The Right Cams...

Looking to upgrade from my current cams and wondering what to go with.

Currently running some very old Kenny Harmon cams, lift about .395 and duration at .050" of 258 degrees (assuming my measurements are correct). I have them set at 107 degree centers.

Combined with a rack of RS34s, a 1075 "10.25:1" kit, a stock 1979 head with plugged emissions ports, ported intakes, cleaned up exhaust and a Kerker exhaust it pushes out 102-105hp at the rear wheel depending on the dyno.

Nice strong hit at 5500 that I really enjoy and a long strong pull through the top with no tapering off in power before I hit my rev limit at 9800. A little soggy down low, but well worth the top end hit.

Should I keep my current cams, or is there a better, more modern grind that works better overall. Or... it there a cam that would give me even more of that POW! midrange hit that I get currently.

Also I would like to replace them because I have the sneaking suspicion that they are wearing out or are not straight. Clearance measured on the heel of the cam is not the same even a couple degrees forward or backward. I have to make sure clearances don't get too tight by setting clearance wherever that cam is tightest on the backside, requires lots of jiggling and measuring - NOT FUN.

-Dave

Damn Beef... Seems you have a pretty good combo configuration now...

The RS34's may be the stumble where as Buzz over at Dynoman described to me, they are a beautifully designed racing carb @ WOT, awesome... In the low/mid end, they'll stumble a tad where they'll just not perform like a smaller set of CR 29's would....

Based on what I described in my build & riding style, took his & others advice (same) and went with the CR's.... I asked 29's or 31's... He replied, your displacement & cam selection, stick with the 29's.... Advice well taken...

When doing my research for my ideal build, I found the .365 better suited for my riding style where designed more for low end to mid range power band performance... I also went two up on the rear sprocket...

Little 1015cc surprises quite a few others up to 6Krpm...

While on the highway running 5th gear @ 65mph @ 4500rpm, just twist her and she pulls away... No need to down shift... Seriously, she pulls strong up to 90mph quickly with no stumbles, flat spots etc... Just pulls steadily in the upper range.

Downfall @ ~ 100mph +, she still performs well but this is where my riding buds newer bikes take the old girl. Pulls well yes but not as strong as in the low/mid ranges...

Based on cam choice, sprocket gear selections, build etc.... calculates out ~ 128mph max which is more then I need on a street ride...

I guess it boils down to what exactly are you looking for.... PM Larry C, he'd surely be able to provide some guidance on what you're looking for...

Let us know what you end up with...

OMR

beefsquasher wrote:

Looking to upgrade from my current cams and wondering what to go with.

Currently running some very old Kenny Harmon cams, lift about .395 and duration at .050" of 258 degrees (assuming my measurements are correct). I have them set at 107 degree centers.

Combined with a rack of RS34s, a 1075 "10.25:1" kit, a stock 1979 head with plugged emissions ports, ported intakes, cleaned up exhaust and a Kerker exhaust it pushes out 102-105hp at the rear wheel depending on the dyno.

Nice strong hit at 5500 that I really enjoy and a long strong pull through the top with no tapering off in power before I hit my rev limit at 9800. A little soggy down low, but well worth the top end hit.

Should I keep my current cams, or is there a better, more modern grind that works better overall. Or... it there a cam that would give me even more of that POW! midrange hit that I get currently.

Also I would like to replace them because I have the sneaking suspicion that they are wearing out or are not straight. Clearance measured on the heel of the cam is not the same even a couple degrees forward or backward. I have to make sure clearances don't get too tight by setting clearance wherever that cam is tightest on the backside, requires lots of jiggling and measuring - NOT FUN.

-Dave

I've seen cams like that before Dave An old set of Andrews. Clearance would go from .002" to .006" from one side of the base circle to the other.

I take it you're running Shim On Top. That's a pretty nice feature to have. Look at a Cam Motion Z4 if you want to keep that and go a little more cam.

Specs at bottom of page www.flowbenchtech.com/porting/CRH/kz-data.htm

Another thing I just thought of....

