Want a 860cc XS??

There's a kit for sale in Australia at the moment http://www.ebay.com.au/itm/YAMAHA-6...Accessories&hash=item1e68400072#ht_500wt_1413 the copper gaskets can be made here http://www.coppergaskets.us/index.htm , hadn't realised there were already pictures of this kit on this thread

I've started collecting the parts for the Isuzu 880. The pistons, with rings and pins, weight 540 grams. The stock piston assembly is 390 grams. I figure the new redline will be 6400 rpm which will keep the forces on the rods the same as the stock setup at 7500 rpm. So you are loosing about 15% of the rpm but gaining about 35% more displacement so there is still a net gain. Plus, the pins are offset 1mm so if you put them in "backwards" it will be like having a 4mm longer rod which should reduce piston side load (friction) by about 5%.

This will be a long term project. I'm going to collect the parts and tooling as time and money allows. There are plenty of other irons on the fire and very little time or money so don't expect any progress for quite some time.

I think I found a source for new ductile iron sleeves at $10 a piece. Ductile iron is stronger than standard iron sleeves. Since the sleeves on an 880 are so thin, the added strength is a welcome benefit. Of course, like the pistons, the low cost means it won't be a drop-in. They will need to be fabricated.

Hey Riggs - did this ever get of the ground...??? progress.....???

I've been collecting the tooling a bit at a time but things are real tight right now so progress has stalled. It'll happen, just not any time soon.

Tagged / subscribed / waiting with baited breath.

Resurrecting an old thread, I know.

Curious if this ever had wings and flew or if the testing fell flat. Anyone have any details on the follow up?

It's still in the works. Plans changed a bit. I'm using sleeves from an Allis Chalmers tractor and forged Panhead pistons. The motor I was going to use needed crank work so I got sidetracked making a new center crank pin.



Got sidetracked from that working on my chassis dyno.



Too many projects and too little time.

AussieHard said:

Want a 860cc XS??
Big bore kit for the 447 motor to 860cc?? Mmm Sounds good. Wonder if this is a good idea though? It is the original cylinders bored out...is there enough metal in it??

760cc is common and often comes with a new casting from Heiden or Mikes XS etc to allow for the bigger internals and keep the wall thickness.

Love to know if anyone has any experience with this???
Is it a off the shelf kit?

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..................... hi years ago i met a guy at scorsby swap meeting which was down on ferntree gully road and that day ,i was walking around and i spotted a xs650 motor ,,,but when i spoke to the dealer he said it was a big bore kit and to make it a 1000cc he,d also put a lump of steel plateunder the barrels to lift it up the thickness of the plate was 1 cam chain link thinkness ,,,,,he,d pulled it out of a sprint bike but i ended up buying something else regards oldbiker

Hooligan83 said:

1000cc XS650 on the dyno..

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How much hp and tq did it make on the good hot pull?

mrriggs said:

Isuzu Trooper pistons (87mm) have the right pin height for 447 rods (close enough anyway). You can pick up a new set of four, with rings, for $50. I haven't figured out where to scavenge used cylinder sleeves but even with new sleeves you could piece together an 880 for a few hundred bucks.

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Hi, with some ingenuity it could be rather simple. Just get a 73 and up case and the cylinders and have them bored and sleeved to 87mm. The studs should be replaced with some from ARP. Just clean up the head ports with a sandpaper roll and a valve job . Have a 256 cam profile ground, The best XS cam made. I would like to use an XS2 head, but I don’t know if it fits the 447, and use points and coil and BS 38 carbs. That would be a sweet 880!

AussieHard said:

The Crank.
With a rod of origin the maximum displacement that can be achieved is 880 cc. For more displacement is mecessaire change the crankshaft crank pins in the displaced orbits. The piston stroke from 74 mm to 82 mm 90 84 86 see, with pistons 500 XT 87 mm bore and stroke of 84 mm results in a displacement of 998 cc. There were two ways for displaced orbits the crank pins is it was the original linkage was amended, be it a linkage was made to measure.

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To do a 998, I believe that the 553 European crank is needed. It has thicker flywheels and rods. I’d think to get an 8cc stoker would require some geometry. An 880 is enough for me , put a rephrased. XS2 cam in it with a good sandpaper roll cleanup, some Devcon in all 4 port floors to increase velocity and lengthen the intake manifolds with 2 inch plate aluminum shaped like the ports and shape the regular manifolds to the ports, put studs into the heads and nut them with blue loctite, add an inch to the rubber for the carbs and use the BS38 carbs supported to the frame with black painted plumbers tape so the dont shake around. 2 K&N filters as big as will fit. Put the clip on the richest slot on the needle. Torque is what this engine is about. 1 5/8 head pipes back to straight through Bubs. Stiffen the swingarm, put a fork brace on it. Good adjustable rear shocks. Stiffer fork springs. If runners hot get some of those cylinders from Hieders with the deeper fins and an oil cooler.. As long as it’s Red/ White/ Black and Chrome with a bolt on Yamaha emblem on each side of the tank, long fenders with a chrome fork brace and XS 650 on the side covers and the big laced wheels and nice tires I’m good. If an 880is too big how about a 799? Lol.