FE/FC coolant overflow issues.

went out today and was riding and on 2 seperate ocassions for no apparent reason I had coolant come out of the overflow tube. Not a lot but enough to run onto the exhaust and steam up and some dripped from the skid plate. Happened when I came to a stop with the bike still running. Fan didn.t kick on or nothing. Once I was going about 30 before I stopped and the other time about 50. Didn't happen for a while after the first time and after the second time I called it a day and rode back to my truck and it didn't happen at all during the ride back. Like I said I rode about 65 miles and stopped and slowed down to a stop probably 10 times and it only happened twice. Checked fluid and I barely lost any. A little low that was it. Bike never overheated, fan never kicked on. Anybody have any ideas?

Sounds like it was too full of fluid. Fluid should be at top of fins inside radiator anymore than that it may or may not spit some out. I would keep an eye on it and if it starts to dip below fins you may have an issue with fan but if it stays consistant above fins your good to go. I used to top our 15 fc450 off with fluid because of same issue when it was new and it finally found its happy place and stays just above fins so I leave it alone now

this was sudden. I hadn't added any coolant and this hasn't happened in the past. Have about 3300 miles on it.

Has the fan kicked on at all? Mite want to double check its working, my fan always kicks on at least once during a ride. Mine has steamed me a few times but usually on hot humid days when I'm just flogging it lol.

No the fan did not go on at all. It was 55 degrees out the day I rode. I let it idle for about 10 minutes and shut it off and still no fan.

Bad radiator cap.

Paw Paw

Would that make it puke before the fan kicks on?

Bad rad cap, or faulty thermo switch. I've read at least one other instance of the switch going bad. Check the switch, check the fan.

Could be any of the above, if you came to a sudden stop when this occurred it could of spit a bit of fluid out the overflow tube. Ours has done it on steep uphills and downhills before. IMHO let the bike idle for a while til its nice and hot and shut it off, let it heat soak for like 30 seconds and fire it back up and check for fan kicking on. The fan isn't that loud when its running so make sure you see it moving. Also if its the rad cap and its puking fluid the fan should be kicking on because the bike is running hot. Id ride it and see if it does it again, just keep and eye on the fluid level.

The cap can be bad and the fan not come on as it is not hot.

Paw Paw

How do you check the switch?

I highly recommend you run a high-pressure radiator cap I bought mine from Cycra. I also recommend upgrading to a propalyene glycol coolant. They have a much higher boiling point and then the Ethylene glycol coolant like the crap that comes stock in our bikes. In my situation my thermo switch that triggers the radiator cooling fan took a crap after about 1500 miles. I highly recommend bypassing your stock thermo switch with a toggle switch and running your fan manually. The fans on these bikes are extremely durable and it will not hurt anything if they run continuously. I wired a second fan to my left side radiator. both fans are manually controlled with the toggle switch I have had no problems with my bike getting hot now that I've made all these changes. I would have to say of all these upgrades wiring your existing fan to a manually controlled toggle switch will be the best upgrade you can make. like a said it's not going to hurt anything if you're a fan runs continuously. Good luck throttle on! My Fe 501s runs cool on even 110° days no problems! we put it to the task last summer

Replace it with a toggle switch! it will not hurt anything if your fan runs continuously!

Might have been the problem. Put a new cap on and ran the bike for 10 minutes and the fan kicked on and no overflow.

A bad radiator cap One that's not sealing properly may prevent pressure building up in the system but eventually the coolant should and will get hot. The thermo switch is exactly that. Not a pressure switch. Radiator caps are cheap though Can't hurt to replace it

Still keep an eye on your coolant overflow. You will actually probably smell coolant before you notice it otherwise as it drains onto the engine cases under the skid plate. I say this as a result of my experience. When my thermo switch Crapped out it did would fail intermittently thus make troubleshooting a nightmare. Finally I started my bike cold and let it warm up and idle until the cap opened and sent coolant out the overflow. The fan had not come on. The fan is controlled by a thermo switch not a pressure switch. Even with an improperly sealing cap your coolant will still come up to temperature eventually. Its probable that your fans thermo switch is just beginning to crap out and will eventually completely stop working. Good luck