Xs engine fix up

[willyt]

Hi guys, I've pulled my engine out of my xs650 and taken the head and jugs off.
Main reason was oil leaks from the head gasket and the plug/bolts that hold in the cam chain guide.

Now I'm not too sure if it's worth going further. Usually with cars I would just go and replace everything but it seems hard to find a lot of parts (in New Zealand).

Think the carbon deposits don't look excessive and no obvious wear marks on the sleeves, still can see the hone marks. Rings don't look obviously worn and it wasn't smoking.

But it's all apart now so is it worth going through and replacing everything?
I'm not too keen on splitting the crank case open.

Any advice appreciated.

 

[peanut]

unless you are aware of any problems in the crankcase then my advice would be to leave well alone. Its a lot of work and if you haven't done it before there are lots of problems you could come across ..not to mention the huge expense.

What would you do for instance if you split the cases and found your crank bearings and gears showing signs of wear ? leave them as is or replace ? Have a look to see how much just those would cost to replace.

To make sure you don't have any further problems I'd recommend that you skim the jugs and head even if its just on a piece of wet and dry. That way you can spot any low spots that will cause oil or compression leaks

. Also it would pay to apply Threebond 1104 liquid cement to both the cylinders and head around the cam chain tunnel and around each of the stud holes to prevent any further leaks. One owner recently had to remove his head 3x times to stop a persistant oil leak .
Do replace both the camchain guides, its expensive but you'll not regret it .

I would hone the bores and replace the rings as they are cheap enough. Decoke , lap the valves and you should be good to go.

 

[TwoManyXS1Bs]

Three things in your pics seem odd.

- The pistons look different.
- The front camchain slipper looks like the early flat style.
- The standing oil in the right rear outer stud should have drained at the cylinder base drain hole.

See how much trouble pics can create?

 

[peanut]

Three things in your pics seem odd.

- The pistons look different.



See how much trouble pics can create?

you little hawkeye you

I completely missed that .
It looks like it might be a 'Bitsa' engine (bits of this and bits of that)
Just goes to show we shouldn't take anything for granted

 

[Michaelo]

Yep, they are different, burning differently too, replace them as well, rings, pins etc, Geoffs XS here in AU, can get parts from him, I've a set of standard rings as well, pm me Willy (fellow NZ'er) you can have them at cost + freight.....

 

[vincejames]

You guys blow my mind every time! Good eyes!

 

[willyt]

Thanks guys, yea it definitely is a bitsa. Was meant to be a 1978 but definitely not, frame and engine numbers different.
So this oil that's not draining? Blocked up drains we think?
Thanks heaps for the help.

 

[650Skull]

Your engine is an early XS2 engine, commonly called the 256 engine, 70-73. The differ from the 74-83 447 type. As an after thought, 447 internals, Crank, rod,and pistons can be installed into earlier 256 cases so before ordering any pistons check the rods, they will have 447 or 256 stamped on them. Cannot have 256 rods on a 447 crank or pistons or vise versa.

If you did split the cases then all parts should be checked for wear or defects and replaced as necessary. Can't do half measures as has been advised

Your manual has the specs to check for side play on the con-rods and small end play. This will give you an indication of the condition of the crank. Not a comprehensive one.

Hold off on Goef'sXS, he is expensive and good quality pistons and rings can be got for half his price from cruzinimage.

Store; http://stores.ebay.com/cruzinimage-...86787011&_sid=526414511&_trksid=p4634.c0.m322
Pistons; http://www.ebay.com/itm/70-73-YAMAH...ded-/161019611496?vxp=mtr&hash=item257d844968
Gasket set; http://www.ebay.com/itm/YAMAHA-XS65...282-/161946032006?vxp=mtr&hash=item25b4bc5786

Here is a review thread on the cruzinimage pistons.
http://www.xs650.com/threads/cheap-piston-sets-on-ebay.26971/

 

[willyt]

Thanks for that! That's lose prices are looking good.

