That's seemed to me... will try some things.... one will be a metamorphosed RR12 who changed the powerband trying to find brutal mid and high rpms losing some of the low-end that has.

and the other will be a NS12 or RS12 with a very close gearing. The RS12 loves to whine a lot.

What kind of gearing tried you tried on the MTX3 (if you still use it) in the warm-up race... planning to carry 20/25, 20/26 and 21/27 for pinions on 0.8 gearing. Probably the 20/25 will be a little short, but need to try it. 20/26 with 58/53 is mine stock gearing for mine local track, a little longer than Ft. Myers (900Ft long with some ample turns and two hairpins).

One thing that scares me the sh*t what is the stinger size on the exhausts is the maximum under ROAR rules? 5 or 5.2mm? All mine pipes go at 5.1... and need to know if need new pipes.

ROAR rule is 5mm max. on the stinger. I wish they'd move up to 5.2mm though. My favorite pipe (so far) uses that size stinger.

I have been trying to modify engines by myself, with out guidence. They end up being fried. (literally, they pop!!) How do you guy measure your cuts (leangth+depth)? Is there a tool? Is there a book that I can get that explains the correct process. I want to learn how to do this. It is very interesting to me. Please help. (Most of the engines that I modded were really really cheap. I don't have a lot of cash, but you have to start some where.)

Later,
-Dust

Hey Dust, are from revelation, the guy who is working in shop?
If you are, I will come one day ( may be this weekend) and I will try to help you with that.

I used to work there during the summer. I got to school in Pasadena. It was would be hard to keep my job while playing 3 sports and traveling back and forth. I live in Upland, so I have to wake up really early to get to school on time. It would be a real mess if I had to work during the week. Tell me when you will be going, and I will try to meet you there. I am currently running a non- modded MR-12. I have a brand new NS12 3 port, that is still in the box. I might mod that one. The NS12 is pretty fast as is, i might modd it, I don't know yet.

Thank you for your kindness,
- Dust

I might be there late afternoon on Sunday, if not I will send you PM with other day or we can meet on CP ( I am planning to be there tomorow).
Edward

Hey TG (or anyone) you got any info or advice for modifiying the taper on the bottom of the sleeve? I'm not sure what a steeper taper does as opposed to a less steep taper.

I do very steep taper there, right under the exhaust port. It is free up piston. Under the exhaust port we don't need any sealing, so the more we take out-less friction we have there. It is only guyding piston to go straight. Sorry can't release phisical numbers-this is one of the numbers can be disclose.
You need to try, lap it little by little and will see the difference, once you got overlaped-you will notice the piston will hit top line of exhaust port on sleeve. When you got to that point, just mesure it and do little bit less.

Thats cool I was a little stumped and needed a hint (which you provided)


Thanks, Never thought to mess with exhaust I've been playing with boost and transfer. I will give it a try........too bad its 28 degrees outside so no testing for a while

ps - Can't wait to see how the PS12 does at the winter Nats - Good Luck

You are very welcome. Any questions I ready to answer, even some real numbers can provide, beside some key numbers.
I can't wait to see how PS12 will perform too
Thanks for wishing luck to us.

Fellow modders.....I was wondering when you adjusting intake port timing do you raise the top of the port or lower the bottom. So far I have only raised the top....just was thinking what would happen if I lowered the bottom.

I would love to help, but realy didn't understand what do you mean by "raise top " or "lower bottom"
In induction we always talk about when it is open and when it is close ( duration can be calculated or mesured).
So , do you advanced in opening or closing? What power band you want to have from your engine?

Ooopss!! Sorry for the confusion.....I'm talking about the transfer ports opening on the sleeve....So far to increase transfer timing I have been grinding the top of the transfer port (top meaning edge of transfer port opening closes to TDC). I hope that mad it a little more clear.

And my question is...Would I need to grind away at the bottom of the transfer opening for any reason (bottom meaning edge of transfer port opening that is closes to BDC).

I got question. Don't touch botom of ther port-it changes nothing. If you want to change timing just cut the top line of sleeve.

In general terms, what performance change do you enhance if you increase induction by advancing opening or retarding closing of the crank opening.
I.E. advancing opening = more torque
retarding closing = more top end
Or is it the opposite.
Same way with transfer ports, what effect does it have to rise the port or lower it.

AFM