valve springs

[mack]

Ok guys, is there a tolerance for these springs. If not where are replacements available.

[bikerphil]

If the free length has decreased more than .080" (2mm), replace it. From the Yamaha OEM manual.

[mack]

bikerphil

Don't suppose you have picture of what a cooked valve looks like?

[DGXSER]

Easier thing might be for you to post a picture of yours and let the gang advise you on it.

[Ivan]

Mack,

In Wichita KS there is a place called "Atlas Spring and Axle". When I was working for Detroit Diesel there was an old German off brand diesel engine that someone brought in for a top end overhaul. Basically we had to have everything made new. Valves, guides and springs. Atlas was able to make the springs in house. If it can happen in Wichita KS, I'll bet it can happen in most large cities. Price may be a factor though.

Also, if you look at the Desmodromic valve write up on wiki, there is a very good explanation of valve float and how it is eliminated in modern engines. It may be possible to procure a progressively wound spring to raise the redline a touch on our ol' trusty XS11 engine.

[bikerphil]

Don't suppose you have picture of what a cooked valve looks like?

No I don't, I've never "cooked" one before. I just rely on my 30 yr. old springs and keep it under 10,000 R's.

Oh, you're talking valves now. Nope, just pics of bent ones.

[fredintoon]

Don't suppose you have picture of what a cooked valve looks like?

Hi Mack,
you gotta take the valve out to look at the seat area. No picture but if the seat is a full circle it'll most likely lap in good again. If the seat is any kind of D-shape it's cooked. If it's heart shaped it's absolutely f**ked.
Check the stem to guide clearance too, the numbers are in the book.

[mack]

thanx

Well if the tolerance is .080 " for the springs I may be OK. The worst reading I got off my calipers was .047" short from listed length. However these measurements could be somewhat arbitrary. I'm going to have a friend measure them with a different set of calipers and we'll compare. Prior to cleaning the valves and seats, it was obviuos that the carbon had turned to a concrete like substance and while there appeared to be a slight shiney ring around the valve seat, it was by no means a continuous seal throughout the valve shoulder. I've removed the hard crap and cleaned the valves and just dropped them in to see if they seat and all looks good now. I will still lap all of them but i'm going to put the old springs back in. After reassembly and a compression check, I plan on running the engine through a break in process and will drain out the oil after 500 miles. I'll pull the headers off and look into the exhaust ports and check to see if I have any wet oil in there again. If so then I'll be looking at the rings next winter and new springs for the valves. 18 years is a long time to sit, so I'm keeping and open mind.

[bikerphil]

After lapping the valves and reassembling, a good test is to place the head on the bench upside down and fill each combustion chamber with gas. Let it sit for 15 min. If the valves are all sealing good, the chambers will remain full. If a valve is leaking, well you know the rest. HTH

[dbeardslee]

The easiest way I've found to get the crud off the valves was from a tip on XS11. Put 'em in a drill press and hit them with an old hack saw blade with the teeth turned around backwards being careful not to hit the seating surface. The rounded part of the blade works well to get the stuff off the face of the valve. Takes about 30 seconds for each one. Spinning them at slow speed in the press will also tell you if you have any bent valves as there will be a very obvious wobble. The first time I did it I tried chemicals and elbow grease to clean them and it took forever. Also, after lapping the valves you'll want to make sure and check your valve clearances again in 6k miles. After lapping the gaps can close up fast as they wear in. My $.02

[trbig]

Just a tip... When I lapped my valves, I did it very lightly and it still changed my shim sizes by two sizes on most of the valves, so you won't be able to use the ones you had in there. Your best bet is to get at least a set of four and check one side at a time (Ex and Intake) of the thinnest shim you can find. If you just randomly throw one in and it happens to have no gap (Touches the cam lobe) then you have to take it apart again and have no guess as to what it will need yet.


Tod

[dbeardslee]

Just to add to what Tod said - when you're setting your clearances with the head off - which is easier IMHO than with it installed - make sure you only have one cam at a time in. You have to do a lot of turning of the cam shaft, and if they're both in you're liable to bend a valve if both shafts are in place. You might also want to use a couple short pieces of 2 X 4 to set the head on so the valves don't hit the surface the head is sitting on.

[Bigleo]

valve springs

Hi,
I replaced my springs last year. They are made by Kibblewhite Engineering, and are available from Dynoman.net.
Leo