Engine overheated

[Sejati]

I have issue in the engine overheating.
I put oil stick with thermometer, and when it’s hot it shows more than 120 degC, up to 140 degC (pardon my metric system)... and the engine loosing its combustion and shut off, and can not be started again. Until became colder below 120 degC, and it can be started again.

It seems loosing it combustion or pressure at high temp oil, possibly stall valve, or jammed valve ?
It might be lack of lubrications due to oil thinning ?

Does anyone have this experience?

Anyone have suggestion of the correct engine oil brand and type ?

[Barry]

140 C sump temperature sounds very hot for an air head. Two possible causes are retarded ignition timing  and weak fuel mixture so they would be worth checking.

With oil temperatures that high you should be using a 20W50 oil as a minimum or 20W60 if you can find it.

[Bob_Roller]

Were you in slow traffic for an extended period of time ??

It's common to see oil temps of 120 C during the hot season here, air temps of 41-49 C .

Never had an issue with the engine running in these conditions .

Follow Barry's recommendations, do you have any issues with poor fuel quality ??

[Sejati]

I think I have too lean fuel as well, last time I check I have white spark plug tips. What is the best way to increase fuel mixture ? By the pilot idle mix screw, or by throttle valve idle screw ? I think those only applied for idle setting. Any other setup I need to adjust ? The plunger needed position ?

In my case, I have a lot of traffic jams, and stop and go.

The phenomenon which I experienced, which engine seize to operated when it is hot, has anyone experience before?

[Sejati]

With oil temperatures that high you should be using a 20W50 oil as a minimum or 20W60 if you can find it.

I have set the idle timing only by feeling, rotating the bean can a bit, until it reaches around 1200-1300 rpm at idle. If I turn more it will increase the idle rpm, or turn clockwise will eventually lower the timing and shut off the engine.

For oil currently using 20w50, but I need to change it to better brand, I suppose. need the brand recommendation as well. Or I will try to fine 20w60 also. I see many oil here sold to specify Harley Davidson spec, is it any good to be used ?

[Tony Smith]

I think ignition timing is one cause of your overheating.
Please read up (Snowbum's site awaits you) on how to set timing and idle speeds.

Suffice it to say you are going aboout it backasswards. As a rule of thumb -

First set velave clearances
Second set timing
Third - balance carbs, set idle speed etc.


And, the external adjustments are for idle mixture only. Main jet mixute is set firstly by the size of the main jet itself and then secondly by the height of the needle valve. It might be very worth your while to check that all the internals of your carbs are present and are the stock sizes. One thing that will screw your mixture control right up is that there should be a large washer under the main jet - many people mistakenly throw this away thinking that a previous owner could not find the right size washer. The over sized washer is close to essential.

[Tony Smith]

To which I should have added. -

Check the bob weights for free and correct movement in the Beancan.  If they are not moving freely the correct procedure is NOT to squirt boat loads of WD40 into the poor thing, takke it apart and lubricate with a high temperature grease (Silicon grease if you have it).

If the pivot posts for the bob weights are worn - buy an aftermarket beancann replacement, preferably one that has electronic advance and retard. I faced this decision relatively recently and decided that the day it would have taken me to make u new, oversized, hardened pivots, bore the bob weights and put all back together was better spent riding. I bought an Emerald Isle beancan and ICU and love them.

[Sejati]

Thanks Tony for this advice.

[Sejati]

I have done just now setting valve clearance. Found only slightly off setting, and then readjustment and retorque the nut.
After restart, seems the same issue of idling high rpm.

Next the timing setting.

So I had done replace the old bean can with Emerald Isle bean can and it’s new ICU, but issue remains.

First I use EI beancan, with old ICU, start okay, and max out at about 4000rpm before stalls. This is because no mechanical advance trigger.

Then I switch to EI ICU with advance selector. The bike only start with advanced idle setting, also idle at about 2000 rpm. If I turn the bean can clockwise to retard a bit, it won’t start, even with enrichment carbs. Only when start at advanced 2000rpm idle, then I can turn bean can clockwise and reduce idle to 1500rpm. But it won’t restart again.

I observe the flywheel OT mark is arrived early at about 45 degree before TDC. But piston and valves are doing okay in timing for open and close. I assume timing chain is okay. So I assume it is only the flywheel error marking.

I think I need to find strobe timing light for inspection.
Anything else maybe?

[Sejati]

One other thing, at the advanced setting with EI stuff, and it start at idle 2000 rpm, when I open throttle, it directly stall and shut off.

[georgesgiralt]

Hello Sejati,
You wrote :
"I have done just now setting valve clearance. Found only slightly off setting, and then readjustment and retorque the nut.
After restart, seems the same issue of idling high rpm."
Of what nuts are you talking about ? The valve rocker play adjusting and locking nut ? Or the head holding nuts ?
If they are the valve adjusting one, the measurement has to be made once the nuts are secured because, otherwise, you may turn the screw a little during locking, making the adjustment invalid. If you refer to the cylinder head nuts, you have to set the valve lash AFTER torquing those nuts to the proper value.
Last but not least, set both carburetors for base setting before starting the bike :
Set the mixture screw to the base setting and set the idle screw also to the base setting. Generally, the mixture screw should be gently put to full close then opened a half turn and the idle screw should be set barely touching the tang and then a half to a turn more.
If your mixture screw is way off, this could explain the high idle. But this should have been addressed by a thorough carb cleaning and renewal if not done recently.
I'm not familiar with EI products, but at idle, the advance should be with the "S" or idle mark showing. It is near the OT mark but it is NOT the OT mark. Which is for top dead center mark. S mark means initial advance setting and Z mark means maximal advance setting to be reached above 2500/3000 RPM.
So you should set the bean can position to have the S mark stable in the window at idle and have the ICU set for 26° which is the maximal advance for our engines.
Hope this helps.

[skippyc]

Just a reminder EI ignitions physically retard the ignition from full advance to starting timing. Unless the can guess when the next trigger point is coming.

[Sejati]

Hello Sejati,
Of what nuts are you talking about ? The valve rocker play adjusting and locking nut ? Or the head holding nuts ?.

Dear George,
After torqing headnut, i adjust nut adjuster and torqing the locking nut. And after all dine, reconfirm the clearances for all valves.

I Will try to Reset carb setup, especially the mixture valve.
It is the one position inside the bowl, right ?

Thanks for your advice

[Sejati]

Just a reminder EI ignitions physically retard the ignition from full advance to starting timing. Unless the can guess when the next trigger point is coming.

Could you help to elaborate more on this ?

[Tony Smith]

The current confusion seems to stem from you trying to use timing to adjust the idle.

Stop doing that!

Also, a more reliable way of setting timing is to do so at around 3,500rpm and set to full advance - the idle timign will look after itself.