Eliminating four-stroking

grahamcamm · Post by **grahamcamm** » Mon Jul 13, 2009 8:24 pm

How can I stop my silver century plus fitted with an Amal 2 jet carb 25-1 from four-stroking? Thanks

Vic · Post by **Vic** » Tue Jul 14, 2009 6:12 pm

have you verified that it has the right jet for 25:1 or have you tried a 10:1 mix as I suggested.

See what charlesP says in his reply to john1952 about the effects of using the wrong mixture for the jet fitted. Agrees with what I already said I think!

But why a second thread on the same subject?

grahamcamm · Post by **grahamcamm** » Tue Jul 14, 2009 8:09 pm

Vic wrote:have you verified that it has the right jet for 25:1 or have you tried a 10:1 mix as I suggested.

See what charlesP says in his reply to john1952 about the effects of using the wrong mixture for the jet fitted. Agrees with what I already said I think!

But why a second thread on the same subject?

I've checked the carb and according to SOS FAQ's the number 40 indicates it's had the 25-1 conversion.

As for the second thread, you was the only person replying (of which I am grateful), but your last sentance was 'Maybe someone else will have some ideas', so I thought I'd start another thread titled with your diagnosis to hopefully get a response off others.

Even though it has had the conversion I will try it at 10-1 and see. Is the screw where the cable enters the carb for cable adjustment only or is it for altering the fuel mixture richness? I know I may sound mechanically thick but I am.

Vic · Post by **Vic** » Tue Jul 14, 2009 8:46 pm

The screw on the cable is just for adjusting the cable
There is no mixture adjustment.

Only other reason I can think of for it running rich is that float is not controlling the fuel level correctly.

phil · Post by **phil** » Tue Jul 14, 2009 10:49 pm

For those who may not be aware of it, the cable adjustment allows you to setup the throttle, so that the throttle body [moveable piece] in the carb is shut with the throttle all the way off. That is way the motor is intended to be shut off. Remove the storm cowl to see and adjust it.

phil · Post by **phil** » Tue Jul 14, 2009 10:53 pm

According to the diagram Vic supplied, I should have called it the "throttle valve piston" item#7, rather than throttle body.

grahamcamm · Post by **grahamcamm** » Tue Aug 04, 2009 7:27 pm

Well it looks like I've solved it. I stripped the tank and carb several times and when put in a tank to test it always ran great but when out on the boat it kept miss-firing in rythem and when at rest would weap fuel. Anyway, I was sat there on Sunday watching my floats when it came to me. Engine trim! I altered the trim so that the engine was more square to the water line and since then it never missed a beat all the way back and now doesn't weap fuel when not running.

Vic · Post by **Vic** » Wed Aug 05, 2009 10:54 am

Thanks for letting us know the outcome.

Easy to overlook the obvious but some carbs will happily work well out of upright. The Amal is not one of those I guess.

Post by **John@sos** » Wed Aug 05, 2009 12:29 pm

Good outcome, well found,
Regards,
John

Saving Old Seagulls

Eliminating four-stroking

Eliminating four-stroking

Re: Eliminating four-stroking

Re: Eliminating four-stroking