northern scot · Feb 15, 2021

ive a 1983 2 .25 88 inch ,ive using it more in the snow up here. it has a weber on it ,it was running ok[tho lacks low down pulling]
yesterday i noticed it was idling lower and exhaust ,sort of pop popping ,today i had to adjust mixture screw near right out to get the revs ,at tick over higher. the landy nicks along at 50/55 ok ,but at lower revs its hesitant ,the carb in only 2 years old and less than a1000miles since fitting .ive set points and they look ok. the engine has done 49,000 since new,ive sucked hard on advance / retard pipe, and noted increase in revs
i change the inline filter every year too...any ideas?

Colthebrummie · Feb 15, 2021

Webers are a bit notorious for carb icing in cold weather, do you think it might be that?

Col

Stanleysteamer · Feb 15, 2021

northern scot said:
ive a 1983 2 .25 88 inch ,ive using it more in the snow up here. it has a weber on it ,it was running ok[tho lacks low down pulling]
yesterday i noticed it was idling lower and exhaust ,sort of pop popping ,today i had to adjust mixture screw near right out to get the revs ,at tick over higher. the landy nicks along at 50/55 ok ,but at lower revs its hesitant ,the carb in only 2 years old and less than a1000miles since fitting .ive set points and they look ok. the engine has done 49,000 since new,ive sucked hard on advance / retard pipe, and noted increase in revs
i change the inline filter every year too...any ideas?

Does sound carbish.
Tried removing jets and blowing them through?
Water in the tank?
Best of luck!

northern scot · Feb 15, 2021

Stanleysteamer said:
Does sound carbish.
Tried removing jets and blowing them through?
Water in the tank?
Best of luck!

thanks,ill look in to that ....ive ordered a recon HIF 44 A SU carb last week and kit from hnj engineering last week, had enough of little webers ! 9 to 1 head off ACR too ,and electronic points should do the trick

Tall Ratbag · Feb 16, 2021

Remove and clean out the idle jet. It's on the side of the carburettor - you don't need to take the lid off. When you've done this, the idle mixture will be very rich, so, be ready to screw the idle mixture screw back in a bit.

Marmaduke · Feb 16, 2021

I'm watching this with interest. My webber carb ain't much cop either. One day it's revving it's nuts off the next and most usual is it won't idle. I've fitted a rebuild kit and it's still the same

Gord Wedman · Feb 16, 2021

My brother recently had the same problem with his 2.5 in his 109. Was running great with a new Weber and electronic ignition. At first he thought it might be a vacuum leak but couldn't find any. Finally took the carb apart and found much very fine sediment plugging things up. This was fine enough to go through the inline filter so now he is going to install a 40 micron filter or even finer. Tanks must need a good cleaning.

northern scot · Feb 16, 2021

Marmaduke said:
I'm watching this with interest. My webber carb ain't much cop either. One day it's revving it's nuts off the next and most usual is it won't idle. I've fitted a rebuild kit and it's still the same

to tell you the truth , they are not the best of carburettors , very prone to any fine sediment getting to jets ,which are hard clean and icing too!

northern scot · Feb 16, 2021

Gord Wedman said:
My brother recently had the same problem with his 2.5 in his 109. Was running great with a new Weber and electronic ignition. At first he thought it might be a vacuum leak but couldn't find any. Finally took the carb apart and found much very fine sediment plugging things up. This was fine enough to go through the inline filter so now he is going to install a 40 micron filter or even finer. Tanks must need a good cleaning.

great ,ive seen them on e bay for £5.99,will try

Colthebrummie · Feb 16, 2021

northern scot said:
great ,ive seen them on e bay for £5.99,will try

The problem with fine, low micron filters is that they clog up fast if there is any contamination in the fuel. If you fit one, make sure it can easily be swapped out at the side of the road.

Col

northern scot · Feb 18, 2021

weber carb update ,took it to bit ,found dirt /particles in float chamber ,2 of the jets sit at very bottom of chamber ,,so get clogged up 1st,slow running jet on side of carb had tiny particles in it , got can of compressed air and cleaned carb .put back together and going ok,apart from icing!!there is tank filter, sediment bowl,inline filter, filter in carb ,but still got blocked......SU hif44 on way ............

Gord Wedman · Feb 19, 2021

Exactly the same set of filters on my brother's 2.5 109 and same result. Going to try better filters rather than spend more money on a different carb. Any carb can be clogged by sediment. Might install a large Racor type fuel filter.

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