Need motor advice for XJ650

Could anyone tell me whats all involved in redo'in the top end of a 1980 650, as far as a ring job on a motor that has over 40K+ on it. My motor got bumped, and it fell over while sitting on the floor and the valve cover flew off, in which a cam sprocket was cracked.

So i ended up with the head coming off to get to the chain, because i could'nt turn the motor over enough to find the link in the chain that comes off for chain removal.

I plan on do'in a valve job while the head is off, but the book state that the valve spring, guides and head bolts should be replaced because the head bolts are stretch bolts.

Not shore what to do at this point. (Please Advise)

 

The cam chain doesn't have a spring link, you just unbolt the sprockets, get a quote for all the parts you mentioned, then maybe look for a replacement mill.

 

What book are you using?

 

With that many miles, unless the cylinders are pristine, you're looking at probably having to go oversize on pistons and rings. So you'd have machine shop work, etc., (boring, probably resurfacing the head or cylinders) on top of a whopping bill for hard to find parts.

I gotta go with Wiz on this one; as common as they are it would probably be easier and cheaper just to find another motor (or parts bike) with half the miles on it.

 

Street, couple questions:

1. 1980 -- is your bike a 650 maxim or a 650 special?

2. where are you located?

I have a few engines around, I'm sure others do, too, so there's probably something close-ish to you.

Dave
in central NY

 

The Haynes Yamaha XJ650 & 750 Fours manual that i orderd from Chacal

 

Yeap a 180I Maxim 650, and i reside in Uniontown, PA.

 

Did your motor show signs of being worn? low compression blowing smoke anything? Does your HANEY (ref to Beverly Hillbilly's, Petticoat junction and Green Acres) manual show you how to measure all the wear points the cylinders valve guides valves springs, it can all be measured. Miles on these bikes does not really mean anything unless you have first hand knowledge say the bike belonged to my dad from new then there is no telling how many miles are really on it.

 

I took a compression test on all four cylinders, which where roughly 90psi cross the board. I did this test with the motor out of the frame, sitting on a piece of cardboard on the gerage floor. The valve cover just resting on the motor, which flew off when the motor got knocked over, and cracked one of the cam sprockets. While i was monkey'in around with the broken sprocket, the piece broke all the way off, i then unbolted the cams, which one thing lead to another and now i have the head removed. I guess my hole got dug a little to deep :roll: 8O

 

There's plenty of XJ'ers relatively near you down there. If you end up needing an engine, I'm about 4-5 hrs drive north of you......up where it's nice and cool. Only about 90 today, and I put on about 125 miles today for a PBTF Ride For Kids.

Dave Fox

 

Not shore what another engine wood cost me, but if i were a bett'in man, i'd say that the way the cylinder bore looks on this motor. I bet that i could get a way with a quick hone, throw some rings in it and keep on truckin.

Pulled the block (jug) off the pistons, removed one of the pistons from its rod, and every thing seems to look pretty good. Slid the piston in the cylinder bore with out the ring on it, and the piston ear was nice and tight in the bore, very little movement at all at the top of the piston.

 

Keep is posted on progress..........

Dave

 

yeah there was no ridge at the top of either of the cylinder bores, so i feel a new cross hatch with a quick hone, and a new set of rings should put some new life back into the motor.

 

There's Engines for sale on Ebay.
Breakers.
Junk Yards.
Salvage Company's.

Once you tally-up the Parts you'll need and include the Lower-end Parts, too; buying a Used Plant to "Get-moving" becomes a Time and Cost Saving alternative to repairing yours.

 

Point well taken there Mr RickCoMatic. but how cool would it be to have some brand new slugs in a 30yr old motor? I know it'll give ME a worm and fuzzy feeling besides i did spot an XJ650 motor on Ebay for $300, with 30K on it 8O . But the block and head that i have are in great shape, and i plan on a new set of pistons and rings, and having the head reworked, which should make the motor like new again.

Yeah i plan to do a project close to what Crath put together with his black hardtail which is why i got my bike. 8)

 

Stopped by the mechine shop that usually go to, and had the cylinder block and pistons checked out, and it looks like i can get by with a cylinder hone and a new set of rings, so im gonna go with it. :?: Does anybody know if the big long cylinder head and block bolts, must be swapped out for new one's, or can i get away with the old bolts :?:

 

You don't have to use New Cylinder Head Studs.

You "Should" use a New Head Gasket.

 

Just remember that if you build the top and don't reman the bottom as well you will now have a weak link!!!!
All that extra compression and new stuff on top will make her run like new, but the mains and rod brgs will be 30 yrs old!!
>

 

Since the head bolts i have can be reused, will i then have to apply the black sheathing that needs heat shrunk'en to the head studs, if so will i need to put sheathing on all the bolts, or just the short ones :?:

 

You don't need sheathing, either.
The Sheathing is added to the Engine Studs to prevent the Studs from hanging-up during the manufacturing process.
The speed-up the build.

Wire Brush the Studs Threads.
Before you Mount the Head ... Oil the Threads by toothbrushing on some light Oil.
Clean the Acorn Nuts and lightly Oil them too.

Incrementally, torque the Head in the Inside-out Opposite-X Pattern.
Run-it.
Let cool.
Re-torque to Specs.

 

Cool i guess i can find the torque specs in the book.

 

I agree you dont need the sheathing.

Keep this up and you'll be riding in no time!!

 

I here ya :roll: yeah me and this bikes got, what they would call a love hate relationship thing go'in on. Because i tried to get ridd of her atleast five times, and each time i decide to keep the bike, it gets torn farther apart. And the wife throws an F-bomb at me about puttin money into it. Guess i just cant let her go, (he he he). :roll:

 

The bike or the wife! 8O
:twisted: :twisted: :twisted:

Post some pics of the beast as she is now (the bike I mean) :roll:

 

You should have seen all the heck my wife raised when I broght my bike home...
It didn't end until she went for her 1st ride.
She thought she'd never see it.

She just didn't have the vision!!!!

 

I would if i knew how, not exactly the computer guru of the yr here

 

Yep, along with the tightening pattern. Don't forget the ones that are UNDER the head.

As far as posting pictures, you can do them as "attachments" but there's a really low limit and you end up having to delete older posts to allow new ones. It's better to get a Photobucket or other picture-hosting service account (free) and "imbed" them in your posts. Just be sure to resize to a civilized size, or use the service's "thumbnail" feature to link to full-sized pics.