 

[650Skull]

I added some info to the first paragraph in my post...........Check the internals just in case they have been changed over

 

[Michaelo]

Sorry for the bum steer Willy, Skull is right, cruzinimage is way cheaper....I thought there was some controversy over quality though, must go back and read the "cheap piston thread" thread. In any case, Skull has way more experience on these engines than I do .......and he lives just up the road.....ha!

 

[willyt]

Cheers they have 256 stamped on them

 

[TwoManyXS1Bs]

Reiterating what 650Skull has posted, it appears that your frame serial number shows an early 1971 XS1B, and your engine serial number shows a 1972 XS2. Back who-knows-when, a variety of work was done on this bike, with some intermixing of period parts. There were some significant engine changes during the 70-73 run. These engines are referred to as '256' engines, and some parts interchangeability can be tolerated, and some not. An example is the camchain tensioner system, consisting of a front slipper, middle guideblock, and rear tensioner. The 256 engines used either a type 'A' system or a type 'B' system, and all parts must match their respective system.

We could speculate as to what happened back then, maybe someone used the 71 frame number to select engine parts, maybe someone couldn't get the proper parts and used what they could, maybe someone needed to clear-out old inventory, maybe a glom of engine parts were laying around and it was assembled from the pile, who knows.

Now, I don't know if you're a perfectionist, or a "just get by" kinda guy, but my suspicious nature would make me want to tear it down, confirm, and inspect every single part.

That said, I'd recommend downloading the 71 and 72 parts and service manuals from this site:

https://thexscafedotcom.wordpress.com/tag/1971/
https://thexscafedotcom.wordpress.com/tag/1972/

The 70-73 service bulletins thread has an engine change chronology at the end.

http://www.xs650.com/threads/yamaha-xs1-xs1b-xs2-tx650-tech-bulletins-service-data-brochures.31022/

There were a minimum of three different piston types used in these early engines, compression ratio changes, and it looks as if you have a mismatched set. The CruzinImage piston set will work fine if you want to go that route.

The fact that your engine seemed to run fine is both good news and bad news. Good, in that whatever mismatch is in there is tolerable. Bad, in that this could lead to complacency, and fool you into allowing a mismatch condition. But, not to worry, this is a great forum, with dozens of eyeballs at the ready to help...

 

[willyt]

I was looking for a project so brought a cheap one in pretty rough condition so I've got what I paid for really.
So whoever has put this together has done a rubbish job, no wonder it leaks oil. I think it has been sitting in parts for some time as there is some rust evident on a few parts and there are scratch marks from I'm guessing trying to clean off old gaskets.

I am so stoked on this forum site! So much gold info on here and you guys know a lot.

I'm a little snowed under at the moment so the engine is going to have to wait a few weeks before it gets much more attention.
How are you guys prepping the outside of your engines? I've read a bit about paining the engines leading to over heating so not keen on that. A friend has been vapour blasting engines and his look great. I have a cabinet sand blaster at work so considering carefully blasting the outside.

 

[TwoManyXS1Bs]

The fellows that have posted about "vapor blasting" have shown some remarkable pics.
I really like it.

Here's a couple threads with more info on the camchain tensioner systems:

http://www.xs650.com/threads/top-end-noise.39691/
http://www.xs650.com/threads/excessive-timing-chain-slack.42215/

 

[5twins]

Sand blasting is a bit "rough" for these alloy parts. Glass bead blasting is a better choice. But, and this is VERY important, you ABSOLUTELY must keep that stuff out of the internals. Only blast outside surfaces and block off all holes into the interior very well. Glass beads and bearings don't get along.

 

[willyt]

Because you guys seem to know so much and have eagle eyes I wonder if you can tell me what parts my Frankenstein looking bike has from what models.
I wonder if the rear swing arm and forks are of a later model ?

 

[TwoManyXS1Bs]

The only "XS" I see in there is the engine, frame, horn, and rear fender. I see a sliver of a swingarm, so I guess it has one. Not much to go on...

 

[5twins]

Yes, that thing is so changed around, I don't even know what I see. A little XS650 remains but most of the running gear is changed (wheels & forks).

 

[azman857]

I think the frame is KZ 750 with the rear fairing..