rebuilding, when is enough?

[Dutchy]

Hi all, first post, first bike, first mechanical descision to make.
Recently aquired a 1980 xs650 special because I saw "punkskalar's" and "greatscott's" (gordon scott??) builds and thought... "i must have one!" amazing is all i can say.
ANYWAY, it's the start of a long journey and my first issue is the left hand side exhaust is pissing out smoke. tried riding it for a little while to maybe seat the rings. no dice. I have been told to do the rings and valve stem seals by friends. pistons by others. too many opinions to settle on one, so i figured i should get the top end rebuilt. good choice? my in-law told me if i get the top end rebuilt it will be too much for the bottom end and screw it up. so now im thinking shit.... full rebuild? or will the bottom end stand up to it? i have been quoted 2.5k for a full engine rebuild. (in melbourne australia btw) its that a little exxy? or not a bad deal? and if a rebuild is needed would it be worth going the 750 kit too? sorry for all the questions but Im new to this and trying to learn as much as possible and everyone i talk to around here isnt much help or they just say "i dunno, do what ya want" so don't hold back with any advice but please keep it as laymans terms as possible until i start to learn more mechanical speak.

cheers,
Dutchy.

P.s if there's anyone in Melb, Australia. is there a good shop/ mechanic for these bikes.? im having trouble finding anyone that will work on something older than 20 years.

 

[gentlemanjim]

My money is on valve stem seals - a simple and cheap fix. Go there first, build the bike of your dreams and at any time in the future you can do the total rebuild though I doubt you will ever need more than the top end, maybe clutch plates. That rebuild price is absolutley insane!

These guys should be a big help. http://www.xs650.org.au/

You not flooded out?

 

[pa23driver]

unless theres something wrong with the bottom end rebuilding the top end won't hurt it any.
i would do the following before making a decision
1) check the compression, it should be within the 130 - 150 psi range. if its out of compression try spraying some penetrating oil in there, let it sit, and check again in a few days
2) change the oil and look for black plastics bits or lots of aluminum dust. it is a sign of the front guide bar wearing badly

if you do decide to tear down the down the top end just get everything measured to see if it is within spec (pistons, bore, valves), lap the valves, new rings, gasket kit and you're on your way (assuming everything measures good)

the 750 kit will increase the cost in parts for a rebuild by almost double (so thats up to you)

have you considered working on the thing yourself? i imagine labor aint cheap over in australia and it really is an easy engine to work on - i had a lot of fun rebuilding mine

 

[Dutchy]

ha hah!!! put a smile on my face with your words of encouragement that its most likely a simple thing. fingers crossed. guys thanks heaps. i was 50/50 with working on it myself as this will be the first thing (mechanical wise) i will have touched. to be honest i was scared of maybe biting off too much... you know, pulling it apart and thinking... what have i just done!?
right hand side is 140 psi, left is around 35. so yeh that aint good.
will do all you suggested pa23driver. thanks alot. i might give it a crack myself. after all i have been watching alot of youtube videos. ha.
gentlemanjim, cheers im off to build the bike of my dreams but first... clutch plates? easy fix there or a pain?
and nah, not flooded out down here. that's a bit more up north. poor buggers. thanks for the link as well.

 

[jamesgs4]

start ignoring your in-law when it comes to bikes. rebuilding a top end will not damage the bottom end in any way at all.

 

[gentlemanjim]

Before you go for the top end, make sure that the cam chain is adjusted and that the valve adjusters on the low compression cylinder are not holding one of the valves from completely seating. Again it may just be a burned valve. Still not so major or pricey. If you've never did all things mechanical this engine is not for beginers. XS Aussie should point you in the right direction. What you doing up isn't it around 4:00 am there? I have some business associates in Perth, Chalres Friedlander of WTS fame.

