'77 XS650 Cafe attempt

[nicholauslee]

Hello all,
As I just said in my recent post under the intro section, I'm new to this board, even though I've been stalking it for a while now. I just picked up a 77 Yamaha xs650 earlier in the week, which I plan on making into somewhat of a cafe racer-esque project.
Thought I'd post on here to get advice and knowledge as the build goes along.
First things first though, this bike smokes more than Don Draper!!! I got a service manual and am currently tearing the bike down to get the top end opened up to see what i'm dealing with.

 

[nicholauslee]

Re: Just starting my first build.

The bike as it was when I got it home.

 

[nicholauslee]

Re: Just starting my first build.

Bike as it was after a day.

 

[nicholauslee]

Re: '77 XS650 (first build)

I've been working on this quite a bit, and learning a lot in the last couple weeks. Just an update of my progress.
I'd like to do things a bit better, but I'm also trying to have everything done by spring/summer, which is very very soon.

 

[CarolinaBoy]

Re: '77 XS650 (first build)

Have you considered getting a sealed battery? It wouldn't have to sit so tall and could bring the height of that bump stop down.

 

[nicholauslee]

Re: '77 XS650 (first build)

Yeah, I've thought about it, and I'll probably do it within the year.
However, I'm working on a paper thin budget here, and the motor isn't even back up and running yet. So it's down the list of to-do's a little bit. I figure I'll make the seat, battery/electronics box, and fiberglass housing with the stuff I have for now. Since it'll be my first time messing with fiberglass, I'll probably want to redo it within 3-4 months anyway, and then I'll get a smaller sealed battery and make everything better, or... I'll just wait until winter and strip a bunch of the electronics stuff out anyway.
I'm learning as I go, so everything I do I'll want to redo better asap.

 

[nicholauslee]

Re: '77 XS650 (first build)

Just layed down some fiber glass. still have some sanding and smoothing out left, but it'll give you an idea of the shape so far.

 

[nicholauslee]

Re: '77 XS650 (first bike)

I've been doing a lot of little stuff lately, which is why I haven't been posting much lately.
Got the head (heads?) back from being worked on today and dropped off the cylinders. When I got home though, I noticed something a little odd. My piston rings don't seem to match up quite right. My cylinder is marked 964, which as I understand means it's 74.964mm. My compression ring (top ring) is marked with RN with no numbers, which if I understand correctly means it should be a standard bore ring. However, my wiper (middle) ring is marked R with the numbers 25 on the opposite side of the split, meaning it's a first oversize, I think. the expansion rings don't appear to have any markings on them at all that I can see however.
Just wondering if I'm confused about this and it makes sense to you guys, but it seems to me that at least one of those rings can't be quite right? Shouldn't they both be marked the same? As I said I dropped the cylinders off so I can't check the bore size on them until I get them back, probably later this week.
Also, here's how she looks so far.

 

[jchrisk1]

Re: '77 XS650 (piston ring question)

If you haven't already, go to xs650.com to find out about your rings. You will get a fast and accurate response. Those guys really know their stuff.

 

[nicholauslee]

Re: '77 XS650 (piston ring question)

thanks jchrisk1, I was a member for about 2 hours, next thing you know, I've got some new piston rings in the mail.

 

[nicholauslee]

Been working away at it. Starting to get put back together.

 

[Rossicle]

Looking great so far man! Nice job on the seat bump. The engine is looking nice and clean too!

 

[nicholauslee]

Finally!
XS650

 

[john83]

Hotness!

 

[nicholauslee]

couple little changes. got a few miles on it, but having some problems with fuel delivery i believe. i can usually make it about 10-15 miles and then it just wants to stall out going down the road. sometimes you can keep it running by just twisting the throttle all the way and it'll kick back in and be fine for about another 5-10 before the same thing happens. when it does die out though, you can kick it over within a minute or two and it starts right back up and it fine for about 10-15 miles again.
thinking it's either a vacuum being created and the gas isn't flowing. or a clogged filter, or something in that area anyway.

 

[nicholauslee]

Well the motor is back out. Started smoking really bad. Time to tear it back down and see what to do next. This thing has been more problems than I ever expected.
On the plus side, if I don't see the problem right away, it may be time for a 750 big bore kit. I mean if I'm going to be waiting all winter to get it on the road anyway, might as well do something to it. amirite?

 

[Rossicle]

Indeed! I've been thinking about doing the same thing! Sorry to hear you're having troubles.

 

[ProSimex]

Thats a shame your having problems again Bike looks good though. Ive been thinking big bore as well for a while now. Are those pipes straight through? I replaced the side cut pipes that came on mine and installed some decent reverse megaphones and the difference in torque was very noticeable. Do you have a vaccume petcock on there? that might be part of your fuel delivery problem. Also how are the carbs and did you check float level height. maby your leaning out your engine anf frying your rings with those pipes.

 

[nicholauslee]

These are the pipes I have on there now http://www.lowbrowcustoms.com/index.php?l=product_detail&p=793 although for a few days there I was running straight pipes. I had the spray painted black megaphones on there that were on it when i bought it, (in the video) but one day i went to start it and the baffle blew out one side. So I just pulled them off and waited for the shorty's to show up in the mail. Also they are non vacuum style petcocks.
I haven't gone through the carbs yet, I'm actually really trying to avoid that if possible, although I'm thinking it's not really avoidable at this point.


I did in fact just get the top end all pulled apart a couple days ago. the rings don't look bad from what I can see visually. However there was obviously some oil pouring in through one of the exhaust valves, and one valve had so much carbon it was not seating properly. I could probably try to throw new guide seals in there and clean the exhaust and combustion chamber out and try to get a couple rides in before winter, but I think I'll just take it slow, tear it right down and do it right over the course of the winter.

 

[ProSimex]

There is nothing scary about pulling carbs apart. The worst that will happen to you is you'll find your slide diaphrams are shot. Alls ya gotta do is order new ones from JBMindustries and yer set.