First project - looking for some advice.

[Jame5on]

First post. I have been lurking and learning for about a year and finally decided it was time to get dirty.

Bought a crusty Ebay engine planning on rebuilding it.

its a 75 and seems to be complete. Not much other information given on ebay.

The exterior is completely oxidized and the carbon build up in the exhaust ports is thick and black.

I had planned on spending the time and working through a full overhaul with electrical upgrades.

however once I pulled the covers it seems to be in very good condition inside. The oil came out black but no metal in the oil or the upper filter or on the magnet.

Wondering if I should keep it together and clean it up and try to run it?

I can put the valve cover back on and get a compression tester... what other things could I check to help make the decision?

What suggestions do you have for cleaning it up if I keep it together? polish w/ polishing wheel on a die grinder? can I tape it and paint it while it is together?

Any help or suggestions are appreciated.

 

[TwoManyXS1Bs]

Welcome to the forum, Jame5on.

Lessee, first off there's some really dark oil staining in there. Either severe neglect, or lotsa ring blowby.

There's a scrape ring on the pressure plate.

Missing alternator brush block?

Just looking for clues:
Pull and inspect the sump filter.
Disassemble and check the oilpump.
Loosen the camchain adjuster, see how much slop in the camshaft rotation.

 

[Jame5on]

Thank. Will do

 

[Jame5on]

some more pics of my tear down

any observations are appreciated

twomanyxs1bs when you ask about the cam are you refering to left to right (seams tight) or should I get out an indicator and check for runout?

thanks in advance

 

[weekendrider]

You might consider checking the rotor ohm. This can be done in place.

Un-sticking the clutch plates.
If they come out as one bundle and hang together it would take a lot of kicking to free them.

JBWeld your sump filter in the weak spot. Use the search button keyword sump filter and by 5twins. He has posted the picture in several threads so it shouldn't take long to find one.

 

[Paul Sutton]

My first projects were two stroke RD250/350/400, then I jumped to car maintenance and then to an XS1b. I always made a plan as to what I wanted to achieve at the end. I suggest you first decide what to want to achieve. For example:

• Do you just want to understand what is in an XS engine and maybe use it as a donor for another bike? If yes then you may not be interested in replacing parts but just familiarize yourself with the technical specification e.g. tolerances of critical components and perhaps practice a few techniques like decoke and valve grind. This will give hours of fun.
• Do you want to use this engine in a two, three or four wheeled off road project? If this is the case then you might want to do a complete check of tolerances and replace all seals and possibly even go as far as a rebore if necessary.
• Do you want to put this engine in an XS frame to be ridden? Here you will need to decide how strict a parts replacement process you follow. Before considering a rebore you should get the bore measured because if it is within tolerance then you may just need to go for new rings.

If you know what you want to do then you can measure all the tolerances, cost things out and determine if it is worth spending. At the end of the day you will have learnt a lot about engines and will be well placed to take on a full bike project complete with a donor engine.

 

[fredintoon]

some more pics of my tear down
any observations are appreciated
thanks in advance
View attachment 89989

Hi Jame5on and welcome,
the photos tell me the motor is too crudded up to do a minimal fix to get it running, it'll need a total teardown & rebuild to run good.
Also the oil pump faces seem to be scored like a 78rpm record and the casting has what looks like nasty cracks in it.

 

[Jame5on]

1st - thank you for the input... really appreciated. I have been lurking for about a year and looking for a motor to play with.

Paul Sutton - right now I am tearing down an engine - in the future I will probably rebuild the engine. then maybe put it in a frame... one step at a time. I have worked on all of my cars and build the mountain bikes I ride from parts. If I am going to ride a bike, I want to have built it. so the short term goal is tearing this down in an organized manner with the goal of a running engine.

weekendrider - the clutch plates came out and are free from each other

Not sure how to tell if they are still good?

I will take the multimeter to the shop and check the alternator next time I go to work on it.

Fredintoon- I cleaned the inside of the case where the oil pump sits

do the grooves affect the function once I rebuild it? should I hunt for a new cover? I could machine it smooth - would this help?

The cracks almost looking like casting defects to me. they are not visible on the outside

in other news
stripped the head and the jugs

valves are caked w/ carbon

There are not machined rings on the exhaust valves or seats only on the intakes

I am assuming this is not ideal

Pistons are caked

ring measurements are between .356 and .405
one of the seal rings cracked and one of the right seal rings was discolored

not sure if this means anything.

after removing the rings I dry fit the piston into the sleeve and could only fit my smallest feeler gauge in with it.

looking forward to your thoughts

thank you

jame5on

 

[TwoManyXS1Bs]

...twomanyxs1bs when you ask about the cam are you refering to left to right (seams tight) or should I get out an indicator and check for runout?

Oh, it was just a quickie test of camchain stretch. Remove the tensioner and rotate the cam fore/aft to get an idea of how much the chain has stretched. Since you've broken it down this far, a new camchain is highly recommended anyway...

 

[Paul Sutton]

I was told years ago by the auto-mechanics teacher at school that you should heat rings up before trying to fit or remove them - not so hot you cannot touch them. Even hand temperature makes them less prone to snap. As with so many things I got this advice after I broke one.

 

[XSLeo]

Jame5on, How much riding time do you have? If none to not much perhaps starting with a complete running bike may be a better first time bike.
That way you can learn more about how an XS650 runs and rides.
Starting with just an engine, then trying to build as bike around it can be a daunting task.
Leo

 

[fredintoon]

Fredintoon- I cleaned the inside of the case where the oil pump sits
View attachment 90006
do the grooves affect the function once I rebuild it? should I hunt for a new cover? I could machine it smooth - would this help?
The cracks almost looking like casting defects to me. they are not visible on the outsideView attachment 90007

Hi Jame5on,
the oil pump parts distressed condition shows the motor's dreaded PO ran the thing on oil that had grit in it.
Remember, the XS650 motor don't have effective oil filters. The cooking oil strainers it has instead only stop the large chunks and let the grit slip right through.
Yet another reason for frequent oil changes.
I'd advise against machining those distressed pump gear faces because that will increase the gears end clearance and thus decrease the pump's efficiency.
I'd say lap them to a smoother finish with fine grinding paste on a lapping table.
And I hope you are right about those cracks actually being casting defects.

 

[Tomterrific]

I bought my junk XS and was delighted to see clean oil. Until l pulled the sump and found a half inch of black goop. Low compression too. I got it fired and 100 miles later the compression was up to spec and a quick oil change cleaned the rest of the engine. Now I have twice the miles as when I got the bike. A worn engine doesn't mean worn out unless it is broken. Use 20w-50.

Tom

 

[weekendrider]

Oil pump rotors and a cap could probably be sourced from breakers but how concerning is the base and what could be done to clean it up if anything?

 

[Paul Sutton]

Jame5on - I like your idea of building your own bikes. Should be quite easy to get a donor bike of some sought to take the XS engine. Like Tom said above, once everything is washed clean, inspected and measured up you may only need a few replacement parts.

 

[Jame5on]

I have never done this before and thought that the new guys might like to know... this took me 1 day