valve seals

[calgarychopper]

Question for the more experienced xs mechanics out there...

My engine has the Mikes shorter valve seals installed on the guides.I have a lot of white smoke coming out of the left side exhaust on every start-up.Let the bike sit and cool down and same thing.

It burns for a minute or two and goes away.Doesn't seem to smoke while riding.

I am suspecting an exhaust valve guide leak as the plug does not appear oil fouled.

Now for the million dollar question...can the seal be replaced without taking the engine back out of the frame???

John

 

[pa23driver]

i don't see any way of replacing valve seals without pulling the engine

 

[XSLeo]

Yes, it can be done. New seals, fresh build? How many miles on the engine? It may quit after a few hundred miles.
I have rolled the engine over till both valves are closed, fill the cylinder with 1/4 rope. Roll over engine untill it quits turning. The rope holds the valves closed. Now use a lever with a hole in the right place to allow you to press down on the spring retainer to pull the keepers out. Release the lever, pull springs, replace the seal, replace the springs, lever down the retainer, install the keepers.
Using compressed air works too.

 

[calgarychopper]

XSLeo

Thanks for the reply.Yes this is a new top end rebuild.Mikes 750 kit with a light port and polish.I used the new valve seals in the gasket kit.I have 150 miles on the engine now and the smoke on start-up is consistent.Burns for two minutes and clears up.The right cylinder burns clean.

I found some info on another forum where a guy made a tool out of a pipe coupling and used a bolt in the rocker arm to compress the spring.I have a lathe and milling machine at work so I can make one myself.I like your lever tool idea as well.I will take my bike to work and give either system a try.

Thank you
John

 

[XSLeo]

My 750 kit smokes just a bit on the right and a bit more on the left on start up. By the time I shut the choke off the right side has stopped and the left is barely smoking. By the time I gear up to ride the smoking is gone. I'm not worried about it. If it staryed smoking more than a few minutes I might worry.
On yours it may stop, ride it 1000 miles, then see how it smokes.

 

[Punkskalar]

I've tried that Pipe thing with no luck what so ever. I found it faster to just pull the engine and do it proper.

I've also had very bad luck with MikesXS shorter valve seals. I found a guy on Ebay that sells "Viton" valve seals and they are the jam!! Not shorter, but I machined my guides to work. They seal 100% better than the MikesXS ones. I used to feel bad about a little smoke on my bike, but now its a thousand times better...

 

[hein weijers]

Hello John,

The problem is almost certain the the oil scraper ring. The tension of the bronze spring in the oil scraper of the big bore set is to low. The problem is always on the LH cilinder because it gets more oil than the RH cilinder. As long the oil is cold, the ring cannot scrape it all off.
It is easy to stretch the bronze spring max 0,5 mm (0.02") in length to increase the tension on the oil scraper rings. Jerry van der Heiden, the specialist in Holland, recommends to increase the tension to a level that it takes a 5 kg (11 lb) load to push the piston in the oiled cilinder with only the oilscraper rings in place.
Maybe this link will help http://www.steffi-graf.ch/ look at "XS650" under "Nachspannen der Ölabstreifringe"

Hein

 

[XSLeo]

If he knows this is a problem why not use a better oil scraper ring in the kits? Then We wouldn't have to tear down an engine to fix the problem?

 

[calgarychopper]

Today I machined up a tool from a 1/2" steel pipe coupling and replaced the exhaust valve seal.It was basically a waste of time because the new one I installed on the rebuild was fine.It was a little tricky to do but not that hard.Only took a few hours.

I think I will swap out the oil for some synthetic 10w40 and see if its better.Pity I have to wait for spring now as we are all snowed in.

 

[hein weijers]

Don't ask me Leo I understood that if the spring tension is too high, the wear of the cilinder will increase. So the ring manifacturer will choose a low spring tension, too low in case of the XS left cilinder.

Hein

 

[XSLeo]

Calgary. It may have been a waste of time but how would you feel if you pulled the engine, pulled the head. And found out it was ok?

 

[BigBoreSwede]

Hello.

This seems to be a REAL problem and I´m curious about this "strech" method........but I don´t understand shit!!
Sorry guys, but it´s because of my knowledge in English. There must be some words here at the thread that I misunderstand. "Streching the spring"......I totally lost here.

Anyone who can explain in "idiot english"?

Thanks/BigBoreSwede

 

[calgarychopper]

Since replacing the seal I have replaced the 20w50 oil for 10w30 synthetic Lucas motorcycle oil.I have only ran the bike twice since then as we have a shite load of snow here.

I could tell right away it made a big difference.The first run was just to bring it up to temp-running in my shop.I waited a few days and fired it up again--this time there was no smoke from the left cyl.

I have the bike scheduled for the World of Wheels in a couple of weeks.I will run the bike a few more times in my shop this next week.

 

[XSLeo]

I saw some thing some where explaining how to stretch the oil ring.
On an oil ring you have three parts, two outer rings and a center ring. The center ring provides the pressure of the two outer ring against the cylinder walls.
There is a way to stretch this inner ring to provide more pressure. If you look at the center ring you will see it looks like a bunch of w's hooked together. If you can hold the ring and make the w's longer it, this makes the ring longer, this stretches the ring.
By stretching the ring it is larger in diameter, so it fits tighter in the cylinder and pushes the two outer rings against the cylinder walls harder. This should help the rings seal better.
Just looked at Hein's link that is the one I was thinking of, it's in German and my google translator won't translate it.

 

[BigBoreSwede]

Ohhh....shit. I´m totally stupid

I was so in to this valve stem seals that I did not realize it´s was all about the oil ring on the piston. Now all makes sense

So this thing streching the oil ring, is that something all of us 750 riders should do when putting the engine together?

"Calgarychopper"....is there anything you should think about changing from 20w50 to 10w30 synthetic?? I know the threads tend to get HUGE when it comes to oil and I don´t wanna go there.

/BigBoreSwede

 

[XSLeo]

I don't think the 10w30 is right to use. Most 10w30 oil have friction modifers to make it extra slippery. This lets cars get better milage.
The extra friction modifiers don't agrre with the clutch, the clutch will slip.
A 10w40 doesn't have the friction modifiers and the clutch will be ok with it.
One way to tell if an oil is ok with our clutches is to look at the back of the jug. It will have a JASO MA rating. This means the oil has been tested and found to work with wet clutches.

 

[calgarychopper]

The Lucas synthetic oil I am using is for air cooled motorcycles with wet clutches.

a few laps around my shop and two good burnouts later everything is looking good.

I will run it some more when I take it to theWorld of Wheels.