the 3 1/2 Moto Morini as well. Nothing wrong with them.



Chris
Click to expand...

No Gilardoni kits for Le Mans motors I have seen in years, if ever. I will have a couple of Eldo cylinders nikasil plated to match the pistons, which I went ahead and bought.
 
No Gilardoni kits for Le Mans motors I have seen in years,if ever.
Click to expand...

Well they definitely existed and were available for a long long time but have gone from the occasional production run to maybe the occasional run to maybe never again from what I can see! I have ordered from Agostini in Mandello as they are a bit cheaper even with shipping and are just down the road from Gilardoni so they have a chance of knowing what is going on. Agostinis are also very pleasant to deal with.

Harpers seems to still have them on their website: http://www.harpermoto.com/index.php?dis ... t_id=69240

I understand that this may just be a ghost in the machine - still if you can get the Gilardonis do!

Don't get me wrong as a plan 'b' plating cast is not a bad thing to do - nikisil will last a lot longer - you just can't run the same tight tolerances (4 thou?) which means less blowsy, less noise, longer life.

As an aside the 950 kit if they have it does not produce much more power however it does add more squish which can be useful if your area has lousy fuel.
 
Chris R said:
No Gilardoni kits for Le Mans motors I have seen in years,if ever.
Click to expand...
Don't get me wrong as a plan 'b' plating cast is not a bad thing to do - nikisil will last a lot longer - you just can't run the same tight tolerances (4 thou?) which means less blowsy, less noise, longer life.
Click to expand...

Fred isn't plating the original iron liner cylinders, he's having a set of Eldorado cylinders replated with Nikasil. For all intents and purposes he will have the same thing as the Gilardoni kits at a reduced cost. Especially since Gilardoni uses Asso pistons on some kits (the pistons with the V7 Sport kits were Asso anyway).
 
And it's not for cost-savings. Even when Gilardoni does a run of cylinder kits, they haven't included the Le Mans 850 versions, which use a different piston.
 
Fred isn't plating the original iron liner cylinders, he's having a set of Eldorado cylinders replated with Nikasil. For all intents and purposes he will have the same thing as the Gilardoni kits at a reduced cost. Especially since Gilardoni uses Asso pistons on some kits (the pistons with the V7 Sport kits were Asso anyway).
Click to expand...

Got you - I forgot the eldorado's were chrome plated on alloy. That actually is a pretty bright plan as you should be able to do it for about half the cost I would think of a set of Gilardonis.

I don't quite understand the prejudice against Asso - my original T4 came with them so they are good enough for Guzzi. I put over 90,000 miles on them and the blowby/leak down remained pretty much stable.

In contrast, I had a beautiful set of Cosworth forged pistons - I worked at Cosworth at the time- and they were much more shagged at half the mileage. Being a sample of exactly two this is hardly a definitive example and having go faster parts in the one engine no doubt I used my wrist more but I think it does hint at common engineering lore - forged is good for racing, cast for daily plonking.

And damn these auto-correctors: 'Blowby' is corrected to 'Blowsy' - which isn't even a word!
 
Chris R said:
Fred isn't plating the original iron liner cylinders, he's having a set of Eldorado cylinders replated with Nikasil. For all intents and purposes he will have the same thing as the Gilardoni kits at a reduced cost. Especially since Gilardoni uses Asso pistons on some kits (the pistons with the V7 Sport kits were Asso anyway).
Click to expand...

I don't quite understand the prejudice against Asso - my original T4 came with them so they are good enough for Guzzi. I put over 90,000 miles on them and the blowby/leak down remained pretty much stable.
Click to expand...

What "prejudice against Asso"? Nobody has posted anything negative about them that I can see.
 
Another option to consider. I had a pair of 850T cylinders bored & plated by Millennium to an 86.5 mm bore to keep a reasonable cylinder spigot thickness. I got a set of pistons from JE. This was all via Mike Rich about 3 years ago for 850 LM spec heads. The total cost was about $960 US with me providing the barrels.

I think that he may still have some of those pistons as he got JE to make a couple extra sets for him.

http://www.mikerichmotorsports.com/

GD
 
That would be sweet, but I already have the (cast) Asso pistons on the way. Are those forged slugs?

I built a big-bore motor for a friend's Le Mans 1, and he had some monster Venolia forged pistons that we used (in iron bores). The clearance recommended by Venolia was huge compared even to the clearance for cast LM pistons in an iron bore. Seems to be fine when warmed up, but it sounds a bit loose cold.
 
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