Kawi2strokes.com Forum

Does anyone know what a good cylinder head temperature would be ???

In all the decades I've had my H2 I've never checked that, sorry. Is there a particular reason you're asking?

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If it surges, that's normal, upshift.

I have a Klein Infrared Thermometer, next time I run the H2 I'll post it.

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This is true. Where I grew up the hills were so steep and long, when your ball rolled down the hill you just said "screw it"...

I've always thought it would be useful to use the temp sensors on the plugs with a small display to show plug temperatures. While the actual temperature might not be that important it might be useful to see if any cylinder is off significantly from the others. If you had a cylinder go lean you might get a little warning before burning up a piston.

Just speculating,

Dave

Walms on the Canadian board did/does that with is 500. With all the miles I've put on my H2 in the last 44 years, I can't say it's something I'm concerned with though.

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If it surges, that's normal, upshift.

What is a lot more significant isn't the actual metal temperatures is two things.

First, the combustion temperature, and that needs a second thread near the spark plug, with a direct read sensor into the chamber to read the burn as it occurs, directly.

Second, that all 3 chambers burn consistently, and uniformly between themselves.

For an air cooled two stroke, important, but a real pain to do. The under the spark plug sensor read would work.

Another thing to consider, the center cylinder is supposedly a hotter runner. Not so, they usually run a touch cooler, unless some top tuner insists on removing the front fender. The fender deflects air flow off the rear of the tire from diverting air flow onto the center cylinder. The fender both stops that deflection, and helps guide air flow to the center cylinder and head.

I run plug temp sensors. Temps from 250F- 290F. 250-260 for most normal riding, I’ve seen 300 when really on it. Drops fast once I back off.
There a big tuning help. Get the temps close by adjusting the throttle cables. And Tuners right, center cylinder is usually slightly cooler by 5 to 10 deg. It will get close to the same temp at slower speeds but cooler at higher speeds.

It's funny that every time I've had a set of H2 cylinders bored, the shop offers to give the center cylinder more clearance because it runs hot. And it hasn't always been the same shop! I have to tell them not to do that, and have a very sincere look on my face.

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If it surges, that's normal, upshift.

I get so many questions on it because of the temp gauges. When I show people the temp gauges when it’s hot they ALWAYS think it’s because I jet the center different and they argue with me about it!!! I’ve given up and just agree now.

OH and it does wheelies all the way through fifth

There is NEVER a reason to run loose piston clearances, nor "looser" center cylinder.

Even when we ran the 171 horsepower H2-R engines, with forged pistons in Yvon's bikes, piston clearances of no larger than .0015 worked better than all those worn out bores freshly clearances to .003+ loose. We never seized the engines, and thet always ran incredibly well.

One main loss with loose piston clearances is too much piston rockover at TDC and BDC, and the piston splayed down and up the bore, destroying effective ring seal.

The rings are nit barrel faced, they are square. The more rock over and splaying, the less ring seal, the shorter the piston life, the worse the engine runs, no matter if it is a single ring H2-R, ir two ring street H2.

And, YES, the second ring expanded on street pistons is nescessary, should never be left out, it helps to reduce piston splaying, and helps with ring seal..