Exhaust Valves

[Goinboardin]

Last winter I had a high idle issue pop up, and my sled was just generally not running quite right. Ended up in catastrophe, but one of the things I noticed after that was my exhaust valve looked like it was just starting to kiss the piston. Upon further inspection, yes it was definitely just starting to touch the piston. The shoulder on the valve that stops it from dropping too far into the cylinder was rounding off. Anyway, it never did break, and will not be run again. I just ordered two new SS valves (already have updated bellows and correct light weight springs). Here's a pic of the valve, surely just before failure.

Edit: those pictures suck. especially the right one.

 

[MORSNO]

Good post, another reason to do preventitive maintenance and give everything a good inspection.

 

[Kraven]

Last winter I had a high idle issue pop up, and my sled was just generally not running quite right. Ended up in catastrophe, but one of the things I noticed after that was my exhaust valve looked like it was just starting to kiss the piston. Upon further inspection, yes it was definitely just starting to touch the piston. The shoulder on the valve that stops it from dropping too far into the cylinder was rounding off. Anyway, it never did break, and will not be run again. I just ordered two new SS valves (already have updated bellows and correct light weight springs). Here's a pic of the valve, surely just before failure.

Edit: those pictures suck. especially the right one.

You need to check the piston to valve clearance even with the new exhaust valves as the "STOPS" in the jugs themselves become worn over time.

The only way to resolve that is:

1) Lightly grind the curved end of the exhaust valves

2) Buy new jugs

3) I believe MILLENNIUM TECHNOLOGIES (Wisconsin) rebuilds those contact stops (contact areas where the exhaust valve hits the "seat")

Hope this helps

 

[Flange509]

My 08 800 did this, wore down on the stops of the valves enough to gouge both pistons pretty good.Had 3k on the valves

 

[Goinboardin]

Good to know Millenium does that. I suppose they burn a bead in there then machine the stop flat again? New jugs are spendy, that would come out of the "new" sled fund...counterproductive.

I'll be sure to check clearances, if I do have an issue I think I'll just take a little off the valve. But my valve that looks OK (not rounded like the one in the above pic) has clearance with the piston, so I'm thinking my cylinder "seats" are OK.

For discussion's sake, it would also work to weld around the valve side of the stop on the valve stem, then put in the lathe and make the seat flat, but thicker, and would hold the valve "out" more. In either case, welding the ss valve (would take some care/experience to not warp it too) or the jug is not within my welding abilities and I don't have access to a TIG anyway. But I have experience with the grinder!

 

[Kraven]

Good to know Millenium does that. I suppose they burn a bead in there then machine the stop flat again? New jugs are spendy, that would come out of the "new" sled fund...counterproductive.

I'll be sure to check clearances, if I do have an issue I think I'll just take a little off the valve. But my valve that looks OK (not rounded like the one in the above pic) has clearance with the piston, so I'm thinking my cylinder "seats" are OK.

For discussion's sake, it would also work to weld around the valve side of the stop on the valve stem, then put in the lathe and make the seat flat, but thicker, and would hold the valve "out" more. In either case, welding the ss valve (would take some care/experience to not warp it too) or the jug is not within my welding abilities and I don't have access to a TIG anyway. But I have experience with the grinder!

PISTON TO VALVE CLEARANCE: As long as you have the ex. valve to piston clearance sounds like you're good to go.

WELDING THE EXHAUST VALVE: For those thinking about it, I wouldn't recommend welding the ex. valve (although in theory it would resolve issues and I noticed you said for discussion's sake) as that would weaken the valve and I'd hate to see your next post being a picture of a portion of the exhaust valve (what use to be one piece is now 2 or more pieces) being inside the cylinder.

Agree with you on the cost prohibitive replacement of the jugs, just sayin'

MILLENNIUM'S FIX: I have not yet seen a "rebuilt" set of cylinders, don't know if them weld them or drill and press a hardened 1/4" or so diameter "pin" as the new contact area?????

I had over 6400 miles on my 2002 EDGE-X 800 with no issues, although I did replace the aluminum exhaust valves with TITANIUM valves which were before the stainless became available.

BTW, How many miles on your sled?

 

[Goinboardin]

Good call on welding the valve, I bet they wouldn't last long doing that.
I should be between 3500-3800 miles.Original valves, but not original cylinders. Looking at my old jug, (last 3 cast #s are 202) the valve seat area looks nice and square. The bore is in good shape too, but the skirt is chunked off in 3 places, so now its a nice paper weight. So I would speculate that the aluminum valves wear more than the aluminum jug.

I hadn't thought about adding a press in piece, I'd be worried it could fall out since it wouldn't really have much to "bite" into. Welding the jug shouldn't hurt anything, they weld on them to fix deep scoring. Just have to hone/machine them straight if they were to warp at all.