alloy barrel & heat

[Danger]

i bought an alloy 225 kit off ebay some time ago which ive had tuned an just got back today from mick abbey top bloke an top job by the way , now i think i read on here somewere that if i paint the barrel an head black say would this help dispence heat better am i rite or should i just not bother an if so what should i paint if with, exhaust paint or sumit to that nature all info would be great thanks lads

[soulsurfer]

Wouldn't do any harm painting it in black exhaust paint IMO

[shanetv175]

dont for get to drill 4 holes in the piston and cross them

[Danger]

not sure wot you mean an Y,gave mick my piston an he just shortend the skirt , so why should i drill 4 holes an cross them a pic of wot you mean would b great and advantages from doing this thanks

[Danger]

can anybody else shed anymore light on this as i havent a clue thanks

[carlos fandango]

there lubrication holes....usually when your having heat seizing problems..... so if its seizing on the four stud locations the holes would be put in the piston there, or on an rb225 af were drilling holes in the piston where the exhaust bridges are to keep the bridges cool.
I cant see that you need them unless your having seizing problems though

[Diablo]

Don't get too wrapped up with this. Painting the barrel black may or may not work. We discussed it on another thread some time ago and Tony I think came up with the idea that on a Lambretta it may be more prudent to paint the inside of the cowling. Using a steel lined alloy barrel means theres little point anyway. If it was a cast barrel the difference may be worth pursuing.
Either way your talking parts of a degree and if your set up is that prone too seizing something is very wrong anyway.
Pay more attention to making sure the flywheel cowling is a close fit to the fins and that there are no gaps for cooling air to escape from etc. Also measuring compression ratio and timing accurately should be more of a concern, then you can concentrate on jetting.
I wouldn't bother drilling any holes in the piston unless you know what your doing regards ports etc Unless the holes are drilled in the right place they will do more harm than good. A good synthetic oil, a decent piston and an accurate bore is what you need.
Don't trust an Indian barrel to be accurately bored. Take the barrel and the piston to a respected engine reborer and get a precision hone done. I would recommend .004" on a 225.

[shanetv175]

I never had a problem up on till latley (3500 miles) when see started seizing so bored the barrel, new piston, with holes in line with the stud holes and crossed them .about 10mm above pin. another 1000miles no running in and striped it and no wear marks where the studs are and still going strong

[bristolmod]

black paint "absorbs" light (thats why it appears black- basic physics).

Doesn't it therefore absorb heat as well which is the opposite as to what you are trying to achieve?

I'd agree that the difference either way is likely to be minimal.

Chris

[CPH Lambretta]

As to painting the cylinder black or not, its all down to where the heat is coming from.
If the heat is coming from inside something (like an engine) then a black surface will give off more heat.
If the heat is coming from an external source (like the sun or a heater) then a black surface will absorb more heat.
But I think the difference will not be very great if you paint it black or not.
My engine is painted black by the way, but thats more because it looks cool! :freak: