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Discussion Starter · #1 ·
I just recently got my cheetah together here are the stats

421 cheetah pv motor (not cub)

blaster pistons
19cc domes
vforece 2's
+4 timing
nology coil and wires
small bore oof shearer pipes
39pwk's
14" k&n filters

jetting as of now
main 155
pilot 48
dek needle middle clip
5.0 slides

Gas: C12 mixed 32:1 with techniplate
br8es plugs

elevation around 600ft

Seems like its running out uptop

Never messed with a powervalve motor so not sure where to start

any kind of help will be appreciated

thanks
chris
 

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Discussion Starter · #3 ·
QUOTE (REDLINE @ Jul 27 2009, 06:05 PM) index.php?act=findpost&pid=51332You should check to make sure your powervalves are opening, make sure they are clean and have no burrs, and you can pull the springs out to get them to open easier just to see if that is it?

I cleaned then before final assembly.
It does fine when I launch just falls on its face when I hit 3rd or 4th gear.

will the bike run right without the springs in the pv?
 

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Discussion Starter · #5 ·
QUOTE (REDLINE @ Jul 27 2009, 06:09 PM) index.php?act=findpost&pid=51334You will loose some low end, but if it wakes up the top end you will know that is what it is.......

Does my jetting seem close
I used the same start point as my 392 cub just uped the mains I think the main is too small
 

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QUOTE (Chugger @ Jul 27 2009, 03:30 PM) index.php?act=findpost&pid=51336Does my jetting seem close
I used the same start point as my 392 cub just uped the mains I think the main is too small


Hey Chris,

I am running a 4 mil 72 bore (472 cc) pv motor. It is funny because every time it skips a beat, I always point my finger at the pv's. They really haven't given me much trouble. I think we caught them sticking once on the dyno and that was it.

I think your real question is jetting though. It is a little tougher with the big carbs but we settled with a 160 or 162 mains with my 38 pwk's. You should be pretty close with a 155. Are you running a stock ignition? I tried the Ricky Stator stator and it ran great except for the top end around 9000 rpm it would break up pretty bad.
I like your needle choice. I am running a dek on the third clip. The pilot sounds good but that doesn't affect top end at all.
If the pv's are opening up all the way then you may want to look at the electrical like stator, plugs, and coil.
When I had a similar issue, I went to the extremes on the main jets to prove to myself that this wasn't the problem. You could try a 165 and see if that helps.
Sometimes there can be a fuel flow issue as well. I have known some tuners to try to run the bike with no main jet to see if the bike is getting enough fuel. You would probably see a heat issue though if fuel flow was an issue.
Good Luck. Keep throwing those darts and eventually you will hit the target.
 

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Discussion Starter · #8 ·
Still throwing darts been working alot lately but finally have a day off tomorrow

I did find out that the top of my slide broke and is dropping the slide too far which wont let the bike idle on the right cylinder. But I checked at wot and there is no obstructions.

I am gonna jump to 165 mains and see if this helps.

I have a stator plate but picked up a dyna fs and am gonna try that on some different curves. the damn tuning kit for the dyna didnt show up yet.

I am running a stock stator not an off brand. also I am running a nology coil and wires I have heard rumors that they will not work with the dyna fs is this true?

Hopefully I will have this pinpointed before the race saturday if it lies in the carbs I have a set of 35mm a/s that I can toss on.

any more input is appreciated timing jetting etc.....

thanks again guys
chris
 

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I had the dyna fs........Drop that thing. If you have a timing plate, stock stator, a stock CDI, and nology coil and wires...then you have all the parts you need to run the fastest motors you'll ever build. Tim at Titan racing has set record after record with that exact combo. I took his advise and dumped the dyna (it likes to break up over 9000 RPM) got everything that said "Ricky Stator" off my machine and I'm happy as a clam. I have a "Ricky" flywheel, Dyna fs, and stock coil for sale or trade if anyones interested...... Yes, a nology coil can cause problems with a dyna, but not if your CDI is in the rear. Oh, +7 on the timing on gas.
 

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Not sure if this is what yours is doing but when I had the original Cheetah PV motor and tuning it we found a fine line with what spring to run. What we found is at a certain point in the RPM (if mem serves correctly about 10,500 rpm) the PV's will actually close slightly and the bike feels like it falls on its face. Now if you change the spring and keep a lighter spring in the PV then you will lose a little on bottom but they will stay open longer on the big end but at some RPM point in the upper range the exhaust pressure drops off and will allow the PV's to close.

I know this sounds crazy but that is what we found in tuning the one I had.

Oh and I can't understand why everyone has such problems with Ricky Stator. I have their 200 Watt Stator and the Dyna FS and my bike runs flawlessly all the time. During tuning we were spinning my motor to 11,800 and it never missed a beat. I have all of my stuff mounted up front under the tank along with the coil and a voltage regulator that charges my battery. I run BR8EG plugs on E85 +8 degrees of timing and I am happy as a clam. So just wondering what gives with all the problems you guys have? Just wondering
 

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The "older" ricky stator stators were very good. I started with one of those and had no issues until the bolts came loose that hold it on and it got destroyed. Now that Ricky is dead, their stators just don't work right. The customer service is excellent! I worked with Mike to try to get the stator working right but everything we tried failed. He sent me 3 different stators to try, different pickup coils, etc. but the bike would always break up around 9000 rpm or so. I have the dyno runs if you want to see them. Funny thing is that the bike ran better in the lower rpm range than it every has but the higher rpm issue made the bike useless for everything but mellow dune rides. The other funny thing is that my riding buddie has a newer style Ricky stator stator and it has no issues at all.


Let's no steal Chris' thread though on Ricky Stators. Many have stories about issues they have had.

Back to Chugger's ordeal.

I also like +7 on the timing. +8 is too much on the edge. Your timing seems low but that would not affect the top end condition you are describing; it would just cheat you out of some hp.

Who cut the domes? What is your port timing? Has this motor ever run right while you have had it?

Mailman
 

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I would still do some testing on the dyno to determine if what you are seeing is the PV closing at high rpm. Like I said it sounds crazy but that is what I had with mine.
 

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(I've got the 472 4mill Cheetah with the power valves just like "Mailman") You can take the powervalves out, open them up and put a spacer (washers or cut hollow rod) in place to hold the valve open. You won't even need the spring in place at that point. It'll cost you next to nothing to try. You can even buy the blockoff plates for that motor. (you have to match them to your motor/piston you can't just throw them in) Then you can rule out the powervalves and find the real problem. Not all of the "ricky" parts are junk. But the newer stuff has a history of working fine one ride and not working at all the next. Or worse, when your far from base camp on the dunes! As for "Nology" coils, they seem to only affect the DYNA FS box and that's about 50% of the time.
 
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