How hot is too hot?

[SeattleDiver]

Hi all,


I recently picked up a 82' kz305 B that had been sitting in a garage for 20 years. It has around 8500 miles. It runs fine, but I have zero experience with air cooled motorcycles (or liquid for that matter) and I am curious how hot these are supposed to run?

If I idle it for a few minutes I will get readings in excess of 300 F on both cylinders. Getting within 150+/- F of when my synthetic oil says it starts to break down due to heat gives me some concern. I just got the ability to test heat yesterday so I have yet to take it on a ride and test the heat afterward, but just by feel I know it is still blazingly hot. I will test heat after a ride after work today.

I have the manual but it doesn't seem to state anything on proper operating temperature for the bike. Does anyone have an idea of what temperature ranges I should be seeing normally?

Thanks

Steve

[MFolks]

you will need a shop fan moving air around the cooling fins if you plan on tuning it up while the engine runs. I do the same on my air cooled 82 GPZ1100 B2

[Nessism]

Yea, don't run the engine too long without air blowing over it - use a large fan when doing chores like syncing the carbs.

Regarding your temp measurement, you can't judge oil temp by measuring the metal temp on the outside of the head. If you really want to know what's going on, hook up an oil temp gauge and judge that way.

Air cooled engines do tend to run hot is the summer, particularly when you are in city traffic. You already have synthetic oil which is a good hedge against the heat so you should be fine.

Good luck.

[Ericthejet]

Huummmm.
IMO your air cooled engine can idle all day long with the proper oil in the crankcase but airflow is best. I'd say once off the choke you have 10 minutes before you need to be vigilant.