XJ650 on air

ok.. so I have been trying to get some pictures rounded up on my build..

Obviously, I haven't completed it yet, but its getting there piece by piece..

Ive always been into slammed cars and hot rods / rat rigs.. Had to take a stab with a bike, but i want it to be ride-able, so looking for a good 6-7 inches of suspension travel, with the bike laying frame on the ground to park. The rear uses a cantilever setup while the front will use an extended linkage version of a girder setup (44 degree rake)

Lets just start this thread with some pictures to get you up to date..

layout


frame started



rear cantilever setup - using idler sprockets welded to plate for a bearing surface



engine mocked up and more rails added for rear half of frame



top tube rolled (2 directions) - cross bar is temporary (all small tubing joined with solid bar plugs welded in both ends to join)





Cantilever levers tacked in and shock mount started








Getting everything square and level - have the head tube tacked on..




Lots of work left to do but its a start... of course you dont see a heap of "Seat of your pants engineering".. most of this has been mocked up a few times using different ideas until we find something that works.

 

Good to see such a radical mod! Good Luck, I'm definitely interested in seeing where this goes! Looks good so far...

 

Very interesting. Can't wait to see more.

Am curious on the drive shaft section. That'll be fun to see.

Good luck and keep on clicking pix.

 

ahh.. driveshaft here is our plan:

carrier bearing in end of swingarm (where ujoint used to be) - extend driveline a few inches to clear carrier bearing, then a two piece driveline to the motor.

so in order,

engine , ujoint, 2 piece driveline (might just incorporate a slipyoke on the engine side like stock if the travel is short enough to work), ujoint, second driveline through carrier bearing, diff

when pumped up to riding height, the drivelines all make a fairly straight line, so as long as its true and fairly balanced, all should* be well.. not that it doesnt make me nervous.. lol

 

Ha, sweet. Now I'm REALLY anxious to see it work =)

 

Sorry for taking so long, but i moved - and got a shop again built a bike lift with a friend, and now im finally back to work..

Here is another detail shot of the rear suspension as it sits - needs reworked now that i know how much lift i need - had waaay too much lift in the rear, and this allowed me to get the pressure for the airshocks down..



Getting a start on the scratch-built frontend with some new custom trees..



Finished up the basic build on the front-end - as always, thanks Doug for the fabrication help!



This shot shows where the shocks are mounted, but only shows one and doesn't show the mounts.. I have the mounts completed now, but no pictures yet..




Some side notes for others attempting to use air-shocks for things other than designed.. the dampening qualities of two airshocks on the front of a motorcycle is uhm.. a bit overkill. The shocks restrict movement to the point that i have to put 50 lbs of pressure in them to get it to start lifting (overcoming the dampening effect) - and when it does lift, it goes all the way up with little control.. no stopping halfway.. Dropping it back down is just as bad - i remove ALL the air and count to 20 before it goes down again.. so.. I went ahead and gathered up some courage and drilled holes in the shocks. They are oil shocks, so i assumed that letting the oil out and welding up the holes would allow them to lose most of their dampening qualities.. This worked GREAT - the suspension works as advertised for the moment - but when i ride, i may have lost the shocks that i may desperately need, so im either going to cut one shock in half and drill a hole or two in the valve (then refill with oil again) or try a much lighter oil. Maybe a combination of the two. It probably wont need more than one properly working shock, so i will just leave the other void of oil..

The bike from tip to tail is now 10' 6" - with 6 inches of frame clearance when lifted. Here is a pic with my wife on the bike for scale.. sorry guys, she is camera shy..



If i see interest in the project, I will keep posting.. so far it seems limited, so I'm not sure this is the proper forum for such hackery..

 

No, we're interested. But only if the finished product runs and can be ridden and doesn't turn out to be another "trailer queen." SO MANY of these projects never finish; or the builder discovers way too late that the motor wasn't viable to begin with.

This one's ambitious and artistic; I just hope it produces a motorcycle not an expensive (in money and labor) paperweight.

Keep up the good work, let's see it running down the highway at 80mph. Then I'll be impressed, even if it's still in primer.

Wrap the pipes and put a tractor seat on it and you'll have an instant following. Especially if you put the taillight on one side.

 

I get that.. This is a long term project for me, as time is a bit limited.. I dont know the scene in this board, and thought it might be too extreme.. I was hoping that posting here would be a good source of caffeine for my motivation on this.. although, as you can see, im not deterred from moving along with the build regardless..

As to exhaust, it will consist of the 4 downpipes going to a can mounted in front of the engine - tossing the expelled gasses to the right and forward. I hope to incorporate a 50s style flamethrower to the tip (spark plug)..

Haven't figured out the taillight location or the seat material yet, but now that i know what everyone else is doing, i will avoid them.. lol

 

I second the vote of interest.

I'm still pretty new to these forums myself, but I'd say the scene here is close to equal parts restorers, bobbers, and café racers. And while the full-on chop is rare, at least from what I've seen, it is nonetheless drooled over.

But definitely everyone wants these bikes to be safe and mechanically sound. What you're doing will obviate most of the things that are preached on here: brake lines, rear brakes, fuses, etc. I'll admit that I started my build not knowing anything other than what I wanted the bike to look like. It was only by reading post after post after post here that I realized that maybe I should have left the airbox original, but that at least I was on a good second path. Likewise, I'm being a good little XJBiker, and have checked the valves and will be checking compression this weekend. When it's warm, I'll need to do a plug chop.

Bottom line, I can't wait to see where your build goes.

 

thats really cool prOzac,will be watching your progress.if you go to thrashmetalsilvers (82 xj 750 seca bobber) you will see a photo of his drive shaft extention.this is how mine looked before i remachined.i didnt take any pics.just pull the driven shaft out the rear of a basket case motor i have and i think that if you found another uni/tailshaft you could manufacture an intermediate shaft.good luck with the rest of it cheers scruff

 

The driveline on http://www.xjbikes.com/Forums/viewtopic ... rt=30.html is exactly what i had planned for the rear driveline - the intermediate shaft will need to be a two piece telescoping driveline, as the pivot point will be a couple inches behind the ujoint connecting the two. Im going to have to do some talking to get my local driveline guy to build me one (its a tractor implement, don't you know)..

Front-end from the front..


Top shock mount tacked.. Its hard to tell how massive that front end is - those 4 links are about 8" center to center. All pivot points and bushings were turned on a lathe to insure it wont rattle down the road.. I need a lathe now


Last night's progress.. started on reinforcing the downtube by tying it into the chassis..



To give some credit to folks so far, i would like to mention My wife, Traci for the support and ears, Doug at WestTech for the help with welding, problem solving and problem spotting (he is a mad tig welder and fabricator), AJ at WestTech ( http://wti-fab.com ) for materials and tool time, Andy & John at 8thDayCycles ( http://www.8thdaycycles.com ) for more tool time and advice and last, but not least is the folks in this forum. I couldn't tackle a project of this magnitude without all your help! This is my first ground up bike build, and the combined expertise is invaluable.

 

cool looking project to be sure. you are quite the fabricator. I look forward to seeing it done.

CN

 

about your shocks, inside them, the air is the spring part and the oil is the damping part. the less air volume there is the faster the pressure builds that in turn pushes the oil.
so far so good
if you were to add some kind of air reservoir, like the piggy-back shocks have, you'd get more spring action.

 

Looking really good! I'm definitely interested in seeing more.

Regarding your speculation over interest in your project.. when I rebuilt my XJ650 I posted for nearly a year sporadically. Responses here were ONLY regarding comments concerned with the quality / functionality or questions directly related to something I was doing that someone else planned on / was doing / planned on doing. MONTHS later I was still getting comments after I completed my build (or at least completed my postings about it).

Moral of the story: Just because you don't get a ton of feedback don't stop posting. Many members here are likely watching without commenting to prevent spanning your build thread with 'cool build man' posts. We all want to see what happens, and for those who want to go back and read over it for their own future reference we would rather not have to scroll past pages and pages of comments supporting the build - we want to see what YOU have to say, not what others think about YOUR bike; unless of course it is helpful criticism and questions that keep you on the road and alive with things that we misunderstand or that we think may have been overlooked.

Keep up the good work and keep up the postings. I'm looking forward to seeing more!

 

Good info BluesBass.. Sometimes its difficult to know whats really going on in a forum, and i haven't been here before this build, so im happy for the clarification.

Polock, I agree with everything you said there, except for the spring rate part. If this was an air cyl and not an airshock (which uses an internal air bag), it would almost be fixed without an external expansion chamber for the air. Since it is a bag, however, air pressure will adjust the spring rate (at least that's my understanding).. If the ride is too harsh with the suspension at full lift, that will be the first thing i do The build accomodates 2x 3/4 gallon or so air tanks to take some load off the compressor, so it should be a simple matter of relocating the valves to use the tank as an airchamber - of course thiss will demand more of my compressor as lift will be on demand. I made note of this when i bought the compressor.. its got plenty of airflow to keep things charged up - i may even have 3 airtanks if i go that way to keep pressure in the system all the time..

 

Don't know how I missed this before, like where this is going. Like the frontend, think you'll need a gusset at the goose neck. Was worried about the backbone at the rear til I saw the new pic with the change.
Will be following this one, good luck with your build.
Keep the pics coming.

 

Ya- i will be gusseting the crap out of the entire frame once im happy with the suspension d&d - right now, its basically tacked together really well at certain points so i can strip it down, retrue everything, final tack, tig, gusset and tig some more.. its getting there.. I may actually do that next, as im running out of things to do before the driveline buildout..

oh - on that note: the driveline build has a different structure now. it will use two one piece drivelines. I will use the original driveline as expected and couple it to another one-piece driveline.. The intermediate driveline will be supported with a carrier bearing - ending with a flange at the stock location (in relation to the main driveline). There will be little to no front to back movement by supporting the intermediate shaft, so no need for two-piece.. I was wondering about driveline size differences between the 650 and the 1100 though if someone has both drivelines handy - do they use the same u-joint?

I was wondering if there was a bolt-up (or fairly bolt up) rear wheel swap I could use to get a disk brake back there, as i will be running no front brakes for awhile (will eventually go disk up front as well, with a proportioning valve - actuating both brakes with the foot pedal)

 

I would not consider the bike safe without a front brake, PERIOD. Your front axle contributes to 70% of your braking, by riding without that front brake on a bike that you are building by trial and error and don't know the handling of you are signing your own death certificate. I'd focus on making the front brakes work FIRST, then worry about a rear disc conversion. It is MUCH safer and doesn't risk having your rear wheel slide out from under you, especially with how far forward the center of gravity will be - so far it looks like there is going to be very little weight on the rear axle and certainly not enough for adequate braking. We want to see you finish your bike, not vice versa.

 

Without starting anything here, im fully aware of the characteristics of a bike without a front brake.. Im working from the rear forward due to the need for front disk brakes. This bike weighs too much to just rock a drum brake on the front (which the bike has right now) - and then a drum brake on the rear. Getting disks on the front is easy if i can find a disk for the rear (just lace up a new hub for the front).

This bike will have stripped handlebars and hidden controls. i will be using a hidden throttle on the right and a hidden clutch on the left.. foot shift, and 1 brake pedal. Again, i understand the safety issues. If that drove my build completely, this bike wouldn't be built. Hell, a ton of custom choppers all over are built using spindles on the front. Riding a bike has risks. Riding a custom bike has 2xs the risks. I dealt with that before i started.

If i can find the parts for the front brake before the bike rolls, awesome.. If not, I will be avoiding the highway and just using it around town at low speed.

Now, that being said, if i can't find a rear disk, and im forced to use drums on the rear, im limited to linkage and not hydraulics. At that point, i will be using linkage to use both front and rear drum brakes on one pedal without proportioning. I wont use a drum on the rear as my only brake. The question i asked was intended to get hydraulic disk brakes on front and rear eventually - just working from the rear to the front, because of the shaft drive and its limitations...

 

according to a post on http://www.xjbikes.com/Forums/viewtopic ... brake.html , I should be able to bolt an xj900 rear swingarm up? Can i get a confirmation of this before i run off to ebay?