Ok the gage is mounted and I put the probe 7" down the pipe as recomented,I started it up and the gage goes instantly to about 400 - 500F.
I let the motor warm up abit and then went for a run up the street, I cracked the throttle about 1/4 open and within 100ft the gage goes to about 1100 - 1150F instantly, so I stopped, the temp fell right away back to 500F or so.
I made another go at it and the same thing happened at a 1/4 throttle then I snaped it to 1/2, but it didn't go any higher.
My questions are......
Is this normal?
Should it be this high under no load?
I've got a 320 in the main,Should that be enough.
I should mention there is a heavy premix in the tank, Maybe this is causing extra heat.
Looking for some guide lines to run by.
I will be rejetting before my next run to see if this brings it down a bit.

P.S. It does have alot of snap even at 1/4 throttle runs,
I feel the front wheels aren't long for the ground once I get this gage and jetting closer Thanks RCR.

 

I think the melting point for alloy is 1250deg, but you would need a CHT to get that acurate. As the gas comes into the cylinder, it cools the piston, head and sleeve, but the exhaust has no cooling, so I think your readings should not be giving you concern.

At 1/2 throttle, you are not on the Main Jet yet, and only using the PJ and needle. Lift the needle but one notch (put the clip down lower), and then run the same tests. Remember to write the results down for future reference.

Aslo check with Rick Ritter as to what temp range is the best for peak performance.

By the way, what brand of EGT sensor are you running. I have been looking at the My-Chron from Australia or the Digatron. The My-Chron is about 1/2 the price, and a smaller unit.

 

ScrambledKiwi
The gage is a autometer, Pyrometer 2 1/8".
Real nice gage and seems to respond really quick.
The best price I found was on ebay.
I'm going to raise the needle and if it seems to come down,If it does I'll up the piolet and put the needle back to the center.
If I didn't have the gage I wouldn't worry, But when you have 1200 DEG f. STARING YOU IN THE FACE, It gets me to wondering.
I was just looking for some readings to compare it to.
Thanks Zman

 

You should richen the mid-range by raising the needle. Then work on your main. You need to determine the main size you need first, then when you get it jetted properly, start making changes to the mid. It sounds to me like your mid-range is not far off at all.

 

I would also like to know what the normal temps are at various throttle opening. I've melted a piston at 1/4 throttle with only 1050F reading on the exhaust gauge. Now I have it jetted so that it doesn't exceed 1000F at 1/4 throttle, haven't had additional problems yet(knock on wood!). 1200F or so is generally the max temp you would want to see at wide open.

Just my 2 cents.

Jason

 

I have seen a Banshee run at 1250deg at the head. The only thing that kept it from melting the head and piston was the incoming gas. I have heard that you can peak to 1280 for short bursts as long as you don't let of the gas suddenly (no throttle, no petrol).

What carb, jetting and altiude you running?

 

ScrambledKiwi
I've got a stock carb bored out from RCR and running a 320 main and a stock piolet.
I'm at 175 ft above sea level.
I raised the needle one notch and it came down 200 deg.F
So now I'm 950F at 1/4 Throttle with no load on the quad. I'm looking for a 1/2 spacer to raise the needle again, I'd like to see 900F and then go to 1/2 throttle runs.
This was the best money spent so far,
You see I melted down at 1/4 - 1/2 throttle in the first place. All my wide open jetting runs told me nothing before.
I think every thing is back under control,
Thanks
ZMAN

 

Zman

From memory the stock PJ was a 35. This might be OK, but if you are using the stock needle, you may need a different one. I changed my needle when I was having jetting problems after a pipe install, and hey presto, problem fixed.

Another thing you might like to consider (or not) is that if it is running so hot, you may have a stuffed gasket somewhere. Being watercooled, it is unlikley to be a head gasket, but it might be a reed gasket, or the reeds not fitting correctly. This would allow air to mix AFTER the carb, and any jetting changes will not compensate.

I am haveing jetting problems at the moment as well. I have just had the sleeve bored 1mm, and put in a bigger piston (not by choice) and I also installed a 39PWK carb from HPD at the same time. Mid and bottom are like the morning after a bad curry, but the top goes like a weasle on speed - whippeeee. I will be out hunting this weekend, but my gun will be 4 wheel drive, and my prey will be Yamahahaha dinosaurs and furry rodents!

 

i am also concerned about the temps in mid range. i have the hpd big bore kit 39 kehin no air box. i live at 3300 ft. my machine also runs at a load 1100 and climbs until i flick the throttle. full throttle 1250 and i back out. my plug reading at full is light tan. i did a piston ck after 8 tanks of gas, and found no carbon build up at all. i am calling hpd tomorrow to see if this is normal. it seems that any adj i make the bike just dont run the same. now it tears up everytheing with no bogs or cutouts.i rin a 162 main 35 piolet, air screw 1.0-1.5 needle 2 down with half washer. any info would be great.

 

Peewee
From all my test runs with the e.g.t. I can lower the mid range temps by 200degs by raising the needle one notch.I'm at 900F until 3/4 throttle and then it goes to 1100 degs on short bursts of wide open.
I've not held wide open yet for any great distance yet.
I think that if your able to climb over 1250F your to lean on the main and are running on the edge of a burned piston.
I've worked in a heattreat facility and the only thing that keeps coming to mind is.....
Pure aluminum melts at 1200F, anything other than pure, such as a piston melts sooner!
I know there is piston wash and the piston doesn't see all that heat but it's within inches of all that heat!! I'm keeping mine on the safe side for awhile, At least until the pains of the last rebuild go away.
Happy jetting!
Stay Kool!