 

[oldbiker]

hi guys i live in australia ,,,victoria,,,,, theres some great yamaha xs650 club members in australia .. that are a wiz.. on xs650/750/840 kits etc rephasing camming banging direct pull carbs etc.. you could try david taylor in baxter .he,s brilliant on these motors.. and he,s easy to talk to .. i think he,s got about 9 of xs650 .with various mods .. and he,s well known for doing a great job .. if you have the space its worth doing it yourself.. as bike shops usually quote 80-100 pr/hr and most of them do not like working on old bikes.. because they make alot more cash on standard electronic upgrades or services hooking up all the gagets... they can easily make 700 in a couple of hours servicing an r1 gsx1000 or a duke.. etc.. try doing it yourself you will get satisfaction and enjoyment from it not relying on bike shops all the spare s try mikesxs he,s grest and 4-10 day delivery to melbourne ... good luck regards oldbiker

 

[MB-Ian]

If you are on the west side of melbourne theres a little shop called Professional motorcycle tuning in airport west and the owner, Darrel, is very knowledgable on XS650, I counted 5 biked and engined he was working on when i visited a week ago.

I.

 

[Dutchy]

cheers again. more great advice will take all on board. It's 08:30 am here in melbourne. i work nights so almost time for bed anyways. thanks for all comments of possibilities, i still want to start doing a bit of work on this myself as half the reason i bought it but i might take it slowly as she goes.
oldbiker, cheers i will look into checking out dave taylor, would just be nice to learn a little bit off the experienced than just wing it. i did get a cafe seat / fork tubes and dampers from mikes to get the bike's RWC and was impresed with the turn around.
just glad to be hearing that a full rebuild or even full top end might needn't be the case.
Thanks again.

dutchy.

 

[Dutchy]

thanks MB-Ian, will look into it

 

[CDNTX650]

what color is your smoke? white? mine was so white it looked like a mosquito fogger...Stem seals were bad.

 

[Dutchy]

yes mate. white smoke. alot of people have said stem seals for sure... would that effect the low compression on the left side though? i wouldnt have a clue.

oh well... i rip it apart on tuesday so fingers crossed.
thanx again all for the replies. took that scary edge off what im about to do.

 

[gentlemanjim]

"would that effect the low compression on the left side though"?

Seals will have no effect on the low compression. My guess is a burned valve. Even bad rings will pump up a bit more if you squit some oil in there. I wish you well on this endeavor. If you are patient, take lots of pictures as you go along, follow the manual and have the appropriate tools you'll get her done! There's a boat load of willing help right here and don't forget those Aussie boys they are on top of this like white on rice.

GJ

 

[Downer]

hey guys im having the same issue on the left side also smoking and a little bit of oil in the exhaust pipe head and i tiny bit of oil behind the valve cover on the left side ive read a few other threads saying its the valve stem seals and how to change it without removing the head but going through the valve cover so my questions are do you think it could just be the seals? and is it a good idea just going through the valve cover? any other tools that i could make to compress the spring? im also not to confadent pulling the head yet i just got her running a couple weeks ago thanx in advance

 

[XSLeo]

The intake seal can cause oil burning in the engine. Engine vaccum pulls oil past the seal. Exhaust valve seals may leak into the exhaust while the engine is not running. While running exhaust pressure pushes oil up the valve, nor draw it in.
Oil around the valve adjusting cover may be a bad gasket on the cover.
Oil burning is more often the oil ring or bad head gasket or intake valve seal. The headgasket often blows from the cylinder into the cam chain tunnel. On the intake stroke oil is drawn in through the bad headgasket or intake valve seal and burned in the cylinder. A bad oil ring won't scrape the oil of the cylinder walls leaving oil to be burned.

 

[XSLeo]

Another thing about rebuilding, the quote you mentioned don't sound bad if they rebuild the crank as well as the top end. Half that price or more will be in labor. You can do what needs to be done and save most of that labor charge, and you will have the satisfaction of knowing you did it yourself.
The engine is not as complicated as some might suggest.
A good repair manual and lots of pics as you tear it down. Lots of zip lock bags for parts, labeled so you know what goes were.
Getting the engine out and the head off will tell you a lot about your engine. Once you have the head off, pull the valves and clean and inspect the valves and seats for wear. Often lapping the valves is all they need.
Taking the jugs and pistons to a machine shop to gets them measured up to see how they are is not to expensive. some places free if you have them do any work.
The repair book will give you the procedures to check the rods side play and side to side play. A check of the end play and run out on the crank is a good idea.
Once you get everything checked out then you can decide just what needs doing.
I like my 750 kit. More power less, vibes, no reduction in reliability, all good things.
It will cost more than a set of pistons and a bore job.
Good luck with however you do it. You will enjoy the bike however it gets done.