Dgoodsy's xs400 maintain/restore/build thread

I planned on taking the tach apart by cutting the bezel off and trying to see of I could find anything obviously amiss inside, this coming week sometime. I rode the bike around yesterday a little bit and the tach was acting lazy, but I took it for a drive this morning and the tach was back to functioning correctly. So I guess I won't disassemble the tach until it acts up more permanently, it seems good to go for now though!

I looked into my charging issue last week and while testing resistances at the alternator plugs I found some out of spec (open circuits). I traced the wires under the bike where they come out of the alternator cover and found then to be hanging lower than made me comfortable, and with some suspicious electrical tape. I pulled off the electrical tape and found 2 splices, one in a white wire and one in the green wire. One splice was broken and the other was loose, but I may have done that while pulling the electrical tape off. The splice "repair" wires were just twisted together and taped and were oily as heck.



I did my best to degrease the wires, restripped the existing wire and soldered in new wire. I shrink wrapped the repaired areas, then taped each wire bundle together and pulled them up closer to the engine.

I checked the resistances of the wires as per the Haynes manual but the wire colors on my bike for the alternator plugs don't match the manual. Haynes says to check resistance between the two green wires. As you can see from the picture, my wires in that bundle are green, blue, yellow and black. So I checked resistances between the 4 wires looking for something around 4k ohms and didn't find anything. However looking at the manual now I see that is says 4 ohm, not 4k ohm for the field coil. Doh!

I reconnected the plugs and started the engine to test battery voltage. I measured 13.3 ish volts with some revs, up from mid 12s prior to wire repairs. Voltage seemed to increase slightly with revs up to 5000rpm, only going up .2 or .3 volts from 2000 to 5000rpm. I will have to test again for 4 ohms across the field coil, anyone know for sure which quite colors I need to look for on my bike?

So measuring at the alternator plug I get ~4 ohms between green and black wires, and about the same between the blue and yellow wires. All other combinations are open circuits. I think that part is fine.

I tried to measure resistances/complete circuits at the rectifier as per the manual and can't get any complete circuits there. Between red and each of the three white wires I get open circuit no matter the orientation of my multimeter leads. I triple checked this because I wasn't sure how it would work like this. What's going on here? I thought this would mean the rectifier is toast and there would be no charging at all, but if you read on you will see that's not the case.

Measuring battery voltage while running I get ~12.3V at idle and ~12.8V @ 4000 rpm, and slooowly climbs to 13V if I hold the revs there for 5 seconds or more.

Before I quit tonight I took the headlight fuse out and measured battery bolts again. Without the fuse in I get 12.5V at idle and right up to 14.5V at 4000rpm. So does this mean I have a headlight issue? I have a 10amp fuse there so it can't be drawing any ridiculous current. Or is that a sign of a weak battery? I'm leaning towards the weak battery.

The multimeter might not put out enough voltage to break over the rectifier diodes.

As you kind of figured out, that's the field coil connector, not the alternator stator connections. The stator wires are the very worn white ones in your first picture.

I'd check them out before worrying about the headlight or anything else.

OK, that make sense with the rectifier, I won't worry about it until I have other reason to, it seems to be functioning.

I should take the stator cover off and check the wires in there I suppose. There was one broken wire under the bike that I repaired already, the others looked fine.

Rode my bike on the highway on a weekend trip, over 300kms on Friday, mostly into a stiff headwind. It was almost all the bike could do to maintain the speed limit (110km/h).

I went to start the bike this morning and the choke rod wouldn't pull out. There was some play in the rod but if felt like it was running into something. I took the carbs off to investigate. I find that the detent ball on the choke rod was binding and wouldn't release the rod. I disassembled it, and with sing WD-40 got it working again. Reassembled and everything is working as is supposed to.

I made the return trip home yesterday, weather was much nicer for me. It was sunny the whole way and there wasn't much wind which was a nice change from the ride on Friday.

I put on just over 500 kms (300 mi) over the weekend, for the trip home i strapped my backpack to te seat behind me rather that wearing it on my back which was a good idea I that I should have had on Friday. The bike ran fine, struggled in the wind on Friday like I mentioned, but I took it easier and cruised along at 105km/h for the most part on the way back Sunday and the bike handled that just fine.

My biggest issue at this point is the seat. It's fine for short trips (and honestly I didn't really notice it on the trip on Friday) but coming home yesterday my hind end got to be quite sore. I stopped for fuel about half way back and the last 130 km stretch made me question doing the trip again. I'm not sure how these seats are when they are new but I wonder if 35 years has deteriorated the foam enough to make it less comfortable when spending lots of time sitting on it.

And this brings me to my next point - how hard is it to make a comfortable seat? I know people make their own seats, and i like the looks of the solo seats but wonder just how to make it comfortable for longer trips. is it just a matter of using thicker foam or making it wider or..? Any links to seat builds that are style AND comfort oriented? (I only seem to find ones that are primarily concerned with how the seat looks). on my trip home I was toying with the idea of building a solo seat and a detachable passenger seat/rack. My buddy and I some day want to do some camping/touring/adventure trips with our bikes.