Is the head ideally Ported/Polished for these larger 34's?

OMR

So the Z4 cams are still ok for shim on top? I assume that that is the absolute maximum lift for SOT retainers.

-Dave

I have .410 cams in my bike and they are ok for stock buckets I was told but at that size it's possible to spit a shim, any bigger and underbucket would be a good safe insurance plan. Those are some big cams and I put a lot of miles on my bike. I made the mistake of doing just the top end when I probably should have just replaced the blown head gasket and left my motor stock and focused on my 79. Not to digress, but these .410 cams seriously stretched out my stock timing chain. I now have a heavy duty timing chain and liska rollers and billet stuff that hopefully will allow more life before cases have to be split and timing chain replaced. I don't even care to say how much I have spent on this motor in just parts already. Hopefully it's bullet proof this time. I bought an 03 zrx 1200r and I will tell you for the price of my gears and crank work I had done I spent more on that stuff than I spent on the whole bike with titanium header and one off parts! Building the bike so its fast is nice but buying a bike that looks old and screams is better IMO and have two bikes instead of the money for a brand new zx14 in just your engine alone.
How many miles do you plan on riding your bike before having to tear it apart and refresh it is the real question you should be asking before you go any bigger with the cams.

I know, I know, it's a kz thing but it's a big price to pay for a little more performance on an air-cooled motor which will run much hotter and stand the chance of overheating at every stop light.

saxjonz wrote:

I have .410 cams in my bike and they are ok for stock buckets I was told but at that size it's possible to spit a shim, any bigger and underbucket would be a good safe insurance plan. Those are some big cams and I put a lot of miles on my bike. I made the mistake of doing just the top end when I probably should have just replaced the blown head gasket and left my motor stock and focused on my 79. Not to digress, but these .410 cams seriously stretched out my stock timing chain. I now have a heavy duty timing chain and liska rollers and billet stuff that hopefully will allow more life before cases have to be split and timing chain replaced. I don't even care to say how much I have spent on this motor in just parts already. Hopefully it's bullet proof this time. I bought an 03 zrx 1200r and I will tell you for the price of my gears and crank work I had done I spent more on that stuff than I spent on the whole bike with titanium header and one off parts! Building the bike so its fast is nice but buying a bike that looks old and screams is better IMO and have two bikes instead of the money for a brand new zx14 in just your engine alone.
How many miles do you plan on riding your bike before having to tear it apart and refresh it is the real question you should be asking before you go any bigger with the cams.

I know, I know, it's a kz thing but it's a big price to pay for a little more performance on an air-cooled motor which will run much hotter and stand the chance of overheating at every stop light.

Now I see why you got the REX. Jerk.

beefsquasher wrote:

So the Z4 cams are still ok for shim on top? I assume that that is the absolute maximum lift for SOT retainers.

-Dave

That's what Cam Motion says. S.O.T.

Awesome tips! Thanks, Larry, I don't care what others say about you!

dont listen to him,i just got off the phone with nads.com.
nads says what you want is wk480 off apes site,you can always build a 1500cc motor to go with it later! :laugh:

In the picture you'll see 2 S.O.T. Kawasaki OEM buckets. Bucket on the left is an older style. On the Right is a J model Bucket.

J has narrower oil groove than the KZ and the shim fits a bit more snug into the recess.

What used to be done is to fill that oil groove with silver solder and machine the surface flat.

With cams that contact the shim closer than .040" from the edge of the shim, it's possible to rock the edge of the shim down into that oil groove.

Rocked enough, it can dislodge the shim. Then things get ugly.

NEVER install a shim without oil on the bottom!

They can and will spit a shim, it's just a matter of when. I'm thinking this went at a gear change at redline in 4th gear. People watching said at gear change it went stupid all over the track. Guy spent a long time in the hospital. I'm not saying it didn't spit during the wreck, rev limiter was set at 10,000, but something caused the bike to go nuts and I'm thinking it may have been oil from the hole.
Not trying to sway anyone away from what the manufacture says but I'm not going to chance it.