Nikasil Aluminum cylinders from Molnar

A customer who is building a short stroke motor is asking me about Andy Molnar Alum Nikasil cylinders without liners. Anyone have any experience with these?

Well, they look good to me, but I guess we'll have to wait for info from someone actually running them to be sure. Nice to see multiple sources now that Steve Maney is no longer making them.

The interesting bit is that they offer them in 83 mm bore size (Nikasil only). The only 83 mm bore Commando cylinders I've seen are the ones Steve Maney did for his 1007 cc kits, but he had to move the bore centers apart to do it, along with wider crankshaft and cases with the through bolt holes moved out a bit. 83 mm bore in a standard pattern cylinder leaves very little material between bore and rear through bolt counterbores. I'd worry about head gasket seal and bore distortion. Be great it they can make it work. That would give you 975 cc with standard 89 mm stroke crank.

Ken

Ken

The 83mm cylinders are for the Maney 1007cc cases. Nikasil without iron liner. It looks like Andy is the first to offer Nikasil cylinders without liners and in 68, 73, 77 & 83mm bores.

1007 is a very small market. There are WAY more 920s out there, so why no 81mm offering ?

Fast Eddie said:

1007 is a very small market. There are WAY more 920s out there, so why no 81mm offering ?

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Maybe he needs a push. But he's already too busy with Manx, Ducati, Matchless G50 and Vincent parts. He barely even advertises the Alum cylinders. The website link to the cylinders (above) is nearly impossible to find on the internet.

I never knew of this business until now.
Holy sh*t, I could spend way too much money on that site, especially in the frames section.

Trying to file bankruptcy on your bankruptcy just don't fly... Beware if you sleepwalk also.... No telling what financial damage one may awaken to in the morning...... But ossifer I wuz only dreemin.... say it ain't so.

I know it isn't answering your question as I can't vouch for the barrels in use, but I have seen them in the flesh. They're truly a thing of beauty!
I'm planning to use a set on a race motor I'm building, with funding currently being an issue .
Andy's products have always been top notch and the quality of the castings is superb. I've been buying from him for 35 years and trust his work absolutely.

Fast Eddie said:

1007 is a very small market. There are WAY more 920s out there, so why no 81mm offering ?

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He would do 81mm cylinders in a minimum quantity of 10 if someone asked him. Seems to me that he should just offer them (no one else does).

What are the potential issues with aluminum cylinders? Are they problematic to seal at the joints? Is the loss of 5K of weight the only advantage?... Other comments from those who know.... Thanks

Advantages are lighter weight, better heat dissipation, and bling.

Disadvantages include higher thermal expansion coefficient (affects valve clearance settings and fastener clamping force), and lower bulk strength properties (need thread inserts to avoid thread failure, more susceptible to bore distortion for big bores).

That's all I can think of offhand. There are probably others.

Ken

I have several bike with alloy jugs with sleeves. Nikasil is attractive but slightly frightening as it is one more notch up the
disadvantage scale especially if you have never been there previously.
Ten pounds. Pick up a ten pound weight and it is surprisingly heavy.
Guess you pay the asking and take your chances.

lcrken said:

more susceptible to bore distortion for big bores

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Yamaha's use cast alu blocks in their inline 4s. I wonder is the problem is obviated by more bores or the liquid cooling?

acadian said:

Yamaha's use cast alu blocks in their inline 4s. I wonder is the problem is obviated by more bores or the liquid cooling?

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Some of both, probably.

But the real problem with the 920 Commando cylinders is that the thickness of the cylinder is very limited in certain areas because of the locations of the fasteners, in particular between the bore and the counterbores at the top of the cylinder for the through bolts (and a couple of other areas). When that gets too thin, you find the bores distorted at the top of the ring travel, and the rings don't seal properly. The bike will still run ok, and with lots more low and mid range grunt, but won't make the top end horsepower it should, and will eventually smoke a bit. At least that was my first expriences with iron cylinder 920 conversions. With sleeved cylinders (iron or aluminum) with iron liners, boring and honing the cylinders with torque plates seems to solve that problem. With aluminum cylinders with Nikasil coating I'm not sure how that would work out. It seems to me that the manufacturer would need to bore, apply Nikasil, and hone, all with torque plates installed. And I would still worry about more distortion because of aluminum's higher thermal expansion coefficient, as well as it's effect on the clamping force of the through bolts, which influences the amount of distortion. But for these cylinders that's all speculation. We really just have to try them and see how well they work. I would expect them to work well in the 750 and 850 bore sizes. I'd only be concerned at the 920 bore size. The fact that they do not need liners does leave a bit more material at the counterbore locations, and maybe that's enough. Now all we need is someone to cough up enough cash for a batch or 10, and we can find out.

Ken

I have never been into over-boring to get more power. Does it really make a difference ? Was Steve Maney's 1007cc Commando extremely fast or was it just himself being fast ? Theories are good, but it is what work's better in practice which is important. If the piston weight is higher in a big bore motor, perhaps you are more likely to leave a piston behind and are steel con-rod's heavier ?
A better way to go might be to use standard bore with a billet crank and stronger cases, and Jim's long rods and light pistons - then move the rev limit upwards by using a longer duration cam with a slower lift rate and less maximum lift.
In Australia many motors have been destroyed by the 'big is better' bullshit.
Methanol is great in near-standard Commando motors - they love it.

acotrel said:

I have never been into over-boring to get more power. Does it really make a difference ? Was Steve Maney's 1007cc Commando extremely fast or was it just himself being fast ? Theories are good, but it is what work's better in practice which is important. If the piston weight is higher in a big bore motor, perhaps you are more likely to leave a piston behind and are steel con-rod's heavier ?

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If you look at the dyno results from Steve's 750 engines and his 920 engines the difference is very obvious.

Ken

A Maney 1007 built to race spec is incredibly fast Al. Don’t kid yourself !

lcrken said:

Now all we need is someone to cough up enough cash for a batch or 10, and we can find out.

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Currently collecting bits for a 750 racer I plan to run in P2 class over here. I can't get my hands on Maney cases anymore, but I just may pull the trigger on one of these

acadian, there are still some SBR billet cases available here in NZ

Brooking 850 said:

acadian, there are still some SBR billet cases available here in NZ

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Thanks! Private sale or is there a vendor you can point me to? I've bought parts from Road Relics before but that's the only vendor in NZ I'm familiar with