TV175 PHBH26

[Storkfoot]

Don't worry about bubbles in the fuel pipe, unless you have an in line filter added that is.

It is really hard to diagnose issues like this over the internet. But if you are happy that your timing was set correctly (I'm assuming you have electronic ignition?), that you have a correctly gapped plug, that your air filter is clean and that you have no air leaks around your inlet or exhaust manifolds, then have a read of this:

http://www.lambretta.co.uk/downloads/carbsetup.pdf

Whereabouts are you?

[greenfingers]

I'm in Woodfrod Green, North East London - bottom of the M11.

It has the variatronic kit which I took off last year and replaced the start and then took the piston out to check the rings etc. No wear or damage but replaced the oil seal because there was a tiny bit of oil on the inner side and thought it was worth the effort.

No fuel filter but huge bubbles (maybe an inch long) but not sure if its was reaching the level where I needed to switch to reserve. I'll run it with the side panel off this week - open it up and have a look down at the pipe.

When iI took the back plate off the variatronic I etched around it to make sure it went on exactly the same place. What should the gap be on the plug? - at the moment its an N4C which it ran perfectly on since I had it. I could do with checking the gap if you could tell me what it should be…..

Hey ho….I think its fuel/carburation related somehow - at least it runs I suppose. Bit smokey - I might try dropping the clip on the needle one groove see if that reduces the smoke a bit….

Thank you for your advice - I appreciate it..

Martin

[Storkfoot]

You say there was no wear or damage. Did you check the ring gap or notice whether there was any noticeable blow by? If the engine has been used over a year or so and for a few thousand miles, I just tend to replace the rings as a matter of course anyway whilst I have the top end apart.

In terms of the plug gap, I'm presuming that the Varitronic is the same as other electronic kits (can a Varitronic owner confirm please ) and it should be 0.5mm to 0.6mm.

Leaning the mid range as a trial is not a bad idea. If you raise the clip to the 2nd from top, this will leave the needle lower in the atomiser and reduce the amount of fuel coming through, thus leaning the mid range. Don't go ragging this for a long time though in case it makes it too lean. Read the link from Camlam on setting up a carb. That is very important.

[greenfingers]

I have read through and thank you…

The rings looked fine to me…to be honest i took it out this morning and other smoking reduced right back once it was hot. I.ve just got this rapid loss of power at times toasts bothering me now. I'' take the engine out at the weekend and check for air leaks..

Blow by…? would that be visible - I didn't notice anything suggesting the rings had failed…...

[rossclark]

Blowby usually shows as carbon or staining below ringland

[greenfingers]

Thought as much. No - none of that…

I reckon must be a slight air leak somewhere…

i'll put up with a bit of smoke…….

[Rich Oswald]

Rich - what should the gap be on the plug you suggested…??.I'll get one this weekend.


I'll try the plug and gap as Rich suggested - after that I'll have a look at the needle and jet. Are they likely to have altered or worn in 2 years though??? Again - genuine question….

Thank you lads….

Martin

Sorry for late reply but I run a plug gap of 18-20 thou.

Rich'

[greenfingers]

Actually - I think I've solved it. The rubber manifold between the carb and the inlet manifold was pushed on too far and I don't think it was sealing properly…running far better now.

I'll buy and plug and cap, set the gap then run through the cam lam running stuff for setting up the mixture screw…


thank you everyone!

Martin