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Discussion Starter · #1 ·
Finally got my 400ex put back together. Stripped out one bolt on the valve cover (way before it even got close to the torque spec) but other than that it went ok. Starts and runs now (havent got a chance to ride, been putting wheel bearings in) , it smoked at first (replace valve guide seals) but cleared up right away. But I think I messed up on the exhaust gaskets? The top enbd rebuild kit came with two thick copper washers and I assumed those were it, but the heads had some carbon buildup or something very strong on the exhaust ports on the outside, maybe enough to keep it from sealing properly because now a lil bit of smoke comes out from the exhaust by the flange. Doesnt fly out, just looks like cigarette smoke. Did I use the wrong gaskets? Im sure it could change once I get it out and test drive it, just wanted to see what you guys thought first.
 

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Did you tighten the exhaust bolts up evenly? If so, it might quit smoking after you run it a little.
 

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Discussion Starter · #3 ·
Yeah I went back and forth when tightening, and they should be right at or around 25 ft lbs each. Im hoping it'll go away. What size main jet should I be running? I've got a 165 now, but with a HMF pipe, K&N filter, and no airbox lid I think I saw I should be running a 170? He also said it was bored out to 408 (I forgot to check when I had the head off) but he wasn't an honest guy. All I know is that its got a sleeve in it now.
 

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did you make sure that the old ones came off? they are usually mashed so flat and covered with carbon, it is easy to overlook them.
 

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Discussion Starter · #5 ·
Now that you mention it, I remember trying to get somethin off the exhaust ports that sounds like that, but the exhaust no longer leaks. It was just a drop or two of oil that fell on the pipe. The valve cover bolts arent torqued down, they wont even get halfway to the torque spec before they feel like theyre going to strip ( I say this because two of them did ), and oil is coming up through the head of one of the bolts. Ill throw some silicone on it and hopefully get it sealed up. Main problem now is that my motor still smokes at startup if its been sitting. Once warmed up it doesnt smoke and runs great though, so I dont know if I should mess with it again and risk stripping out more bolts or just live with it
 

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Finally got my 400ex put back together. Stripped out one bolt on the valve cover (way before it even got close to the torque spec) but other than that it went ok. Starts and runs now (havent got a chance to ride, been putting wheel bearings in) , it smoked at first (replace valve guide seals) but cleared up right away. But I think I messed up on the exhaust gaskets? The top enbd rebuild kit came with two thick copper washers and I assumed those were it, but the heads had some carbon buildup or something very strong on the exhaust ports on the outside, maybe enough to keep it from sealing properly because now a lil bit of smoke comes out from the exhaust by the flange. Doesnt fly out, just looks like cigarette smoke. Did I use the wrong gaskets? Im sure it could change once I get it out and test drive it, just wanted to see what you guys thought first.
i know your not going to like this..buttttt..if you don't drill out..and re-tap the valve cover bolt's that broke off..it wont ever seal right..as for the smoking problem..sounds like either your valve guide seals or your valve guide o-rings..yes..there is o-rings that should go on the valve guide steems...most ppl don't install these..because you have to remove the valve guide steems in order to put them on..i normally don't do this myself..it's too much of a pain to remove these. i would pull your rocker box back off..and re-check your valve guide seals ( these are easy to replace )..and while you have your rocker box off..drill out..and re-tap your valve cap bolt holes that broke off.
 

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Discussion Starter · #7 ·
I think your right. I let a friend who's in college to be a mechanic do it because he said he had alot of practice doin it and I had none, but I think he may have forgot to replace the o-rings at the bottom of the guide stem. Am I going to be alright running the motor like this for a lil while? I'm moving an hour away from home for school and wont have much time to ride it, let alone pull it apart.
 

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It shouldn't hurt it, just keep an eye on your oil level.
 

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if your asking if it will be ok by leaving the valve steem guide o-rings out..yeah..you should be fine..like helmut said..keep an eye on your oil level...only time i have ever seen ppl use the o-rings for valve jobs..is when you get a bent or broken valve steem..other than that..i don't ever use the o-rings for the valve steems when i do a top end job..as long as your valve steem guide seals are on the top of the valves..and on right..you should be good. if your valve guide steems are bent..well..your gonna have to remove them..and replace them..or you will burn alot of oil..loose compression..and worse..break a valve from your piston.
 

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Discussion Starter · #10 ·
Actually I took it out the other day after letting it sit a few days, and the smoke was nothing compared to what it had been. Maybe the new seals had to be "broken in" or somethin rather? I also put in a 175 jet instead of a 165 (studdered at full throttle) and now it runs a whole lot better, but I may jump it up to 180. Didnt have time to check the plugs and see if I was running rich or lean, but it hauls butt now.
 
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