My first xs650

[Xs420special]

so this is my first xs. Ive had a gs that i hard tailed by myself for about 2 years but recently i aquired a 79 xs650sf for free! The downside? Every nut and bolt is removed and sitting in boxes. After sorting through ive laid everything out and it seems that everything is there to put a running motor together. As far as the motors main pieces and parts, most of it looks like its in good shape other then a little bit of grime from sitting exposed for so long.

The goal is to build a nice little bobber. I have a good idea what people may say but i want to hear some oppinions as far as motor upgrades. I plan on doing it all myself so i would like to keep it basic while still putting together a mean little machine.

 

[Uhlaf]

First of all, what year is your XS? There is a XS identification thread if you need a hand.

 

[fredintoon]

Hi Xs420 and welcome,
all apart, you say? Just the power unit or the frame too?
I'd say put it all back together and see if it runs. Then ride it around the neighborhood to see how you like it.
After that you can decide what you want to build it up into.

 

[TimeMachine]

"XS420" really, uh oh.. Good luck

 

[Xs420special]

First of all, what year is your XS? There is a XS identification thread if you need a hand.

Its a 79 sf model. I already know what i have. Im just looking for ideas as far as making this bike simple. Carb tuning, engine mods, ways to hide electrical, so on and so forth. Anything but rephasing (for now)

 

[Xs420special]

Hi Xs420 and welcome,
all apart, you say? Just the power unit or the frame too?
I'd say put it all back together and see if it runs. Then ride it around the neighborhood to see how you like it.
After that you can decide what you want to build it up into.

Every nut and bolt is pulled off. Tho some simple hardware is most likley missing. As for it running, im certian it will. The condition of this motor is pretty great. Pistions look awesome stock internals are 100%. The wiring and ignition stystem are beat but i wont fuss over that to much as its easily replaced. Just looking for tricks and tips to get it running better then it was the last time it did run. Such as small engine mods, diffrent products, ect. Trying to be creative!

 

[Xs420special]

"XS420" really, uh oh.. Good luck

I dont need luck i need constructive and creative advice. 419 and 421 were taken to btw

 

[5twins]

There are a few things you usually do when in one of these. Replace the valve guide seals, they're 30+ year old rubber. Usually the front cam chain guide needs replacing too, along with the cam chain. Check ring end gaps but 9 out of 10 times, they will be too big and need replacing. Check piston to cylinder clearance. If OK, just new rings will do. If not then a re-bore will be needed.

Check the valves for leaks. Usually you find some minor ones and that can be fixed by hand lapping the valves into the head. The exhausts are more prone to this. They run hotter and take more of a beating.

You can "port" the head. We're not talking a full race port job here, just a basic cleaning up of the rough factory castings. I think it helps and makes them run a little better.

 

[retiredgentleman]

Also with the engine opened up, it would be a good idea to measure the valve guides for wear. Use a dial indicator to measure this. Its in the Service Manual.

 

[fredintoon]

Every nut and bolt is pulled off. Tho some simple hardware is most likley missing. As for it running, im certian it will. The condition of this motor is pretty great. Pistions look awesome stock internals are 100%. The wiring and ignition stystem are beat but i wont fuss over that to much as its easily replaced. Just looking for tricks and tips to get it running better then it was the last time it did run. Such as small engine mods, diffrent products, ect. Trying to be creative!

Hi Xs420,
no you ain't. Certain, that is. You are certainly hopeful and may even be confident but you won't be certain until you get it running.
Like they said, replace the timing chain, it's guides and the valve seals with new ones while it's apart.
but I dunno about working on the head beyond cleaning the crud out.
There's those who REALLY know what they're doing and there's those who've made the engine run worse.

 

[Paul Sutton]

Do you have a photo of the parts all laid out? It would be nice to see what you started with and then compare it with the finished item some time down the line.

 

[Xs420special]

Hi Xs420,
no you ain't. Certain, that is. You are certainly hopeful and may even be confident but you won't be certain until you get it running.
Like they said, replace the timing chain, it's guides and the valve seals with new ones while it's apart.
but I dunno about working on the head beyond cleaning the crud out.
There's those who REALLY know what they're doing and there's those who've made the engine run worse.

