81 vacuum advance question

[motoman]

My guess it would be less physical rotation on the 81's since the mechanical is electronicly done. But, not owning a pre 81 for comparison, can't be positive.

[motoman]

My guess it would be less physical rotation on the 81's since the mechanical is electronicly done. But, not owning a pre 81 for comparison, can't be positive.

Then again, the pre 81 mechanical is seperate from the vacuum advance assembly.

[3Phase]

Phil, the XS11/XJ11 all use ported vacuum from the #2 carburetor. You can't see it move but the XJ11 has a totally keen analog electronic vacuum sensor that's wired to the TCI instead of ye olde vacuum advance pot used by the XS11s.


George, do you have a timing light to go with that manual? From what I remember working on Brant's Venturer the vacuum advance plate moves more than 5 degrees but check the manual.

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[GLoweVA]

George, do you have a timing light to go with that manual? From what I remember working on Brant's Venturer the vacuum advance plate moves more than 5 degrees but check the manual.

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Scott, yeah i downloaded the manual from bug's page and it looks like the vac adv on the 81 should be 15 deg.
Don't have a timing light.
I ended up swapping in an adv diaphragm assembly that i had from another engine that does rotate/ extend enough to give me that much deflection/rotation.

Been running him all week, getting about 36mpg, but I've been pushing him hard on the slab trying to figure out if my upper rpms are weak. I might have to up my jets from 110s.

Compared to the SG, the H seems a little lacking in the 5th gear acceleration dept.

[motoman]

Scott, yeah i downloaded the manual from bug's page and it looks like the vac adv on the 81 should be 15 deg.
Don't have a timing light.
I ended up swapping in an adv diaphragm assembly that i had from another engine that does rotate/ extend enough to give me that much deflection/rotation.

Been running him all week, getting about 36mpg, but I've been pushing him hard on the slab trying to figure out if my upper rpms are weak. I might have to up my jets from 110s.

Compared to the SG, the H seems a little lacking in the 5th gear acceleration dept.

There is some noticable difference between the two anyways, if the SG and H still have the original model carbs on each. Having the SH carbs on mine for some years as opposed to the original H carbs, I definitely notice the more responsiveness at ALL different speeds of the SH carbs. Especially on the slab going over dips in the road, and the slighest movement of the throttle just from that motion is way more felt with the Special carbs.
The 80-81 Special carbs have the shorter, quicker taper metering rods, along with the 110 mains across all four. Those metering rods(5GL16) make it the 'bar-hopper' it was.
The 80-81 Standard carbs had the longer, blunter metering rods(5Z???...CRS), and staggered main jetting of 115's outside cyl. and 120's inside cyls. It would 'get there' the same as the Special, just not initially as responsive at the lower or higher rpms. This actually made for a nice, lumbering tour bike with no surprises.
Those are the differences I noticed, having had both carb sets on the same bike, each for a decade or so.
That MAY be what your feeling as the difference......anyways, JAT to throw in the mix.

[motoman]

To add, 110's in the 80-81Standard carbs would definitely make bike a bit 'anemic' feeling in the upper rpm range, and would slow down that time it takes, specially a 6K throttle snap in third or fourth gear up to 8-8.5K.
IMO, a 'happy medium' main jetting of those Standard carbs would be the 117.5 range across all four, 115's as a minimum for any LD cruisin' at a constant speed.

[Nightengale]

Been a while

Haven't been on in a while, but if you need it George I have a sonic cleaner to clean the carbs if you want to clean those carbs really good. Also I have been running my 81 without vac adv. with no problems since I have fj1200 carbs.

[GLoweVA]

Haven't been on in a while, but if you need it George I have a sonic cleaner to clean the carbs if you want to clean those carbs really good. Also I have been running my 81 without vac adv. with no problems since I have fj1200 carbs.

Thanks John, they were pretty clean, they had just been sitting too long and the slides kind of 'froze up' . They're working good now.