Still backfires

[tjello327]

Well I am out of ideas. My 1986 125hp force likes to backfire when I start it cold. Once it starts, its o.k. The timing is set at 28 Degrees BTDC and it still backfires when I start it cold (using very little choke.) I am starting to wonder if it has something to do with the choke. I set the choke like the manual said by using the piece of paper as a gage between the butterfly & the carb bore. I am starting to wonder if a little more gap might be the way to go so the carb gets a little more air when at full choke. Any ideas as to what this backfire may be caused by?

Thanks Forum,
Tom

 

[john from md]

Re: Still backfires

Engines back fire through the intake when the mixture is too lean. If you are using "very little choke", that can be the problem. It can also be that your carb rigging has the trottle plates improperly set.

Idealy, when starting a properly adjusted Force engine it should go like this.

1. Pump ball a couple of times
2. Set throttle to fast idle
3. Push in key to set choke and turn key.

The engine should start after a revolution or so.

If your cables are not adjusted properly or your choke is not adjusted properly, you will have hard starting problems.

To do it right, you have to start from scratch and adjust the cables first.

If the throttle cable is not set right, it throws everything else off.

John

 

[tjello327]

Re: Still backfires

Thanks John, I never tried to start this engine with the trottle at fast idle yet. I always left it at idle, turn the key, choke it for about 1-2 seconds and it would either backfire are start fine. I understand what you are saying about opening the throttle plates a little, this may let a little more air in too.
I will try it!

 

[tjello327]

Re: Still backfires

Well I tried starting my engine at fast idle and it started right up with no choke. No backfire!

Thanks