No smooth cruise mode?

[CWO4GUNNER]

I don’t mean to be so dogmatic and like all of us there will always be stuff I have no clue about. But in this case I am speaking from experience. Get yourself  a Bandit 1200 Clymer manual off Amazon for $20 as they make the most comprehensive manuals I have ever used., and use it for future maintenance.  Don’t get me wrong, dealership repair is wonderful when under warrantee as it is their inescapable responsibility, but if out of warrantee (which I assume is the case) it is in their t interest to make as much money off you as possible to your breaking point. If you must get out of warrantee service performed, try and find a good independent sport bike repair shop. In the mean time stop dump out that mystery oil and stop using it, at least until you find out what the problem is, check your carb vacuum hose and vacuum plugs for leaks. The easiest synchronizing gauge I have ever used and worth the money is the Morgan CarbTune. Anyway good luck and learn to do it yourself.

[Have Blue]

A chain requires zero preload to transmit power efficiently.
An overtight chain shortens sprocket, chain and bearing life and does nothing to enhance performance.

Blue

Hello Brandon, thank you for your input.  You have a very good point about the chain.  I can guarantee that is not the problem.  I am a chain tension fanatic!  You can have the hottest raced-out engine between your legs, and it won't do  you squat, if your chain is too loose.  Thanks again, Paul
05 B12S

Don't know what you're talking about with the oil mix.  Our bikes are designed to run on 87 octane; maybe by running a higher octane, your bike is having problems with burning the higher octane.  I run 87 in mine and have never had this problem.

+1

These engines run low compression ratios and don't benefit from higher octane...with that said I run 89

If you haven't done so already I would suggest checking the chain as well.  If your chain is loose or old it could contribute to the jerky feeling (especially at lower mph) when your niether on the throttle nor off the throttle but just running a "cruise" or "maintenance" throttle setting.

[H2RICK]

Hmmmm....a few observations about my experience with my B12S:
In Cowtown, we are at 3500' (~1100m) ASL so our octane requirements are more modest than you folks at/near sea level. As well, our relative humidity is very seldom above 80% and mostly in the 50-60% range, so less octane is required again, compared to you folks in more humid areas.
Having said that, I've run both 87 and 93 to make a comparison test for my own info.
1) I noticed that the bike was crankier at startup and warming up with the 93. With the 87, it starts and warms up like it's supposed to. Inexplicable....at least to me.
2) No seat-of-the-pants difference in outright performance, although a set of Chrondeks or a stopwatch might tell a different tale.
3) The engine did NOT seem to need higher octane fuel even on my two trips into deepest, darkest BC this summer, where the altitudes are much lower than Cowtown and the humidity somewhat higher.
As a reference point, though, my '82 GS750, used to run MUCH stronger over the same roads when using 93 octane.
I guess the GS had a somewhat higher CR compared to the Bandit ???

As to the Marvel Mystery Oil additive, Banditclimax, I'd bin that really quickly. The only reason you'd want to use something like that in your fuel is to lube the valve stems... and no modern engine since at least 1980 or so has required that. In fact, engine manufacturers go to great lengths to insure that NO oil gets sucked down the valve stem into the combustion chamber in order to keep their unburned hydrocarbon emissions within EPA limits. Modern valves and guides are built to run with minimum/no lubrication whatsoever.
My .02.....

[solman]

I've had similar problems before and here is my 2 cents.  Save your money and get the cheaper fuel.  It doesn't hurt it to run higher octane, but you aren't going to benefit from it.  A possibility to fix your problem would be to install a fresh set of spark plugs.  I've had issues on the B12 twice on running bad at lower rpms, and both times resulted as a spark plug issue.  It has amazed me in the past in multiple situations in where I thought it was a fuel problem and it turned out to be a spark problem.

[kedeg_97B12]

And the Bandit does have a fairly hefty compression ratio.

9.5:1 does not make high compression. Betcha it really has less than that by the time you calculate squish and such.

[Banditclimax]

I don’t mean to be so dogmatic and like all of us there will always be stuff I have no clue about. But in this case I am speaking from experience. Get yourself  a Bandit 1200 Clymer manual off Amazon for $20 as they make the most comprehensive manuals I have ever used., and use it for future maintenance.  Don’t get me wrong, dealership repair is wonderful when under warrantee as it is their inescapable responsibility, but if out of warrantee (which I assume is the case) it is in their t interest to make as much money off you as possible to your breaking point. If you must get out of warrantee service performed, try and find a good independent sport bike repair shop. In the mean time stop dump out that mystery oil and stop using it, at least until you find out what the problem is, check your carb vacuum hose and vacuum plugs for leaks. The easiest synchronizing gauge I have ever used and worth the money is the Morgan CarbTune. Anyway good luck and learn to do it yourself.

Thank you again for all of your great input.  I'll let you know the results ASAP.  Best regards, Paul

[Banditclimax]

And the Bandit does have a fairly hefty compression ratio.

9.5:1 does not make high compression. Betcha it really has less than that by the time you calculate squish and such.

Thank you again Rocketjock.  Best regards, Paul

[Banditclimax]

I've had similar problems before and here is my 2 cents.  Save your money and get the cheaper fuel.  It doesn't hurt it to run higher octane, but you aren't going to benefit from it.  A possibility to fix your problem would be to install a fresh set of spark plugs.  I've had issues on the B12 twice on running bad at lower rpms, and both times resulted as a spark plug issue.  It has amazed me in the past in multiple situations in where I thought it was a fuel problem and it turned out to be a spark problem.

Thank you Solman, simple and inexpensive.  I'll let you know the results ASAP.  Best regards, Paul

[Banditclimax]

Hmmmm....a few observations about my experience with my B12S:
In Cowtown, we are at 3500' (~1100m) ASL so our octane requirements are more modest than you folks at/near sea level. As well, our relative humidity is very seldom above 80% and mostly in the 50-60% range, so less octane is required again, compared to you folks in more humid areas.
Having said that, I've run both 87 and 93 to make a comparison test for my own info.
1) I noticed that the bike was crankier at startup and warming up with the 93. With the 87, it starts and warms up like it's supposed to. Inexplicable....at least to me.
2) No seat-of-the-pants difference in outright performance, although a set of Chrondeks or a stopwatch might tell a different tale.
3) The engine did NOT seem to need higher octane fuel even on my two trips into deepest, darkest BC this summer, where the altitudes are much lower than Cowtown and the humidity somewhat higher.
As a reference point, though, my '82 GS750, used to run MUCH stronger over the same roads when using 93 octane.
I guess the GS had a somewhat higher CR compared to the Bandit ???

As to the Marvel Mystery Oil additive, Banditclimax, I'd bin that really quickly. The only reason you'd want to use something like that in your fuel is to lube the valve stems... and no modern engine since at least 1980 or so has required that. In fact, engine manufacturers go to great lengths to insure that NO oil gets sucked down the valve stem into the combustion chamber in order to keep their unburned hydrocarbon emissions within EPA limits. Modern valves and guides are built to run with minimum/no lubrication whatsoever.
My .02.....

Hello H2RICK, thank you very much for all the great and logical information.  I appreciate the time you took to help me out on this.  I'll let you know the results ASAP.  Best regards, Paul