Coolant through carbs?

[sceptre1963]

Hi,
I have a strange question, on my UK spec EN450 which I am rebuilding it has a pipe running to both carbs which looks like it was connected to the coolant circuit via a little hose tail on one of the head tubes and a fitting on the bottom radiator hose. Has anyone come across this? the picture shows the plpe which is connected to both carbs with a hose tail on each side at the bottom near the starter.

[bmwpowere36m3]

I haven't seen this on carburetors (other than aircraft), but on FI throttle bodies this is pretty standard. Coolant is routed through the throttle bodies to keep the plate from freezing stuck... which can happen when the temperature drops and the humidity is high.

[sceptre1963]

Do you think I should blank them off or connect them?

[bmwpowere36m3]

US-spec EN450s don't have it so I wouldn't be concerned with removing it. I did the same on my car ('98 M3) and I drive it yearround, no problems.

[zekkfett]

Personally, I'd leave it. It is designed to help the carb warm faster, to better atomize the fuel/air mixture; for better economy.

There are situations where the engine will be warm, but the carbs not yet warm enough to run correctly without a LITTLE choke to help get you going. Some motorcycle carbs have a special gasket between the carb and engine block to help this transfer of heat.

[eaglerider]

I have never seen anything like this....not even on pics of European EN400's (same as our EN450's). Has someone changed the carbs to something other than stock???