SlowMoe

Obviously the more power you have the faster certain things like bearings and clutches will wear. Not to mention faster piston speed with the 4mill engine for a given rpm meaning shorter ring life. Theoredically of course

Bump. C'mon someone needs some awesome pipes

Another possible benifit of cutting the piston as I described: Think back to the scenario where the port is barely cracked open, and there is considerably more exhaust open area, only now imagine the piston in the upstroke at an RPM greater than the exhaust port/ pipe combo peaks at there is still some positive pressure inside the expansion chamber trying to force fresh mix into the cylinder. That return pulse has a larger area to pass through and theoredically it will fill the cylinder better and create a stronger, longer overrev. It could however be argued that this may be negated by the decrease in the return pulses' duration and the fact that below peak rpm there will be more area for the early pulse to bleed back out of the cylinder, meaning less power before peak, in a way creating a similar effect as increasing exhaust duration, but without decreasing the power stroke, therefore leaving more available torque throughout the rpm range than actually raising the port. Hmm. So 1. Should cause pipe to come on later 2. Should cause peak power to rise 3. Should allow better overrev

Sale pending on the cylinders. I ill have pics of everything else on Friday. Thanks!

Although cutting the piston in the manner described will obiously cause a weakening to some extent, Idon't believe the edge of the piston is as critical of an area as others on the piston; when was the last time you heard of a piston failing at the edge? It'd like I said earlier I have cut as much as 3mm off the crown at the edge near each of the 4 transfers and ran the snot out of it like that with no issues. Not that I would ever recommend anyone else do the same. And I agree that the cut piston won't flow 100% of the gas that a port cut to the same area increse would, however I believe it would be close. At this point I believe both of our arguements are based on speculation however I do believe there is more real world eidence supporting my case. I would love for someone to actually test this.

Ok got my wife to take pics of the pipes. Sorry for the poor quality she apparently was in a rush. There are two dings but she only took a picture of one of them, the other is similar in size but she said she couldn't find it. For those who don't know anything about these pipes, they are very similar to a shearer or CPI pipe. Supposed to be just as quick at the track as either.

The frame is the one in my sig. I can have more pics on Friday. It has stock J-arms, +8 swingarm with works dual rates up front and Marin Shaw competition rear. It will come with a full set of plastics minus front fenders, and everything minus the engine, pipes, carbs, and throttle cable. The frame is much lighter than an A-arm frame, so they are typically much more desired amongst drag racers.

If it is a rz350 top end I believe the exhaust will hook up directly to the banshee exhaust. The rz exhaust port is around 200* fully open not sure what it is closed. You will need the servos for the poweravalves, and I'm not sure but I think you need an RZ350 wiring harness as well. So cylinders, powervalves, servos, harness. Not sure if the CDI and stuff is compatible

I have a set of vitos fat bastards in great condition. 2 very small dings only one is visible. They pull like a shearer on top but are supposed to have a wider powerband. Actually made by Matt Shearer. $425 shipped, will take pics if you are interested.

What about this one?

They are definately big bore BUT they don't have much, if any poring done to them so you might be talking about 65 or so hp on those. Prolly more like 55 On the other hand I hae some drag ported cylinders for sale that I would bet my left nut make 10 to 20 hp more than the ones right there. And mine still have 4 bores left.

Carbs................SOLD Pingel................SOLD

Ok now I would like to demonstrate what effect this modification would have on the blowdown area. In this picture the area above the red line represents the total blowdown area. Now in this picture the red line represents the piston crown as it is approximately 10% through the blowdown phase. Notice the area of th port that has been uncovered by the stock piston vs that of the modified piston. From the looks of this crude diagram you have 100% or so more blowdown area at this point. That means that you have (theoredically) double the pressure bleed inside the cylinder. Now your blowdown phase is roughly 30% complete. At this point your modified engine still has roughly 25% more blowdown area Ok now you are at the end of your blowdown phase and the transfers are just starting to crack open. Your blowdown area advantage at this point is roughly 10%. So realistically you have between roughly 100% and 10% more blowdown are more with the modified piston s the stock piston, which could be expressed as a mean (average) number which I forgot how to determine, but let's say conservatively that we have a mean gain in blowdown area of 20%. That, in my opinion would be very significant indeed when coupled with the possible effects of the amplified return pulse...Again, this is only my theory.

This is a more realistic example of how the cut would look.

Ahhhh I knew someone else out there had sense. I have a dyno near my house but with the way I work plus my family it would be tough to do any testing. Not to mention I'm selling the bike BUT this is something of great interest to me. I'm going to try to make a better sketch of what I think would be the best way to do this mod. Gimme a few.

Were you using a deck height of zero? If so what are the numbers with a .020" deck height?

I doubt it. The ports asymetrical APPEARANCE is intentional. If you hog the outside transfers out all the way the will be bigger than the inside ones. Upon taking a quick glance they may look to be the same size.

I got that one as a spare when I bought the 10 mill PV cheetah bike. Not sure what it was used in I'm assuming it was the cheetah

The engine was disassembled to send the crank off to be inspected because I was going to a drag setup and wanted to leave nothing to chance, even though my original crank had already been trued and welded by a site sponsor about 15 riding hours prior. It ended up being out of spec so I bought another crank that was good. I then bought the cylinders, pipes, reeds, clutch and everything has been sitting there collecting dust and by the looks of it will continue to because of my work schedule. I should be getting payed for the carbs any time now but I reckon I'd sell the rest of the engine for $1400 shipped, or $1800 with the pipes. No way I could take any less than that unless the rolling frame sold first.

Somebody needs some hateraide Anyway 1. The exhaust "hump does have a huge chamfer. 2. The white ball in the transfer is styrofoam. 3. The transfers are left asymetrical intentionally; with the quality of the work throughout the rest of the cylinders i highly doubt he just forgot to make them symetrical on both cylinders. Do you realize that one set of runners has the potential to be enlarged a good bit more due to being on the outside of the cylinder? Both mains read 19mm across. Look closer. They are symetrical. 4. There are no serious gouges; none at all that snag my fingernail. Pics make them look bad. 5. Boyesen ports are drilled at the angle I typically see them at on banshees. 6. Intake bridge is flat. All in all I really believe this guy knows what he is doing. A close look at these cylinders shows some real quality. The transfer runners are super smooth and have been sculpted really well.

Bump. someone needs some top notch cylinders here

Well obviously it won't do anything to actually benifit the squish, but in a real world situation is it actually going to cause a problem? I mean how many cc's of fuel is that cutout actually going to displace? IMO not enough to make a difference. And as far as reliability is concerned, Vito's is still putting their name on a product that is manufactured with such a cutout and subsequent altering of the squish band. IMO if there were any chance of a reliability issue they would not be selling it. Just my opinion. But think just for a minute the actual amount of blowdown area you would add by cutting your piston like this. 1-1.5 mm average acrosss the port could be an 8-10% increase in the total blowdown area of an already ported cylinder, without messing with the duration, not to mention the possibility of creating a significantly stronger exhaust pulse.... All speculation aside, I guess it would be something that would have to be tested in a real world situation, and although I am not going to recommend anyone try it, I think it would be interesting to see the results. I mean Vitos got 5 hp, that's pretty significant....

There are 2 10018MO7200's And 1 423MO7200. They do not come with rings, and are all in good shape $60 shipped

Builders have been "chopping up" their pistons for decades. You just have to be smart about it.

Sale pending on carbs, pingel. Pics of cylinders: