Update on my XJ

Well, since the weather's turned a bit warmer, I've been itching to get going on mine. Now since my friend just got his '06 R6, I'm really wanting to get going, so I've done a little work the past couple weeks.

Here it is when I got it a few months ago:





Here it is after a hosing down and a $30 Ebay fairing, a painted grab rail and a decent stock seat:





Big difference, huh? I think it looks pretty good, really needs the Seca style handlbars to go with the fairing though.

Anyway, now for the bad news. Got a new battery for it, and after fiddling a little bit with the electronics, decided first thing to do would be a compression check, especially since when I turned it over by hand it felt a bit easier than it should have (with the spark plugs in). My worst fears were confirmed with the reading going 100, 50, 0, 50 across the cylinders. So, I guess I'll get to try my hand at motorcycle engine rebuilding. I'm an automotive machinist by trade, and build motors all day, but my motorcycle experience is somewhat limited. I think it'll be a good learning experience, but it doesn't look like my XJ will be on the road anytime soon. :cry:

I guess the good part about it is that this gives me an excuse to do a total tear-down on the bike and rebuild it front-to-back. I'd like to buy a different bike just to get me riding, but can't afford to do it. My project vehicle budget just comes a little bit at a time. Maybe it'll be ready by next spring.

 

Joel, sorry to hear about your dilema.
Well one good thing you'll get to know your bike from one end to the other. And take care of all those little things that would have popped up eventually. Once you get it going it should be ready to go for some time to come.
I'm just down the road so if theres anything I can help with let me know.
Oh, by the way it sure looks much better.

 

Joel, did you do a wet test as well? For all the work you would need to pour into the motor, doesn't picking up a motor off of e-bay sound like a reasonable alternative to the cost of rebuilding? You can score cherries for pennies if you know how to surf and get a decent person to take picures and compression readings. Or chance could favor you with just a hung up valve. Gotta tear it appart to find the cause. I had the good fortune of picking up a spare XJ750 for $150 delivered to LAX from a wrecker in Utah. Tight as can be too, pulled the oil sump pan and the internals were spotless!! Compression was really tight too (the numbers escape me right now). Options are out there. I hope your able to optimize your options. With your machining knowledge, you should be able to whip that dog into a purring motor in no time. Best of luck to you buddy. Let us know what you find.

 

Yeah, I'll be keeping me eyes peeled for motors (missed out on a 750 a few weeks ago that went for $100), but either way, I'd still like to build this one just to get the experience if nothing else. Also, have a line on a good 750 rotating assembly for $100 shipped, so we'll see how that goes.

I had kind of thought the whole time that the motor would need to be gone through. The previous owner said he lined up against a Nissan Pulsar because he wanted to see how fast the bike was, and got beat. 8O I knew that didn't sound right. Oh well. Might get the motor pulled out this week, I'll be sure to take lots of pictures throughout the process.

 

only problem with used you don't know? could be worse then ya got now? rebuild like you said the exsperiance is invaulable. like my freakin speling 8O

 

I can agree with you Chevy, there is a risk. Don't spend it unless your really sure or can afford to lose the money. Your spelling? Well, practice makes perfect so get to writing more often! You seem to know a bit about a lot, so let us in on your knowledge! Thanks big guy! Rob.

 

Oh yeah, I got a good enough deal on the bike that I'm not worried about that aspect. I could easily part it out and make my money back plus some. But, I can't afford to plunk down $2000-3000 to get a decent used one, so I'm pretty much committed to getting this one on the road.

Actually a friend of mine has an '82 XJ650 that he's fixing up, and we went in together and got a parts bike last month for about $200. But, then we found out it has a cylinder low on compression too... :roll:

Oh well, that bike is actually in a lot better shape than mine, but it didn't have a title, so I plan on using a lot of parts off of it. All that he needs from it is the motor/tranny, which he's planning on using for a custom built boat. 8O

BTW, just bought a 750 rotating assembly, so now I'll know firsthand about the 650-750 internals swap. Figured that way I can go ahead and bore the block out and start with a fresh bore without having to break down and buy new pistons from the Yamaha dealer. All I'll need now is rings, bearings, and gaskets. Plan on doing a full valve job and rebuild of the top end as well. Actually getting pretty excited about it now.

