Strange temperature variation.

[John Schmidt]

I've had a slight miss on the right side for some time, seems to be #1. Yesterday while letting the bike run to circulate some "vitamin B-12" (a/k/a Berrymans B12), I decided to do a temp check so got out my handy dandy gun and took some readings. Hmmm...#1 is running a good 12-15 deg. cooler than #3 & 5. Curious, I went to the left side and #2 is doing the same compared to #4 & 6. Run the engine at higher rpm's and the temps go up on all cylinders but the difference of #1 & 2 to the rest are now increased. I've chkd. the spark for both cyl. and can draw the nice blue charge out over 1/4" on either cylinder. I used a long pair of hose pliers to pull plug wires while running and do get a drop but not as significant as on the other four cylinders. In the process I discovered the insulation on the handle of the hose pliers has a crack in it, thereby allowing me to experience first hand the strength of the spark. 

Next I'm going to pull the plugs(new) and compare again for any indication those two cyl. might be running a little rich. All mixtures are set at 2 1/4 turns out. I've ckd. the valves twice now, no issues there. I've ckd. plug wires at the coils...same result. Any thoughts or suggestions? If you hit the throttle as usual....the old gal screams. Could it be coincidence I still have a partially plugged low speed circuit in two carbs even after an ultrasonic bath and new guts throughout? Got me stumped!

[Jims99]

Those two cylinders are running lean. With everything you have done, I would assume no vacuum leaks. I would try turning mixture screws out 1/4 turn. They don’t seem to be off much.
Cooler when cold and hotter when hot is lean. 

[Ken aka Oil Burner]

I used a long pair of hose pliers to pull plug wires while running and do get a drop but not as significant as on the other four cylinders. In the process I discovered the insulation on the handle of the hose pliers has a crack in it, thereby allowing me to experience first hand the strength of the spark. 

I agree with possibly a touch more lean on the front two cylinders. Unrelated, but a little story that I can never forget, for reasons you'll understand after reading.

When I was about 15 or so, my older brother was building a 73 Ford Torino. We just finished a garage overhaul of the engine and dropped it back in. We were excited to get it started, but he hadn't picked up new ignition parts yet, so the old cap, rotor, and wires went on so we could try to fire it up. Brand new MSD coil, but everything else of unknown vintage. He hopped in and cranked it over. Cranking slow, so I tried to retard the timing a little by turning the distributor. Instead of grabbing the vacuum advance, I put my hand right on top of the cap to turn it. Well, I got a charge from one (or more) of the wires. Here's the unforgettable part. That charge found a way to discharge to ground; directly from "the boys" into the LF fender. That is something that sticks with you. Not for a good reason, either. 

[indybobm]

i know that you have probably synced the carbs but that is my first thought on this. Since you raised the idle and it had an effect on the temperatures I would retry syncing the carbs. Are you using a Digi-Sync?

[yrunvs]

If he's letting the bike idle to run B12 through the slow jets wouldnt the motor be considered warm/hot and so wouldnt a cooler reading indicate a rich condition? or am I totally wrong? ???

[John Schmidt]

i know that you have probably synced the carbs but that is my first thought on this. Since you raised the idle and it had an effect on the temperatures I would retry syncing the carbs. Are you using a Digi-Sync?

Yes, used a digi-sync both low and high rpm. Forgot about this earlier but that low speed flutter started before I pulled the carbs for rebuild, just continued after as well. Just checked the plugs, #1 was all black but not wet so appears to be running rich. The rest were all clean....are new plugs. As a matter of extra caution while messing with it I replaced the #1 plug wire which made a big difference but not total. I didn't clean the plug before reinstalling it so probably still dirty, will ck. again after a short run this week.

Re. running the bike while mixing the B12, it was up and down the rpm range(by me) but mostly lower rpm in case the low side needed some extra cleaning. I dump it in first, then start the bike. Yrunvs, you're right. Usually engine temp will respond with cooler temps with more raw fuel introduced momentarily. I'll take a ride in the next day or so to see if that plug cleans up and the miss/flutter is gone.

[Jims99]

If he's letting the bike idle to run B12 through the slow jets wouldnt the motor be considered warm/hot and so wouldnt a cooler reading indicate a rich condition? or am I totally wrong? ???

It will give a cooler reading if rich after it’s warmed up. When cold, will run hotter if rich. (1 Reason for choke). Once warm the richness helps keep temps down. Lean will get hotter when warm.

[John Schmidt]

While working on the Valkyrie, at times I can't help but wonder what were the Honda engineers thinking when they did this or that. Adjusting the mixture is a prime example. I have five cyl. that appear to running lean at 2 1/4 turns out, one a bit rich at the same setting. I'd like to try opening up the five part of a turn and close the rich one just a tad, but getting to those screw heads is near impossible without removing all the intake feeder tubes. I've often wondered how the 1200 Wing carbs compare in size and performance. The mixture control screws are on the side and in plain view and when I rebuilt them for my GL1200 project a while back they were easier to work on. Wishful thinking I guess! So unless someone has a better idea, in the next couple days I'll be pulling the intakes to enable me to adjust the mixture control. Thanks for nothing on that one Honda, you really blew it. And yes....I have the tool with the little 90 deg. gears on the end which does absolutely no good if you can't see what you're doing. 

[Vermonter]

So unless someone has a better idea, in the next couple days I'll be pulling the intakes to enable me to adjust the mixture control. Thanks for nothing on that one Honda, you really blew it. And yes....I have the tool with the little 90 deg. gears on the end which does absolutely no good if you can't see what you're doing. 

I'm not one to blindly defend manufacturers, but the fact that they even _produced_ this thing as a production machine with six independent carbs on a flat six is pretty way-out, and there'd be nearly no way to have everything ideally accessible while at the same time looking decent. In this case, can't have its unique attributes without a few unique challenges and possible frustrations...

[CoreyP]

Who said all the carbs need to be set the same way?

You are going to have variations from carb to carb for different reasons. It's a matter of how anal you want to get?

You don't have a new bike, so.......

[John Schmidt]

Vermonter & CoryP, I've worked on trucks, planes, cars, motorcycles, etc., and have been riding 2 & 3 wheeled motorized contraptions of one type or another for over 70 years. I'm quite familiar with the ins & outs of designs where it appears the item you're working on was installed first then the rest of the machine was then built around it. Found that especially true working on aircraft in the military. And in my younger days many of the vehicles had multiple carbs....at least mine did. 

Over the years, having worked on all the models of the Wing from '75 forward it was especially interesting that the carbs on the 1200 "appeared" to be of approxitmately the same size as those on the Valk. If so, or even close, why not use something with similar design if not those very carbs! The 1200 Std. I recently rebuilt was a dream to work on and adjust, especially when it came to carb sync and adjusting the mixture control. I know full well the starting point per the Honda shop manual is 2 1/4 turns out and that is only a suggested starting point. My irritation is simply the adjutment procedure for the mixture control, it's ridiculous from the standpoint of accessibility. The very set of carbs I rebuilt had those controls set anywhere from 1.5 to 3.5 turns out. For now, I'm taking a short ride, going out for b'fast and run a couple errands. I'll check the plugs when I get back and if acceptable I'll leave it alone and concentrate on getting ready for the trip to Asheville.