66mm and 67mm pistons. any experience?

[moriniuk]

I've suddenly got the urge to carry on with the engine development on my race bike. The reason for this is that I've just recieved my 500 heads back from being gas flowed. It only took 15 months!
I currently use standard 350 heads on 64mm bores (370cc) using Vertex pistons as supplied by NLM.
Whilst I think that the 500 heads will work on the 64mm bores, I'd prefer to go a bit bigger, to a full 400cc.
Wolfgang Tritsch in Germany supply 66mm pistons and Ducati Dortmund Developments supply 67mm pistons.
I presume that to use these on standard 350 barrels that they would need to be re-sleeved.
Has anyone had any experience of any of the above?
The next problem is the exhausts. I'm going to use modified Kanguro headers, so I'll have to fabricate some new collets.
Would anyone with easy access to a lathe be interested in making up these collets?
Howard

[3narf]

Hi Howard, hope you're well.

Have you thought of the obvious (I'm sure you have), Dart 400cc parts, ie NiCaSil plated alloy barrels? Must be cheaper and less hassle than sourcing stuff from Germany.

Assuming the 400 items are still available, of course...

[moriniuk]

Hi Andy, Yes, I´ve thought about 400 barrels. They appear to be a bit scarce. I´ve been on the look out for some for a while, although not too seriously. I´ve got loads of spare 350 barrels and I don´t think buying things from Germany is such a big deal these days. They look like quality forged pistons and they´re not very expensive. I might just give the 66mm Wolfgang Tritsch ones a go anyway and demote the 64mm ones I´m using at the moment to a spare engine.
H.

[EVguru]

I don't think NLM have any 400 barrel kits left and they were something like £800. I think I have the last set they sold on one of my Darts.

There's plenty of meat in the liners for boring out, but I'd be tempted to get barrels bored by the piston supplier, or at least get detailed advice about bore clearance. OEM Morini pistons appear to be of a high expansion alloy in comparison to others and many engine re-manufactureres just use a standard rule of thumb in absence of other information.

Ducati Developments are using 1000cc VW Lupo pistons with an approximation of the Morini combustion chamber machined into the (dished) piston crown. They were previously using Polo pistons with a much less convincing combustion chamber shape. It does look like a cost effective option and if you've got contacts at Mahle, it might be worth getting a set to experiment with and you'd end up with spares!

[huub]

i dont know how your german is , but here
http://ital-web.de/forum/viewtopic.php?t=237
you will find the details about the 67 mm lupo pistons. (from a AER 999cc engine )
they fit using the stock liners, even the weight is virtually the same as the original pistons.
i paid 65 euro each, but i cant help you with any experience, rebuilding the engine is still on my to do list...

cheers , hubert

[moriniuk]

Thanks for that Hubert, I´ll need to brush up on my German.

Thanks as well Paul, but for $800 (sorry no pound sign on Spanish keyboard) I´d want the rest of the bike too.

Howard

[EVguru]

Well, I didn't fit the barrels and did only pay £1100 for the whole bike.

Although it had six months Tax and MOT it had almost nothing right with it. The airbox was in bits, the inlet stubs were loose in the MEZ ported heads, the exhaust system was loose and leaking at every joint. The barrels had been fitted using about half a tube of hylomar (I was picking lumps out of the pushrod tunel with a pearl catcher). One tappet was missing it's locknut (found down by the exhaust valve) and the rocker had been ruined by the end of the pushrod. There was a preload spacer missing from one fork leg and a guide bush missing from the caliper.........


It didn't cost me any money, but did take a couple of weeks to sort out. It still needs the rear brake and damper looking out.