will not go beyond 6000 rpm

[JJH]

I have a 79 R65.  In third gear I am maxed out at 5500-6000 rpm (about 60 mph).  This is with the throttle wide open.  The engine does not sound/ feel bad it just does not rev past this point.  What should I be looking at.

[Tony Smith]

I have a 79 R65.  In third gear I am maxed out at 5500-6000 rpm (about 60 mph).  This is with the throttle wide open.  The engine does not sound/ feel bad it just does not rev past this point.  What should I be looking at.
 

Boy that's a wide open field.

I'd start by looking at the points, are they genuine BMW or Bosch type meant to go in a VW?

Are they worn down? If so replace or regap.
Are they burned? If so replace points and condenser.

Next I'd maybe be looking at carb diaphragms .

The above is about all i can think of that will leave you a perfectly running engine that just "stops" at a particular rev range.

[tunnelrider]

Does it go beyond 6000 revs in 4th or 5th?  I'd check my throttle cables haven't become too loose, stretched or detached first. Then look at the throttle grip linkage at the handlebar. All good there, provided the brakes or some other mechanical part aren't holding things back (which I'm sure you'd be able to hear or smell) then I'd suspect the carbs or timing.

[nhmaf]

I'll repeat what the others have said for the most part.
Does the bike sputter or misfire at all when it gets near 6K?  Or does it  just seem to slow and not go above?

If it is sputtery, I'd start with the checking the points and condensor.  If not, it is possible that you got an air leak (it doesn't take much, a tiny pinhole in the diaphragm can do it) or some other malfunction in the carb that is preventing full fuel/air flow from the main jet.   Has anyone recently worked on the carbs?  Also (without engine running) make sure that the cables and twist grip do allow for the full travel of the throttle levers on the inside edge of the carbs - if they won't go full travel, the issue may be simply cable /throttle tube adjustment (improper placement of the pull chain in the twist grip assembly could also do it).

[montmil]

...improper placement of the pull chain in the twist grip assembly could also do it.

So true and easily overlooked. The alignment marks on the throttle gears are often missed.

[tunnelrider]

When I bought my second hand R65 I also bought a repair manual.

[marcmax]

I had the exact same problem on the second LS that I bought. Started and ran fine up to just over 5000 rpm. Then it was like a governor on the engine kicked in and the engine had nothing left to give. I dug into the carbs and found a series of small perforations/tears in both diaphragms. Replaced both diaphragms, runs like a scalded dog now and have never had another issue.

[tunnelrider]

Great work Marcmax.

[Justin B.]

+1 to marcmax.  My R100 was the same except my "wall" occurred a little lower in the RPM range.  My diaphragms were a mess!

[georgesgiralt]

Hello;
I will add to check if the choke is closing properly.
With old and rusted return springs, th choke stays partially on and here is your problem.
Check also static advance and full advance. -you'll check static when setting the points didn't you ?

[JJH]

I finally got a chance to work on the bike.  The issue was loose throttle cables.  Thanks for the help!!!