zx50 highests speed reached?

[zombie]

Yeah the dash is all the same! Sid... Remember when we were talking about kerfing the piston? Cut a PIE shaped wedge into the dome facing the exhaust port. Start at the center, and slope it down. You will create a compression release that will allow you to decrease the squish band. That is what raising the jug does for you. Better power, but more heat is the enemy. I know this sounds like an un-livable situation but it may be the cure to the jug you have. I have mentioned a few times a Mako 490cc that I used to run. It had ONE OF parts in the combustion chamber that cost a fortune to run, but it beat the dog cra> out of 600cc enduros every time. You have done everything else to get this kit to run, and I think you will see incredible results from wedging the piston. Try taking 1/2mm off the "wedge". then you can put the jug where you need to.

[wordslinger]

kerfing the piston?

...now just what the hell is that..

..never heard that term before...

.......dang.....

..i have so much to learn..

[zombie]

It's cutting a shape into the dome that will FORCE the gases to escape. The entire up stroke will see less compression on the exhaust side of the piston, and because of that you can increase the overall compression ratio. I have NEVER had to attempt this on a 50-100cc engine, but Sid seems to have a unique situation. He is running as cold a plug as you can easily find, and still getting pre detonation. It seems to me he needs a 1 of solution. If kerfing the piston is the answer........ so be it.

[wordslinger]

...i could do that to the 4-stroke, couldn't I...??

[zombie]

It's the same as Hemi Pistons. They have a shape that transfers the heat away from the valves, but there is no need for it in your scoot. It May work for Sid because he has a heat condition that nothing else seems to cure.

[sidthesloth]

That sounds interesting Mudfreek, how would you like to post up a pic so I can see what I am missing out on? Mine is an '07.

[sidthesloth]

Sorry zombie I got a little side tracked. I have got a BR8 plug in at the moment but will put the 9 back in when I get to work at it again. When I lowered the cylinder a little that increased the compression and gave back what speed I lost with the torque spring. Next time I take the cylinder off I will see the result on the piston as to where it is getting hot, last time it l;ooked to be around the exhaust side. By kerfing the piston will the lower the compression? Also, won't that open the exhaust port earlier? These may seem like silly questions to you but I am trying to get a handle on what I am about to do. If I do this perhaps I can lower the cylinder a little more? With the current setup I now have room to move both up and down, within reason.

[mudfreek]

ok as soon as i can i will

[mudfreek]

my bikes an 04 and the other dash i have is an 03 wich is my back up once i reach the 12000 + km mark

[zombie]

You answered all your own questions. The idea of a wedge is more of a release for the gases to follow,  this will allow the heat to flow vs, wait for an exit. I did this on both pistons in an RD 250 Yamaha 2t. I ran open pipes @ 2 1/2' long, and milled heads. The stock bike did 90 ish mph. The finished bike did 128, and could climb a wall if the tires stuck. I had to kerf that one because the open pipes melted pistons, and expansion chambers had to be custom made. (too much $ back then). Lowering the compresion doesn't really occur because of the shape. It is more of a path to follow than removal of material. I put a few more details in the other thread.

[sidthesloth]

Cheers zombie, will follow up on the other thread.

[thebatman]

what thread is it?         sids???   i seen all that in handbook but wow,    seemed a bit on the difficult skill level...

[zombie]

Naw! It's easy breasy stuff bat... Just follow the clues to the cure!

[thebatman]

elementary my dear watson, elementary......hmm., guess ill just have to stick with watson and wait till inspector holmes find all the clues???.. RLMAO....easy breezy huh?? whew!!!

[zombie]

Keep in mind I am 52 dog years old, and have been riding bikes since I was 9. My first scoot was a 69 Vespa that I converted into a "dirt bike" when I was 14. I've been blowing schtuff up longer than the books have been around.