2004 Honda 400ex engine/oil problem

[Khoranic]

hey guys, I have a 2004 400ex. I just installed a 426 big bore with new weisco piston/rings. The first start went good for about 10 seconds, it started right up with no hesitation, then it started blowing whitish blue smoke out the exhaust badly, after that it started blowing oil out of the exhaust. I think the o-ring at the bottom of the cylinder that sits around the sleeve ripped when installing. my engine also use to smoke a little when cold before the big bore kit then stop after warm, which was due to my valve seals, i also believe the valves came a little loose but not bad. The bike runs great, starts great, full compression, no power loss. i will blow through my entire oil reserve in maybe 30 minutes, thats how bad its shooting the oil out the exhaust. What do you think the issue could be?

[rappy97]

Did you do proper break in?

[Khoranic]

after first start I took it out to an open area and ran it for 15mins and got on it a little but not too bad, then shut it off and let it cool down.. then I started it again and ran for 30mins same thing.. by this time I ran out of oil. I used Rotella 15w40 for break in, not sure if that could cause any issues?

[rappy97]

Yeah, I'm thinking a small part of the problem was how it was broke in. On my motor, I let it just sit for 15 minutes idling, then let it sit until it's stone cold. Then let it idle for 30 minutes, then cool down. Then 45 minutes idling, then cool down. Then beat the crap out of it LOL.

[Khoranic]

hmm, I cant let mine idle like that.. it is air cooled and will over heat especially with the big bore if left idling too long.

[Khoranic]

I have bought new rings, gasket set and valve seals.. just waiting for it to get a little warmer out to install them. Im hoping that those will fix this issue..

[rappy97]

On my air cooled motors, I place 3-4 fans blowing on the motor to help cool it...

[jerod400ex]

400EX Extra oil cooler install - ATVConnection.com ATV Enthusiast Community

if u ever have problems overheating in general u might wanna check this out...... its a cheap way to improve running temp

[marioweldinginc]

Also add a Spal fan. wire it in to run when the motor is running.

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[jerod400ex]

Also add a Spal fan. wire it in to run when the motor is running.

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yes can do tht also:yes:........ so hows ur ex goin mario:wink:

[Khoranic]

I haven't really ran into it overheating besides letting it idle for like 10 minutes without any movement, but I was definatly thinking of going the spal fan route for extra piece of mind.

[marioweldinginc]

yes can do tht also:yes:........ so hows ur ex goin mario:wink:

Waitin on the motor, cleaning up the frame and plastics, changing all the bearings, collecting 450r shocks and having em revalved, straightening rear axle again. Adding some cooling tricks too! Im hoping all is back together by end of march but now it doesnt look it

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[marioweldinginc]

I haven't really ran into it overheating besides letting it idle for like 10 minutes without any movement, but I was definatly thinking of going the spal fan route for extra piece of mind.

I havent had the experience but of what Ive read so far its not so much of an overheating problem with the motor but alot of the time its the carb getting heatsoaked from the additional heat the motor puts out. A warm carb heats up incoming air and causes the bike to be down on power. Sometimes its confused with overheating. Whether its true or not im not sure but a heatsoaked carb was an absolute nono when I was dragracing back in the day. In between runs we would put bags of ice on the motor and put a box fan on top of that. How to solve this on the trail i havent figured out yet but I will. I have one solution which involves Co2. I need to figure this one out though.

So far my cooling tricks involve a fluidyne cooler, spal fan, scoops and maybe a Co2 or water setup. Nitrous is too expensive.

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