LCGB Forums

Posted: **Wed May 03, 2017 8:26 pm**

I've stripped down the engine in my recent Lince acquisition. The inside of the crank case, bottom of the piston, barrel spigot - everything in the top and bottom end is heavily carbonised, there are carbon deposits blocking the transfers, even, like lumps of coal... :shock:

The barrel itself is very mucky and bit rusty outside too and for some reason quite a lot of silicon has been smeared around.

The bore itself is basically spotless though and measures up as standard. I've tried a new piston and rings in it and the tolerances are spot on.

What can cause this level of carbonisation?

What's the best way to clean up the cylinder? I don't really want to blast it as I'm not planning on a rebore.

Posted: **Wed May 03, 2017 9:17 pm**

You could try baking soda

Posted: **Wed May 03, 2017 9:39 pm**

peejay might be able to tell you how his Club Members went about a similar issue...by now!

peejay wrote:hi peeps
i'd like to share a couple of clubmate's experiences with you

1 - standard GP 200 barrel, piston, head, carb, AF bigbore. 11,000 miles in total (5,000 with exol at 2%)

no smoking, plug colour good, starting ok.

huge build up of carbon in transfer ports, i've never seen this before.

top and bottom ring sticking.

2 - standard SX 200 barrel, head, piston, carb, Ancillotti big bore. 5,000 miles in total (3,000 with exol at 2%)

no smoking, plug colour good, starting ok.

huge build up of carbon in exhaust port (almost 50% of port) nothing in transfers.

all 3 rings free.

both scoots probably run at 45/50 mph most of the time.
all the previous talk about this oil seems to be centred around tuned ali barrels.

could this fully synthetic race oil be just too good for a standard set up?

is it maybe making the engine run too cool to burn all the oil?

both these scoots have previously run for years (including rebores) with Rock Oil fully synthetic at 2% with virtually no build up.

your answers on a postcard would be really appreciated

PeeJay

Posted: **Thu May 04, 2017 1:03 pm**

That's almost exactly what mine looks like.

What thread was that?

I have to say the oil seals were bust and there was near 2 litres of oil and sludge in the chain case.

Can running with burst oil seals cause this?

Posted: **Thu May 04, 2017 1:12 pm**

Have left it steeping in a bucket of paraffin for now.

Posted: **Thu May 04, 2017 2:18 pm**

rossclark wrote:That's almost exactly what mine looks like.

What thread was that?

Board index ‹ Lambretta Help ‹ Series 1, 2 & 3 (currently on page 7)
Exol oil and standard barrells
Postby peejay » Tue Feb 21, 2017 10:43 am

Posted: **Thu May 04, 2017 3:55 pm**

They all used to look like that after sever years without a de-coke before the advent of synthetic oils. Same with exhausts. I'd nip down to B&Q and buy a pack of Caustic Soda and a plastic bucket. Leave the barrel in the caustic solution for a few days and it should all hose off clean. Be VERY careful with it though as it gives off chlorine gas when first mixed and can also burn your skin and clothing badly

Posted: **Thu May 04, 2017 7:04 pm**

I found after soaking a while in paraffin

this worked well on the piston although mine wasn't quite as bad as yours but it took a few goes with some Scotchbrite .
Washed it off with clean water and dried it quickly with a heat gun.
I used a combination of toothpicks and Mr Muscle to clean out the ring lands.

I didn't use it on the barrel though.
I carefully scraped the thick off with a blunt Stanley blade then cleaned up the inlet & exhaust ports with a Dremmel.
Then I used a drum type flap wheel oiled up as a makeshift glaze buster.
All very low tec but hey its how I roll.

Posted: **Thu May 04, 2017 9:17 pm**

coaster wrote:They all used to look like that after sever years without a de-coke before the advent of synthetic oils. Same with exhausts. I'd nip down to B&Q and buy a pack of Caustic Soda and a plastic bucket. Leave the barrel in the caustic solution for a few days and it should all hose off clean. Be VERY careful with it though as it gives off chlorine gas when first mixed and can also burn your skin and clothing badly

Good shout I need to get some caustic and spirit of salt anyway as the tank is very rusty inside too.

Posted: **Thu May 04, 2017 9:29 pm**

I forgot to mention, the instructions should tell you but always add the caustic soda crystals to the full volume of water, never the other way round.

Get 2 packs while you are at it and when the cylinder is clean, mix up another batch and drop your cowlings in there, a couple of days with regular stirring should get all the crap off as well as the paint 8-)

Posted: **Thu May 04, 2017 9:30 pm**

coaster wrote:I forgot to mention, the instructions should tell you but always add the caustic soda crystals to the full volume of water, never the other way round.

Get 2 packs while you are at it and when the cylinder is clean, mix up another batch and drop your cowlings in there, a couple of days with regular stirring should get all the crap off as well as the paint

Don't use it on any ally parts as it will dissolve it :shock:

Posted: **Fri May 05, 2017 12:59 am**

Yep, cheers, Colin.

Whoever had hands on it in the old country certainly also had a fetish for silicon, nearly everything is slobbered in it. Body work, casings, cowlings, even the engine mounts and cones...

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