Let's talk top end's.

And I am back ladies and gentlemen.

'82 xj650j, 20100 miles on the ticker. 90psi dry 140psi wet holds steady across the board. We know what this means.

It's time for a topend! Rings, base gasket, head gasket, orings top and bottom, and valve guides/seals/shims.

Problem is the OEM parts are EXPENSIVE.

What are the options for aftermarket parts. eg. does cometic make gasket sets? does wiseco make ring sets? etc. third party vendors?

Let me hear what you guys and gals have to say. Parts, tips, procedures. anything you can say I want to hear. 8)

 

Have I been too forward?

 

I'm not sure about gaskets, other than what Len sells, but Wiseco used to make pistons and rings. They don't list them in their catalog anymore, but they have (or used to have, been a long time since I last inquired) a longstanding policy of making pistons and rings to order (at additional cost of course).

 

I have seen big bore sets on the bay for less than two bills.

 

There are parts out there from multiple suppliers. You have to search around to find the right price and part, but it can be done. I would start with XJ4Ever to see what he has and prices since you know it will be right. But you can also try out other options like cheapbay or..

http://www.bikebandit.com/houseofmotorc ... #sch225310

You may not need valve guides with that low of mileage, but you'll have to measure tolerance when you get in there. Look at the plus side when your done it will run like new! Maybe better.

 

20,000 miles? Just running in! Presume you mean its over the clock for the second time!

 

The problem with big bore kits is the extra stress on an old crank shaft.

 

Lack of information here. (Has it been standing still for 15 years? have you pulled it out of a lake?)
If it's only got 20100 miles on the clock - try to drive 500 miles and see what the compression is then.
100000 miles should be no problem for these engines.

 

+1 on pirok's stuck ring theory, if not the trying to ride it out plan...

If the mileage is correct and the bike's been standing a lot then the piston rings could well just be stuck, causing your low compression numbers. Or the valves could be hellish tight but I'd doubt that as the numers are even.

Before tearing the engine apart when it may not be worn, I'd personally use a good fogging oil & let it sit in the cylinders for a few days, occasionaly turning the motor & replacing it.

During this time I'd be checking and setting the valve clearances and cleaning the carbs, wet setting floats & bench syncing them so they're fit to at least start the motor up for the next step.

Then I'd replace the engine oil with cheap (but still wet clutch friendly mineral, max SG grade) oil and run the motor up to temperature then check the comps again with the engine hot, all plugs removed & TCI unplugged & throttle held open.

If you see any improvement then I'd concentrate on refurbishing the brakes, replacing tires etc to make the bike safe, syncing carbs and THEN try the ride it out method & you should see a steady improvement in compression as the miles rack up... Also change out the cheap oil for good quality mineral and new filter after around 50miles/2 hours of running, this is to flush out any crap loosened up by awakening the beast

 

You asked for opinions. So here's what I have to say...

I did a top end rebuild (1 new piston, 4 new OEM rings across the board, new gaskets, etc.) several years back on my 650 and honestly, I wouldn't do it again. The costs involved really put a burden on an early 20's aged guy like myself. Now if you're 50 or 60 years old with too much $$ to hold in your wallet, then have at it. I felt obligated to do the top end rebuild cause it was my first and only bike at the time. The fact of the matter is that there are plenty of other bikes out there in my opinion to toy around with. Do what your gut tells ya; there's plenty of help around here to help if you decide to tear it apart

 

http://www.ebay.com.au/itm/FOUR-New-Nos ... 1078wt_689

 

K-moe Im gonna get on the horn with wiseco and see what they have to say.

razz- thanks for the headsup, ill check into that but i dont think a big bore is really worth it with this bike.

mercman- I'll keep looking, I know bikebandit well. The parts are around but buying the individual OEM parts is cost prohibitive given the age and value of the bike. I'll spec it all before I buy any parts

adrian- im not sure, It does seem premature I know. Also thanks for the link.

orangenblack - I agree. No need to start hopping up an older engine like this placing additional stress on internal components

Pirok- i did suspect stuck rings it was sitting for about 10 years in a barn, I have solved this on other engines in the past with some marvel oil in the cylinders, like is stated below, seems to work better then the fogging oil, but this one has not freed up and does burn some oil! Might even be some mechanical damage causing it, won't know until I open it.

750EE29rbloke- see above, I'll try running it a bit more but I am thinking its just premature wear, I have made this determination through experience with many many engines. Also, carbs have already been through the ultrasonic with bowl gastets and needle valves replaced and fuel levels set and butterflys bench set. The engine does run. I checked over the valves too, if i recall one or too were a bit on the tight side but not anything crazy, cant remember the exact numbers, I'll wait to set them up for now. As for the brakes and tires, done and done.

Moellear- yeah i know what you mean, If I can't get costs down for parts the project will be scrapped and parted out, been there done that, gotta do it sometimes as painful as it can be.

 

No worries, it is possible that even if it isn't worn the rings may be stuck enough to not free up for some reason (just had to strip an engine for that reason, it had been "winterized" with something down the bores that gummed the rings up more and more as it ran, might've burnt off after a while but the guy broke the bike & I bought the motor as a spare)

I don't know how many miles you have put on it so far, but if it doesn't improve in 500 miles or so then you're probably right to be stripping it. If you do & the pistons/bores turn out OK, Wiseco do rings by size & that may be an option if you can't find a set for the specific bike.

I'll try and drag up the chart I used to "build" a set of correct sized rings for an old Suzuki before now (lists all different ring thicknesses/profiles/materials and bore sizes, find the set that matches the originals)

I had to use the old oil ring expanders when I "built" a set, as the set with correct top & middle rings had a thicker expander for the oil ring, the new oil scrapers were right though. That was probably a one off though as there's plenty of options.

EDIT-: here it is, click "additional accessories" on the right of the page & open the PDF file, scroll down past sleeves & 2t and you get the list of 4 stroke ring sets... http://www.wiseco.com/Catalogs/Motorcycle.aspx Think they start on page 5 of the PDF

 

Have you checked the valve clearance yet?

 

20,000 not that many miles have you checked the valve clearances yet? and if by chance they check good then the best thing to do is look for another motor much cheaper than all those parts and machine work

 

diggin that avatar

 

Waldo,

I'd recommend getting the valves properly in spec first off, since you'll at least have a known good head & cams then. If it does end up having to be stripped in the end and it turns out the bores & pistons are OK, it'd be quite cheap to get a set of rings from Wiseco (most expensive set would work out at $240, most would work out around half that).

 

Low mileage engines are 100-200$

Look around.

That's what I would do in an economical sense.

If you're doing it as a fun project, by all means go for it!

 

Buy a used engine, rebuild the original for fun. Then you will have a spare.

 

Forgot how cheap motorcycle bits are over there, $1-200 you'd be lucky to get an old smoker engine that price over here!