Yes good point im not certian but i am fairly confident. I got it of my girlfriends dad. He took a video of it moments before he took it apart. The funny thing was that he broke it down for no reason other then to give his uncle a project, but it never happend and it ended up sitting. All mentioned parts will be replaced though. Im at work now but i will post some pics for you guys in the am when i get back to it.

 

[Xs420special]

Do you have a photo of the parts all laid out? It would be nice to see what you started with and then compare it with the finished item some time down the line.

Good idea man. I do have some pics. Ill post some when i get home to give an idea of what im working with.

 

[Xs420special]

There are a few things you usually do when in one of these. Replace the valve guide seals, they're 30+ year old rubber. Usually the front cam chain guide needs replacing too, along with the cam chain. Check ring end gaps but 9 out of 10 times, they will be too big and need replacing. Check piston to cylinder clearance. If OK, just new rings will do. If not then a re-bore will be needed.

Check the valves for leaks. Usually you find some minor ones and that can be fixed by hand lapping the valves into the head. The exhausts are more prone to this. They run hotter and take more of a beating.

You can "port" the head. We're not talking a full race port job here, just a basic cleaning up of the rough factory castings. I think it helps and makes them run a little better.

Yes thank you. This is good info right here. All of this will be looked into. As far as cleaning up the casting, will a dremmel with a small brass wheel do? Or is there another way?

 

[Exploding Coffin Emporium]

I dont need luck i need constructive and creative advice. 419 and 421 were taken to btw

Who cares if you smoke pot man lol I'm dying over here with the 419 and 421 taken thing, nothing wrong with a doober every now and then. Did you get manuals yet? That would be my first step. Fred hit it on the head, put it back together first and get it running as it is, then start customizing, don't put the cart before the horse you know.

 

[Paul Sutton]

Just read the comment above from ECE. I also agree, Fred is correct. Get it together and see how it feels and sounds. It is no big deal to lift the engine out later if you want to do certain modifications. Check the specification of everything as you go and make sure the bearings do not have surface rust from standing. I look forward to seeing this thread grow as your bike progresses.

 

[Xs420special]

Heres a few pics of where im starting. I figured working from the top down makes sense,since the jugs are at my friends house being checked out and cleaned up. My game plan is to remove the rockers, clean up real nice, and make sure there is no appartent ware / dammage, and then move on. New cam chain, cam chain guide, valves and valve guide seals are on the way as of 20 minutes ago. Thanks for the input so far guys

 

[schlakeandbake308]

looks like some bacon grease in that rocker top lol! But seriously, give that stuff a good cleaning. Ill give you my bit of advice... trust me, its not as valuable as many of the folks on here, so keep that in mind. Ive done a couple of these now and there are a few things I've picked up. On these motors, if the cam shaft surface of the rocker arms has any "divot" or "valley" at all, and isn't perfectly smooth, replace it. i have chased ticking all over the damn place and drove myself mad over it. Second, if youve already got the motor open, go 1st overbore and get clean walls and pistons that you know are good. there are some great machine shops in cleveland, one in particular that i can remember was over between the clinic and case western's campus, but i can't remember the name. shouldnt be more than a couple hundred for new pistons/rings and bore/honing. Third, the cam chain guide stopper... not the guide on the swinging arm attached with 4 screws, but the one that attached with two bolts in the cylinders. get it from boats.net. i have had two from mikesxs that stripped out their threads with me trying to torque them on. less than 2 lbs of torque broke them. one i used an epoxy, and thread repair to try to do a quick fix and if fell off into the motor when it was running. the OEM part is expensive, but its worth it.

Cam Chain Guide Stopper 256-12231-01-00

 

[schlakeandbake308]

http://www.boats.net/parts/detail/yamaha/Y-256-12231-01-00.html

 

[Xs420special]

http://www.boats.net/parts/detail/yamaha/Y-256-12231-01-00.html

Thanks for the link man. Ive already orderd a new cam chain guide so im good on that when it comes in. But surprisingly all of the crud on it came off very easily after a good soak and scrub. Pulled the rockers as well to examine them and clean behind them. All looks well in that department.