Rode over 40 miles with no coolant!!!

I have an 06 YZ450 that I ran for about 40 miles with no coolant. I was on a ride recently and everything was going great. I was running the bike hard and coming around a corner and the rear started to slide out quick. I saved it barely and then the bike started to misfire badly. I first thought I must have broke something when I got sideways, but I did not over rev or anything. The bike just started to cut out and then it finally stalled. It was very hard to start, but it ran. It was fine down low, but once I got the RPM's up it was just popping and cutting out badly. I did manage to limp back about 20 miles just cruising in 2nd. I had to crank up the idle to prevent stalling, but it made it back.

Since the bike had 80-100 hours I was getting ready to refresh the top end (just for preventive measures). I warmed up the bike so I could drain the oil and the bike was running fine. I could run it hard without any of the issues I had on the last ride. Once I started the tear down I found out the coolant was completely dry! I figured I was going to see some piston or valve damage. I am running Amsoil Synthetic in it. I could not find any wear or damage at all! I was shocked that I could run it that hard without coolant and not cause any damage:excuseme: . My only guess to the cutting out and popping is that the head was getting so hot I was detonating the fuel from the head being so hot. Not sure if thats possible, but once I refreshed the top end it ran like a champ once again. I did find the O-ring was cracked on one of the inlet pipes and that caused the coolant loss, so at least that has an explanation.

Anyone know or have this happen to them? I am swearing by the Amsoil after this though. I think that may have saved me from having even more damage!

its a yamaha :busted:

its a yamaha :busted:

+1 :worthy:

+1 :busted:


My dad's 06 450F lost all of its coolant but it went onto the head pipe so it was obvios when it gave out. Replaced the radiator and filled the coolant and no probs since!


I ran my yamaha it175 so hot i burned a hole in the piston. I let it cool down and the aluminum covered the hole in the top of the piston. I went another ten miles before it died

now i just got a new piston and am going to install it this upcoming week

cool.. that was lucky

The same thing happened to me, it wasn't completely dry but close. Check your water pump seal, once it start to go you have keep a very close eye on your water level until you change it. If the seal is your problem.

I did have a bad seal and it was replaced. I think it may have went bad from the heat though as the bike was holding coolant just fine before this ride.

Since my top end refresh I have 14 hours on it with no real issues. Only thing is it did overheat once when I was in the mountains and trying to get past some ice and snow. It started to boil over a bit. Sure enough 40 miles later it ran it almost dry again. I have noticed once its low on coolant it will use it up. I am checking it every ride. No loss other then that one time.

I did order some Engine ICE from TT. I was running WaterWetter in it.

My only guess to the cutting out and popping is that the head was getting so hot I was detonating the fuel from the head being so hot. Not sure if thats possible...
That's probably a good guess. It's possible, that's why we have to run a certain octane rated fuel, so that it doesn't detonate from the heat.

James Toseland (Honda Superbike rider) lost his coolant in a crash just after the start of one of the 2007 races, he rode it as hard as normal and the bike made it to the finish line. The commentator suggested that maybe the water from the track(wet race) was keeping it cool, but I was still very surprised because they're full-on, high-strung race engines.

I lost most of my oil once :applause: on my 06 YZ450 because I only tightened one drain plug! Luckily it was the front plug that went missing because I'm guessing that the forward momentum of the bike kept the remaining oil towards the rear of the engine and kept it circulating. Whenever I slowed down I heard a screeching noise. I'm not sure how long the plug had been missing, but she's still going strong, I've done about 40HRS since that little drama.

Your lucky, about 7 years ago (before I went to four strokes) I was racing a YZ125 in the 125B class and had the radiators get filled up with mud. After the first two laps I noticed the bike would want to die if I backed off, so I held it wide open and just pulled in the clutch for corners. The bike finished the race (I even got third), then died. I found that eh piston had melted and when it cooled it turned my top end into one piece. I had to lift the jug up and cut the rod to get the engine apart.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now