 

Bought 10 full engine kits, 5 for my 650, 5 for my 750, from a fellow on flea-bay for about $200 (a bit more than the cost of one kit from most manufacturers) delivered. He runs a store called mrsuperdeals and has made me several great deals, especially when I buy in bulk. Pitty your friend is swiping the motor off your donor, that would simplify things greatly. I bought a wrecked machine as well and that donor has been a great parts bin. Storage was an issue (still is really) untill I plugged that donor motor in. Purrs now. I'll get to my original some day. Good luck on your efforts.

 

Well, the donor bike is down on compression on one cylinder too, so it would probably be looking at the same amount of work.

 

Have you checked for maybe a tight valve?
Just my $.02

 

Yeah, I might do that before we tear both motors down, but one way or another, this one will be torn down. If I use the motor from the donor bike, he'll rebuild mine and use it in the boat project. Haven't talked to him in about a week or so, he runs a body shop and has been very busy the last few weeks.

 

Just angle for the parts before he does, if your lucky, you might need to fix a valve or just re-ring the sucker. Happy hunting.

 

Well, I've got the parts bike here now, so I'll try to do some checking on that motor this weekend. So, the possibility is still there to swap rather than build, but I still want to build eventually. :wink:

I'll keep you all updated. Oh, and managed to score a XS850 too. Locked up motor, no title, not sure what it'll be good for yet... 8O

 

Starter parts, oil cooler parts, hmmm... I think you can harvest most of the electrical parts too. I've not been inside an XS so I don't know what all might work but I've been using spare XS electrical parts for years. Front suspension swap is nice, should have dual front disk and air adjustable valving (yes, they will swap in on a Maxim).

 

Yes, it does have the dual front discs and air adjustable forks. Have any idea if the rear wheel would swap on? Point being, it's disc rear. Anyone have an idea of why they went back to a single disc/rear drum setup on the XJ? Overall, I've gotta say I actually like the 850 better than mine, but the 3 cylinders are just such oddballs... :lol:

 

Wouldn't know without eyeballing the two machines (sorry, don't have an XS laying about). The three cylinder is an oddity. Your probably better off in the long run loosing it to the 4 cylinder. Easier to find parts for the 4.

 

When you did your XS fork swap, did you just bolt the dual rotors to the stock Maxim wheel? I really don't want to switch to the straight spoked XS wheel...

 

I'm not 100 percent on this but I think there is a plastic cover on your wheel, the opposite side from your caliper, that can be removed to install another rotor.

 

Yeah, mine does have the plastic cover over the bolt holes, just wanted to double check. I'll probably pull the rear wheels off of both bikes to see if there's a possibility of swapping over the XS's rear disc also. The one on this bike is in pretty sad shape, but if it'll swap, I'll get a new disc and rebuild the caliper. Got my 750 crank/rods/pistons in today, but might not end up using it for a while now depending on what kind of shape the parts bike motor is in.

 

Bad news Joel. I have never installed the XS front end on my XJ. I have the parts but never got around to it. I have measured the slider tube diameters and they are the same so you can use your existing tree clamps but other than that I've not enough info to give any help. It is conceivable that this should be a straight over swap but I'm not sure if the XJ rim rotor depth would be the same as the XS. You would have to measure it out (or I would once I get myself moved in and my junk sorted out). That would be the only parameter I would see as an issue swapping the rotors onto an XJ rim. I have seen a few XJ's with rotors that look exactly like the XS rotors so I'm reasonably sure they will swap just got to watch the alignment with the caliper. Best of luck buddy.

 

Thanks! I'll definetly take pics and post up when I tear down the two bikes, hopefully it'll be a nice straight-forward swap!

 

OK, just did a compression check on the parts bike motor (the XJ650, not the 3-banger :lol: ), and got 50, 60, 70, 100. Squirted some oil in each of the cylinders, and they all jumped up to 120-125. Now, I know that usually a jump in compression #'s by squirting in oil is evidence of bad rings, but could it be that the motor's just been sitting for so long that the oil in the cylinders freed up some stuck rings? I'm very tempted to go ahead and throw this one in the bike and try to get it running for this riding season, then do a rebuild over the winter. Whatcha guys think?

 

I think you should throw it back in and run it. Engines that sit tend to have sticky rings. A good run with an oil change should be just what the doctor ordered. I've seen this issue a few times and have yet to pull an engine for it. I've always gotten my compression back with a little oil and some TLC. There is my two cents.

 

Awesome, I think I'll go ahead and pull it out this weekend, check the valve lash, change the oil, and swap it in. I guess the next big step will be going through the carbs!

 

Always a good idea on a sitting bike! Sticky float valve seats could spell a lot of trouble for you if you don't get them first! Go get 'em!