1981 430CR Carb Tuning Question

my 87 430 engine is pretty close at
390 main
q8 needle jet
6dh20 needle-2nd clip from top
40 pilot
1.5 airscrew
3.0 slide
1.6 btdc, using mini 6 motoplat.
50/50 blend of vp110 leaded purple/91 e0
dynoport pipe, stock type cr straight core.
165 psi compression kicking wot until gauge quits climbing, 14/52 gearing, stock portwork


tiniest bit of fourstroking at times on main, or if i go any leaner anywhere. if i switched to straight pump fuel i would need to go a notch richer everywhere, as the vp does have a richening effect. pulls hard thru entire range, sometimes surprising a bit in the midrange. the straight core silencer really pumped up the midrange and top end, as power wheelies in 3rd/4th are a bit sketchy at times. sneaky torque..starts 1 or 2 kicks, hot or cold. it does like "kick primed" slowly when cold a few times.

r0 to r4 is a somewhat large jump...remember 1 number change is like 2 or 3 needle clip positions in effect somewhat.

Thanks for sharing. Have to go out and take a look soon on that WC 430 I Just got.

Very interesting slide number too

Others again share your setting its been a while since we all have talked about jetting a 430

Definitely going a different direction than Picklito on the main jet. He does live, as do I, in Nor Cal. But the jetting spread is pretty large between what you and he are saying. I just want to make sure I'm not cooking the engine at WOT. Regarding the specs for a '87 430, I'm not sure we're comparing apples to apples. Maybe I'll throw in a 470 main (from a 450) for a comparison and see if its better or blubbery.

Here's the jetting on my 81 cr430 . Main jet 450 , pilot 40 , stock needle 3rd clip , r-0 needle jet and slide cut to approximately a 3 . I'm running a mossbarger reed block using boyeson reeds from a Yamaha banshee asche/ procirciut pipe , no porting just cleaned up mismatches . Timing set to 2mm btdc . Running 91 non ethanal gas with maxima k2 @ 40-1 .

Timing 2.0 is where I always start on an air cooled 430 build.

As for the main jet... I started with these bikes in 81/82. They were delivered with 45/2.0/6DH3-4, 440 (or 430 as I mentioned). Between the rich low end jetting and the screen in the spark arrestor, it was almost impossible to get a freshly uncrated bike started and warmed up without fouling a plug. If you did get going, and then dropped into our sea level sand washes... the plug would be white within seconds if held at WOT, and you'd have the described BING BING BING hanging idle when throttling down. I've run up to 560 mains to get the bike to keep its cool across a sand wash. Now, if you're MX'ing and your WOT throttle runs are just a couple seconds, then ya you'll be "able to get by with" a much smaller main. My woods bike has a 480 in it, but that's for Stonyford, which stages around 1400ft and runs up to almost 6000. It's 35 pilot, 3.0, 6DH3-3, and the 480.

This is the way to do it. Find the blubbery jet and work down. And, yes, the liquid cooled bikes can run much smaller main. I don't have nearly as much experience with them (air cooled 430 nut case here!).

Mofo we should take the bikes out!

By 1981 this was my 3rd husky . As you mention , my cr430 was delivered with a 430 main jet but unlike yours there wasn't a spark arrested or screen for one as delivered . Yes , most of my riding is " mx style " and no , I'm not wot down miles of sandwash . And is the fuel the same ? If we were both buying the same race fuel probably . But i'm using pump fuel trying to stay away from any gas with ethanol . I've noticed a difference in the way it runs just by using ethanol free and had to go leaner because of that .
Then there's the typical east coast summer humidity here that you may or may not get . As you mention about nd vs. Wot down a long sandwash there can be more that factors into jetting a bike .

Right, no spark arrestor to clog on the CR's, and no humidity in a SoCal sand wash! We do have 'normal' humidity up here in NorCal, and much slower speeds in the woods. There's essentially nothing left here except the "may contain 5-10% ethanol" gas, with Moonbeam's ridiculous taxation applied. Can't say I've noticed different jetting need with the ethanol, but it should be there a little bit.

Maybe west coast cr's came with a spark arrested , mine didn't . Wouldn't know about west coast humidity as I've never been there but talking to a good friend that moved to socal he always talks about the weather. I do know when I went to ethanol free had to reject as it ran poorly .

Since you changed the slide from 2.0 to 2.5 you may want to changed the pilot jet to 45 instead of 40, and the main jet at 410. see if that helps

My 430WR is running 45 pilot, 3.0 slide, 480 main, 6DH3 needle, and R-2 needle jet.

Yes, we should! Where do you live?

Do the leakdown test first. That in itself could eliminate the carburetor as the problem. Most of what you describe are symptoms of an air leak.