My engine has got the ADHD!, Can't get my engine to idle at less that 1000 Options

[tornik550]

On my dual weber 44idf, 2258 engine- I cannot get my engine to idle at less than 1000 rpm. I have backed out both idle speed screws all the way. I unhooked the linkage. I played with the timing (which will slow it however it runs like crap). I adjusted the mixture. I even put new throttle plates in the carbs and synced them. I made sure the throttle shafts were not bent.

My old throttle plates were worn which I feel let too much air in. I replaced the plates with new ones which I thought would correct the problem. I was able to get the idle to go down from 1200 to 1000. I shined a light under the plate after installing them- I can see a very slight amount of light from between the plate and barrel wall.


Any ideas?

[rhodyguy]

re throttle plates. when you have the/a carb off, turn one up side down and open the throttle plates. you'll notice a slight bevel on the plate edges and when closed a number with a degree mark on the bottom side. the bevel is illustrated on p.31 the CB manual. a 40 weber i'm looking at has 76*, which i presume is the degree of bevel on the plate edge. the plates need to be installed with the 76* marked side visible on the bottom of the plate and facing what would be the center line of the engine. if the bevel is in the wrong orientation i think the contact edge could be holding the throttle plates slightly open with contact on one side of the bore and a slight artificial/built in premature opening on the other side of the plate that will effect the idle circuit that you can't adjust out.

if the throttle shaft bushing are spent that's a whole dif factor. owning a serviceable set of webers or dels and having them rebuilt is far cheaper than purchasing a NEW pair of carbs. i seem to remember postings about there being manufacturing/qc issues with new webers.

k