Valve adjustment questions

I've got an XJ650J, I think, based on the frame number starting with 5N8. The Clymer manual lists both intake and exhaust valve clearances as .16-.20mm for the 650J, but .10-.15 for intake and .16-.20 for other models.

The service manual I have says .10-.15 for intake and .16-.20 for exhaust.

Which is it? I'm more inclined to believe the service manual...

Also, I thought that 1982 models were YICS models, without the half-moon plastic inserts in the RH side of the head. Mine (1982 XJ650J according to the frame...) is non-yics and does have the half-moon plugs. Can somebody please straighten me out?

Finally, it looks like some of my exhaust valve clearances are between .203 and .229 mm (using standard feeler gauges). I think this is just barely too much and would cause the exhaust valves to not open far enough, and for too short a duration. What real-world symtoms would this exhibit? If I go down .05mm, then it would put me somewhere between .153 and .179, which seems on the tight side but it may be fine.... Thoughts?

Thanks! Aaron

 

The consensus is that the Haynes manual is wrong; they should be the same as all the other XJs, .10-.15mm intake; .16-.20mm exhaust.

The '82 650 Seca was a non-YICS motor; do you possibly have a "Maxim-ized" Seca? If the valve cover doesn't say YICS on it, it's not a YICS motor (although the YICS motors do have half-moon shaped plugs on the tight, they're part of the big gasket.)

Get a set of metric feeler gauges; your conversion is off somewhere. Valves are either in spec or not, if they're out, the next sized shim brings them in. Loose is better than tight, as they tighten up with wear.

 

OK, so upon further inspection, the serial number on the tranny starts with 4H7 - meaning the engine is from a 1980 XJ650G. That clears up that point, and I will use the .10-.15 mm for intake and .16-.20 mm for exhaust specs.

Here's the issue that I'm running into: I'm using a go/no-go approach, and on all but one of my exhaust valves, .203mm goes and .229mm does not go. I can't get any more accurate than that with the feeler gauges I have. Since the shims come in .05mm thickness increments, going one size UP to decrease the number would move me to a range between .153 and .179 If my measured range is on the tight side, I would lean more towards where they're at, but if the range is on the looser side, I would go up one. Here are my measurements:

1 int: .102-.127 (shim:265)
1 ex: .178-.203 (shim:265)
2 int: .102-.127 (shim:265)
2 ex: .203-.229 (shim:260)
3 int: .102-.127 (shim:265)
3 ex: .203-.229 (shim:265)
4 int: .064-.076 (shim:270)
4 ex: .203-.229 (shim:270)

So I think that I just need to fix intake #4 and put in a 2.65mm shim;
And possibly go the next size larger on 2, 3, and 4 exhaust - to a 265, 270, and 275 respectively.

Does that sound right? I guess I can install them as above then recheck on those exhaust valves and see where I'm at. I'm just afraid that by putting in thicker shims on those it'll go from a tiny bit loose to pretty tight.

Thanks,
Aaron

 

gimme a ninja any day. loosen the locknut, turn the screw, tighten the locknut.

why can't they ALL be like that.

 

Oh right, I forgot to mention: on the intake side, the specified range is .05mm. on the exhaust side, the specified range is .04mm. This is what I'm having a mental block on for some reason, because if you need to adjust minus .045mm to get into spec, then a plus .05mm shim will put you out at plus .005 over spec. Now that makes sense, but in my case say I'm at .209 on an exhaust valve. If I go one size bigger that puts me at .159 which is the tight edge of tight, and technically out of spec. Which is better, .209mm or .159mm?

Or maybe the question is, why is the exhaust valve clearance range smaller than the range of adjustability?

 

How about "Fitz was going from memory and should have looked at his own how-to?"

Intake is 0.11mm- 0.15mm, sorry.

If you have a choice between being almost too tight or almost too loose, go with loose, and keep an eye. Loose should tighten up on its own by the next adjustment unless there is a problem of some sort.

 

Actually you were probably just looking at my post that says .10-.15mm which is totally incorrect - I guess I just made that up or something =]

So anyway, do you think I should stay at the .203-.229 number for my exhaust valves(loose rather than tight)? Or, do I really need to get a more precise number before I make that decision?

Thanks for the input!!

 

Yes. Loose over tight. .203mm is fine.

http://www.amazon.com/Tools-2274-Metric ... B000COBUQM

About the only one commonly available, and available almost anywhere, even some Sears stores.

 

Sweet... got that K-D gauge set from napa. made it much easier to figure out where i was. got them all adjusted, now if i get some time to sync and colortune i should be in business...

 

Man, fired the bike up on my lunch today and it actually started right up with no choke! Amazing what having correct clearances can do for a guy/bike. It sounds like there is one extremely loud valve, so I will ride it around the neighborhood like this, then let it cool and recheck all the clearances to make sure there isn't one that's a touch too loose.

Then sync, tune, sync, tune and go!

 

When I first got my first XJ550, I thought it ran GREAT. Then I adjusted the valves; the first time I fired it up was to put it away and I accidentally pulled a wheelie in my jammies and slippers! Nearly messed myself.

A loud valve after adjust might just be it needs to get all oiled up again too. But do check once cooled.

Don't leave it on the sidestand, it will "tick."

 

Why is this? Does the oil have a hard time making it the tall side of the valvetrain when on the sidestand? Is it generally a bad thing to idle the bike on the sidestand?

 

It was a known "customer perception" issue; Yamaha issued a tech tip and a part number for new camshaft caps with slightly tighter tolerances to substitute if a customer really complained about it.

The tech tip also explained that it was simply customer satisfaction and had nothing to do with the reliable operation of the motor.

I believe it was because when parked on the sidestand when hot, the cams could "drift" downhill slightly and tick against the caps before they centered themselves back up. Yamaha didn't actually say.