'82 XJ750 Maxim Build Summary + Links to Tech threads

EDIT: I changed the title of the thread, and since I am posting specific threads elsewhere I have included the links to those. Hopefully this will help other members.



Hey everyone, I'm Nick.

I picked up my first motorcycle from a friend last week and have been scouring this site for hours upon hours every day after work.

I bought a 1982 Maxim XJ750 for $200 from a friend. It has ~7200 miles on it and before I picked it up it sat for about 8 months.

That said, it started right up, and seems to run well. It was given to him by his uncle as a first bike, and since it has stayed in the family since new, I suppose you could almost call it a one owner bike.

The front and back brake pads/shoes were changed a year and a half ago, and the lines were as well. I made sure to check per the recommendations on this site, and as to avoid getting flamed early on

As I said before, it starts and idles very well, but it seems that it is a little sluggish between 1k-4k RPM (Normal for these?). After that, however, it pulls quick! Since I have little mechanical experience, I'll be referring to this site (and posting) frequently. I'm extremely happy with the purchase and will be sure to post lots of pictures (And LOTS of questions) as time progresses.

My next "immediate" project is to check the valve shims. I'll be rebuilding the brakes/master cylinder and upgrading to SS lines this winter, as well as going with a carb rebuild.

First things first are getting myself some clamps and bars (Can't stand the two piece bars), round headlight, gauge cluster, solo seat, rear fender, and rear taillight. If any of you fine folks have any of that for sale, shoot me a PM!

My first question is this: The bike seems to run pretty hot (temp wise, based on everything being hot) and smells a little, but I truly have no idea if that's normal or not for these bikes. Is there any way I can easily check to make sure internal temps (or temps off the engine) are normal?

I'm anal, which is a good thing, but sometimes it gets me paranoid.

Also, the bike is in good condition and I will likely be parting it out as I go along, so I'll be sure to post those items in the For Sale/Trade forum.

Pics to come soon. Thanks everyone.

 

Congrats on your purchase.....great price ...great bike....those 2 piece handle bars have a nice style to them....you should keep them.....personal opinion ....post some pics before modifying it.......expect to sink another $600 to $800 to get it right thou......

 

200 bucks?!?!?! Sounds like you stole it. Does you friend have another?
Seriously, that's a good deal and you're headed in the right direction. Get the valves in spec and service the carbs. That might take care of the heat problem.
When you get that thing running good, bring it to Erie so we can have look at it. I feel like an orphan up here all by myself.

 

Five of a kind, I don't hate them, but they've gotta go. Currently looking for handlebar mounts to accept some 7/8 bars and then they'll be up for sale. I do have funds set aside for all the fixes. By spring I would like to have all major components rebuilt.

Bmarzka, if he did, I would have scooped it up too!

Do you folks know of any round headlamps that will easy wire in? I'm very bad with electronics and so I won't be swapping the atari until this winter. In the meantime, I was hoping I could simply swap a headlight in there very easily.

 

Well it took me long enough but here are some pics. I apologize in advance if I upset any of the purists in here. The two below are about an hour after I brought her home.




How she sat two days ago. I have since removed the original tail-light for a small light/Plate holder combo that I made. Since adding it, my "TAIL" warning comes on, however I think it's because there were two bulbs in the original and only one in this, which leaves two wires exposed.





Next up is new blinkers (Standard Bulbs), New headlight, and new gauges, followed by new suspension. By then I will be ready for some fun mountain rides as the leaves change, then we'll head to the basement for a winter overhaul. I plan on doing everything I possibly can to put the bike in tip top shape.

I'm having a few throttle issues with the drag bars (Throttle wont set back to idle when I pull the clutch in, and sometimes it revs a little high) so if anyone has suggestions they are greatly appreciated. Have a safe and fun weekend everyone.

 

Concerning throttle issues: valves in spec? Did you do a vacuum sync? Throttle cable kinked and/or binding?
Polock and I are meeting at Geneva on the Lake this Sunday. You're welcome to join. Maybe some of the Cleveland folks can make it.

 

Dialed XJs should pull hard through all the gears/revs. It sounds like a too lean (not enough gas) mixture issue. Or faulty coil. But, my guess is dirty carbs and possibly out of spec valve shims. I've encountered both these situations and they can blend together making diagnosis difficult.

Coils are straightforward to test with a multi-meter. It's outlined in the Hanyes/Chilton manual, or probably find a how-to on this site.

If the bike idles well but fumbles with throttle the first place to look is the main jets. Above the jets (they are in the float bowl) is the emulsion tubes, the slide needles fits into these. The emulsion tubes have small perforations in them. When cleaning the carbs you can push or very gently tap with a wood dowel, the emulsion tubes out and into the carb body (they go up into the large intake space). I've pulled emulsion tubes that were gunked horribly. No amount of tuning will help unless your carbs are spotless (that and valves shimmed).

Too lean is often a result of air leaks around the carb or air/fuel mixture screws. Replace all the O-rings when doing a rebuild.

You can check for air leaks by hosing a bit of (unlit!!) propane around the carbs and intakes. If the revs pick up, you have a leak, hence a leaned out mixture. Often the manifold intake boots look ok , but have tiny cracks in them that come with age. Touch pricey to replace but makes a world of difference (they can be resealed but that's a pain). Also check the air filter, if the foam seal is crumbling the carbs are pulling more air than needed.

Lastly, take a look beside the choke plunger, if the air/fuel screws are still capped then they need to be uncapped and this will allow you to tweak the air/fuel mix. These carbs are touchy. Sometimes a 1/16th tweak is the difference good and not so good.

XJs run hot, and run better when hot, but not too hot. Sounds like it's running lean if it's getting oddly hot. The smell could be lots of things... could be the engine varnish cooking after sitting and breaking down a bit, accumulated gunk in the exhaust, and so on. Nothing like starting up a fresh rebuild and watching all sorts of vapor/smoke come off freshly plated and painted parts. It all settles down after a few good runs.

 

Bmarzka and Bruce, thanks for the helpful replies, I really to appreciate it!

I was telling Pollock through PM that I'm in his area occasionally for flight lessons. It would be cool to meet up with you folks soon, so thanks for that invite to the lake, however I've been busy with work and weekend activities.

I've also been neglecting my girlfriend to work on this thing so...I had to stop that a little haha. I got some new, non LED blinkers that I'm having a tough time with (The front right will light up but not flash, and the rear left will light up and not flash, but the other two don't function at all) and the headlight/cluster is the next project.

 

Get your girl friend to help you with the bike. Win-win situation.

 

Back from the dead!

I've been very busy with work and haven't done any work to the bike since August. It's been good to me so far! Runs well and starts up every time.

Unfortunately It's going in the basement for the winter, but I've started to acquire the tools I need to take care of the engine/carb/clutch work, and then really figure out where I want to go cosmetically.

I also managed to pick up a very lightly used craftsman motorcycle jack yesterday on the cheap, so I'm pretty excited about that.

That said, I can't seem to get my collector off. Putting it on that jack with the collector attached would be no bueno, right?

I can't figure out what I'm missing. Is this one of those "more kroil" moments?

Anyway, attached are a few pics that are doctored to make the bike look better.

I look forward to seeking all of your mechanical advice this winter.

 

Hey everyone, a little progress update. Currently waiting on the proper feeler gauge set and carb parts to be shipped in from Len at XJ4ever, so that I can button up my carbs and replace any out of spec valves.

In the meantime, I bought a '73 cb750 to start working on later this winter. It happened to come with a cb450 hawk tank/side covers/round front headlight, and actually the tank seems like it may very well fit on the xj with very little modification. I think I like it. Thoughts anyone?

 

Looks like you've been infected with MAS, too. Just be aware, there's no cure............

 

Hah! I've got a fever...

 

That's way cool. Same as the '78 Hawk that I had years ago, even the exact color.

Gotta say I still like that style......nothing wrong with creating something special, I say go for it.

 

Thank's guys. Like this Maxim, I really stole the CB. Came with Comstar wheels, new un-mounted conti's, and tons of CB450 parts (and engine!). Picked it all up for $450. Not sure how it runs as the PO ripped the wiring harness out, but it has great compression and clean carbs.

I won't be touching it until I get this Maxim running/looking ok.

Back to the Yamaha:

As stated earlier, this bike ran when I got it, and pretty darn good if I do say so myself. That said, I've never wrenched on a streetbike and I figured I might as well get it back in Tip-Top shape.

First I disassembled the carbs and cleaned them. They were pretty clean already as you will see in the linked thread below, but now they're sparkling. I took a ton of pics so I hope that it will help someone down the road. Chacal (Len) was also very quick and helpful with the carb parts I needed.

*Speaking of Len (and the rest of you guys). Right after I bought this bike, and up until I bought that cb750, I had been spending A LOT of time on other bike websites, figuring out what I wanted to do for a cafe racer: which bike I wanted, what the online communities were like, parts availability, etc. I have to say that no other sites I've seen have the resources and matter-of-fact knowledge that this one does. It really is great to be a part of it, and everyone here who dedicates their time helping others should really be proud of that. Thank you all.

Carb Disassembly: http://www.xjbikes.com/forums/index...-taking-apart-carburetors-lots-of-pics.48063/

I then measured the Valve Clearances. Three times actually, because the first two times I was doing it incorrectly. Please don't make the same mistakes I did, and read through the thread I started:

Valve Shim Adjustment: http://www.xjbikes.com/forums/index.php?threads/valve-shim-adjustment.48032/

Chacal and Hogfiddles really helped out, and the Shim Pool that Hogfiddles Runs is a great resource as well.

I am now waiting for the new shims to come in the mail. After installation I will attempt to make one of those Twin-bottle carb sync tools.

At that point, I will have the two main engine issues sorted. Valves in spec, carbs cleaned and synced, and bike idling properly in stock configuration.

Gurus, please don't turn your backs on me: I am going to order pod filters. As a starting point, I will be using the method that Streetbrawler used, by inserting the stock carb-to-airbox boots within the pod.

I will also be keeping the airbox in case I regret my decision.

After I get those hooked up and hopefully idling I will be done messing with the engine until spring. Next will come cosmetics. I will strip and paint/powder the frame and components. Then I will do the same with the motor (Probably all silver, with black valve cover. Or, Black bottom and top, with silver jugs).

I believe I will be doing some sort of Brat/Tracker mish-mash, as I'd like to have this a two up bike. I'm going to use the cb450 tank, with a flat seat. I'll keep the stock footpeg locations and the drag bars, but I'm going to need new controls to house a flat-sitting Brake-lever/MC. Cheap and/or effective solutions welcomed!

Then, finally, I will be doing the part that I dread the most: Re-wiring the thing. Probably minimally, as I have NO idea what I'm doing and am most definitely nervous about that.

 

you have a junk yard up there somewhere? tell them what your doing, they always have a lot of master cylinders. that said i put a lot of miles on a Chinese on from ebay but i don't think you could get a re-build kit for one of those.
look at eastwoods.com for frame and engine paint, a little more $ but good stuff

 

There's supposed to be a motorcycle "Junkyard Mecca" near Butler but I haven't made it up there.

Good look on the paint guy!

I have never done serious painting and I need an excuse to buy a nice compressor, so we'll see where that goes in the spring.

 

I got a master cylinder for a Yamaha R1 off eBay for relatively cheap that I used on my bike.... that's an option for you if you keep your eyes open

 

this might be the place in Butler http://www.cyclewarehouseonline.com/ it's right in downtown by the courthouse, takes hours to look at all the stuff neatly laid out. used bikes ready to ride.
http://pacyclesalvage.com/ this one is not quite as orderly, it's more of a "come on back, see what you want" kind of place. wrecked bikes ready to rebuild

 

Polock, I've been to the Cycle warehouse. Really, really cool place. One of the guys was nice enough to take me upstairs in the ancient freight elevator, and they had tanks, parts bikes, and frames galore. Prices are ok, but I'm certain I could find whatever I need there if I was in a bind and needed a specialty part.

As for the Cycle salvage place, I have not been there yet. I've been meaning to go but life gets in the way. Is it inside by chance, or are all of the bikes outdoors?

Also, I'm currently Dealing with Syncing the carbs with the Two bottle method, found here: http://www.xjbikes.com/forums/index.php?threads/how-to-make-a-2-bottle-synch-tool.15650/

 

in the summer it's 50/50. I was never there in the winter, probably more like 80/20.
take some tools for the self-serve bargins

 

Will do.

I have some unfortunate news it seems. It looks like a.) my frame has bent from sitting on this jack so long. Or b.) I know the bike had been laid down before I got it but...It's twisted. I feel like I would have noticed it.

New frame?

 

I'm still scratching my head about the frame. I don't really know what to do about it, or how it happened. I hope it's something I just overlooked, because the bike rode well back in September, even at highway speeds. Suggestions welcome. Here's a picture of the tank I'm definitely going with. I need to get the fitment right but I think it's going to look great, and the petcock is on the proper side already!

 

can you get a different angle picture, that seems like a strange place to bend a frame

 

Sure, here's some more. Hopefully these show up better.



Definitely going to keep the fender instead of buying a brace and running without it. Working on shortening it, but wanting to round it off.

I will probably use some sort of semi-circle template at the front and back so that it's rounded.

 

it's been awhile since i had a maxim but there was a strange looking bend in the frame there. if the wheels were on you could try this
http://www.yamahafz1oa.com/sportryderswheelalignmentmethod.shtml
then with a carpenters square check that the wheels are square to the ground. if that all checks out the rest of the frame doesn't matter

 

No, that kink in the tube should not be there..........this is the vertical frame tube, right side, just before it joins into the upper (horizontal) tube at the gusset, correct?

BTW, XJ650 Seca frames are different from Maxim or Turbo frames.

 

Thanks guys, and yes Len you are correct.

I knew the bend shouldn't be there, just don't know if this is going to put a significant kink...in my build. Again I believe it was there when I got the bike and it was fine cruising at interstate speed.

I'd love to bondo it and call it a day but that doesn't seem like the proper thing to do...

 

Waiting on a few things in the mail, so it's back to cosmetics in this post. I have managed to get the front mounts of the cb450 tank to fit onto the stock XJ mounts. I did this by first removing the large rubber bushing thingys, then beating the inside of the CB tank with a hammer to widen the mounting location just a tad. Then I measured and ground off about an 1/8th of an inch on each mount on the cb tank to give me just a weeee bit of wiggle room.


Now I have a fitment issue. The petcock extends pretty far down and if I were to take the pictured tape measure out, the petcock would rest on the carbs, which I do not want. Further, this will make seat fitment an issue as there will be a mighty large gap.

I'm wondering if I can just screw in the petcock to provide more clearance, or If I'll have to cut off some of the tube that it screws onto, then re-thread it.

Lastly, I have started to take a wire wheel to the tank in order to grind off the paint. No idea what color I will go for here. I know for certain that the wheels and frame will be staying black, but everything else is up in the air.

Anyway, still looking for frame solutions if I need them. I don't plan on selling the bike (If I ever get tired of riding it I'll throw it in my mancave as a conversation piece) and if it doesn't affect riding at speed then I probably won't get a new frame. If it does, oh well, I'll purchase one and move everything in the spring.

 

Revisiting the Petcock issue: It will not screw up any higher, so it looks like I'll have to grind off the threaded stump and re-thread if I want a petcock.

What's holding me back from simply removing the petcock and putting a hose directly from that threaded hump, to an in-line fuel shutoff valve, finally to the in-line fuel filter? Seems like an easy enough fix, no?

 

I have two 750 frames and both of them have that same indent. looks like clearance for the battery.

I would cut out the petcock boss and move it forward. that would require purging all the fuel out but it's not impossible.

FU

 

Well CN, that is some great news, thanks!

As for the petcock, the tank is completely drained but I don't own a welder yet so at the moment that's not an option. I wonder if one of the cheap harbor freight welders would work though, because I am going to need a hoop welded and I can't take the bike out of the basement until spring. Further, with the way the tank will be sitting I don't know that it would be the best idea because it would be up to tall. I think I'm going to go with my original idea, as it's cheap and should be effective. I needed new fuel lines/filter anyway.

This is really the only thing "holding me up" because once it's mounted I can work on a battery box, my electronics/wiring, and then fiberglassing a seatpan.

Thanks for the input!

 

Got my shims in the mail tonight, so I'm swapping them out shortly. Big thanks to Mr. Dave Hogfiddles for walking me through the shim pool instructions then sending them my way so quickly.

Pods are almost on. Note that I used the stock carb to airbox boots instead of the tiny boots that came with the pods. This was a very easy swap with a heat gun and I'm hoping that it will make tuning easier as well.

Also note that they just barely fit without touching the frame

 

I can verify--I just went out and checked my 750 and it's got the same bend. My 650 does not have it. Nice build so far, love what you have done with the bike.

 

Excellent, thanks again! It really made my heart drop when I first saw it.

As for the bike...nothing exciting going on at the moment. Doing some bodywork on the tank while I try and find someone to bend me an upswept hoop for the rear frame.

My measurements show that the rear of the frame is 9 inches from OD to OD, but the closest pre-fabbed hoop I can find online is 8 & 7/8ths inches. Not sure if this will fit but I may just bite the bullet and get it to see. Otherwise I'll have to find someone local to do it.

I've also started printing out wiring diagrams...but I'm still trying to find the confidence to do it. It's either that, or I shell out $300 for a SparckMoto harness.

 

Not a ton of progress. Got the fender cut and shaped:


Still needs refined but it's the size I want.

Tank is completely stripped with a wire brush. I'm not sure what to do about the honda badge mounts yet. Unfortunately they take some grinding and then filling.

Apparently people have learned the hard way that it takes a ton of filler and sanding to cover it, so grinding is the better route.

Not too much though, as it will put a
hole in the tank. I also mocked up the headlight with zip ties until I pick a mount.

I used this diagram to get the Atari out of the way, but it's temporary. It does work though, if anyone's looking for a quick way to clean up the front.

 

niiiiiiiiiiiiice!

 

A grinder will cause swirling in the surface that will show up in the paint unless you use a coat of body filler. Paint stripper is a good alternative.
Liking the front fender.

 

Thanks guys. I don't know how to paint so that's something I'll have to learn. So me using the wire brush to strip the tank was a bad idea? I figured several heavy coats of primer would cover up all of the swirling.

Aircraft stripper does work well, but I used the kind in a tub instead of an aerosol can, and since there was some surface rust in the tunnel of the tank I just figured I'd hit the hole think with a brush. It didn't take TOO long.

Edit: to be a little more clear. As they are now, The badge mounts on the tank will protrude from the paint fairly noticeably if I leave them this way (Even with body filler over top). The trick is to take a dremel or small angle grinder and carefully grind it down into a concave, then fill it with body filler.

Primer should take care of the rest of the tank without body filler, no?

 

98% of a "great paint job" is really "great bodywork". If you aren't good at it already, you may want to enlist the services of a bodyshop, etc. who will be good at it, and once you get it back from them (already primered, sanded, etc.) then go to town with painting it.

 

But then I would lose the satisfaction of doing everything myself! I have the patience to do a good job (I think) and my thoughts are that as long as I have enough body filler (In actuality the only think that should need filled is those mounts), primer, and sandpaper, I'll be able be able to use that patience to prep for a great paint job.

I'll be using a compressor/gun and will "build" a vented paintbooth.

I'm also going to go heavy with some spraymax 2k clearcoat which I understand is the ticket to a fuel resistant paint job.

 

i'am sure you have a auto paint supply place up there. walk in and tell the man you want to paint your bike and you don't know squat about paint, fix me up.
that's what i did and i learned more in 45 minutes than i could have in days on the net. everything will be compatible and it will be just like the paint on your car

 

great advice!

FU

 

Yep, people loooove to share their knowledge with those who have less.

 

Polock, great idea and I'll probably be doing that in the spring. Paint is literally the last thing on the agenda for this bike.

Holidays were slow. I practiced a little polishing on the engine covers. Not perfect, but I don't need it to be. Anyone have suggestions for filling in the "Yamaha" with something black? I'll be buying the YICS emblem from Chacal in the spring.

Finally, I'm working on fabbing the rear tank mount, which also requires some lift. I just started welding so I'm just practicing and seeing what kind of mounts I could do that I'm confident will be functional and strong. Light would be good too, but it is not required.

In the next week or so I'll be practicing welds and waiting on my hoop to come in. The rear of the XJ Frame is 9" OD to OD (According to my calculations), and it looks like my best option is going to be from SpeedMotoCo, as theirs is 8 & 7/8ths from OD to OD. I can't find anything bigger, and am kind of in a rut, because I don't know if I can stretch the SpeedMotoco hoop to fit. Suggestions are welcome, as I'm really stuck here, and the tank mount and the hoop are the only thing holding me back from making my seat and re-wiring the bike.






Now, here is the ROUGH start of the tank mount. Some things to note: THESE ARE MY FIRST WELDS. EVER. I will have my technique down pat before I actually make the final mount. The mounts are three pieces of thinner steel square tubing mounted together. Once again, this is my first weld ever, and there are tons of mistakes. I am having a buddy help me with my technique and my final mount. He will also be mounting the Hoop and slugs for me.




I think that I will have to grind half moon cutouts into the bottom of the mount so that the tubing fits on to the frame for a proper weld. Criticisms, comments, suggestions welcome and encouraged. Thanks for looking.

 

Heeeeeeeeey, nicely done! Tough to say, but you *might* be running a tad cool--maybe juuuust a bit more heat. I could be wrong. Looks like it'll definitely hold in any case.

 

Appreciate it. You may notice (I certainly did messing around tonight) that those welds you see there have a nice big valley in the middle without any "Flux Pool" for lack of better words. I was definitely moving the gun too fast. Those are also ground down completely, which I won't do on the final product, for structure's sake. It's fun, and frustrating, but if it weren't for this bike I would have never attempted welding.

I'm at that funny point in the build where I feel like I'm at a standstill because I don't SEE a lot of changes since nothing new has been added to the bike in a while. Its been lots of tedious work; Cleaning crevices, degreasing, sanding, polishing, staring at wires and diagrams. Oh well, the build goes on!

 

I know what you mean, only too well. Keep going, yer doing wonderful work.

 

Still polishing...now I'm currently working on the generator cover.

Does the generator (or the stator I guess you'd call it, the outer, larger cylinder with the wires, part 3 on the diagram) need to be positioned any certain way when I screw the cover back on? Or do I just push It back into place?

 

It snugs up back in place, but..........you'll notice that there are 3 "scallops" or recessed areas in the stator outer frame, and these recessed areas provide clearance for the generator cover mounting bolts to pass thru the stator. You can see one of these recessed areas in your picture at about the 11 o'clock position.....the stator needs to be rotated counterclockwise about "1 hour" so that the recesses line up with the holes in the engine case that the cover bolts screw into.