Cylinder and Head Temperatures

xsjohn · Posted: July 26, 2007, 12:26 pm Post subject: Cylinder and Head Temperatures

It’s been about a year since I decided to cool this thing down since I ride a lot in the summer…. 200+ miles a day and spend quite a bit of time on the express at about 65 miles an hour…..

I started with probably the hottest and leanest of the xs’s.. (80) …. I now sell a custom jet needle kit to fix this problem and mak it run like a top........
Heads are easy to cool with oil but the cylinders are the heating problem....

Went from 265+ degrees cylinder temperatures to 240 @ 90 degrees ambient on the express……………230-240 backroads.....

The casting on the cylinders originally had a tiny bit of clearance so the air could blow between the cylinders…..Yamaha never finished opening the vents when they were cast…Well I opened them some more……. Bound to help it stay cooler.......

Another realistic approach I thought of would be to enlarge the existing fins on the cylinders....This would increase dissapation and be in the realm of possibility... look at those punny fins......another 15 degrees off the cylinders in the summer would put it right in the ballpark...Maybe 3/4 to 1 inch front and sides and more in the back because of less air flow..Welded on in sections and smoothed ....Maybe a couple of strips on the sides of the lower 2 head fins to match the enlarged cylinder fins.....Wish I was a welder it would already be done.......

John

beys · Posted: July 26, 2007, 2:46 pm Post subject: Re: Cylinder and Head Temperatures

John... one summerday your bike will break down with frozen pistons...! Laughing

xsjohn · Last edited by xsjohn on May 29, 2008, 7:59 pm; edited 3 times in total

Since lots of people don't understand this subject and how it effects their ride I typed in “lower intake temperatures more power” in google……found some interesting discussions on the topic………

GOOGLE................
Higher intake temperatures reduce the air density and thus power and torque. ....

lower intake temperatures mean more power is exerted from the engine.

Lower air intake temperatures results in lower EGTs and visa versa.....

Cold air carries more oxygen . Hot air is more expanded and carries less oxygen...

Cooler intake air temperatures increase air density, while reducing the tendency for detonation (ping) and can create more engine power. ...

That's a large part of why engines are stronger in the winter than in the summer.

There are other factors. Colder air has more oxygen because it is more dense than hot air. The engine monitors for excess oxygen in the exhaust, and adds fuel to compensate. So colder air allows for more fuel and more power.

xsjohn

wally

…. I now sell a custom jet needle kit to fix this problem and mak it run like a top........
Heads are easy to cool with oil but the cylinders are the heating problem....

John

You say you sell custom needle kits what does it include & how much are they
also payment method do you use paypall

Wally

JDoza

xsjohn wrote:

…. I now sell a custom jet needle kit to fix this problem and mak it run like a top........
John

Yes...Please tell us how to get a set of your needles and pilot jets. How do you prefer payment? Pony Express, Carrier Pigeon, Sign over my wife and a few kids, Money Order, PayPal. I am flexible, Please let us know.

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Yamaha xs650