| Author |
Message |
    
Bprigge
| | Posted on Friday, July 24, 2009 - 08:18 am: | 
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Hello from Minnesota,
I have a 97 S3T with a flat spot in the power curve between roughly 4000 and 4600 rpm. It doesn't miss, it feels like a motor would feel if it had a dip in the torque curve. It's there hot or cold but more so when cold. The bike is stock except for a Vance and Hines muffler and runs really well except for the power sag.
This is my first Buell so i'm still learning their foibles and 'unadvertised features' I'm thinking about pulling the carb off for a close inspection but thought I'd ask first. Is this possibly normal behavior for a carburated S3T? I saw a dyno chart last week that was run on an S3 and it actually had it's torque peak right where mine has a flat spot. Any advice appreciated, thanks, Bruce |
Bluzm2
| | Posted on Friday, July 24, 2009 - 02:37 pm: |
|
Check the jetting.
You may have the 42 pilot jet and the low speed screw may still be "corked".
Low speed jet should be a 45 (maybe a 48), with the mix screw out 2 - 2 1/2 turns.
Lots of info on how to do all of this in the Knowledge Vault.
Brad |
Sparky
| | Posted on Friday, July 24, 2009 - 03:02 pm: |
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Before you take off the carb, take off the gas tank and look at the intake manifold. That's a tubular casting that connects the carb to both heads.
On it should be a vacuum fitting with a short hose connected to the VOES (Vacuum Operated Electrical Switch). What this device does is switch the ignition module between two ignition curves, one with relaxed timing for full throttle performance and the other for part throttle conditions and economy.
-- Make sure:
1) the hose is not cracked and
2) the VOES is connected.
There may be another vacuum fitting on the carb that should either be blocked off for non-California models or go to a charcoal cannister for Calif. bikes. If it's blocked off, make sure there are no cracks in the rubber.
On the exhaust side of the motor, there could possibly be an exhaust gasket out of place where the exhaust pipe joins the head. This is a ring gasket made out of squishable metal material. It easy to get this thing distorted when fitting the pipe to the head, resulting in a portion of the material sticking into the exhaust stream and disrupting the performance, however small this disturbance might be.
After you sort out the power dip and you're after a little snappier throttle response, try installing a Screaming Eagle ignition coil and some performance spark plug wires along with double platinum spark plugs. You'd be grinning with every twist of the throttle. |
Bprigge
| | Posted on Friday, July 24, 2009 - 06:03 pm: |
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Thanks Sparky and Bluzm2. I was wondering what that little vacuum operated switch above the intake manifold did. The vac line is good and hooked up. Guess i'll start with pulling the carb and checking the jetting etc. It's going to have to wait a couple of days on account I sprung a serious oil leak today. I'm starting another thread. thanks again, Bruce |
Bluzm2
| | Posted on Saturday, July 25, 2009 - 12:39 am: |
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Bruce,
Ping me offline, I may be able to help you out.
Brad |
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97 S3T Flat Spot