New XS owner, finally!

shotgunjoe

shotgunjoe

XS650 Hunter
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Hey guys, nice forum, lots of good info.

I've been trying to get my hands on an XS650 for about 5 years... things just haven't lined up, till now.

I have a 78 special... it runs... smokes quite a bit at anything above idle. I can't tell you anything about its history, since I got it from a guy who got it from a guy. I did a compression test on it, it came in at 145 - 142 respectively. Compression seems too good for it to be rings, but what do I know. I'd hate to tear the engine apart only to find that it only needs valve stem seals.

I don't have a leak down tester, otherwise I'd have already done it. (nor do I have a shop compressor)

Any helpful suggestions? I've read as many old posts as I could find on the topic, most of which point to rings, but the compression readings were much lower than mine. (even though they were within acceptable limits)
 
Welcome aboard and congratulations on finally getting your bike.
Now.... What color smoke? Has it been sitting for a long time? Did you dump the old gas and put in fresh gas?
You sure it's not overfilled with oil? How is it running overall? Besides the things you mentioned the carbs could be dirty, floats set wrong, or out of sync
Do the basic setting of the cam chain, valve adjust, etc, before you start tearing into anything.
It sounds like you have already been doing your homework but just in case here are some good thread to start with:
http://www.xs650.com/forum/showthread.php?t=367
http://www.xs650.com/forum/showthread.php?t=2736
These and others are located in the TECH Section located at the very top of the page.
Otherwise lots of good people here to help you if you need it.
 
I don't know how long it may or may not have been sitting... the gas was fresh from the guy I got it from (he parts out these thing, shame). Oil level is perfect, and it looks very clean. Runs pretty darn good, a little stumble every couple minutes or so while idling. The smoke appears mostly grey with a hint of blue.

I had planned to disassemble carbs, record current settings, clean, and sync them. Valve adjustment is good, already checked. Also I read every one of the post in the tech section. :D

No gas in the oil. Petcocks... well, they flow when turned to 'PRI' and 'RES', even when no vacuum is present, but shut off when turned to ON.

Thanks for the quick replies gentlemen.

BTW, I also bought a 74 TX650 frame from the same guy, and will be building a bike for the wife with it.
 
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Another question for you guys... The wiring was a bit butchered when I got the bike. I have fixed most of it (eliminating the safety relay got the starter working again, and eliminating the reserve lighting device got the headlight working again), however one thing that has me a stumped. There was apparently a wiring failure at one point, which caused about a foot of the ground wire for the rectifier to be melted, PO decided to TAPE the wire and cut all the white wires... any GOOD reason why they might have done this? Could the original damage have been caused by an overcharging condition?
 
If the white wires are cut you have no charging system. You will have to go through the charging system methodically and get it back in working condition. No hard knowledge on this but I believe a common "death of charging system" on motorcycles is the owner running the bike with a bad battery. Battery is toast, owner jumps bike or starts it with a battery charger and then rides it, the poor alternator tries valiantly to a charge a battery that just soaks up juice endlessly, never taking a charge. The alternator finally overheats and dies because it is overworked. The factory manual and curly's charging guide both will give you tools to track down and fix the issues.

On the petcocks you need to pull a vacuum on the petcock vacuum line to be sure the diaphragm isn't shot. Doing this with your mouth is a bad idea! Putting on clear lines so you can see any gas leaking is a simple way to check. Leaking vacuum diaphragms are common on this year and will cause an extreme rich condition. Gas should not flow in the reserve position when the engine isn't running. It is likely the black rubber seal in the petcock is shot.
 
if it's smoking real bad i can guarantee it's valve stem seals. My 74 had awesome compression and super low miles....But smoked whte/grey so bad i was scared to ride it. Tension on the stem seals was non existant. New stem seals, and voila.
 
Awesome guys! Thanks. I will update after I have something further.

My Odometer reads 15673 miles... but could be wrong.

My RD350 PMA should be here within a few days... I will install that, new valve stem seals JIC, go through the carbs, and rebuild/replace petcock(s).
 
CDNTX650 said:
if it's smoking real bad i can guarantee it's valve stem seals. My 74 had awesome compression and super low miles....But smoked whte/grey so bad i was scared to ride it. Tension on the stem seals was non existant. New stem seals, and voila.
Click to expand...

When you did the valve stem seals, did you do it with the head on?

Is it possible to pull the top cover to do the valve stem seals without also replacing the head gasket?
 
fuel for the fire... so to speak.

Things I've changed visually... Added a set of vintage Inter-Am 'Tracker' style bars, flipped headlight mount, and lowered guage cluster. I hace a ratchet strap on the forks in the pics because I was testing how far to lower the forks.

Today I did a peg 'modification', which I documented in the Controls forum category.


P3280330.jpg

P3280331.jpg

P3280332.jpg
 
Made some progress on the motor. Got her out of the frame, pulled apart and inspected. Found out the engine is actually rebuilt, but the valves and exhaust ports were covered in oil... pretty good indication that the valve stem seals were damaged. Removed the head, and disassembled the valvetrain to find that the seals 'looked' new, but when I removed them the 2 exhaust valves were torn. All new seals (greased up for no tears) and gaskets installed, only to find that the gasket set doesn't come with new top sealing washers... grrr. Tried every bolt place within 20 miles and no one sells copper washer with the dimensions I need, so I am now waiting for the ones from Mikes XS.

Wish me luck!
 
Motor is back together, back in the bike. Runs great, no smoke!! WOO!

Made a few changes... Swapped everything over to the TX chassis. Installed a RZ350 PMA, and used a 85ish Virago reg/rec (4wires and works great). Still running points, and this bad boy is a 1 kicker. SO stoked. I also scored a set of 19/18 spokes in excellent condition...

Will post pics as soon as I can.
 

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