Buzz Killl?

[Ben70_imp]

Long story short, it is possible to install an exhaust cam into the intake side and reduce the harmonic buzz that I for one find annoying.
Thanks to PowerDubs for breaking trail in the cam experimentation. His "Cams Anyone" thread got me interested in the possibility of just using an exhaust cam for the intake side.
I looked at the total duration of the exhaust cam vs the intake cam and the difference was one degree on the "normal" lobes, 10 degrees less on the narrow cyl 1 and 2 lobes. Exhaust cam lift is about .004" less than intake, meaning to me less volume.
Before anyone gets too excited I will let you know I lost 5 hp, and as much torque. The loss was at peak hp so it is essentially 2 or three hp in the 3 to 4 thousand rpm range.
I dynoed it before and after with the nice folks at Freeman's Choppers in Chico.

That's me on the left and Nicole and Will. I won't bother posting the graphs, they are linear, the only difference is the "after" line is lower. Nobody wants to see a picture of the small fish you caught.
It also showed lean running, both before and after. I sent the computer off to Guhl's and I plan to have the original intake cam rebuilt so the lobes for 1 and 2 are the same as 3 and 4. I would welcome suggestions on a shop for that. Seems like PowerDubs had to wait for stinking ever for his, but since the work I require would be more straightforward I would hope for decent turnaround.
As far as running down the road, it is great. I have ridden it for 90 minutes a couple of times, once with no numbness in my hands and once with some tingle just starting. Normally I begin to have problems after 30 minutes or so.
The loss of power is not noticeable in real life, at least to me. I took it up to well over the speed limit a few times and it seemed to get there as quickly as it ever has. It doesn't have the growling howl it used to have on spirited acceleration, but it does have a very healthy exhaust note with the Yosh exhaust.
Other than the tingle, the thing that really bugged me about the staggered cam lobes was when I was reading some years ago about all the attention to detail the design got, then when they got this jewel built it didn't sound ferocious enough so they went back and designed in a noise.
Don't get me wrong, I love engine noise of all kinds, lawn mower to jet. Harleys too if they aren't just obnoxious. But when designers and builders weigh and measure everything to get a smooth mill and go back and change it to make it seem more authentic it bugs me.
The motors back in the day made that hot noise because it was a byproduct of the relatively unfettered machines of the day.
Anyway, I ramble.
Bottom line it is smoother. Acceleration is good, decel is good. It seems to be happier with any rpm you happen to be at. Maybe just me but seems smoother, with no harmonics on the way up in rpms.
Looking forward to getting my box back, and will start looking for a cam shop. I am sure I will end up with at least as much power as I started with, maybe more, but I am quite happy with the direction this is going.
Don't do what I did without expecting a loss of power. I was mainly interested in the rideability aspects.
If you want smoother, AND a hot rod, try PowerDubs grind with the stagger taken out.
Plus, he did some other things with the intake, etc.
Will let you know what happens.

Ben

[the Ferret]

wow, thats interesting. so you bought a stock exhaust cam and installed it on the intake side?

[Ben70_imp]

Yup. works great for what I wanted, but I am sure the original lobe shape on 3 and 4 is optimal, which is what I will go for. not looking for a hot rod, but back to even would be good.
I was worried that it wouldn't fit, or the oil passages would be wrong, but it is fine. If I hadn't lost power I wouldn't bother with anything else other than the reflash. Dyno showed it running lean up to about 6000 rpm, before and after.
I know the buzz doesn't bother you, Ferret, but I had that thing on and off the throttle at cruise yesterday and it was like twisting a rheostat. Magic carpet smooth.

Ben

[the Ferret]

yea it doesnt bother me but thats not the point, it was bothering you and you did something novel to fix it. I think thats pretty cool.

[GoldOxide_imp]

Harmonic buzz? Is this the same buzz felt through the handlebars?

If so, no Grip Puppies could remedy? I found the Puppies made a significant improvement.

[Ben70_imp]

I tried GPs, rubber mounted risers and different gloves.
I could have maybe lived with it, on real long trips(over three hours) something happens and it quits bugging me.
But, I still didn't like the idea of the imbalance. When I was a kid, my dad was friends and partners with a genius cam guy who had a shop in San Jose. Used to push a broom a little for him and he always had two or three lathes running. This was before CNC and at least as much art as science.Local dirt trackers and hot rodders kept him busy, and in the mid sixties he had one in an Indy car.
Anyway, some of that stuff seeped in. Also spent most of my working life as an auto diagnostic tech and tuneup/ driveability guy.
Messing with good cams to make a better noise just twists my panties.
I know Triumph went to 270 degree crank for effect, and Harley guys revolted when the old fashioned rumble was messed with a few years ago.
I am quite happy with the sewing machine qualities of the way it runs now. Hope to do it right, and at least get back to even on the HP.

Ben

[GoldOxide_imp]

I believe I feel what you say Ben. Thanks for expressing that.

[pekingduck]

Like you, I am annoyed by the high frequency buzz, and by their design reasoning.
I read PowerDubs' thread with interest, although his goal was power, not smoothness.

I have 2 questions: Has Don Guhl verified there is a stagger in the stock ignition timing between the left and right cylinder pairs, and is he able to set timing to be even across the board? (I don't think the ignition is staggered because one coil is for cylinders 1-4, the other for 2-3.)

[Ben70_imp]

pekingduck, when I get a call from him I will ask, probably middle of next week.
However, as you note, 1-4 and 2-3 share coils. 1 and 4 are piston pairs, the pistons are both at tdc at the same time, as are 2 and 3. Automotive systems that share a coil between piston pairs have a waste spark occurring and the same thing happens here. I have a 90 horse 4 cyl Honda outboard that does the same thing.
That is why I agree with you that it is not staggered. I also think I would have lost more than 5 hp if that were the case. Also, why stagger the closing of the intake valves for effect then reset ignition timing to try to "fix" it? Not saying it couldn't be done, but I think it would require one coil per cylinder.
Any question could easily be answered by removing the timing cover and using a timing light to compare 1 and 4. If the mark is in the same place, timing isn't staggered. I never considered it a concern or I would have done that.
Also interesting to note is the manaul shows the firing order 1-2-4-3 rather than the typical 1-3-4-2 usually seen. However, this still makes 1-4 and 2-3 piston pairs.

Ben

[peterbaron]

Very interesting read and experience, thanks for sharing Ben.
Also, PowerDubs posts were always pleasure to read, very knowledgeable!!
I wish, he was as active as before....maybe soon????