timing/compression questions

[oldestschool]

 

87 to 93 pumpgas

 

what kind of timing advances and compression are you using?

I am planning to build a Cheetah 535 to put in a 2 wheel street frame and use a programmable ignition.

 

I'd like to keep the oil pump and use pumpgas so I don't have carry octane booster and oil or look for a place to buy race gas everywhere I go.

Thanx

[2001Stroker]

First, do not use octane booster. It's not consistant, and will lean you out.

Second, what oil pump? Cheetah's do not use oil pumps. You pre-mix.

 

To get the compression low enough for straight 93, you'd need somewhere between 28cc and 30cc domes, considering your timing and elevation. lt1bird's Cheetah PV 535 is in a streetbike. His has 27cc domes, and 0 timing. I believe he's using straight 110, but could probably get away with mixing 50/50. My Cheetah PV 535 has 25cc domes, +7 timing, and only runs on 110 octane. You need to explain more about your motor, and give your elevation, to really be able to tell you where to start.

[oldestschool]

Sea level Florida.

a 535 w/39 PWKs ported and piped to get a wide powerband.

say 5,000 to 10,000.

From what I've read so far it looks like MX porting would suit me best.Possibly by flotek

Oversized radiator.

Completely programmable ignition so I believe I'd be able to set advance at any point in the RPM range.

 

I had assumed I could retain the stock oil pump on the RZ cases,thanks for letting me know.

 

I have built racing 2 stokes before for MX and track and maintain a V6 Yamaha outboard with 6 carbs,2 fuel pumps,6 coils but only at 1.5 hp/cid.I know it'll take some tweaking to get right.I just wanted a baseline...trial and error works best when someone else helps with the trials.

 

lt1bird,seblo and anand from all the other forums are the inspiration for this.

 

[2001Stroker]

Your "powerband" will pretty much be from idle all the way to the top, because you'll have power valves. It's gonna pull from bottom to top, almost like a 4stroke, but have the 2stroke power and RPM range. Cheetah cylinders come from the factory, pretty much drag ported. You can get a clean-up port, just to get the rough castings off, and you can get a little more out of the drag port, but you ain't getting an MX port from a Cheetah. It's already ported way past the specs of an MX port. It also comes with intake boost ports, and exhaust boost ports, and 3 large transfers. You're absolutely going to need a large radiator for it. It makes some heat. What kind of pipes are you talking? A 535 needs to breathe. What is it going in?

[oldestschool]

Right now it's looking like an 05 R6 frame with whatever mods I need to keep it around #300 wet if possible.But I plan on building the engine first and doing more homework on the frame.The Mitos and FZR400 framed bikes also look pretty good and have some impressive race records.

 

 

I imagine it will take custom BB pipes,either I buy some Banshee pipes and cut those or have them

made.I had heard of engines seizing due to inadequate breathing from smaller diameter pipes and stingers.

 

I don't plan on cutting any corners and I know it'd be cheaper to just buy an R6 and add money but I raced RD/TZ/TDs for a while as a young man before joining the Navy and have a very soft spot for YamalubeR,bees in tin cans and smog.

[2001Stroker]

Sounds like alot of fun. Personally, I'm not a big fan of Yamalube. I tried it, and it burnt dirty as hell. I just recently switched from Maxima SuperM to Maxima Castor927, only because it has additives to help keep the powervalves clean and operating well. But, to each his own. Good luck with the build. Keep us updated with it.

[oldestschool]

I've heard that about the Yamalube.Things change.

I will be looking into oils as well as every other detail.

I want to get as reliable a motor as possible and carbon doesn't help.

 

This will be a long term project but I'll take pix as I go.

1/2 the fun will be sitting on something I pieced together from hundreds of parts that were not intended to be fit together and making it right.