Setting Ignition Timing

[sshehriyar]

Aoa,

I have a Suzuki Mehran 2003 Model and it has a problem that when I press the accelerator, the engine bogs down for a while and then jerks forward. I noticed it happens when the Ignition Timing is set on the 5-7 BTDC. I'm not using a timing gun so I might get it 2 3 degrees off but I still think I have it about right.

I remember the mechanic advanced the timing, without using any light and stuff and I didn't feel the engine bog down on acceleration.

Is the engine bog problem related to Ignition Timing? I'm thinking of advancing it more (to about 10 BTDC) and see if that removes the jerk. The only problem I saw was the car seemed to rev fast on idle (can't confirm cuz have no RPM meter).

I see everywhere that people say the timing for mehran should be 5 to 7 but I'm not sure why the engine bogs when set on those.

What are your thoughts on this?

[sshehriyar]

I fiddled around and found out it was the air/fuel mixture screw that was causing the jerk. I retarded the timing to 5 degrees BTDC because the engine was getting hot and using water for cooling combined with high engine temperature doesn't sound good.

I adjusted the mixture screw to about 2.5 turns after tightening it and that's where the jerk has disappeared. I mean others say that screw should be 4 turns out but if I take it out to 3 turns it starts jerks when floored.

The tighter I turned the screw, the more engine revs increased, guess because of the richer mixture. I just turned it outward as much as possible so the carb doesn't gulp all the fuel.