11 replies to this topic

[paul1380]

Just wondering if any one out there knows anything about weber DCOE 40 carbs as i am running one on my 1380 the problem i am having is the left hand chamber is richer then the right. Plugs 3-4 are black with soot whilst 1-2 are a good brown colour. i have checked for air leaks ect ant ideas???

[Dusky]

Mixture Screw on both sides adjusted?
Same jets on both sides?

[gazza01]

Turn the idle mixture screws all the way in, count the turns and importantly where the screw finishes, in other words they may not be in the same position when fully turned in. Dont force them to tighten as the body is soft metal and the screw will chew into it. Then unscrew 1and a half turns out on each if an old weber, 3 turns if a new weber. Always though make sure that you can hear the engine coming into tune. A lot of it is in the listening. If you have already done all this and still have 2 black i would check to make sure the idle jets are the same type and have not been messed with, some people drill them out, so i would renew them anyway. also check the idle screws are the same length as there are two different types. If this is a used weber it may be possible that one of the fuel ways is partially clogged and if you are tuning both sides the same amount of turns one will be correct and the other black. By the way what size chokes are you using as a dcoe 40 seems a bit small to me for a 1380 as far as getting max power from your engine.

[paul1380]

Thanks Gazza01 this is an old used carb i have renewed both of the mixture screws as they had been over tightened at some point. I will check to see if some one has drilled the left one out. I have set them both 11/2 turns out as it runs nice any thing over this and it runs rough the idle jets have been replaced as well all jets are the same each side.

I am using 36 chokes.

Thanks for your help  

[Dusky]

Check for cracks in the carb body if theyve been overtightened before. If the thread was repaired the idle drilling can be blocked Note that the 1.5 turns is a ballpark and that the fine adjustment of the idle should be done with a co tester.

How are the carbs mounted? Sometimes the O ring in the misab plates gets dislocated

Edited by Dusky, 06 March 2016 - 09:41 PM.

[Howie1000]

I have the same carb and did up nuts as tight as they'd go, but only recently found out the Thackery washers are meant to be done up to a set tolerance.

[paul1380]

checked no cracks in the carb or manifold i have turned the right hand mixture screw out 1 1/2 turns and runs ok but the left if i screw it in till it stops the engine will speed up and run nice screw it out 1/12 turns runs rough??? i must have a blockage in the crab some were time to strip it down give it a blow trough to see what is coursing the problem.

 

Thank guys for you input ill let you know what if any thing i find :)

[nicklouse]

reading the above it sounds like you are doing one at a time.

 

do them together.

[paul1380]

I see i thought they had to be done one at a time ill give it a go thanks

[hhhh]

I have the same carb and did up nuts as tight as they'd go, but only recently found out the Thackery washers are meant to be done up to a set tolerance.

 

Ahem, that's "Thackeray:" http://gglotus.org/g...asher/misc2.htm

[Ivor Badger]

Is the mixture out at tickover or at the top end? Have you actually checked the same jets and venturis etc are in both sides

[paul1380]

Hello guy's taken the weber off and have replaced them with twin HS6 and know runs like a dream thanks for all the help.