120HP Ldrive-Jetting for elevation and RPM issues

hismajst

Seaman Apprentice
Joined
May 22, 2010
Messages
35
It has been awhile but I am still stuck with my L Drive. Call me insane, but I have grown a bit attached to it (yes I am twisted!!). It's just so darn easy to work on.These are my latest issues. The local Lake sits at 6050 ft. elevation. I have recieved conflicting info from several reliable sources as to the jetting of the top(main) and bottom carbs for this elevation. Anybody have any success/ideas on proper jetting for this elevation?? From what I have seen there is consistantly a .002 difference between top and bottom jets. I have noticed that it will not idle at the recommended adjustment, and I have had to turn it up ( 1 revolution over recommended setting)to keep it idling, but it smokes like a beast! Could this be related to the main jets not being correct?

Another question-at the Lake this last weekend I noticed that it started overcharging (16V plus) and the tach was reading into the 6000 rpm range. But when I hit it with a photo tach. it was realy in the 5000 rpm range. Is this a CDI issue,stator issue or what?? Then after about an hour and letting it sit (not running) at the marina for 10 minutes it just cured itself?!?!? I have heard that if you have rpm (tach) issues it is usualy related to the stator. Is this correct??Any ideas??
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,715
Re: 120HP Ldrive-Jetting for elevation and RPM issues

4500'-6000'
Top carb .090
bottom carb .088


6000'-10,000
top carb .088
bottom carb .086
 

hismajst

Seaman Apprentice
Joined
May 22, 2010
Messages
35
Re: 120HP Ldrive-Jetting for elevation and RPM issues

Roscoe-you are the man!! Thanks! If the rain lets up here I will throw em in and test er this weekend. Any ideas on a rough idle issue?? I have the idle adjustment air/fuel ratio screw out one revolution over spec., and it will not idle at at recommended setting. Smokes like a beast. Would this have any relation to the main jets??
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,715
Re: 120HP Ldrive-Jetting for elevation and RPM issues

A good cleaning/rebuild of the carbs may be in order.

And poor idle is often attributed to a plugged up fuel recirculation system - all those little hoses that collect unburnt fuel and recycle it.
 

hismajst

Seaman Apprentice
Joined
May 22, 2010
Messages
35
Re: 120HP Ldrive-Jetting for elevation and RPM issues

Just pulled the bowls and found the main jets were BOTH .080!?!? Would this effect the idle too??
 
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