Fluid leaking from radiator cap

So, I purchased a new 2015 FZ1 last March and, since the manual specifies changing the coolant fluid every 4 years, I did it myself a couple of weeks ago. After I filled it the level in the reservoir was slightly over the max (or full) line.

On successive rides the level in the coolant level in the reservoir was dropping, and there were a couple of times there were small puddles after rides. There was also a little dried coolant at various places on the right side of the cowling, eng. etc. I didn't think anything of it until I noticed the reservoir was dry.

So I checked, and concluded that perhaps I did not seat the radiator cap properly. I reseated it carefully this time, filled the reservoir up to the max line, and then rode it to work this morning - a 65 mile commute.

At lunch I noticed that, once again, there was dried radiator fluid on the right side of the bike, and the fluid level in the reservoir had dropped a bit.

Engine temperatures have been in the normal range the whole time.

I'm assuming that, since this is a new bike, and the issues started at the same time I changed the radiator coolant, that I must have done something wrong - but I can't figure out what since it is a pretty straightforward operation.

Thanks -
 
Did you make sure there was no air trapped in the system? if there is air in there, it will exp[and when it heats up and force the coolant to escape through the overflow.

squeeze the radiator lines and they should be firm, if they are squishy, you have air in there.
 
Did you make sure there was no air trapped in the system? if there is air in there, it will exp[and when it heats up and force the coolant to escape through the overflow.

squeeze the radiator lines and they should be firm, if they are squishy, you have air in there.

Thanks - just went down to the garage and tried the hose coming from the bottom on the right side. Hard to rate squshiness - they were a bit squishy, but it took some effort to compress. I guess my follow up questions are:

1. When refilling the radiator in the future, how do you prevent air from getting entrapped, and

2. Assuming it is an air entrapment problem, at some point the air escapes and the problem goes away, right?
 
Did you follow this?

https://www.manualslib.com/manual/804564/Yamaha-Fz1-N.html?page=140

also is there muck around the cap? make sure it is clean and seals well.

I'll check the link later - thanks. I do have the service manual and followed it as best I can recall but it never hurts to recheck.

As for cleanliness - I'll have the cowling off this weekend for other reasons and will check the neck where the cap sits. Again, due to the newness of the bike (now w/slightly over 4K miles) I don't think that will be an issue -

And for the last two commutes of 65 miles/ea the problem seems to have greatly diminished - so I'm inclined to favor your earlier theory about air getting trapped in the radiator when I refilled it.
 
I never fill the reservoir more than half way between max & min [2008] otherwise it will lose water out of overflow when hot ,this happens to a lot of vehicles , i only fill to max when engine is well & truly hot.
 
I never fill the reservoir more than half way between max & min [2008] otherwise it will lose water out of overflow when hot ,this happens to a lot of vehicles , i only fill to max when engine is well & truly hot.

Worth remembering the next time I do this. The problem seems to have gone away (touch wood), leading me to believe that it was air trapped in the system. When I did the initial fill through the radiator cap it overflowed well before I put in the coolant capacity stated in the manual (2.25l), also reinforcing the idea that there may have been air trapped in the radiator. Just wondering how to get around that the next time - I followed the manual sequence of "fill - warmup the engine - check level - refill if necessary" but it didn't seem to prevent the problem.
 
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