350x Burning oil

[Fixer_Upper]

Hey guys, I haven’t been on the forum in a while. Unfortunately, I’ve run into another issue. I had to split the cases to get a little piece of metal out of the gears, and after I put it back together it started being a pain in the ass to start, and it would burn a little bit of oil when it would start. Note that I have a 400ex carb on it, it really helps the top end power. But since then the oil burning issue has gotten significantly worse. Worse to the point I won’t ride it because I’m afraid I will run out of oil while riding and cease it. Any input on what my issue may be? I haven’t tore it down yet, but I’m trying to figure out what my problem is. Granted, back when I did the top end, I put 3 new valves in it, with 2 new valve guides. I also put new piston rings in it and it still has excellent compression. One of the valve guides fit a tad loose, so I glued it in there. My guess is that that glue didn’t hold and oil is leaking into the cylinder. It runs really good though, no weird noises, nothing. Maybe a valve SEAL popped off? I’m not sure. Anyways, I will gladly take any input from anyone who has maybe seen this issue, or has heard of it.

[wonderboy]

I've personally never done it, but I assumed that valve guides must be pressed in. If you used some sort of a sealant or glue, that sounds to me like your leak path.

[Fixer_Upper]

I've personally never done it, but I assumed that valve guides must be pressed in. If you used some sort of a sealant or glue, that sounds to me like your leak path.

They usually do. I bought mine from Honda, they’re OEM but I had to ream out my holes that the guides go in. I actually had to buy 3 because the first one I tried to put in broke because the fit was so tight. However I think I accidentally reamed them out too much, hence why I had to glue them. Thanks!

[wonderboy]

So how loose was "loose"? Like it dropped in freely, or it only took half the force to press in? The other thing I'm thinking is that the aluminum head is gonna grow more than the steel guide, so even if a slightly tight fit at room temp, it's gonna only get looser when the engine is up to temp.

It may be worth checking at a machine shop that does head work and see if they can get generic valve guides that will match your dimensions, or maybe only need a bit of work to make fit.

[Fixer_Upper]

I believe it just dropped in. My only question would be why didn’t it do this prior to me splitting the cases? I suppose I should have specified, I tore the engine down twice. The first time I tore it down, I put the new rings, valves, valve guides, etc. in it. I then ran it for a while and a small piece of aluminum got caught in the gears, so I had to split the cases. I didn’t begin having the burning oil issue until directly after I put the engine back together the 2nd time. I’m also guessing the excess oil in the cylinder is the reason it’s so difficult to start too.

[wonderboy]

I see. I know you said compression is good, but maybe a ring got buggered up on the 2nd reassembly. It sucks that it was fine until the 2nd teardown... I honestly don't know that the valve guide would be resulting in you losing that much oil. My understanding is that it just gives you smoking on startup. It's not like oil is getting pumped right to the valve stem... it's just splash.

Without tearing into the top end for a 3rd time, it's gonna be tough to figure out. I don't think anything in the bottom end could be causing this. I guess check your stator cover to make sure it's not full of oil (the area where the flywheel spins). Pull the inspection covers and turn the flywheel over and see if its all wet with oil. If not leaking out onto the ground, it sure seems like it's gotta either be rings or valve guide.

[Dirtcrasher]

Where did the aluminum come from that got in the gears??

Valve guides are always a super tight fit, I warm the head and freeze the guide.

The only part you should ream is the guide itself after is been pressed in, if needed.

If you do a compression test, then pull the plug and drop a tbls of oil in there and it goes up, your rings are leaking. If it stays the same, you have a valve related issue.

Remember though, it may not leak compression with that valve guide being sloppy if the valve still seats well.

But, if you glued in a loose guide you will definitely have bigger issues down the road, that guide isn't providing the support it's suppose to.

Hopefully you didn't ruin the casting, although I could probably bore it and sleeve it with a new guide, lots of work thou.

You could have used cylindrical Loctite to hold the guide, that stuff is GREAT! Or maybe knurled it in a lathe before install, although not the best plan it should work....

[Fixer_Upper]

Where did the aluminum come from that got in the gears??

Valve guides are always a super tight fit, I warm the head and freeze the guide.

The only part you should ream is the guide itself after is been pressed in, if needed.

If you do a compression test, then pull the plug and drop a tbls of oil in there and it goes up, your rings are leaking. If it stays the same, you have a valve related issue.

Remember though, it may not leak compression with that valve guide being sloppy if the valve still seats well.

But, if you glued in a loose guide you will definitely have bigger issues down the road, that guide isn't providing the support it's suppose to.

Hopefully you didn't ruin the casting, although I could probably bore it and sleeve it with a new guide, lots of work thou.

You could have used cylindrical Loctite to hold the guide, that stuff is GREAT! Or maybe knurled it in a lathe before install, although not the best plan it should work....

So, back in the 90s, my dad stripped out the threads for the oil plug and they had to go up a size. That’s where my piece of aluminum came from. When they drilled it out, that small piece flew off inside the engine, and apparently it was lying in the bottom until it bounced up and into my gears. Thanks for all of the information though!