Avanti carb' problem ?

[mick1]

You said in the first post that it was off the road for 2 weeks but could it have been several weeks since you last rode it? Just wondering if the cold whether has a bearing?

Nope....road it to pick up the new Disc brake...pulled up at home dropped forks (got them powder coated) two weeks later on the road again....got me thinking though. it has been cold and i leave the scoot outside, i'm wondering if the cold has got into a small fault in the varitronic and made it worse (or something like that !)

[johnd]

Lose main jet? had that before and it feels like a misfire.

[Adam_Winstone]

^... good call, I had a similar thing with a loose atomiser.

[mick1]

Certainly cheaper than new bits for the ignition !!

When i used the Ultrasonic cleaner i took the jets, atomiser and slide out and cleaned separately. So all got put back in tight.

I'm in no way a mechanic but i don't think it would be the main jet as it is before that kicks in (correct me if i'm wrong !!) it's more the mid-range which i think is the needle/slide /atomiser....like Adam said "good call" and i'll certainly check for loose bits.

[simplex]

i had this a while back... spluttering when revving etc.. so went one by one through possible causes to eliminate, changed CDI, HT lead and cap. changed Stator.. bought new carb & hoses.. but nothing sorted it...
turned out it was the rag I had stuffed in the petrol cap well to soak up dribbles was restricting air flow into the tank. affecting the flow of fuel... took it out and it runs lovely .. specially with all the replaced bits

[nelson pk]

Certainly cheaper than new bits for the ignition !!

When i used the Ultrasonic cleaner i took the jets, atomiser and slide out and cleaned separately. So all got put back in tight.

I'm in no way a mechanic but i don't think it would be the main jet as it is before that kicks in (correct me if i'm wrong !!) it's more the mid-range which i think is the needle/slide /atomiser....like Adam said "good call" and i'll certainly check for loose bits.

The main will still effect it lower down although to a lesser extent as 3/4 to full throttle.
To prove this, take your main jet out or try one 20 sizes up and you'll be in splutter heaven all the way from 1/4 throttle up.
You did say correct me if i'm wrong

When you put your carb parts back together did you re check your float height?

[mick1]

The main will still effect it lower down although to a lesser extent as 3/4 to full throttle.
To prove this, take your main jet out or try one 20 sizes up and you'll be in splutter heaven all the way from 1/4 throttle up.
You did say correct me if i'm wrong

That's the sort of reply i'm looking for.......

Anyway......swapped carbs and works a treat, no spluttering, hic-upping or farting !!

The carb i put on was another Dellorto 28mm with same slide, atomiser and needle but different main and pilot.

I dont think the size of the main (was 122 now 120) or pilot (was 55 now 52) has been the cure, my gut feeling is it may be a worn slide/needle.......correct me if i'm wrong

Now i'm satisfied it isn't the Varitronic i'll try and change parts and recreate the fault and find the offending component. I'll plug chop as well but i think the main and pilot will have to go back to their original sizes.

[nelson pk]

At least you've narrowed it down to the carb

[Adam_Winstone]

Result!