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????
:beerchug:

 

[pekingduck]

Ben thanks for the reply and the leap of faith on actually making the swap. I had been thinking of a possibly easier way of changing cam timing by splitting the cam, re-indexing it, and rewelding it. It would save several precision steps. It would still need to be held precisely in the bearing surfaces (like in an an old head that was shimmed up). What do you think?

 

[Ben70_imp]

pekingduck, re-indexing is not what it needs, it needs more meat on the skinnier 1 and 2 lobes to get the right duration

Ben

 

[pekingduck]

pekingduck, re-indexing is not what it needs, it needs more meat on the skinnier 1 and 2 lobes to get the right duration

Ben

I thought they had just rotated the same lobe contours, but didn't realize they changed the ramps and/or lift. That's even worse.

 

[Ben70_imp]

Here it is:


skinny lobes


fat lobes

They open at the same time, 1 and 2 cyl lobes have been shaved to close 10 degrees earlier.
I think material can be added and then machined down to match 3 and 4.
I plan to find out some details early next week. Will keep you posted.

Ben

 

[GoldOxide_imp]

That is some serious craft Ben.

 

[pekingduck]

Wow, thanks Ben. It looks like they may have ground the original lobes! That's not like them - still, it would have been a quick-and-dirty way to do it. I know that in the recent past, they've un-crated bikes at the US warehouses, taken engines apart, made a change, re-assembled and re-crated bikes.

 

[Ben70_imp]

Sorry, either you misunderstood me or vice versa. This is the original intake cam showing one end, then the other just to illustrate the difference. My plan is to make the skinnier lobes look like the fat ones. I dunno if we are on the same wavelength?

Ben

 

[pekingduck]

Sorry, either you misunderstood me or vice versa. This is the original intake cam showing one end, then the other just to illustrate the difference. My plan is to make the skinnier lobes look like the fat ones. I dunno if we are on the same wavelength?

Ben

I understand. The profile of the lobes was changed, not just the timing as I had originally thought. Was just speculating if Honda made a change to the cams by regrinding flatter ramps after production had started by modifying existing cams as a cost cutting measure.

Wondering how late into the design/production timeline it was decided. The original engineer's discussion on the Honda Global site is gone. You'd think the designers/engineers would have ground the identical, slightly more radical profiles on all the lobes, not just on 2 cylinders. This just sounded like a cheap way of getting a little harshness without a performance benefit.

 

[Ben70_imp]

Well, yeah, but as I understand it the decision was made pre-production. I seem to remember some chatter I read about it just being too smooth, st1300 like.
And if you changed them all, you wouldn't get the dissonance. 1 and 2 are next to each other in the firing order, so it would be more effective at creating the desired effect than evenly spacing the "different" power pulses.
As it was, early reviews spoke glowingly about almost everything about the bike but that it lacked Character. Too refined, etc. yadda yadda...
Don't get me wrong, I love the bike! If someone hadn't let the cat out of the bag I would have just accepted the buzz, and have for some time.
I joined this forum in fall of 2016 and at about that time PowerDubs was just starting his journey. I followed that but ended up just trying the swap to see if even lobes would give the desired effect, secretly hoping the power would stay the same.
It appears that it works for my purposes and if a dyno wasn't available I may have never known I had lost some power. Acceleration to pass, etc. was good and just overall smooth.
However, I want to try to bring it back to where it was before some aesthetician got hold of it.

Ben

 

[pekingduck]

I didn't know about the designed-in dissonance until I had sold my 2013 and bought a 2014 to be rid of the buzz. But the 70mph freeway rpm is so low it kills the top gear roll-on power the 2013 had. Wish I had known about the cam cure before - would love to have kept the 2013.
Keep us posted on your cam regrind results. Cams are the same for all years. Any idea what cam grinder you might use?