Vespa Rally 200 SI24/24 tickover

[storkfoot]

This is a Spaco/Dellorto carb from SIP. I have had it on the scoot for a couple of years but have never been entirely happy with the tickover.

When I replaced the original carb with this one, I swapped out the airscrew from the original Dellorto as the new one was longer and would have needed the bung permanently removing from the back of the air box.

I have just noticed that the profile of the airscrew (the original is the smaller silver one) is slightly different (it's fatter at the end). Would this make a difference?

You may be thinking why not try with the other brass one. Unfortunately, it now transpires that they have a different pitch and when I replaced it I must have forced it in and changed the pitch in the alloy carb on the making

[bazman]

What you like!!
Correct different pitch , old delly turn and a half out , new spaco 2 and half turns out

[gaz_powell]

ooohhh ! easy mistake when new to vespas - did it myself when I first fitted a carb with the longer later type and there is different bung for the back of the carb

gaz

[rosscla]

Lucky then I didn't do that - couldn't get the fecker aligned because of the position of the carb compared to the hole.

[storkfoot]

I have tried it at various different positions including 2.5 turns. No material difference which makes me think the profile of the end of the airscrew does have an effect. I appreciate that there could be other reasons for the poor tickover including the warming up of the weather and an airleak but I am struggling to sort it.

If I had to get another carb and use the correct longer air screw is there really a bung that would cover the screw as it'll stick out of the back of the airbox by a couple of centimetres?

[Ginch]

If I had to get another carb and use the correct longer air screw is there really a bung that would cover the screw as it'll stick out of the back of the airbox by a couple of centimetres?

http://www.sip-scootershop.com/main/bas ... anguage=en

[mickymidas]

To me the silver one looks like a T5 air screw, (1.5mm tip), the rally/P200 air screws have slightly thinner 1mm tip ...............................I think
I had exactly the same problem with unruly tickover until I realised the difference

[storkfoot]

Scoot was in a shed from '77 until 2 or 3 years ago so I doubt it ever saw a T5

I am still playing around and it was a little better going to work and back today. A hunting and lumpy tickover just does my head in especially as I am often in stop/ start traffic going to work.

If I haven't sorted it by the weekend, I'll bite the bullet and get another carb. They aren't too expensive to be honest.

Thanks for all your help and ideas

Ps, Baz I think my improvement today was because I had it 2.5 turns out

[bazman]

Scoot was in a shed from '77 until 2 or 3 years ago so I doubt it ever saw a T5

I am still playing around and it was a little better going to work and back today. A hunting and lumpy tickover just does my head in especially as I am often in stop/ start traffic going to work.

If I haven't sorted it by the weekend, I'll bite the bullet and get another carb. They aren't too expensive to be honest.

Thanks for all your help and ideas

Ps, Baz I think my improvement today was because I had it 2.5 turns out

Did you try the old carb mate , did you not get it ultra sonically cleaned ?
memory of a fish again

[storkfoot]

Yes, I did get it ultrasonically cleaned but the scoot just wouldn't rev. I thought about taking it back and asking the lad to give it another go in the cleaner but when I saw that carbs were only £60 or so, I thought it wasn't worth it, mate.