My lambretta doesn't work - any ideas?

[Feersum Injun]

Petrol in the float? Float needle sticking?? Choke engaged???

[dickie]

Petrol in the float? Float needle sticking?? Choke engaged???

Choke opens and closes fine. Flat not leaking (held under hot water and no bubbles). Needle is free.

Set up on 30phbh with bgm clubman on tuned gt186

128 main
Atomiser av266
Pilot 55
Choke 70
Float valve 400 red tip
Mixture screw 1 1/2 turns out.

I'm at a loss here.

[dickie]

This isn't very pretty but surely it wouldn't affect running? Or would it?

[MickYork]

certainly won't do it any good ..........are they metal filings ?

What's the filter on the carb' look like ?

[Warkton Tornado No.1]

This isn't very pretty but surely it wouldn't affect running? Or would it?

You could spread that on your chips! I think you should check carb filter (as suggested) & run any fuel through your tank & keep filtering it through a paint filter (that fits into a funnel) until you've cleared any cr@p out of the tank & fuel lines then strip the tank again to clean the tap. It's amazing what can get through...

[dickie]

Thanks gents but everything south of the tank is immaculate. I've stripped the carb and it's clean as a whistle.

But I did discover this....

First pic is how it should be...



Second pic is what I found....



I must add that it has run happily like this for a year. Unless it somehow happened during the dyno session. Also I tried another carb; did I get muddled and put my carb straight back on?

It's the mixture screw in case you didn't realise. Can't try it tonight though. Unhappy family.

[Warkton Tornado No.1]

Fingers crossed for you, but that looks a likely cause...

[dickie]

I hate to admit defeat but I'm lost here . I just changed the petrol tap and it's no different. I don't suppose there's anyone in the Newcastle area who's good with lambrettas and has an evening spare this week? Ill buy you a pint; or 20.

The gordian knot had nowt on this.

[Warkton Tornado No.1]

I could lend/send you a Dell'Orto 30 to substitute but it's solid mount. Is yours?

I feel your pain, BTW!

[dickie]

I could lend/send you a Dell'Orto 30 to substitute but it's solid mount. Is yours?

I feel your pain, BTW!

Thanks for the kind offer but mine is rubber mount. Anyway I've tried a different one to no avail. There's nothing wrong with it but it doesn't work!

[dscscotty]

Did you say in an earlier post a 400 fuel valve? also have you tried it with no fuel cap on?

[dickie]

Did you say in an earlier post a 400 fuel valve? also have you tried it with no fuel cap on?

That's right scotty but I've replaced the 400 with a 300 and yes I've tried with no fuel cap.

I am wondering about float height but have no idea how to measure or adjust it. Just a possibility that the tang got bent when it was on the dyno?

[Warkton Tornado No.1]

With acknowledgements to Grandpa, this includes float height adjustments (pages 9-10):

http://www.rotaxjetting.com/PDFs/Docume ... Manual.pdf

[dickie]

With acknowledgements to Grandpa, this includes float height adjustments (pages 9-10):

http://www.rotaxjetting.com/PDFs/Docume ... Manual.pdf

Excellent thanks. That's much easier to what I'm used to doing in the old days with a bank of mikunis! I'll do it tonight when I get home. 20 quid says it's not the problem but I'm fast running out off straws to clutch at.

[mainstand]

If you inspect the reeds & find bits missing, take your exhaust off & rod it through, then shake it out. I've had broken reeds blocking my pipe up before.

[dickie]

If you inspect the reeds & find bits missing, take your exhaust off & rod it through, then shake it out. I've had broken reeds blocking my pipe up before.

Thanks mate, but I've had the reed valve out to inspect and it was perfect.

[dickie]

Float height is bang on. Ive just done another leak check and I can at least say that aspect of my engine building is beyond reproach.

Last gasp is to try new fuel. If that doesn't work I'm selling it.

[nastro azzurro]

Try another tank.
I had very similar symptoms a few years ago and tried everything you have and more.
Last gasp was change of tank and all was perfect.
Tank didn't appear to be the problem, fuel flowed as it should through the tap and tap filter looked clean.
Obviously the vibration when running was making the debris in the tank interrupt the fuel feed.
Tank looked fine so didn't consider it to begin with.

[dickie]

Try another tank.
I had very similar symptoms a few years ago and tried everything you have and more.
Last gasp was change of tank and all was perfect.
Tank didn't appear to be the problem, fuel flowed as it should through the tap and tap filter looked clean.
Obviously the vibration when running was making the debris in the tank interrupt the fuel feed.
Tank looked fine so didn't consider it to begin with.

That's the sort of advice that I'd usually dismiss as nonsense but as I've no better ideas and there is some debris in the tank I think I'll try rigging up a dummy tank. I've got a couple of spares sitting there so it's easy enough. Fresh fuel first though as it's easier. Thanks.

[dickie]

Tank immaculate. New fuel. New fuel tap. ANOTHER new cdi.

I give up.

A man in Doncaster is taking a look on Saturday. I've heard he's quite good with lambrettas.