Lis 125 starting issues

[johnnyXS]

I don't want to contradict anyone but some 125 specials were fitted with a 105 or 107 main jet and a 5899-5 atomiser as you state

I think you are thinking of the SX150 which was the only Lambretta to be fitted with the 5899-5 atomiser that I can find a reference to.
If you know of an official source saying otherwise I'd appreciate a link so I can add it to my records

[HxPaul]

Sticky's second edition,page 246,"carb jetting for standard machines",at the bottom of the page.

[johnnyXS]

thanks paul I'll take a look.
i got my reference from Cambridge Lambretta carb and jet table .
http://www.lambretta.co.uk/downloads/carbjetting.html

[Kristof Lammy pie]

Hi. I think I've read that they tried jets from 99 to 107 and different settings on the late specials and mine is 11/1968 so one of the last.

Maybe they tried sx150 settings to these?

[missing lynx]

I got the info from a dealers parts book I have but it does also state it in Sticky's book but If 37 years of owning, riding and fixing Lambretta's has taught me there are always anomalies in the spec the books say a type should have

[Kristof Lammy pie]

So today I've just gone through the carb adjustments again and altered the mixture screw to one full turn out and the idle adjuster screw fully in and it pretty much starts first time every time now.

However I still feel there is an air leak somewhere so once the u bend and gaskets come I'm going to take it all off and check for leaks.

[johnnyXS]

thats great news well done !

Have you checked your Plug gap, points gap and static timing yet ? I have mine set at 19 deg BTDC but you could experiment with 17-19 .
A degree wheel is a worthwhile investment if you haven't already got one.

[Kristof Lammy pie]

B7 plug 0.6 gap.


Not checked the timing or points. It's something I have never done before so I will need to sit down for a few evening with stickys book and see what I have to do.

[johnnyXS]

B7 plug 0.6 gap.


Not checked the timing or points. It's something I have never done before so I will need to sit down for a few evening with stickys book and see what I have to do.

Excellent ! something worthwhile to do while the missus watches Emmerdale, Corrie ....Eastenders , Strictly etc
You are going to need to buy a flywheel extractor to get at the stator plate. It is possible to set the points gap and move the stator to adjust the timing through the flywheel cutouts but its a right pita ,anyway you'd be best off replacing the points and checking the coils and wiring so you know thats good for a few years

[Kristof Lammy pie]

Exactly that! Lol

[Storkfoot]

If you are keeping it standard, points are absolutely fine and, in fact, there's a lot to commend them for. A lot of people are just lazy and can't be bothered setting them properly. As has been said, read Sticky's section on this a couple of times. Especially get your head around the fact that it is not just the points gap that matters, it's important that they open at the right place. I always used the cigarette paper method and have never had an issue.

When you start getting towards a sporty 186 kit, then maybe go Electronic, as points can bounce. Otherwise, IMO, if the stator's all good, they are fine.

You seem to have the hang of posting photos

When you get to it, I'd like to see a picture of your Slide and your exhaust manifold contact services if it is, as you say, leaking. Don't clean it or smudge it, just take a couple of pics. You'll be surprised what you can tell from this. It may, of course, be blatantly obvious when you get underneath why it is leaking but often it can be the slightest distortion of the exhaust manifold that stops it sealing.

If it was me, whilst I was there, I'd take the cylinder head and cylinder off to have a look at the state of the piston and rings. However, if you don't do this, please be meticulous in checking for any leaks from the cylinder head and base. It usually manifests itself in black oily gunge. Remember that such leaks can be deceptive. I have spent many an occasion, convinced some mating surface was leaking, only to discover it was coming from somewhere else.

Lastly, I think your plug gap is too large. Shouldn't it be .45 to .5? I'm just saying this from memory as it's a good few years since I had a standard "ish" 125 Special on the road.

Please feel free to keep asking questions. Pictures paint a thousand words too

[Kristof Lammy pie]

Hi.

Many thanks for more great advice. I will get some pics up before I start stripping it. I agree with your comments about the head and barrel removal.

A lot of things for me is based on grabbing a couple of hours in the garage without my wife and kids hassling me.

From the brief look I've had underneath it is thick black gungy oil on the inside/underside of the exhaust near the joint to the u bend. I will take a better look and take pics of it when I remove the rear boards tomorrow.

[Kristof Lammy pie]

A few pics underneath.


Bottom of the casing has a slight bit of oil on it.



Left exhaust stud not too bad.




Right exhaust stud leaking quite heavily maybe a snapped stud or crack in the u bend.




Barrel and head gasket look good but you can see the leak blowing against the exhaust.

[Marty ULC]

With any luck it's just a blown exhaus gasket or the nuts are loose. I'm a fan of solid copper gaskets and using the chain guide locking washer as per sticky's manual.

[Kristof Lammy pie]

Hope so.

My bits arrived today

[Kristof Lammy pie]

Does anyone use any sealant on the inlet or exhaust gasket?

[Storkfoot]

No. I just try and make sure that everything mates together well and the exhaust isn't stressed at the swan's neck and tailpipe. This can be hard to achieve and always seems to involve, at least, taking a file to the face of the U bend manifold to get it 100% flat.

I know other people do use a sealant on box type exhausts.

Have you bought a new exhaust as well?

It does look like your exhaust casket is leaking but, as I have said, don't assume this will be the only leak.

[Kristof Lammy pie]

No I've just bought the u bend.

The exhaust is in really good condition,might be original but probably a copy. Annoyingly it has a gouge out of it from the kickstart which really grips me that someone let that happens without grinding the tag off a bit.

[Storkfoot]

I have 4 or 5 u bends knocking around my garage. All are different in shape and length. You'll be very very fortunate to find that the one you have bought matches the one you take off. Be careful, forcing it to fit is bad.

It may well be that is the original exhaust, albeit with a splayed flat tailpipe. However, box exhausts are prone to getting bunged up with rust and gunge. In that condition they will badly stifle performance.

[Kristof Lammy pie]

Will give it a go, fingers crossed I can get it to fit otherwise ive got another lambretta ornament.