help with standard sammy carb - running rich

[theboy]

Hi,

Im pretty new to this forum and its seems a wealth of knowledge! Im hoping I can become a useful member of the forum too!

I have done some searches but im struggling to find the answer to the symptoms i have. I know the best thing to do would be to bin the standard carb (1.3 sammy 1991) but I dont want to go down that route yet.

When it starts its lumpy with a low tick-over but does settle down when warm

The main issue is its running very rich (some black smoke out of the back when you rev it) and you stink of unburnt fuel when you drive it.

1.Can I adjust the mixture? If so which screw is it?
2.Could it be the choke sticking & how do I fix it?
3.Cold start up its lumpy and needs to be revved to get it running smooth ( it doesn't hold a higher tick over initially like i thought it should do on choke)

Any help you can give i would be really grateful chaps,

cheers, Tom

[ScottieJ]

Firstly here's a guide to strip the carb down for a clean http://www.suzukiclubuk.co.uk/diy/15-en ... down-guide

Chances are that it's the auto choke playing up, have a read of section 4 in the service manual http://www.suzukiclubuk.co.uk/pdfs/samm ... 81_434.pdf

here's a bit about the idle/mixture

samcarbidlemixture.JPG (255.87 KiB) Viewed 6715 times

[theboy]

thanks for the info, it would seem messing with the mixture screw is a right pain?! I also need a duty meter?

If you were in my shoes would you strip the carb down and clean as a first port of call?

Could any of the external choke controls need cleaning/ regreasing?

Thanks

Tom

[ScottieJ]

Ignore my previous post, I had a brain fart and it's pulled from a US service manual and the US zukis have an ECM to do woth their emissions controls etc and slightly different set up so you don't need a duty meter.

Not the best pics but you should get the idea for the idle and mixture, make sure it's up to temp and the choke is off and the timing is ok before setting it up, might be an issue if the choke is playing up though. if you give me a few days ill try and scan the carb section of my service manual.

image.jpg (2.62 MiB) Viewed 6693 times

image.jpg (2.03 MiB) Viewed 6693 times

[theboy]

Thanks Scottie, that would be useful.

I have had a look at the mixture adjustment screw and it has a cap which seems to spin? Do I need to pull this off to adjust the mixture?

Also how do u tell if the choke is stuck on or not working by looking at the carb/ in the barrels?

Thanks again

Tom

[theboy]

here is a picture of my carb and the mixture screw (i think). it seems to have some kind of spinning cap on it? Any ideas how this works to adjust the mixture?


image sharing

[ScottieJ]

you should be able to wedge a small flat head screwdriver in between the edge of the spinning cap and turn it.

[Tramp]

I cut the collar off mine and put a saw cut in the blank face - unfortunatley it is almost never the mixture screw (thats why its blanked) and it was my auto choke that was at fault, so i swapped the carb for a weber, I imagine if your zook has done over 50,000 miles it will be your auto choke that's causing your issues

[theboy]

I cut the collar off mine and put a saw cut in the blank face - unfortunatley it is almost never the mixture screw (thats why its blanked) and it was my auto choke that was at fault, so i swapped the carb for a weber, I imagine if your zook has done over 50,000 miles it will be your auto choke that's causing your issues

thanks for the info, I have checked the choke today, its in the closed (horizontal) position when engine is cold. As it warms up the choke flap opens fully (vertical) - would this mean the choke is operating correctly? Or could there me more to it than that why its running rich?

thanks

tom

[ScottieJ]

Sounds like the choke is working perfectly then.

I'd follow the guide for setting the mixture and see what happens. Also what's the air filter like? Might be worth fitting a new one if its quite old.