I replaced the carb holders today. The old ones were cracking but looked brand new on the inside. I replaced them anyways, with new gaskets but i still have the low throttle angle cruising hesitation, (i suspect that to be a carb tuning issue) and it still pops out the exhaust on decel (i now suspect that to be a exhaust leak at the head). The cap and the petcock vacuum tube that connect to the ports on the carb holders are in good shape.

When I replaced the plugs last week one looked rich and one looked lean. I need to get the carbs apart and make sure they are both good and clean, and adjusted the same, and maybe that will clear up the low throttle stumble. I also will be ordering some filters as the stock ones are old and don't look in great shape, who knows when they were last changed. I think i will go with Uni pod filters on the stock pre-carb h-pipe, but haven't figured out exactly which ones i need. Will do some research or measuring tomorrow.

As for my seat idea i found this website that i still need to do some reading on: ( http://www.diymotorcycleseat.com/ ) Has anyone else made their own seat and have advice, tips to make it more comfortable, foam to use etc?

So a few weeks ago I decided to lube my chain, since I had some lube handy and I hadn’t done that yet. And not knowing what I was doing I put on the amount of lube I thought (based on nothing but intuition) was a reasonable amount. The next day my girlfriend and I rode around a little bit on the bike, just around town with a little bit of freeway, but not much. Later that night I noticed black specks all over the back of her (previously cream colored) jacket and helmet, mostly on the left side. I figured I over-lubed the chain, and when I went to look at it, it was a gunky mess. I sprayed it down with wd-40 to try and get some of the lube off and wiped it with a rag. All good to go I thought.

We rode a bit the next day, 50km out to my parents acreage and again she had more specks on the back of her helmet (she wore a black jacket this time, it may have had specks on it but we didn’t look that close), and again when we rode back to town I also had a few specks on the shoulder of my jacket. The chain was of unknown age to me and looked like it had seen a few miles so this perpetually over-lubed chain was the tipping point, and I bought and installed a new chain. No more spitting chain, I thought.

Then this past weekend I rode the bike to visit her, the ride ended up being `300km. When I arrived I had a few specks of black on my back. I thought it was odd, but figured they must have been specks that I didn’t quite get washed out of my jacket and had come to the surface of the fabric (not an expert on grease spots or laundry), surely it couldn’t have come from my chain. I hadn’t added any lube to the chain when I installed it, it only had what it was shipped with. When I adjusted the chain the next day I noticed the chain was far more oily (compared to greasy/waxy) than when I installed it. Didn’t think too much of it. I rode home on Sunday and after the ride I had a bunch more specks on my back, and inspecting the chain I thought again it is even more oily!

So it finally occurred to me that the oil must be coming from somewhere else. Duh! My suspicions immediately went to the output seal. I figured I would check last night so I took the sprocket cover off and was greeted with a royal oily mess. I can’t tell exactly where the oil is coming from so I figure I will replace all the seals in there. I found the clutch rod seal and shift shaft seal (online, but I'm hoping to pick them up locally), but can’t find the part number for the output shaft seal (and I didn’t write down any numbers that I saw on it when I had the sprocket off last night, doh!). Does anyone have the part number handy, or the dimensions and type of that particular seal? Or a source maybe. Also I see in the partzilla clutch diagram (http://www.partzilla.com/parts/search/Yamaha/Motorcycle/1981/XS400+-+XS400H/CLUTCH/parts.html ) there is a dust seal for the clutch push lever screw (part 21), how critical is this? I see it is obsolete.

Any other tips for removing and installing these seals? I hadn’t thought of it too much but was going to use the screw method for removing the seals if I could (screw in a couple screws part way to the seal face on opposite sides, and extract the seals out my pulling on the screws) but I get nervous using that method without knowing exactly how close a bearing or something else is behind the seal etc.

Sorry this is kind of a long read, and thanks for you help!

I haven't had much time to work on my bike this summer unfortunately, due to a busy summer, but I did get around to doing some recently.
About a week ago I finally got around to replacing the seals that were leaking that I mentioned in the post above. When I had the sprocket cover off in June I cleaned off a lot of the oily mess that had accumulated and cleaned the chain so it wasn't over oiled and spitting anymore. I had a bike trip planned with my buddy for this past weekend and I had the seals handy so I made time to replace them.

The clutch rod seal was a simple task, I used the clutch rod itself to pry the old seal out (easy peasy) and the new seal went straight in.

A seal puller made quick work of removing the transmission output shaft seal after pulling out the spacer ring. However I fear I might be replacing this particular seal again, for 2 reasons.

