acotrel said:
BRAIN FADE ! - 79.5mm ? I think my motor is about 890cc. I had a look at the JE website. Their pistons look beautiful, however I would not like to try and negotiate to buy a custom made pair by email. Do you actually have any which would fit the motor when using standard rods ? I presume the pistons you referred to in your post, were the Jim Scmidt items for use with the longer rods. Could the barrels be shortened enough to accommodate those ?
Right. I've been having JE make forged Norton pistons for over a decade. Before that I had them made by Venolia. Mostly I supply them to dealers and shops, but I do sell a few sets each year to individuals, mostly racers. I stock a lot of "standard" sizes, from 73 mm to 83 mm, but also have batches of special orders made from time to time. The 883 pistons are like that. I don't normally stock them, but have a batch made every once in a while, when I have a request for them. I recently had a batch made, mostly because I needed them for a bike build, so I have them in stock. I started having JE make pistons in collaboration with Steve Maney, using his existing design, and making changes that suited us both. These pistons were originally designed primarily for racers, so they are high compression, and not necessarily suitable as is for street bikes. In a Commando engine that hasn't had the head or barrel skimmed, they will give at least 10:1 CR, and more in the larger displacement sizes (883, 920, 1007). They have enough deck thickness that they can be machined for lower CR. I probably should have had the 79.5s made to stock deck height, because I suspect the 883 is more likely to be used in street bikes than race bikes. Maybe in the next batch. They use standard JE rings and circlips. I have the pins custom made, and they are sized for stock connecting rod pin bores. If you are interested, PM me, and I'll provide more info. I'm not trying to use the forum to sell them, just answering the question in this thread, so it doesn't seem appropriate to go on in great detail. I don't advertise them, and if I need to clear some off the shelf, I'll do it in the For Sale section.
These are not Jim Schmidt's light weight, long rod pistons. They are significantly heavier than Jim's, with full skirts, stock pin location, and tall (1.625") deck heights, and are meant for stock length rods. Jim is a friend of mine, and we've shared design ideas, so there is a lot of design similarity, but the light weight, long rod design is his. He's been more willing than I to do special order designs, and if he doesn't already do a 79.5 piston, I'm sure he'd be happy to do so on request.
A little personal opinion here. I don't think forged pistons have any real advantage for a street Commando, unless it's a serious hot rod and gets treated like a racer. Otherwise, a good cast piston is actually a better choice. That's one reason I've only had the pistons made in high CR designs. For sizes like the 79.5 mm and 83 mm, where there are no cast pistons available (at least none that I know of), forged pistons would certainly work, but they are more expensive, and noisier than cast pistons.
Ken
