Okay, I finally got the old girl back together yesterday....

After getting her back together, since we took the battery out of the her and put it in the 300 while this one was out of commission, we just pulled started her. So, my son went to pull start it and could barely spin it over due to the compression. I gave her a try and it fired off on my 1st pull and she sounds great. Can't wait to ride it again. I let her run about 30 minutes to get good and warm, then shut her off to cool. I'll do that a couple of more times today to help seat the rings. I did notice that the fan never kicked on while she was sitting there running, so I pulled the connection apart at the fan switch and jumped it. Then the fan came on as it should. Being that the bike is noisy anyway, I can't hear the fan running, so I'm not 100% sure if it was running when the head gasket blew.

This week, I'm going to install a water temperature gauge and a fan override switch on her just to be on the safe side.

Thanks for your help OPT, I really appreciate it. Below is a few pics of putting her back together.


Cylinder bored and ready to go.




New piston, rings, wrist pin and top bearing. I elected to go with the cast piston verses the forged piston due to this is a trail bike and I use it mainly for hunting.




Piston installed and now comes the fun part...




Finally, got her back together.




Time for some Kool-Aid....

 

Forgot to mention....

While it was running and before it got too hot, I took the 10mm head bolt out and let coolant flow out of the head to make sure all the air was out of the system. I then topped the radiator off again. So, hopefully all the air is out and I won't have anymore problems.

 

That was what I was gonna ask if you didn't mention it! A lot of people forget this important step and have over heating problems on the first start up! Good looking job...

 

Okay....I tried to crank the 400 this morning and she wouldn't fire off. I pulled the plug and it was soaked in fuel, so I installed a new plug (I reused the old plug as it was still firing after the head gasket blew) and she cranked first pull after.

I noticed that the coolant in the radiator was still full, but the coolant in the reservoir was very low. Being I keep the ATVs in the garage, I checked for water on the floor and it was dry. Now I'm wondering where the heck did it go.....hmmmm

I let her warm up (still didn't turn the fan on) for about 30 minutes and shut her down to cool. After about an hour, I noticed that the reservoir was getting low again. I also noticed that the overflow line by the radiator cap was extremely full of coolant. As soon as I opened up the rad cap, the coolant ran back into the reservoir. Now I'm puzzled as the radiator hose that attaches to the motor doesn't seem to be hard when I squeeze it, but the overflow line is.

I cranked it up again and rode it gently down the street and back (BTW....she sure does fill strong) and it runs really good. I shut her off, laid a piece of cardboard under it and after about 30 minutes, I noticed water on the cardboard. After inspection, it looks like water is dripping from where the hose that comes from the radiator down to the bottom of the motor on the clutch side goes into the frame area.

It was getting late, so I didn't pull the bottom inspection plate off yet, but where does this hose go? I'm thinking it should go to the water pump, but I thought it was on the other side of the motor.

Anyway, I'm thinking this was the main cause for the bike running out of coolant to start with and then when I added more coolant, I didn't purge it and it blew the gasket.

ALSO......

I have another question that's not related to the coolant. When I rode the bike, It will stall when I put it in reverse unless I use the override button. Before the head gasket change, it worked as designed.

Sorry for the long post, just trying to get this wrapped up.

 

I have been looking online for the lower radiator hose and it appears to run down to the bottom of the motor on the clutch side, then go under the motor to the water pump. Since the water is coming form the clutch side of the motor, before actually finding the problem, I'm leaning to a hole in the radiator hose. It's possibly where the hose lays up against the corner of the motor mount as it feels awful wet in that area.

Next thing will be finding a new hose. I found several used ones, but if I'm going through the trouble in replacing it, I don't want to install one that I may need to replace in a few months. If you have any suggestions where I can find a new hose, please let me know, but before I order it, I will make sure that is it.

 

I would replace with a used hose,could be worse than the one you have! If you must you can always just cut out the bad section,splice in a piece of metal tube and clamp both ends or buy a new hose (about $40). After you repair it,bleed the system again.Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

Today, I took the skid plate off the bottom of the bike and cleaned the mud and muck out form around the radiator hose, fired up the bike trying to see where the water is coming from. Being that I don't have a table to set the bike up on, I can't tell, but since I cleaned all that crap out from under there, it seems to leak more water then it did.

I'm going to try and pull the lower radiator hose off tomorrow. From looking at it, there doesn't look like there's much room to work with. Is there an easy way to get it out? I know it goes to the water pump, so does that mean I need to removed the recoil starter?

Any help will be grateful.

 

No,you don't have to pull the recoil. It's just a tight hose to get out of the frame. Once out clean it up and see if you can just repair the hose by cutting out the bad section,adding a metal or plastic tube and a couple clamps.Worth a try to help save you over $40 dollars on this preformed hose.

 

I went ahead and ordered the hose. I figured I'm this far into it, another $40 isn't going to kill me. Besides, I hate doing things twice and if it didn't work, I would be kicking myself. Hopefully I can get the hose off this afternoon and then get everything cleaned up so when the new hose gets here, the install will be a breeze.

 

Well, I finally found the culprit of this fiasco.

You can see where the hose rubbed against the motor mount and cut the protection sleeve.

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Through the sleeve and through the radiator hose.

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While I got one of the radiator hose off, I figured now would be a good time to do the water temperature mod.

This is what I used.

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I installed the Tee about 3" from the head in the top radiator hose. I was able to use a couple of cable ties and secured it to the frame rail under the gas tank.

I haven't mounted the gauge yet as I'm going to wait until I get the bike back together as I'm torn between the front fender or making a instrument panel and placing it up by the speedo. Total cost of the mod was about $35

Here is the gauge I'm using. Purchased at O'Reilly Auto Parts

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