markjenn
Well-known member
Hi everyone, I thought I'd relate my recent experiences with carb sync devices.
I've had a Motion Pro mercury manometer set for a ****'s age, perhaps 10 years or more. I've always thought it worked reasonably well until I used it on my FJR a month or so ago and noticed the the mercury in the columns had "air pockets" - areas where the mercury column was interrupted with short segments of air. They were minor but no amount of pulling vacuum in/out would dislodge the pockets and give me an uninterrupted column of mercury. Further, on my Motion Pro, there is a good part of the mercury column that is covered by the plastic carrier that holds the columns so I wondered if there were further air segments below the ones I could see. I finally decided that the effect of the segments was probably minor, so I balanced it as best I could, with a nagging suspicion that perhaps I had a problem with the Motion Pro.
After adjustment, I never thought the bike run as well as before. It had a growly vibration if you snapped the throttle open off idle and the above 5K vibrated seemed worse. The vibration was certainly acceptable, but I wondered if the problem with my manometers might have caused me to worsen the adjustment.
I was just about to order another set of mercury manometers when I heard about the Morgan Carbtune II device. This is a manometer which substitutes stainless steel rods for mercury. It looked good, so I decided to give it a try. As their web site indicates, ordering was painless and it arrived within a week from the UK. It wasn't cheap though - with the poor exchange rates and the tacky 3% surcharge that credit card companies are now charging for currency exchanges, the total bill with shipping for the device and a carrying case was about $120. This is nearly 3x what it costs for the cheaper manometers.
Setup was easy. You do have to do a one-time setup to add restriction dampers in the tubes (basically cutting sections of clear plastic tube to place into the hoses), but it is an easy 10-minute job. The device is compact, set up nicely to hang from the handlebars, has plenty of high-quality and very flexible hose (noticeably less stiff than the hoses on my Motion Pro, but that may be due to aging of the MP), and hooks up to the FJR's vacuum ports very easily. Mostly, it is nice to have something that is isn't so unweidly and that doesn't have toxic mercury to worry about.
Okay, all hooked up. The FJR fired up and I let it warm. Immediately, I noticed that the sync, which looked good on my mercury system, was way off. Once it came up to temperature, I made the adjustment which was MUCH easier than with the mercury tubes. The stainless steel bars are very easy to read, well damped, and it was simple to get them perfectly aligned. Wow, that was really easy.
The 4K sync, while not perfect, wasn't far off, so I'm going to postpone the "Unauthorized TB Sync" (where you adjust the butterfly sync rather than the idle bleed air sync) until another day.
When I went for a test ride, it was immediately apparent that the bike was smoother and had better off-idle response. I'm sure I was mis-adjusted badly with the Motion Pro.
Now there is absolutely nothing wrong with the mercury manometers if you're reaosnable sure they aren't afflicted with the air pocket problems I have. And you can't beat the price. But after this experience, I'm convinced that the Carbtune is a better mouse trap. And between uses, it goes neatly into the back of my tool chest, rather than hanging ackwardly on the wall.
Ride on,
- Mark
I've had a Motion Pro mercury manometer set for a ****'s age, perhaps 10 years or more. I've always thought it worked reasonably well until I used it on my FJR a month or so ago and noticed the the mercury in the columns had "air pockets" - areas where the mercury column was interrupted with short segments of air. They were minor but no amount of pulling vacuum in/out would dislodge the pockets and give me an uninterrupted column of mercury. Further, on my Motion Pro, there is a good part of the mercury column that is covered by the plastic carrier that holds the columns so I wondered if there were further air segments below the ones I could see. I finally decided that the effect of the segments was probably minor, so I balanced it as best I could, with a nagging suspicion that perhaps I had a problem with the Motion Pro.
After adjustment, I never thought the bike run as well as before. It had a growly vibration if you snapped the throttle open off idle and the above 5K vibrated seemed worse. The vibration was certainly acceptable, but I wondered if the problem with my manometers might have caused me to worsen the adjustment.
I was just about to order another set of mercury manometers when I heard about the Morgan Carbtune II device. This is a manometer which substitutes stainless steel rods for mercury. It looked good, so I decided to give it a try. As their web site indicates, ordering was painless and it arrived within a week from the UK. It wasn't cheap though - with the poor exchange rates and the tacky 3% surcharge that credit card companies are now charging for currency exchanges, the total bill with shipping for the device and a carrying case was about $120. This is nearly 3x what it costs for the cheaper manometers.
Setup was easy. You do have to do a one-time setup to add restriction dampers in the tubes (basically cutting sections of clear plastic tube to place into the hoses), but it is an easy 10-minute job. The device is compact, set up nicely to hang from the handlebars, has plenty of high-quality and very flexible hose (noticeably less stiff than the hoses on my Motion Pro, but that may be due to aging of the MP), and hooks up to the FJR's vacuum ports very easily. Mostly, it is nice to have something that is isn't so unweidly and that doesn't have toxic mercury to worry about.
Okay, all hooked up. The FJR fired up and I let it warm. Immediately, I noticed that the sync, which looked good on my mercury system, was way off. Once it came up to temperature, I made the adjustment which was MUCH easier than with the mercury tubes. The stainless steel bars are very easy to read, well damped, and it was simple to get them perfectly aligned. Wow, that was really easy.
The 4K sync, while not perfect, wasn't far off, so I'm going to postpone the "Unauthorized TB Sync" (where you adjust the butterfly sync rather than the idle bleed air sync) until another day.
When I went for a test ride, it was immediately apparent that the bike was smoother and had better off-idle response. I'm sure I was mis-adjusted badly with the Motion Pro.
Now there is absolutely nothing wrong with the mercury manometers if you're reaosnable sure they aren't afflicted with the air pocket problems I have. And you can't beat the price. But after this experience, I'm convinced that the Carbtune is a better mouse trap. And between uses, it goes neatly into the back of my tool chest, rather than hanging ackwardly on the wall.
Ride on,
- Mark
Last edited by a moderator:
