Reviving my 81 xj 550 maxim

Checking your valve clearances on these airheads is not hard. Really it's easy-you can check them in a matter of minutes. The write up on here from bigfitz is well done and the pictures make it simple. Now re-shimming is a little harder and requires patience and more time, but still not hard.

If your battery is strong enough to turn it over quickly and not begin to slow after several revolutions (meaning voltage is quickly dropping) then good to go. Watch your compression gauge and make sure it's not still creeping up before you quit turning it over. It took me about 4 or 5 needle jumps before I maxed out.

 

Revised plan.

Threw the battery on last night, after charging, to see if it will turn the bike over. Nothing. Only a dimly lit neutral light. So, first off, gonna need a new battery. Since I'm on a budget, the battery will have to wait awhile.

In the mean time, gonna check those valves this weekend. I'll see If I can get some metric feelers for a good deal locally. I do have some standard feelers that aren't rusty. I'll post my #'s.

Hogfiddles - Have you filed off the threads on those tiny peened in screws? It's no fun. I did it on my spare #2 carb body & unless I have issues once the bike is up and running the other 4 will have to stay that way. Having to buy a #2 carb body ruined my carb budget otherwise I would have bought more parts. It's not like we're talking just a couple bucks worth of parts, it all adds up. This is just a partial list of parts I couldn't get

HCP3458SET8 OEM Mikuni fuel line Tube O-RINGS, set of 8:
$ 26.50
HCP7120SET8 Aftermarket Mikuni butterfly valve MOUNTING SCREWS, flat-head 18-8 stainless steel socket head cap screw with a 2mm hex-drive, set of 8:
$ 5.50
HCP38BSET8 Aftermarket Mikuni throttle shaft V-SEALS, set of 8:
$ 28.95
HCP39CSET8 Aftermarket Mikuni throttle shaft seal SHIM WASHERS, eight shims:
$ 14.00
HCP863SET4 Aftermarket Mikuni carb FLOAT BOWL GASKETS, set of 4:
$ 13.00

I don't mind taking things apart more than once if it saves me money and helps me learn the mechanics. It's a high probability that we're all gonna be in our carbs more than twice. Hope that quenches your curiosity.

 

Ok, so just to keep all my progress in one thread. Here is a link to my valve clearance thread:

http://www.xjbikes.com/Forums/viewtopic/t=34860.html

My measurements and replacement shims are as follows:

Cyl ~ Intake ~ Exhaust
1 ~ .09, Y260 ~ .10, Y260
2 ~ .09, Y265 ~ .16, Y265
3 ~ .08, Y260 ~ .11, Y260
4 ~ .06, Y260 ~ .06, Y265

1 out of the 8 is within spec (the minimum at that)
After consulting the chart, I should replace them with these shims giving me the new clearance of:

Cyl ~ Intake ~ Exhaust
1 ~ Y255, .14 ~ Y250, .20
2 ~ Y260, .14 ~ GOOD, .16
3 ~ Y255, .13 ~ Y255, .16
4 ~ Y255, .11 ~ Y255, .16


I also gapped all my new spark plugs to .63 and .65 mm.

I've got an order in with chacal on new shims and a new air filter. So close to firing this bad boy up. Unless I run across electrical issues (bad coils, alternator & such) I think this thing will run.

 

I finally ordered my shims & filter over the weekend. Had to pay off that Christmas debt before moving forward. Shame, I wish had ordered them back in November. With all the warm days, I could have easily had it back together. Oh well. Everything should be in next week & installed.

 

Got my parts yesterday. Confirmed what I suspected. The air filter that was in my bike was the wrong filter. It was stuffed in there tight enough to warp the airbox. With the airbox side cover on, the box bubbles out a bit at the top leaving a gap. The air box has been open for a few months and it hasn't went back to shape yet, it may be permanently damaged. I'll try heating it with a heat gun and push it back down. If not, I'll have to make a gasket or something. I'll post pics of the 2 in comparison later.

 

All of my shims are installed! Everything went swimmingly except of course the #4 intake. The bucket tool just would not hug the cam enough to hold it down. So I had to use the wire method again on that one. I triple checked all my clearances before I swapped them. All my new clearance #s came out as expected except #4 exhaust ended up .18 instead of .16, still within spec though.

I would like to get it all back together this week to test fire this weekend. It started getting cold in the garage this evening & cold weather expected for the rest of the week. We'll see what I can get done.

 

Everything put back together this week, new battery charged and installed, gas in the tank and after around 10 years of lying dormant . . .

IT STARTED RIGHT UP!!!!

I couldn't let out the choke cause I haven't set the main idle yet, but man did it purr. Sounds strong and fires right up.

2 things though:
1. The petcock leaks. Actually, I think it is coming from the mounting screws for the petcock. I had completely disassembled the petcock, cleaned, polished & greased everything. Gonna try again to seal it up. Not gonna buy any parts for it since I'm (hopefully) not gonna use that tank.

2. It smoked like crazy! Probably a combination of disassembling the exhaust & putting it back together with the same gaskets & such. Plus, some dobbers had built nests in the exhaust while stored. I cleaned out the best I could but I'm sure I didn't get all of it. This exhaust smoking will be addressed in phase 2.

Thanks to so many of you for the help on reviving this bike. This site is great with a lot of knowledge at our fingertips.


I'm gonna start a new build thread on the modifications I'm doing. Phase 2 will encompass the following:

1. Fit the early 70's Honda cb750 tank on. I will accomplish this by removing the current tank mounts from the frame, fabricating new ones to weld onto the frame and bashing in some of the underside of the tank to clear the frame where it needs it.
2. Cut the rear crossmember/frame off behind the shocks and weld on a hoop.
3. Build a fiberglass tail that goes from the back of the tank to the new hoop. I have quite a bit of experience with fiberglass. Repaired boats & PWC's for 2 years when I first moved here to the lake.
4. Build a seat pan (separate from the tail) and upholster a seat. This seat with bolt to the fiberglass tail which in turn will be connected to the frame. Still working out how I want to do that.
5. Lower the front about 1"
6. Install clubman bars & possibly new levers. We'll see on the new levers.
7. With clubmans & levers installed, I'll measure to figure out length of new front brake hoses (probably stainless) & other lines (throttle, choke).
8. Rebuild front caliper.
9. Check for delamination of the rear shoes
10. With both wheels off, will be a perfect time to fit it with new tires
11. Misc. stuff, lights, polish (maybe) & paint/graphics.

That should get me on the road for the summer.

In Phase 3 I'll:
Purchase smaller Mikesxs guages (with indicator lights), Purchase smaller headlight & fork mounting brackets, drop the headlight a bit, possibly swap front fender with a fork stabilizer, & Purchase taller rear shocks (~13").

Heres a photoshop rendering of what I'm shooting for:




I think with a bit of elbow grease, there is no reason my XJ can't look like that.

 

So, I was dead wrong. :?

No phase 2 yet.

I did a compression test after I got it running only to find out I had very low #'s. I've got it all down in this thread:

http://www.xjbikes.com/Forums/viewtopic ... g+oil.html

Looks like i'm replacing the rings & doing a valve job. On to the engine tear down. I had to get some help maneuvering the engine out of the frame but we got it out. A couple observations after getting the head off:








My #1 piston is a bit concaved when compared to the others. All the other three are convexed. Maybe a lean condition that just hadn't made its way through the piston yet? What do you all think? Here is the #1 piston compared to the #4








Should I look for an ebay piston?


Anyway, I can't get the cylinders to break free. How can I break it loose without busting a fin? I've strategically rapped on it with the handle end of a screw driver. I've also tried a mallet with no luck. What's the best leverage?

 

It took me about 10 minutes of tapping with a screwdriver handle, and then just wiggling it front and back. I did not pry anywhere. I don't reccommend prying. Just patience. Also, tip the motor on its front when you seperate or else dirt and crap WILL fall into the case.

 

I had a hard time breaking mine free as well. It took several 'lovely taps' with a huge rubber mallet before I went on to using a soft block of wood as a buffer and a equally huge metal mallet.

It took quite a lot of love from all directions before it gave way. Either way, the impacts from the sides of the engine were softer and the ones that were along the length of the engine (front + back) were pretty intense to get it free. If you go with the hammer/mallet with block of wood as a buffer method make sure you place the block of wood flush with the fins so you don't put too much energy into a single fin, and strike in a slight angle so you transfer some of that energy upwards and away from the main engine base to get it free.

Patience is key. (Mine took 250-300 blows).

Good luck!

 

I still can't get them off. I've got about 3.5 ~ 4 hours into it. It moves almost 1/8" on the intake side but barely on the exhaust side.
The outsides of the cylinders are free, but the center of the exhaust side is what is holding me up.

I ratchet strap the engine down (laying on it's front) in a "x" patern with 2 straps. I have the engine on small stand I made out of a 3' header board and some railroad tie blocks I screwed together. Even with this thing cinched down I can not pull/wiggle them off.

I'll work at it again tomorrow

 

Double check all the bolts and nuts are all the way off/out. Once the initial seal is seperated it should come easily. Make sure to pull evenly, too. It won't come up angled.

 

The problem I had with the cylinders was a bit odd. I guess some rock/asphalt had made a home along side one of the center cylinder studs. I ended up double nutting the stud and backing it out, cylinders lifted right off with it.

I've been patiently cleaning up things, getting ready to order ring/gaskets & such. Pistons look brand new after clean up, measured with calipers & are in spec. Had to purchase a piston & got an extra one just in case.

I also made a homemade soda blaster that I have been tweaking to get it where I want it. Once I have it finalized I'll show pics. I think I may need to get some actual blasting soda from Harbor Freight or such. The store bought Arm & Hammer baking soda seems a bit too small? Anyone have any experience with that?

 

Yep, and you can't use grocery-store soda, it's just dust.

I picked up a bag of soda blasting medium at HF for around $22 IIRC. Works great.

 

So, it's been awhile but I have made some headway. My budget has been robbed in the form of tubes for my little girl, so i've just been doing the stuff I can with what I have.

Since I have the jugs off and honed, I decided to clean them up a bit.
Cleaned, filed the fins, sanded, cleaned, painted, baked & polished. turned out pretty good.










How to remove the front tank mounts: Punch and drill out the spot welds, moving up in bit size & just but not going into the frame.





I took these off in order to fit on the cb750 tank. I had to pound some sections of the tank channel to clear the frame.






Tank on the frame (please ignore the paint, it's what happens after a night of drinking & staring at masking tape. twice. three times)










I also lowered my head light and bracket and guages. I don't think the headlight is low enought yet so lowering more is in it's near future. Haven't cleaned & painted the welds yet.





In order to lower the guages, center punch the center of the studs then drill out & install underneath the triple tree. Pretty easy






I also got a set of clubmans for $10. I traded a shop my brand new untouched drag bars from my old intruder. They were 1" bars so they were no good to me. I've tried to sell them in the past with no luck, but he took them and $10 for the clubmans 8)


I have many more pics of the final tank position, painted & polished parts and seat mockup, but I'm having issues with my photobucket account. Will get them up later.

 

I ran across these 2 videos of when I got the bike running in February. After about 30 seconds of running, it starts smoking. It would only get worse, I let it run for about 5 min at one point and it looked like I was fogging for mosquitos in the garage.

Hopefully, this honing and new rings will take care of it.

(Sorry, I don't know how to embed the player in the thread)








Also, I've started mocking up the seat, but I think I will hold up. I still need to get that tank down and forward some more. So I guess more pounding is in my near future.

 

Any updates?

 

Hows this coming along