Might be be easier to tell how it idles at 1000 rpm…
Are all four exhaust pipes equally hot on start up ?
Great looking survivor…
The bike truly is beautiful, so thanks. As for the idle speed, it generally rests around 1,200 and I don't think that over the last 10 years of owning it it has ever idled at 900. When I fiddle with the thumb screw it ends up just slowly dying. As for the exhaust, I checked for back pressure on each pipe and they each seemed about equally as forceful.
Should I be concerned about engine damage with the fast idle?
I’m good with the fast idle if you are…
You wrote you never adjusted valve clearances before…or cam chain tension….and your engine was rebuilt by another..
My query, (since adjusting valves for the first with a .002 and .003 feeler gauge and then though a small hole as well as correctly indexing all the valves on or near the base circle for the first time can be a challenge) was based off of the high idle rpm.
Sometimes using such very thin feeler gauges and through a small hole can be a chore. Some have inadvertently lashed these motors on the tight side or at the wrong position and held a valve off the seat a little. Sometimes requiring a higher idle rpm to compensate due to that cylinder’s or cylinders’ idle affected vacuum by a tight valve.
The same reason I asked if the four pipes all heated up at the same time (not the back pressures). A tight intake at an idle can cause its exhaust pipe to run at a lower idle temp. Your air cleaner box is on so you can’t blip the throttle and hear a tight intake popping or spitting back through its carburetor.
Additionally, a weak spark advancer will advance at a lower than desired rpm that can cause low rpm idle stability problems.
For instance, suppose the high idle rpm is near the worn advancer’s advance rpm or worse it’s fully advanced at the high engine idle speed. Now someone lowers the idle rpm adjuster just a little, but it’s enough the advancer retards the timing at the same time the new idle rpm is selected. Now since the engine died, do you readajust your idle mixture circuit to idle at desired 1100rpm. Or do you check to see if the timing is scattering about at the high idle speed and is dropping back to static time causing it to die when one barely changes the idle screw.
Arm chair mechanicing is difficult. You don’t know the person, their experience, or goals. A well tuned and timed engine will easily idle several rpms above or below the desired set point, especially if it’s stock. Usually or sometimes a high idle is merely masking the cause of the normal idle rpm instability. But, it’s an arm chair and its IPad’s tiny tiny speakers…👍
