300EX starting problems.

[trick97gagt]

I have a 1998 300EX. It will not start when it is cold out (40 degrees or colder). Starts fine when its warm out. It has an aftermarket pipe on it (D&D. I'm not sure if the previous owner rejetted when he added the pipe or not. Is jetting my problem or is is just "cold blooded?" Any help would be appreciated. I apologize if this is in the wrong spot. Feel free to move it.

[DADEBOYRACER101]

YOU NEED DO THE JETS OVER

[dajogejr]

I have a 1998 300EX. It will not start when it is cold out (40 degrees or colder). Starts fine when its warm out. It has an aftermarket pipe on it (D&D. I'm not sure if the previous owner rejetted when he added the pipe or not. Is jetting my problem or is is just "cold blooded?" Any help would be appreciated. I apologize if this is in the wrong spot. Feel free to move it.

 

One you get it started (can you get it started) does it run well?

You need to richen up the pilot/airscrew/fuel screw circuit.

 

If the adjustment screw is on the engine/intake side of the carb, it's called a fuel screw. Turning it out will richen the mixture at idle/low speed.

 

If it has an adjustment screw behind the carb, by the air filter, it's called an air screw, whereas turning it in will richen the mixture.

 

You normally get 2 to 2.5 turns of usable adjustment out of the fuel/air screw before you need to go bigger or smaller on the pilot jet. Try richening it up, and worst case....take the whole carb apart and clean it. A gummed up pilot circuit will flow even less fuel as needed by the motor in the cold.

 

By the way, DADEBOY...

 

YOUR CAP LOCK PRIVILEGES HAVE BEEN REVOKED...

[trick97gagt]

Thanks guys. I'll mess with it this weekend maybe. Is it also possible that its too rich already? Whenever I've gotten it to start when its cold out, which is very rare, it'll idle for about 5 seconds then quit. If you touch the throttle at all in those 5 seconds it kills it immediately.