motor getting too hot

[headache]

hey guys i believe that my motor is getting way too hot and not sure exactly why. It is a 366 with je 10.5 piston. I had a stage 1 hotcam in it but have taken it out and put the stock cam back in. has cobra exhaust. jetting is 152.5 main and it is running rich. the plug is dark colored but not wet. i've probably only put 5 to 6 hours on the motor so far but it just seems way too freakn hot when riding for any length of time. It has even melted the end of the spark plug boot. and the high temp paint i sprayed on the cylinder and head is bubbling and peeling some. I have added an oil cooler also like some people on here have by tapping the holes in the clutch cover and blocking the passage, and adding a automotive trans cooler. Should i try a D9ea plug (range cooler) and maybe some race fuel mix? How much oil pressure should these motors have? i've removed the cam cover and had the quad idling and oil is steadily coming out around the camshaft bearing and if i rev the motor oil will actually pour down and a little will splash out, so i think its oiling ok.. somebody help me out before this thing has a meltdown

 

[duneracerweston]

Air ducts? And cheack the oil frow from the little 8mm bolt on the hear my the right rear main head bolt has a philips head inside the regular hex headed bolt with a coper washer crack it about 1/2 turn tell us how the oil flows and you are checking the oil after its been running for like 10min right?

 

[Hdale85]

Usually if you're running rich it runs a bit cooler, hot if it's lean.

I put a new air filter in mine and haven't re-jetted yet so I think it's a bit lean and it seems to get pretty hot. But if you're really rich I imagine that's likely not your problem. I'd guess if it's running hotter then normal would have to be on oil issue?

 

[Jebbysan]

Hey Headache...a few things:
-What color is the plug....white, black, brown?
-Did you add the correct amount of oil to compensate for the added capacity of the cooler?
-Are your fins nice and clean-this may sound stupid....but everything counts.....I cleaned my fins with steel wool...there was a coat of thin Texas clay on them-this did make a difference...i did my case as well....I learned early on messing with air cooled Honda bikes that heat will build slowly and not dissipate when the fins have debris on them.....
-Check your cam timing-this is free and easy....you mentioned doing cam swaps...and though i do not dismiss your mechanical prowess...cam timing that is too far retarded from a worn chain will not open the exhaust valve early enough...causing a build of heat...especially with a 10.25to1 piston and a stock cam.
-Last Tuesday it was 106 here...101 in the shade.....I doubt it was any better in Arizona....I had to shutdown after 45 mins of track time due to the noise coming from the cam tensioner....THIN OIL! 15w40 non-synthetic...on little motors like these it pays to run a quality cycle synthetic....I am swapping to Royal Purple tomorrow to reduce a bit of friction and oil breakdown...Thin oil does not transfer heat like thick oil
simply because it can't stay on parts long enough to absorb the heat.
-Last but not least...verify good oil flow to and from the cooler...

Good Luck and stay cool,
Jebby

 

[headache]

my plug is dark brown almost black. yea timing is dead on. all the head fins are clean. oil is full and clean, i've been running regular Yamalube 10w40. Its only 75 degrees here today and its still running crazy hot.. i'm goin to check the oil flow through the cooler here in a minute...

 

[headache]

ok i checked the oil coming through the cooler and it seems to be plenty to me. I don't know why this thing is getting so dang hot. Maybe its just the compression. I'll get a D9ea plug and some turbo blue gas and put in it and see if that helps it.

 

['00 WO-YA!]

K, so stock camshaft profiles have short durations, wide lobe seperation & ofcourse low lift. When you couple higher compression ratios with camshafts that are designed to increase low rpm cylinder pressure you will in turn increase heat. I'm uncertain about how much overlap the hotcam has but I am certain that it will have more overlap than the stocker. Overlap leaves unburned fuel in the chamber which will to a degree decrease cylinder temp. I'd go back to the hotcam, use a good synthetic oils & as already mentioned make certain that you have good oil flow.

 

[headache]

well it was running just as hot with the Hotcam in it as the stocker, although it definetly had more topend power with the cam in it. seems like the stocker has a little more bottom end power though. i may put it back in though. and change to a better oil

 

['00 WO-YA!]

well it was running just as hot with the Hotcam in it as the stocker, although it definetly had more topend power with the cam in it. seems like the stocker has a little more bottom end power though. i may put it back in though. and change to a better oil

Good idea, a friend of mine made the swap to Amsoil in his Harley engines, he did it for simplicity at the time b/c it eliminated having to use & stock multiple oils & his shop. He was very pleased that after making the swap he found his engine temps to be up to 30* cooler. I'd make the swap, certainly can't hurt-James

 

[Jebbysan]

ok i checked the oil coming through the cooler and it seems to be plenty to me. I don't know why this thing is getting so dang hot. Maybe its just the compression. I'll get a D9ea plug and some turbo blue gas and put in it and see if that helps it.

Check your cylinder pressure....compression test...
If the high octane fuel lowers temp...then you explained it...

Jebby

 

[headache]

does anyone know what the compression limit is on a 4stroke air cooled motor like this? i know a 2stroke is around 160psi. i'm guessing it'd be about the same on this motor. I'll check my compression and see what i've got.

 

[MotoArts]

It's all part of the combo. Cam timing, namely overlap as previously mentioned, bleeds off cranking compression (as opposed to static compression). There is no theoretical "limit" so to speak.

 

[Jebbysan]

It's all part of the combo. Cam timing, namely overlap as previously mentioned, bleeds off cranking compression (as opposed to static compression). There is no theoretical "limit" so to speak.

There is a limit on "pump" fuel......before the onslaught of detonation....but it is determined in part by chamber shape and quench.....
I would say the number is going to be north of 170....

Jebby