Cleaning carbon from combustion chambers

[JackyJoll]

Surprised no one mentioned paint stripper. Dissolves the carbon & you can wipe if off with a rag.

Paint stripper isn’t what it used to be.

It used to strip paint!

[JackyJoll]

Well the aforementioned videos certainly have the air of expertise IMO, he gives off the vibe of someone who knows what he's on about...but YMMV.

I will take the cylinders and pistons to work and measure 'em properly to see what size they actually are. The recommended clearances I've seen from various sources are 4-5 thou, but as high as 6 on racing engines. I shall see what I've actually got.

5 thou is a minimum. 6 thou is ideal. 7 thou will do.

[ZRX61]

Surprised no one mentioned paint stripper. Dissolves the carbon & you can wipe if off with a rag.

Paint stripper isn’t what it used to be.

It used to strip paint!

Ardrox will work, there's also Carbon Off which is sold for use in restaurant trade for cleaning the carbon off pots & pans etc. Oddly enough, it smells EXACTLY like the *good* paint stripper.
The fact they banned it in Califailure indicates that it does indeed work.

[JackyJoll]

Ardrox will work, there's also Carbon Off which is sold for use in restaurant trade for cleaning the carbon off pots & pans etc. Oddly enough, it smells EXACTLY like the *good* paint stripper.
The fact they banned it in Califailure indicates that it does indeed work.

Where can Mr Dazzle buy that?

[ZRX61]

Where can Mr Dazzle buy that?

[cheb]

https://groveshop.co.uk/other-consumabl ... -sps5.html

I can attest it works. Other suppliers available.

[Nidge]

The Triumph factory manual recommends leaving a ring of carbon around the outside of the combustion chamber and piston crown.

Typically normal carbon is relatively soft and scrapes off easily, the hard shiny stuff is the result of burning oil

[JackyJoll]

Take the barrel off and you may find you can skip cleaning the crowns of the old pistons.

[Mr. Dazzle]

I had an exploratory poke with a wooden rod and it's not coming off super easy.

See what happens when I take the barrels off....

[Le_Fromage_Grande]

You can get a spray to do it, it works but it also takes paint off like you wouldn't believe
I think I ended up doing my Kawasaki ones by soaking them in WD40 and then using wet and dry paper

[Yorick]

On my racing bikes, I just used an old flat blade screwdriver, very gently.

[Nidge]

I prefer to use a ground down hacksaw blade (I think it's more forgiving if you slip)

[Le_Fromage_Grande]

You can buy hard plastic scrapers designed for the job, I think mine were about £10 from Amazon

[ZRX61]

You can get a spray to do it, it works but it also takes paint off like you wouldn't believe
I think I ended up doing my Kawasaki ones by soaking them in WD40 and then using wet and dry paper

That's because it's basically paint stripper...

[JackyJoll]

You can buy hard plastic scrapers designed for the job, I think mine were about £10 from Amazon

You can snip a flat side into a copper washer and hold it in a Mole grip.

[Bike Breaker]

They're 360 degrees apart, so one fires while the other is on the intake. That's "the norm" for parallel twins AFAIK - so you're basic CB250, CB500 etc. will be the same I think. Twins that are 180/540 degrees apart rock side to side loads. Modern stuff with 270 degree cranks etc. tend to have balance shafts.

I think the original "big bang" engines were Brit twins re-cammed to fire two at the same time, but don't quote me. This bike sparks both cylinders every time and has completely separate carbs and exhaust for each cylinder, so it'd be a pretty easy mod. Literally just change the cam I think.

Isn't it a 'wasted spark' ignition system wcith a single contact breaker firing one plug on compression while the other sparks at the same time on the exhaust stroke and, therefore, no bang from that pot?.

[JackyJoll]

I think the original "big bang" engines were Brit twins re-cammed to fire two at the same time, but don't quote me. This bike sparks both cylinders every time and has completely separate carbs and exhaust for each cylinder, so it'd be a pretty easy mod. Literally just change the cam I think.

Nutters who altered Triumph twins to fire both cylinders at once, sometimes for a traction advantage in trials, just removed one inlet pushrod and one exhaust pushrod and welded the rockers together. Ignition needed two coils in series, or a Honda-type dual output coil.

[David]

Compression was a bit low before I started taking it apart....about 100psi on one side and nowt on the other. That "nowt" is why I started taking it apart!

And you are seriously considering putting it together like that?
Trust me...pull the barrels off. The skirts will be stained with blow by and i would bet that the rings are stuck.
If you dont do it now, you will very soon....

Even if the "nowt" was down to a valve there will be problems further down.

[Nidge]

Don't forget to put some fuel pipe/rubber bands/cable ties or something similar over the cam follower stems when (not if...) you take the barrels off, they are likely drop out as you lift the barrels otherwise

[Mr. Dazzle]

Cable ties is the top tip I read....

Fuel hose on the barrel studs too to stop the rods getting dinked. That particular tip is in the official workshop manual.