Thread: Carb issue
06-13-2010, 10:05 PM #1
Today I took my slt750 to the lake ! had a problem with idle. The boat would start easy & then start to idle pretty high & thats with idle adjuster backed out If I push one of the butterflys towards the sealing side the the idle comes way down. I read in my service manual on sync. carbs & thought I had done a fair job! Will one or two adj. off allow the butterflys not to close all the way. ?
06-13-2010, 10:39 PM #2
are not the butterfies in the carb evenly adjusted? when the throttle is let go of, they should all have the same amount of adjustment. if they are not adjusted the same each carb will not be synchronized with the other 2 carbs.
you know you might have an air leak somewhere at the carb .....................manifold area if the carbs are pretty much in sync.....................
06-13-2010, 10:47 PM #3
Thats whats weird is all butterflys seem to open & shut at same time. The problem seems to be something is preventing complete closure.
06-13-2010, 10:53 PM #4
one of the sync screw is adjusted too tightly. incorrectly. causing the butterfies not to close properly..................
06-13-2010, 11:09 PM #5
- Join Date
- Oct 2006
- Cleveland OH
I can't remember if your 750 carbs have the additional idle screw stop. 1 on each end carb for the 780. Make sure that's not holding the plates open.
Also make sure to have a SLIGHT play in your throttle control lever. That way, that's not holding them open.
Otherwise it may be carb sync. Even though they appear to be opening and closing equally, they may be slightly off.
Here's what you do:
Turn the idle speed screw down until the choke plates are about 1/8" open between the carb body.
Then take a 1/8" drill bit (using the back side of the bit, not the business end) or something similar and make it it so it JUST slips between the plate and carb body.
Now check the other 2 plates.
If the bit doesn't fit between the plate and body, turn the carb sync screw IN to open it up, or turn it OUT to make it tighter.
Then return the idle stop screw back to original position.
06-14-2010, 07:52 PM #6
Thanks the carb. sync was out quite a bit. started it up & the motor was still wanting to wind up, I sprayed carb cleaner at intake. Sure as Hell sucking air. also had several bolts torqued way way to much. then had two with hardly any torque. Ill write this one off as a knuckle head move or Bud Light consumption, Any ways new gaskets on the way will try again
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By Suthrn in forum 4-Tec PerformanceReplies: 11Last Post: 03-29-2008, 12:48 PM
By cdcats in forum 2-Stroke PerformanceReplies: 16Last Post: 01-14-2008, 05:38 AM
By havoc in forum Yamaha PWC Performance (2-stroke)Replies: 31Last Post: 08-26-2007, 12:45 PM
By Insanediego Joe in forum 4-Tec PerformanceReplies: 10Last Post: 08-03-2007, 01:28 PM
By washingtonrider in forum Yamaha PWC Performance (2-stroke)Replies: 5Last Post: 07-17-2006, 07:09 PM