Anyone consider mounting fan on their carbs?

[tkent02]

,03mm should be fine, unless that was a while ago and it's gotten tighter since.

[Sandy]

I can't imagine taking 15 minutes to synchronize carburetors. Hell, five minutes is a stretch.

Agreed for sure. I hook up the gauges and run it until slightly warm, set a high idle and get everything ready before I pull the tank to check what needs adjusting. Then pull the tank, carb tops if VMs, restart and sync and most times I don't even have to hook up an auxiliary tank. Only if they're way off I may need a fan and extra fuel supply. If the engine is too hot you wouldn't be able to set your mixture correctly anyway so might as well shut it down for a while to cool off.

[mikerophone]

Ive occasionally toyed with the idea of mounting a small fan to blow on my oil cooler while in traffic. So far its never made it past an idle thought....

This thread has rapidly moved past the point where this is as relevant, but years ago I wired 2) 12V computer case fans to the tranny cooler on my 4Runner. When the A/T trans light kicked on trailering a heavy load up in the mountains during summer, I would switch them on and cool the trans down as soon as possible. I too have considered doing the same with the oil cooler on my 83 750ES.

Temp gauge doesn't seem accurate and now that it's getting to 100F in SLC already, note to self...I need to remedy that.

I'm no expert in tuning carbs either, I have the long screwdriver tool and even a fancy remote gas tank and a big fan, but not the carbtune. I just use 4 bottles with ATF in them connected to 1/8" air lines and man is it sensitive! I also can't do it in 15 minutes. One day I will have the carbtune and be able to bang them out like the pros do.

[John Park]

The valves clearances do close up as they get hotter. You might be onto something.

Have you measured this? Usually the aluminum between the camshaft and the valve seat expands more than the steel parts, except for when the exhaust valve gets really hot, and that's over long before the valve cover comes off.

The old rule was that if the motor was quiet and there was good compression when cold, the valves were probably close enough; if you had low compression that came up when the motor warmed then the valve[s] were too tight. In this case, idling shouldn't get the exhaust valve very hot, compared to high speed where it has so little seat time.

[tom203]

I think what could happen is that fuel boils in carbs and we get a bubble somewhere in the network of tubes and pipes which keeps it from spitting fuel into the airflow. At least that's my 25 cent theory.

My fuel injected jeep behaved like this when electric radiator fan failed to turn on ( faulty computer or sensor) - when shut down, residual heat boiled fuel in lines and it would not start till it cooled down implying that fuel pump could not repressure the lines due to residual gas vapor in system

[JTGS850GL]

The old rule was that if the motor was quiet and there was good compression when cold, the valves were probably close enough.

Great way to have burnt valves. Ole GS's don't take kindly to tight valves.

[John Park]

Great way to have burnt valves. Ole GS's don't take kindly to tight valves.

It was an old rule and not one of mine; but it implied that the clearances increased with temperature, which was the question. If they decreased with temperature rise, then they start out pretty small.

[Rob S.]

Shut the bike off. I do this with my car too

My '68 Camaro - no power steering, no power brakes and the cassette player worked without the key (also no A/C). In downhill traffic jams, it ran better with the engine off!