LegendsRacer - Legends & Bandolero Racing Forum
LEGENDS => Engine Care & Tuning => Topic started by: 57legend on October 25, 2007, 03:06:08 pm
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New to legend racing, can someone tell me how to adjust the valves, or should I just take it to the engine shop?
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You do need to learn how to do it, because it is something that you must monitor in order to maintain peak performance. You will need a valve lash adjusting tool. Part number 35-3461 from http://www.motorcyclecarbs.com or just ask your local Yamaha dealer for an FJ1200 valve lash adjusting tool (aka bucket holder) Most folks agree that lash should be .004" to .006" (.101mm to .152mm) on the intake, and .006" to .008" (.152mm to .203mm) on the exhaust. You measure each cylinder with the tops of the lobes of the intake cam and the exhaust cam for that cylinder pointing 180° away from each other, NOT pointing up. You turn the cam lobes by turning the crankshaft with a wrench on the rotor nut back by the firewall. (remove spark plugs first!) There are a few components that set the lash. Just under the cam lobes are some little disks which are shims, situated and held in cups that cover the top of the valve. The cups are actually lash caps that hold the shims, and the shims come in different thicknesses. The shim thickness is usually etched on the underside of the disk and is expressed in millimeters . You change the shims to change the lash.
To begin, you will need to measure and record the lash at each valve, and right beside that, figure how much you need to adjust each one. It will simplify things later to take your measurments in millimeters, and most feeler gauges have both inches and millimeters etched on them. As you measure this, be sure to turn the lash cap cup so the little slot is positioned where you can pop out the shims later with a small screwdriver.
Beginning at cylinder 1 at athe firewall, make a list like this:
I1a E1a
I1b E1b
I2a E2a
I2b E2b
and so on...
For each valve where your lash is out of tolerance, you will need to remove the shim, and replace it with a shim of the right thickness to achieve proper valve lash. If you don't have a stockpile of lash shims, you will need to remove your existing shim and record the thickness in order calculate what shims you will need to order. You can get shims from any Yamaha dealer, but you may be able to swap some around so you don't have to buy as many. 2.15mm is about as thin as you will find. If you need thinner shims than that, you are probably in desparate need of a valve job.
Shims normally have their thickness etched onto their underside. It will have 275 or 2-75 or 2.75, but they all mean 2.75mm.
The lash adjusting tool is used to hold the lash cap cup down so you can rotate the cam lobe out of the way and pop out the shim.
To do this, rotate the crank until the valve needing adjustment is all the way open. Place the adjusting tool in between the outside wall of the cylinder head and the cam lobe and screw the little screw into the threaded hole on the valve cover gasket surface of the head to hold it into place. The goal is to keep the valve lash cap, or bucket depressed. You may have to slightly turn the cam away from the holder to get it to sit right on the bucket as you tighten the screw. Then turn the crank so the cam lobe moves away from the holder, and keep turning til you have enough clearance to pop out the shim.
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Thanks for the info. on the valve adjusting
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Tom, great info there but as everyone knows I need pics.....next time you do a valve adjustment take some pics if you can.
Later,
Al
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Yep, pics are really needed. I'll work on that. I should have some time this coming weekend, and I'll insert them into the post above.
Incidentally, the Hayes manual for the FJ1200 bike does a pretty good job of showing how to do this.
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Thanks Tom.
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My exhaust clearances were in range but I had several intakes that were under .004 in, coming in at .002 - .003. Is that OK being its on the intake side? Will this "loosen up" with age (motor has 8 races since last rebuild).
Thanks
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That is cutting it close on and on the tight side, I like to have mine on the looser side, we had a Yamaha shop do ours one time and they made them to tight and the engine went boom!!!!! Not to say your will however you might want to remeasure them or out a thinner shim in.
Mike.
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GADAWG
They will not loosen up. Chances are better that they will tighten up more as valves stretch and seats get beat into the head. Adjust them and keep an eye on it. You are losing power when you have too little lash.
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JMHO,
I tend to go somewhere in the middle. Although I do agree, that if you start out slightly on the tight side, it gives a little room for wear.
Steve
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Good point Tom. Hadn't thought about the valves stretching when heated.
When checked just before I bought the car the valve lash on mine was...
Intakes .004 - .006
Exhausts .007 - .010
Mike
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resurrecting an old thread.... I've got to do this for the first time, and ran across this article with pictures from a bike forum. Realize it isn't a step by step, but it was nice to see what I was in for before opening it up..... and I saw that someone else was also looking for some pics
http://forums.motorcyclistonline.com/70/8226494/mc-garage-maintenance/fj1200-valve-adjustment/index.html
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where do you turn the crank to turn the cam lobes? Looking at mine, I have an 8mm allen head bolt in the middle of the blue and red thing under where the yamaha cover once was. Will this center bolt turn the whole crank? Pulled the plugs and started to try to turn this, but got to thinking if I turn something wrong here the timing may go all off, and really don't want to cross that bridge.
Is that it?
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Sounds a lot easier.... I also put the car in gear (5th) and was able to just turn the car over by rotating the back tires while in gear, in 5th it was decent to be able to control where I needed it to get to in terms of the cams.
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(http://i274.photobucket.com/albums/jj261/Okiesnake/ValveLashPosition.jpg)
Picture of proper position to insert feeler gauge.
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It is often helpful to hear something explained more than one way.
Let’s say you measure a particular exhaust valve lash clearance to be .12 mm. You decide that you want it to be .20 mm. Therefore it is off by .08 mm (20-12).
You remove the existing shim and see that it has 273 printed on the underside. 273 means that it is 2.73 mm thick. You need a shim that is .08 mm thinner.
2.73 mm – .08 mm = 2.65 mm. You need to replace the old 273 shim with a 265 shim.
Remember, when you install the new shim to put the “265” on the bottom so that the cam does not wear off the “265”. If you forget, you will be mad at yourself next year when you can’t read the number!
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Do you adjust valve lash with the engine hot or cold?
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cold
Randy - RPM
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There is a rather good instructional video on youtube that showed exactly how to set vlave lash. I can't find it for the life of me, maybe someone a little more search savy then I am can find it. I think I seen it as a link on a website first.
Sorry I can't be of more help, but it's out there some where.
An area for these types of videos here in the forum would do us noobies a great bit of good.
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Here is the video. Senior members please advise if this is being done right. I acknowledge I know zero about these cars and I'm trying to learn.
Video is made by RRC
http://www.youtube.com/watch?v=zCa556ObEi8
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ok, I hope I didn't mess something up here.
Why is it so important to pull the plugs when checking valve lash?
I did not see the hinderance of leaving them in, like I said I hope I didnt mess something up.