My 200R!

[NINJA]

Like the bike, cool piece of history. But i was under the impression that these 250r based engines, along with kawasakis tecate 200 were both sleeved down. However the stroke remained the same. It's alot easier to take displacement out of an engine by reducing bore size through the use of drop in sleeves. Using a shorter rod does not reduce displacement. Crank is still throwing rod up the same distance regardless of how long or short rod is. Weather it's a bike, car, or tractor. Engine stroke and bore= total displacement. Connecting rod length will change the rod angle during rotation. Longer rods mean less side load on rod when it on upstroke and downstroke. I run 6" rods in my 406 sbc, with a stock stroke crank and 30 thou overbore. What changes is the placement of the pin on the piston, so piston is not pushed out of cylinder. Piston is now much shorter and pin now runs through bottom ring land. However, it would be 406 cubic inches weather i ran the stock 5.5 in rods or the long 6.0 inch. In a 2 cycle just changing rod length would severly mess up port timing. If Selvy made their own cylinder with altered porting events, it would still be the same stock displacement even if a short rod was used, if bore and stroke was stock. Don't mean to argue with you but there are many things that have to be addressed when changing rod length in any engine. I'm sure there are some engine design gurus on here who can elaborate more on this.

Hey man, nothin like jumpin the gun! You are right on what you say, however, allow me to elaborate. Selvy 200R motors are not sleeved down. Some people tried that but you end up with an undersquare engine and a very narrow and hard to use powerband, not to mention little useable torque. Selvy had their own crank in these motors and yes the crank pin was moved in closer to the crank center. The cylinder retains stock bore but is extensively welded and modified to accomodate this shorter stroke. Hope I cleared everything up for you. I guess I should go into full detail with everything I post in here so people stop trying to school me on the basic fundamentals of the workings of the internal combustion engine.

[Orangecnty250r]

Hey man, nothin like jumpin the gun! You are right on what you say, however, allow me to elaborate. Selvy 200R motors are not sleeved down. Some people tried that but you end up with an undersquare engine and a very narrow and hard to use powerband, not to mention little useable torque. Selvy had their own crank in these motors and yes the crank pin was moved in closer to the crank center. The cylinder retains stock bore but is extensively welded and modified to accomodate this shorter stroke. Hope I cleared everything up for you. I guess I should go into full detail with everything I post in here so people stop trying to school me on the basic fundamentals of the workings of the internal combustion engine.

My cammex 200r had a shorter stroke as well

[scooterroo]

well read what scooterroo said.

sweet...thats 2 i have seen on here now.

OC had the other one...and now this one....i think that makes 2. at least where i am from 1 plus 1 equals 2.

[Orangecnty250r]

Mike in Ft laud has one as well

[RacerRichie]

SWEET!!!!!!!
Glad someone on here got it and and that it didn't get chopped up and sold. Cool trike for a collection for sure. Cant wait to see the FT setup..
RR

[tecat-z]

That's awesome. Some people don't know and that clears everything up. Have a great time on it, and give us a ride report. It's nice to know that Selvys used a different approach than kawasaki. Tecates were wayyy oversquare to begin with at 70mm-64.9. Thats part of the reason they are so rev happy. Big bore short stroke.

[dizasterzrfun69]

OC had the other one...and now this one....i think that makes 2. at least where i am from 1 plus 1 equals 2.

lol thats exactly my point. there isnt many of them around so it was a good trade