Oil plug fell out on freeway!

[XS-Time]

Check the service manual. I don't have it here in front of me but I remember there being a certain procedure to get the crank shaft ,timing chain and cam all aligned properly. If it's off it won't run well at all (if at all).
But it is good news to hear that it is running again.
Sounds like you payed way less for your berings than I did.

 

[ThePsuedoMonkey]

I didn't get off quite that easy, XS-Time: The ones I ordered from BikeBandit were being sold by the sleeve, not by the bearing, so I had a single bearing to split between the two rods. Luckily the crankshaft I had ordered from Ebay already had a set of them in good shape! That was probably for the best, since I really had no idea what I was doing. I am still dumbfounded by how much those bearings are going for.

I went back to the service manual to see what the process was for other ignition models, since the advice for my SH was that "adjustment is not possible" (which is clearly a load if I was able to screw it up without breaking anything), and it mentions something about a timing indicator. I borrow one of these from my dad and play around with it, eventually I find that the coil fires while the breaker point thing is in this position:
so I rotate the disc holding the points as close to this as I can (there is not enough play in it do to the mounting screws). I check the timing again, and it looks OK to me, so I take her for a spin: no stubbornness or backfiring anymore!!!!!!!!!

Thanks for the help everyone! I would definitely be lost without this forum, since the most involved mechanical work I've done before this was replacing the ignition tumbler on my car! If any of you are ever in my area I think I owe you some brews
In the meantime I've only got a few weeks (or months) before the Michigan snow

 

[XS-Time]

Well I'm glad to hear that it is running properly...but i'm not quite sure about what you said.
Firtst of all on the bearings, you have to take the stamping numbers on the crank shaft and the stamping numbers on the case and cross reference them on the chart in the manual to find the right "color" of bearing to go in each spot. You can't just put the bearings that came with the used crank and put them in your case. The cranks and cases were not all machined to the same spec. There were variances between them and the correct bearings made up for the difference.
Secondly I also have a SH model with the electronic ignition. If i remember correctly there is a pointy notch (technical term) on the pick up base plate that should point to a notch in the head casting. That is it, there is no other adjustments. The TCM adjusts for speed ect.

What I was refering to before was getting the cam and crank aligned properly. The drive pin on the cam pointing to the 12 O'clock position, the cam sproket with the pointing pip straight up and the LT mark on the flywheel aligning with the mark on the timing cover.

 

[ThePsuedoMonkey]

I did have the cam and crank shafts aligned before, which was pretty easy. I don't fully understand how the timing system works, but there were two notches in the base plate which I previously had straddling the notch on the head. I thought that module used the pins in determining when to fire each cylinder, like on the breaker point model. Shouldn't my changing this have hurt the bike's performance, then?

As for the crank, I took out the old one and replaced it entirely with the Ebay one, which came with the piston rods and bearings. So those two are fine, though I am not sure about the remaining ones, as I did not record the stamped numbers...

 

[XS-Time]

Yes two notches in the base plate which leaves a "nub" between these notches. Point the "nub" at the gap in the head casting.

Correct , the connecting arms big end bearing already attached to your used crank should be fine. I was worried about the crank shaft main bearings in the cases.

 

[XS-Time]

As for how the ignition system works...The rotor spins past the two metal "pick ups" on the base plate (as in your picture) , If I remember right there is a difference between the two rotor ends. Based on when and how often the rotor triggers the pick ups the TCM decides how fast the engine is turning over, which cylinder is coming up to top dead center and when to fire the spark plug.
Pretty simple. You dont have to worry about dwell, worn out points or advance springs.

 

[xschris]

I know when rebuilding the lower end you should balance the crank. As the crank bearings wear they don't wear at the same rate so you need to use different size bearings to take the play out of it. They make 4 sizes with different color codes, I think they are black, brown, green and blue. Something like that

 

[XS-Time]

On a lot of other vehicles you have a selecton of bearing sizes to chose from so you can machine down the crank and just use the next size bearing. The XS400 was not designed to be able to do this. If the crank is worn you are supposed to throw it away and buy a new one.There are no oversized bearings available. The different color bearings are to allow for the variances in the manufacture of the crank and case at the factory. That is why they are both stamped with numbers for each bearing set. You use the chart to figure which color bearing to use for each crank and case number combination.

 

[xschris]

I was told this by a 40 year yamaha engine tech and the parts where used a lot to true the cranks when he would rebuild them and are still listed on the yamaha web site. I still see some on ebay from time to time, try finding a new crank I think they where like $500+ dollars when they where in stock long ago.

 

[ThePsuedoMonkey]

So I can only find the black and blue color bearings anywhere, which leads me to believe that these were the most common for the stock sizes as well. I talked with the three mechanical engineers that I know, relaying all the information here, and they all tell me that if the main bearings were not the proper size then I would definitely have noticed on the 60+ mile ride I took afterward. They say that if any of them are too tight then it would have seized within a few thousand rotations while under load, but if they are too loose the play in them will prevent the cylinders from operating effectively which would result in me having no power in it. Since neither of these are the case, they believe that the bearings are within spec, but also that I should consider changing the weight of the oil I use as this would be able to make up for small discrepancies in the bearing tolerance (go lighter if tighter and vice versa). To be honest, the bike performs feels and sounds as it did before all this happened, so it's hard for me to discount what they are telling me. Maybe I got lucky on the sizes this time and they were close enough (which would be a lot more plausible if there were only two colors that were commonly used) I'm not really certain if I'm being rational or retarded here...

I did have to readjust the timing mechanism from that nub facing the notch in the head though; after being shown how to properly use the timing light we found that it was firing late by a few degrees. I was just really nervous about running it with that cover off!

 

[xschris]

I think its just as you said. Drive the heck out of it and have fun!

 

[XS-Time]

Sounds like your right. If the bearings were wrong you probably would know it by now.
It's nice when things work out good like that.
I'm glad it is running again.
As a side note to the crank bearings. When I orderd mine from Yamaha the colors that showed up were wrong. The dealer was nice enough to look into it for me. What he found was that the same bearings were used on the FJ1200 but Yamaha changed the colors. The part numbers were the same but the color had changed.
So what does this mean to us? Use the chart in the service manual to find the color of bearing you need. Go to the Yamaha online parts catalog for your year and model and order the part number for the color you need. When you pick up your new bearing from the dealer notice that the part number is right but the color is different. That is ok! If you want to double check ,go to the early 80's FJ parts catalog and look up the crank bearings. You will find the same part number that you orderd with the "new" color designation.
The bearing is corrrect just the color has changed. Lots of fun!!!!