Oil out one exhaust lower rpm high load

[MrStubb]

I'm going to sound like a broken record. My thought since you said early in this thread there was oil in the intake is (insert drum roll) Valve stem seals and stem wear. With your engine under higher vacuum from idle and partial throttle. Oil will be sucked into the intake path. Then when opened up that bit of oil will be drawn thru and burned causing the fog.

 

[foppert]

So upon inspection of the head during a head gasket instillation it looks like i have oil dripping down the exhaust valve now. I already replaced the valve seal however, is there some way i could have screwed it up? Is there a way to test valve seals with the head removed? I think im going to replace the guide with one from a spare head i have around and order a new seal to go with it. Does anyone know if new guides are even sold anymore/where to get them? When i had the valves out i checked to see if i could move the valve around in the sleeve and compared them to each other but they all felt the same so i didn't think anything of it.

 

[foppert]

deleted to reduce redundancy

 

[bcware]

Sometimes the valve guides have sharp edges. I usually smooth them down with sandpaper if they feel sharp and use a LOT of oil to lube the seals before installing them. The bottom line is, yes, you can screw up the install by damaging the seal. It's not as difficult to do as you'd think.

Replace the leaking seal again, don't bother trying to test it; they are cheap and I am not sure it is possible to test anyway. Excess oil on the valve should be evidence enough, but it is also possible that there is too much play in the guide.

Hopefully you put each valve back on the same side of the engine it came from originally.

In regard to the guides:

You'll want a machine shop to work on the guides; they'll bore them out and sleeve them. Typically they aren't replaced. Last I checked it wasn't terribly expensive to do. I'm not sure what is involved on the valve side of the job or whether they can fix your existing valves or whether they'd have to be replaced, but I think you can keep them.

 

[MrStubb]

There is a process where the Valve guides are knurled and then re bored to size. I wouldn't suggest that. I would prefer they get bored about .060 oversize and then bronze guides pressed in and bored to size. Had this done on my 71 GM 350 along with a 3 angle valve job. Worked amazingly well and at that time it was only 300 for the whole job. Good bronze guides will out last the lower end since they're a bearing surface and operating in a hopefully well oiled area. My machine shop even used my old valves since there was so little wear.

 

[bcware]

That's cheap; assuming only 2 valves per cylinder puts the price at about 37.50 per cylinder.

The only thing I am not sure of is if an old valve could be shaped or reduced in size if it isn't perfectly straight. I know there is something done to the stems to make them harder than normal.

 

[Scorpio1963]

I would never have valve quides knurled,its been found that knurling doesn't last and causes more bad than good in the long run.Having been a mechanic most of my life I would just have new guides inserted and only use knurling as a last resort.

 

[xschris]

Valve guides are still around for these bikes for about $20 each. Just replace with new ones and be done with it

 

[foppert]

Can you link to where they are available? I remember seeing them for sale for that much but i cannot for the life of me remember where i saw them for sale.

 

[bcware]

Valve guides are still around for these bikes for about $20 each. Just replace with new ones and be done with it

Can you use a new guide with an old valve? Or would this accelerate wear like mixing a new chain with an old sprocket?

 

[xschris]

If the stem is still in spec. The valves are harder than the guides and should not wear as fast.

 

[MrStubb]

We built the 350 in around 1979 or 80. And the heads & block work were the most expensive. We assembled the whole engine our selves in the middle of winter in an uninsulated garage with a torpedo heater. Not the best idea but we did have one of the quickest 71 Monte Carlo's in the neighborhood. It was the wife's daily driver for 3 years. She loved dusting that little Datsun 280 Z down the freeway ramp. Never should have sold that car.

 

[xschris]

Can you link to where they are available? I remember seeing them for sale for that much but i cannot for the life of me remember where i saw them for sale.

http://www.ebay.com/itm/1976-99-YAM...Parts_Accessories&hash=item2c758401d7&vxp=mtr Here is one on ebay. If you type in the parts number you can get a lot more. These where used on a lot of bikes so many are still around

 

[foppert]

http://www.ebay.com/itm/1976-99-YAMA...8401d7&vxp=mtr

Aren't those the first oversize which would only increase my problem?

 

[xschris]

4H7-11133-11 and 4H7-11133-10 are the part numbers given for it and should be the same part. Check with yamaha for sure but there should only be one size for these.

 

[xschris]

http://www.ebay.com/itm/1976-99-YAMA...8401d7&vxp=mtr

Aren't those the first oversize which would only increase my problem?

An oversize would mean the I.D. of the guide is smaller than stock witch would take up and play in the stem from wear. Just like an oversize plane bearing is thicker than stock to take up play in the crank.

 

[foppert]

Cool, i ordered the stock ones, but might get the oversized ones just to have as a spare.

 

[foppert]

Ok so after replacing the head gasket and the guide and seal of the one valve that showed signs of oil i am still blowing as much smoke as i was before out the right side. I did notice that the right side exhaust gas seems significantly cooler than the left and the same goes for the headers. Should i just replace the rings and get another hone on the right side only?

I also forgot to mention i can now make the bike create bellowing smoke from the right side in neutral just by revving and holding it. Could there be any carb issue that causes this? i know they are not in perfect sync but they are not miles off, and i haven't played with the mixture screws more than half a turn.

 

[xschris]

How is the compression on the right side that smokes? You may need to go with oversize pistons. If the head has all been rebuilt that's all that is left. You should have replaced both the guides for the right side or all of them while you had it apart. Did you lap or re-seat the valves?

 

[Scorpio1963]

Chris you mentioned oversize pistons aren't those about impossible to find?