1. When I was driving the new seal in all along the bottom edge of the seal, the housing gouged and peeled away some of the seal rubber (this happened a tiny bit to the clutch rod seal as well.).
2. I put the new seal in BEFORE I put the spacer back in. This may not seem like a big deal, the spacer ring still pushes in just fine. However when I look real close I can see that the inner sealing lip that seals around the diameter of the spacer ring is half folded under the seal from when I push the spacer ring in through the seal, the other half of that lip is folded out, resting on the spacer ring like it is supposed to be (I think).

I had the seal for the shift shaft handy as well, but didn't have any self tapping screws handy to pull the old one out. It didn't look like it had leaked much or any since I cleaned the area in June, so I figured it would be okay, at least until I replace the output shaft seal, probably shortly. I cleaned, lubed and tensioned the chain, cleaned most of the oil off the bike that had been flung around by the chain and called it good.

After I bought my bike this spring my buddy decided he should buy one as well. We used to live together and had bikes back then too, I had a 2005 Kawasaki z750, he had a 2006 Yamaha r6, and we are temporarily living together again so both having old bikes to tinker on and ride again is pretty fun. He picked up a 1974 Honda cb750 that he and I have been working on to fix previous owners kludges and get it running properly.

We decided a short while ago that we wanted to go on a motorcycle trip together, and decided to go to the grasslands national park here is Saskatchewan this past weekend. We tried to prepare our bikes for the trip and things fell into place quite well, except we were having trouble getting his carbs (we thought) figured out. Long story short, after trying to clean/tune the carbs a small handful of times we figured out the issue is the petcock (brand new by the looks of it), doesn’t flow enough fuel to freeway cruise when in the run position, however on reserve it flows enough.

We left later than planned Friday evening (with his bike running in the reserve position the entire time – eek! At least there were 2 of us) but arrived at our hotel in a tiny village/ghost town in southern Saskatchewan just before midnight. Here in Saskatchewan August can be our hottest month but it can get fairly cool during the nights towards the end of the month. It was probably below 10C (50F) for most of the trip that evening (400kms) and was 5C (41F) when we actually arrived. This would be all fine and dandy, except we weren’t really prepared for it. We were both thoroughly chilled, and the last few hours of the trip especially was not a good time.

The next day we got up and killed time while we waited for a spot to open for breakfast (ghost town, the earliest and only spot for breakfast was a coffee shop and it opened at 9). Then we did some hiking, packed our things and headed for home.

The trip home was much better, it was sunny and fairly warm. It was breezy as well but it was a combination of tailwind and crosswind, so it was much, much more enjoyable than the previous night’s cold ride. The 400km ride in the sun seemed like half the ride in the cold. I was proud of both of our bikes, neither had a breakdown of any sort and handled the 800kms like nothing. I feel a little large sitting on my bike which can leads to fatigue a bit earlier than if I fit better on the bike but I got creative with my riding positions and didn’t even have a sore behind after I got home!

The only thing I was disappointed in was the fuel mileage I got with my bike, about 6l/100km or slightly less. This would put me into my reserve tank just before 200kms/120mi, which can be a bit hairy driving in southern Saskatchewan at night where small town gas stations close early. I have seen a few other here posts on this forum about you guys getting significantly better fuel mileage than that, so I hope with some tinkering I can get it a bit better. I can’t complain though, as I have yet to open/clean/tweak the carbs, or adjust valves (I know, I know, shame on me!). I hope that after my current projects are done and life slows down a bit I can get to that.

That’s all for now, sorry for a long post (again), but I like documenting trips and events with the bike as well as documenting the actual work on the bike, for myself and for anyone who may be interested. I’m hopefull I will have an update for this thread this time next week with pictures even (gasp!).

I have been thinking of getting rid of the orange and painting the bike olive/camo green. I decided to go ahead with it and have been working at it a little bit here and there. One of the bike's side covers had a crack almost all the way through it that was "repaired" with bondo and stickers, so I started with cleaning up that side cover, and then tried my hand at fiberglassing the piece. In retrospect it likely would have been easier to buy a used cover but I like trying to do things myself, so I'm glad I learned a bit about fiberglassing.








In the above picture you can see where the cracks were, the longest stretched right from the bottom of the part to the top "flange". I had to chuckle because when I removed the stickers that I thought were just to cover an ugly bondo job I found the cover was a whole lot more flimsy without the stickers!

I tried one paint color on the covers and really didn't like it, so I roughed the covers up again and tried another color that I ended up really liking, a Krylon camo/olive green.





I prepped the tank and sprayed it as well.



...and put the tank and covers back on the bike. I didn't get to do this until it was dark out so im hoping to get some better outdoor pictures of the bike still.

I like the dull finish of the paint, and especially in this case because the tank is not in the best shape and has a few dings, this seems to make them far less obvious. I was trying to keep the paint project simple and cheap so I am happy with how it turned out so far. I don't have any good spray painting equipment so a rattle can was plenty good. If I was expecting a perfect finish I'm sure it would be a decent story.