15 Head bolts?!?! I swear I only took out 14...

cscarroll · Full Member Joined: Oct 08, 2006 Posts: 112

Ok, perhaps I've officially lost my marbles, but I've got a mystery on my hands.

I'm ready to assemble my '74 head. The manual shows a tightening sequence for 15 headbolts, yet the parts schematic only shows 14. What's more, I triple checked, and I can verify that I only removed 14 originally. I can see the threaded hole for odd bolt, but it's obvious that bolt was not there on my motor. In the manual it's marked #11 in the tightening sequence and is found just above the cam chain tensioner between the carb mounts.

Does anyone know what's going on?!?!?!

Thanks in advance.

-C

xs1961

8x 10mm domed nuts
6x8mm bolts (2 front , 2 rear + 1 each side)
1x6mm bolt (rear below breather)
= 15

jimmythetrucker · Full Member Joined: Mar 12, 2008 Posts: 1283

This is from page 60 of my Clymer manual [begin quoted matter]

6. Replace [head] and tighten both bolts under the spark plug holes and the screw between the intake manifolds. It is a good idea to lightly screw both spark plugs in place at this time to keep foreign matter from falling into the combustion chambers. [end quoted matter]

I notice it tells me to replace the head and "tighten" (not torque) just those three little bolts. I don't think I'd tighten them more than finger tight with a 1/4" drive speed wrench, either (Don't want to ruin that new head gasket) -- at least until I start torquing the head bolts. Then I'd torque them in sequence, just as the diagram shows.

Summing up: It looks to me like there are two types of headbolts on the XS650. In the head-removal diagram on page 50, we see that bolts No. 1 through No. 8 form and hold a compression seal between the firing chambers and the cylinders. The remaining seven bolts -- No. 9 through No. 15 -- form and hold oil seals around areas such as the timing chain well and other points from which oil might leak.

If you removed only 14 and can't find a place to put No. 15 -- Well, I hate to say a thing like this but ARE YOU ABSOLUTELY 200 PERCENT POSITIVE CERTAIN that you didn't put the head gasket in backwards? I've pulled a boner like that exactly twice in my life (once on a 260 Ford V-8; once on a 345 IH V-8). No reason you shouldn't make a similar mistake. It's easy to do if you're in a hurry, if you don't look sharp at all times, if you don't know enough to double-check your own work.

One important element in doing this kind of work -- learn to be a mean-eyed SOB -- especially when you're looking at your own stuff.

There are 15 bolts and 15 holes in the manual. xs1961 counts 15 bolts and 15 holes. You say you got 15 holes and 14 bolts. I say -- Did you tear your engine down for an oil leak? And if you did, maybe you've finally found it. And it don't matter anyhow: If it was my engine, I'd have 15 bolts in those 15 holes when I put 'er together, and I'd make sure No. 15 is the correct length, the correct thread, and the correct hardness grade.

Remember: You're doin' this for yourself -- not for your ex-wife's boyfriend.

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

That little M6 bolt at the rear of the engine is sadly neglected. It's so hidden from view that many don't even know it exists. It's so hard to get to that it rarely gets re-torqued after a rebuild. It's very possible your original one fell out. I found the one on mine barely much more than finger tight when I tore my engine down.

xs1961

So true..
A mate of mine spent half an hour with a rawhide mallet & assorted screwdrivers trying to prise the head off his motor ..then I pointed out that little 6mm bolt he'd missed...Needless to say what condition the mating faces were left in.. Wink