EGT Guage & Probe

[wlightning]

It is impotant wher you fit the probe, My thought has always been this, who puts a scooter through its paces (the racing lads) so then you need to be mates with the top flyers. In the eighties my pals were Dave Webster,Norrie Kerr,Malc Anderson & Ralph Saxelby. Dave is still a big pal and i see him at least once a week for tea, and we have a lot of chat about the lambretta and tunning. So now I let Guy Topper & Chalky look after my bike, Guy is very knoledgable about most things so we set my bike up on things he found out on the net but not from the scooter scene. So melt down of a piston would be around 750. We found that an air cooled engin should aim to be run at 580ish egt,220ish cylinder head temp, with probe set at 125mm from piston skirt (I think).There was no way I could get my bike to run at any were near 580 so after putting back on chalkys dyno set it back to what it was, it now runs 3/4 throttle to full,tops out at 630 egt & 180 head and it loves it safe to ride any throttle position but has took some sorting out. I use a Mychron 4t rev counter,egt,cylinder head & makes a cup of tea also

[gadgetman]

Don't want to be arguementative Carl but I find that unbelievable






.........You having mates !!!!!!!!

[wlightning]

Gadgetman just be carefull what you say,would not want you barred off this site like all others.

[J1MS]

A few good bits of info on the www seem to be available now, Rotax EGT is a good search. But I think it mostly covers EGT's used with water-cooled heads, temp range being 500-630 are normal, above 650c is risky. Also the kart and microlite forums and web sites.
There is some very good info on one of the Physics forums.

[soulsurfer]

My motor was set up using the Stage6/Koso type guage and now runs the best it ever has being smooth through the entire rev range. With the cheap analogue type guage it can go up to 650+degC, but it varies + and -. I've subsequently fitted a Stage6 with stinger type probe at the same header position and inserted 2mm deep. It reads around 580-600degC consistently. With the cheap bullet type probe inserted at 3-4mm with the analogue guage gave no reading. This tells me that you get what you pay for, my belief is that the cheap analogue guages and probes will give wildly innacurate readings that are inconsistent that fluctuate too much, certainly on an aircooled motor. Maybe that's why they're sold for aircraft and not two stroke road use i.e. a totally different application.

[tony]

every egt gauge and probe has its own fitting spec and is designed to work at that spec. Every motor has its own spec.. its own ex timing and area.. its own pipe design.Head design etc. I think you need to look a bit deeper into all this fellas. Its not all black and white.

[J1MS]

every egt gauge and probe has its own fitting spec and is designed to work at that spec. Every motor has its own spec.. its own ex timing and area.. its own pipe design.Head design etc. I think you need to look a bit deeper into all this fellas. Its not all black and white.

Tony I think you are right, reading a couple of in-depth posts on the physics forums explained that much, gas temperatures inside the exhaust system do not account for many other parameters of a two stroke engine, water cooled or air cooled.
But a better, wider understanding of what is being fitted to an engine and how might help decide what it's doing and why.

[wlightning]

every egt gauge and probe has its own fitting spec and is designed to work at that spec. Every motor has its own spec.. its own ex timing and area.. its own pipe design.Head design etc. I think you need to look a bit deeper into all this fellas. Its not all black and white.

I would agree with your statement Tony lots of things can change but it seems you do not need to run hotter than 650 and it depends were the probe
is.

[lambro63]

carl ..........spelling !!!! tut tut.......nottingham high school boy to
ask carl what speed he was doing on his lambretta when he last got pulled by the police on his return journey from matlock ???
temps were running high then carlos......did your egt & prode cool the sistuation down enough before melt down........


regards big pete (lambro63)

[nelson pk]

Hi

I've been running a Koso egt for about 18 months now. An excellent bit of kit!
I dont think its worth getting an analogue readout as these dont seem accurate enough.
As for postioning......5 inches from piston skirt following the bend of the pipe and the probe about 5mm in the pipe.
The temp where mine is safe is about 550 - 600. I think you can get away with up to about 640 but take into consideration that if its reading 640 on an average day, that on a day where the air is particularly cold and thin that you could be heading for meltdown!!
I think you will tend to find that highest readings happen in the mid range because this is the hardest area to jet on the carb.
I've jetted mine so when the revs are high in the midrange and i pull the choke out it starts to splutter a little.
This does cause spluttery spots when setting off at low revs but at least i know enough petrol is coming through on the mid range when i'm cruising.
In my opinion running 620 - 650 constantly is dangerously close to the edge but you do have to make sure your thermocouple is fitted correctly as this will definitely effect temps.
I also set the carb so its over rich and check temps and then set the carb weak and check temps as this gives you an idea at what temp your bike is going to be safe at.
Hope this helps someone.
Pete