Direct cooling v cowlings

[Eden]

550C is safe, I wouldn't want to see much above 600C if I was using an EGT.

Agreed. I try to keep mine under 580 and try to keep cht under 180

[fatfck]

Thanks very much for sensible answers , I know what I'm looking for now, bike has been booked in today to have head re profiled after wooly, cheers ,

[lozmondo]

My cht guage is under the plug, I don't run an egt. The scoot was built 15 years ago before such things were thought about..a VW under plug cht gauge was cutting edge
Under load with cowlings it would hit 250...it peaked at 150 using the big head.

Im not convinced that the readings are at all accurate temperature wise, BUT, the same gauge , same scoot, same mounting point the needle moves hardly at all now the big head is used.

[Scooterlam]

does the temp rise when you stop moving.
if not it might be worth checking the sensor with a hot air gun.
my sky drive sensor read lower and lower as it failed,
Better safe than sorry.

[lozmondo]

yes temp does move up when stationary then drops back once moving

[dickie]

I have just bought an avanti head for my ts1 build which I'll be running with cowling and full bodywork on a series 2.

I don't want to fit a sip speedo or any other type of temperature gauge, simply because I want everything external to look original.

This isn't going to be a superpowerful motor. Probably in the region of 20bhp or a bit less.

Am i being foolish?

[Warkton Tornado No.1]

You are replacing a cylinder head with one that has been designed to shed more heat than the standard Lambretta product. That could only be a problem if it compromised other factors such as the cooling available to the cylinder, changed your squish, your compression ratio etc.

So, it's doubtful that you are being foolish.

The foolish one's are those that fit a big head 'to be safe' then limit it's function by not optimising other areas. Optimising the squish means the head draws heat from the piston. Having a squish of, say, 2.5 mm 'just to be safe' completely wrecks that concept in it's purest form.

Only my opinion, mind you.

[dickie]

Thanks warkton but I was wondering if not fitting a temperature gauge was foolish. I have no doubt that the avanti head is a good move, but I'm hoping to rely on it to keep everything so cool that I can forget about fitting a temp gauge.

See what I mean?

[Warkton Tornado No.1]

It all depends upon how much of a risk taker you are.

EGT's are arguably of the most benefit, their positioning & reaction just has got to be superior to components placed on the outside, rather than inside the combustion process.

But for what you are doing, sensibly, I guess, it's not essential.

With respect, those that are striving to optimise their engines, which is fantastic & god reading, will be the people where monitoring the engine more is essential.

Does that make sense?

[dickie]

But for what you are doing, sensibly, I guess, it's not essential.

With respect, those that are striving to optimise their engines, which is fantastic & god reading, will be the people where monitoring the engine more is essential.

Does that make sense?

Complete sense. Thanks