New to the fold, found a dismantled XS650SF engine

[cpjdekker]

Hello there, I'm Chris from Amsterdam, and recently found a nice dismantled engine lying around in a barn. The PO had it from someone else, who broke a piston on it. The top end, as well as the clutch and the sides came off, and I collected it as in the photo.

A bag of bolts and dirt.

But I have hope! I can do this. However I will probably need your help at points. I already ordered a gasket kit, and the workshop manual came in today. Started cleaning out the bolts, and I started rebuilding the clutch.

My previous experience with motorcycles is based around old Honda's. Did some top end rebuilds with CB750s' and I'm working on a total bigbore rebuild as well. I have a little loveshack called Tin Can Customs. It's a freehaven for folks who build motorcycles, where I share my knowledge, learn from others, and watch the new fanatics improve their skills.

While building on my own contraptions. Because that's what I like most, and I guess that's what we all have in common.

Good to be here! Hope to talk to you soon.

Regards, Chris Dekker

 

[cpjdekker]

And a question. The nummers on the pistons and their corresponding sizes confuse me. What do I have here? It is a 650S2 engine.

 

[TwoManyXS1Bs]

Hey, cpjdekker, welcome to the forum.
That number means the original size of the piston was 74.952 mm. Probably old/worn by now, so maybe not the actual size now.
Try forum search 'piston', follow the threads, you'll find more about this.
Also try google search (search window to the left), using '1972+XS2' to find more about your engine.
Also, observe 'similar threads' listing at bottom of these threads. Most of what you're looking for has already been posted, including links to downloadable manuals and parts lists.

Good luck!

 

[angus67]

interesting facebook.
So, is your shop like open to people that just need some space to work on something?
I had this idea that I rent a small once was gas station, two bay, and just open it to anyone that needed space, helping hand, needed tools, sign a waiver to prevent lawsuits, and if they needed to keep it there overnight, it would be safe, and locked up. Tried to pitch to a few people, but no go.
Don't worry about your new to u 650 engine. these are easy rebuilds. Since you don't have a bike to go with it, make a kick ass gocart, helicopter, trashcompactor, noise maker.,.,.,

 

[TwoManyXS1Bs]

.,.,.,backscratcher, lazyboy vibrator, powered toothbrush,.,.,.,.

Correction to the 1972 XS2, I misread the post, sorry. Instead, go to the 'tech' section, look up the engine VIN, and search on that. You might have an european 533 engine...

A shop owner I once worked for had a similar "Rent-a-Stall" idea. Large shop area with multiple rentable stalls, each with lift, bench, air & hose, community regular and factory tools, ...etc. Bankers didn't go for it...

 

[cpjdekker]

Thanks for the welcome! My engine is a Special II. What are their particular perks when it comes to restoring and performance? Anything I need to watch out for?

And where would I find new pistons for them? Seems Ebay is mostly selling for the earlier engines.

The concept for the Tin Can is kind of simple. I had to learn everything from the internet; noone taught me, because I didn't know anyone. At the Can everyone comes together and share the knowledge. People just swing by and rent the tools for a day (cheap), or stall their project for a longer period of time. New guys get to jump in and become familair with tuning and working on motorcycles, without the threshold of buying all the tools and what not. I already gathered that stuff over the years, so sharing is a logic next step. The workshop has pretty much everything. Mig, Tig, small lathe, drill, frame jig. It's not really making me money, I play even with the costs of my custom projects. So that's good.

And now the XS! I'm excited!

Should I make a new topic for the engine restoration? I can't find any specific SII engine threads...

 

[cpjdekker]

Okay, so, I started the restoration, and everything is going well as it looks like I have all the bolts I need. Except that I have to replace the connecting rod; it's bent at the piston pin. How could this have happened?

This means I'll have to take it apart. I'm going to fab a engine stand in the coming week and gather the parts needed. The gasket set is in, now for a new connecting rod.

It is the XS650 SF II engine, the 1979. Can I swap the connecting rods with a different engine? What is a good source for used parts? I don't need it brand new, just working.

 

[cpjdekker]

Read up today on the parts. Lots of stuff is interchangable. I'll be looking for a 447 connecting rod (the VIN reads 2F0-254787). But more likely I'll replace the entire crankshaft; I can see some damage at the sides.

The piston reads .952. The sleeve reads 004. And I guess the oil scrape ring is brown? What size overbore will I be looking at? I'm a uncertain.

 

[cpjdekker]

Read up today on the parts. Lots of stuff is interchangable. I'll be looking for a 447 connecting rod (the VIN reads 2F0-254787). But more likely I'll replace the entire crankshaft; I can see some damage at the sides.

The piston reads .952. The sleeve reads 004. And I guess the oil scrape ring is brown? What size overbore will I be looking at? I'm a uncertain.

Heers The ring

 

[XSLeo]

Ok. This is all in the repair manual but I'll be nice and explain it. As twomany said the piston is 74.952 in diameter. The 004 on the skleeve is the bore size, as in 75.004. Subtract the 74.952 from the 75.004 gives you the piston to cylinder clearance. That's .052 mm Right in the middle of the .050-.055 spec.
If you measure the piston front to back about 1/2 up from the bottom of the skirts and compare this to the original size you will get an idea of the wear on the piston. Measuring the bore size and comparing it to the oruginal will give you the idea of the wear on the cylinder.
Making the cylinder bore measurments can get tgricky without the proper tools andf skills. I suggest you take the cylinders and pistons to an engine machine shop. Most don't charge much if you let them think they will get to do the work.
I had a local car speed shop used by many of the local racers use. $35 per hole to get a second over bore.
Once you get the parts measured then you can decide just what needs to be done. On mine it only needed a first over but got the second over pistons at a real good price. $25 each for NOS second over pistons.
Get the pistons then take them and the cylinders to the shop and they will bore the cylinders to match the pistons.
If your engine is a US model it will have the 447 internals. If European it may have the 533 internals. The rods are marked on the side. As in 256 have the 256 on the rod, same with the 447 and 533 rods. You need the right pistons for the rods. The rods are all different lengths and the piston are different heights to match the rods.
Leo