New spark plugs to TB sync?

[cyclebrkr]

Hello all,

I was wondering if i really need new plugs to be accurate with a TBS? I'm in between service intervals and the bike is starting to get really "buzzy" from about 3800RPM's and up (around 70MPH and faster).The idle is getting rougher also. I checked the plugs this last weekend and they look great. Thanks!

[Don_Eilenberger]

I think you really need to sort out what needs doing.

 

Before doing a TBS - do a valve adjustment. If my experience is any guide - once the valves are correctly adjusted (including rocker-arm endplay) you won't need the TBS. Mine has remained dead-nutz perfect for 24k miles so far.

 

I can't see what need there would be for plugs unless you've passed the service interval for them, or how these would change a TBS.

[T__]

Hello all,

I was wondering if i really need new plugs to be accurate with a TBS? I'm in between service intervals and the bike is starting to get really "buzzy" from about 3800RPM's and up (around 70MPH and faster).The idle is getting rougher also. I checked the plugs this last weekend and they look great. Thanks!

 

 

Cyclebrkr, spark plugs should have no effect on the TBI sync.. Valve adjustment can effect the balance as well as cylinder compression..

 

On the TBI sync all you are doing is matching the air flow through throttle bodies side to side (mainly across the throttle plate restriction)..

 

As a rule TBI synchronization has less effect as the engine RPM & engine air flow increases.. At higher RPM’s & vehicle speeds the difference side to side is a lower percentage of the total air flow through the TBI units so TBI balance makes less difference at higher speeds that at low speeds..

 

If you are seeing a vibration at higher speeds (that you didn’t have before) maybe look for a wheel balance disturbance,, or loose engine mounting bolts.. Even something simple like changing weight in the panniers or top box can change chassis vibration response to engine input so has anything changed there?

 

With the idle getting rougher also have you checked all 4 spark plugs not just the top plugs? Fouled lower plugs can really roughen up the BMW boxer..

Maybe also check for vacuum leaks around the TBI bodies,, & run a compression test..

 

Are you sure the 3800 RPM & up vibration has changed or have you just become more sensitive to it now that you are looking for a problem in that operating range.. Anything changed on the bike lately like adding a larger windshield or you wearing a different helmet?

 

Twisty

 

[cyclebrkr]

I ran through a check of my valves this past weekend, they were still dead-on. The plugs looked good ( i inspected them pretty closely). I'm just getting more and more buzzy feedback through the bars and the bike overall. I checked the balance on my tires also. The only cause left to check is the TBS. Maybe I'm forgetting something else?

[cyclebrkr]

Twisty1- Thanks for the info, I'll check for vacuum leaks. I also think you're right about the sensitivity. Now that I'm paying more attention to it, it's bothering me even more. Nothing else has changed. Thanks!