smoke house blues

I got my 400 out today and fired it up and it was smoking like a freight train but only for a couple of minutes and then it seemed to be fine. I put it away and tried again later after it had completly cooled down and it was smoking again for a few and then straightened out. I think it must be my rings what a nightmare I was loading up to go to Kentucky to race a harescrammble tommorow. Has anyone had these problems and/ or know exactly what the problem is? I also dented the roof of my new F150 today while waxing it. What a bummer today has been. The only good thing about it all is this just might be the push I need to spring for a 465 stroker. Thanks for all replies.

i dont know what causes it but mine does that from time to time. smokes bad for a minute or 2. i started turning the gas off when i quit riding and it fixed the problem

[400exJOE]

How long have the rings been in for? I wouldn't go dump all that money for the 465 yet. Just put new rings in. Its an afternoon job. As for the truck, a body shop should be able to pull it out w/ a suction cup, unless you creased the metal.

My motor only has maybe 15 to 20 hours on it scince I built a 426. What happened was I sucked water in the cylinder when my air boot came off the back of my carb. It was a muddy race that day I went for about a quarter lap before my motor wouldn't run over 1/4 throttle. I didn't know what was wrong so I finished my lap to get back to my truck. I then took the quad home power washed it and took it apart to find out what was wrong. I noticed it was the air boot and looked inside the carb to see if I sucked muddy water in it but it was perfectly clean inside so was the carb. So naturally I thought everything was OK. I fixed the boot fired it up and it ran great. I parked it back in the garage and when I got it out yesterday and fired it up it started easy but smoke was bellerin' out of her for about 2 minutes then it straightened right out and ran great for a few passes up and down the street. Later before I loaded up to go racing I thought it probably was just a little flooded or something earlier and once it cleaned out it was going to be good. When I started it to check if it was going to smoke again it smoked just as bad. I hate to rebuild when nothing is really wrong but if I ride anyway and it is bad rings then I'll have to have it sleeved and rebored. Still not sure what to do. I always turn off my gas when I leave it sitting so it can't be that. As for the dents in my truck they are small but I will see what a body shop can do. I am also afraid of my rod failing and coming apart. I raced my motor back when it was stock and had a habit of over reving it, which is what I hear causes rod failure.

[NJ300ex]

With that high of a compression i would be really worried of rod failure. Most engine builders say over 12:1 compression on a 400ex you should get a stronger rod. i reccomend the carillo rod. It can be purchased through sparks I belive.

[400exJOE]

OK, I am not the most knowledgable, but I will do my best. He's what I can tell you. On a hot engine, when water gets in the cylinder, It expands from the heat and can scar the cylinder wall. Next, dirt (from the mud) can also scar the cylinder and piston. My best guess is that you did some damage to your rings and cylinder wall and now you are getting blow-by and loosing some compresion and oil is gettting passt the rings and gettting burned. After the motor warms up (2 mins.) the rings probably expand enough to stop most of the blow-by, therefore stopping the oil consumption and burning. I would deffinatly take a look at your cylinder and piston. You may be able to get away with just honing it and buying new rings. It would deffinatly sux thoough if you have to bore the cylinder again because that means 440 and new sleeve. I would wait and see if anyone agrees with my hypothesis on this. I just don't want you to tare down your whole top-end because of my best guess. Get some other opinions first. Best of luck, JOE

[quadfamily]

Ummm, I think you may have been rubbing a little too hard when you were waxing your truck there buddy.........Is there any paint left? Just kidding around. The suction cup method may work like 400exJoe said. The roofs on pickups aren't very strong and it's tough to reach the middle especially if you have an extended cab or worse a crew cab. All it takes is to lean on it a littel bit too hard and you got a dent. The best part is nobody but you will probably ever see it!

I always thought if an engine smokes when you first started it up then it was badvalve stem seals( I know this is true with cars). And if it smoked after it was warmed up it was bad rings? Can someone enlighten me if I'm wrong? Thanks!

I'm pretty sure this doesn't apply here but something else that could cause a car engine to smoke after a few minutes of running is clogged oil return holes in the cylinder heads. But this is also usually accompanied with valve covers leaking pretty badly. I know because I have a truck that is doing this right now. Sorry I know this last part is probably off topic.

I talked to Mike at FDO who built my motor and he said it could either be a bad valve seal or the rings. But he said it sounds more like rings then valve seals. I could rering it and go on but I've rode my motor pretty hard in the past over reving it often when I needed that extra little bit and didn't wanna shift. He told me that some guy's say that rods break becuase of compression but that is not true its because of over reving your motor and stretching the wrist pin hole in your rod until it comes apart. Scince I know I've done this it worries me. If I have to take it apart to rering it I need to replace that rod too. If I go that far I might as well go ahead and stroke it cause I want to anyway. I hate to do it all right now though cause I just spent 2 grand on shocks, tires and various other racing stuff. I also d0on't want to ride a time bomb either. I'll probably just take it in and have Mike look at it and measure my wrist pin hole for wear and if it all checks out I'll just rering till next winter. I'll post back to let you know how it turned out. Keep the suggestions coming. Thanks