My '82 XJ750 "Project Shadow Warrior"

I've been doing a TON of research on my chain drive conversion project and I've found what needs to happen to make this work. From what I've found on Japanese websites about the 1984 XJ750r (OU28) race bike, to they reversed the rotation of the engine to have the middle gear rotate counterclockwise.



Because of the reversal of the engine, a few things in the engine must be changed in order to function correctly. First, the camshafts must be custom made so it doesn't operate backwards in the combustion camber. This isn't a big deal for me, because I was contemplating getting a regrind for a turbo cam. Unfortunately, a regrind won't work because the lobes will be on another side of the shaft.


Next, the oil pump is a gerotor gear style.

A gerotor is a positive displacement pump. The name gerotor is derived from "Generated Rotor". A gerotor unit consists of an inner and outer rotor. The inner rotor has N teeth, and the outer rotor has N+1 teeth. The inner rotor is located off-center and both rotors rotate. The geometry of the two rotors partitions the volume between them into N different dynamically-changing volumes. During the assembly's rotation cycle, each of these volumes changes continuously, so any given volume first increases, and then decreases. An increase creates a vacuum. This vacuum creates suction, and hence, this part of the cycle is where the intake is located. As a volume decreases compression occurs. During this compression period, fluids can be pumped, or compressed (if they are gaseous fluids). Gerotor pumps are generally designed using a trochoidal inner rotor and an outer rotor formed by a circle with intersecting circular arcs. A gerotor can also function as a pistonless rotary engine. High pressure gas enters the intake area and pushes against the inner and outer rotors, causing both to rotate as the area between the inner and outer rotor increases. During the compression period, the exhaust is pumped out.

I'm still in the works on how to solve the flow direction. By having symmetrical ports inside the pump (the xi's are progressive) the flow can be reversed by switching the inner rotor axis 180. Thusly, a cnc oil pump housing might have to be made. I'm not sure the current pump case can be modified?

I don't have a photo of the inside, but the xj's ports look just like this

Because of the the progressive ramp, it limits the position of the axis of the inner rotor. If symmetrical, the axis could be flipped. Here is more info about this:


Next the starter clutch outer assembly has to be flipped. The rollers grab in one direction and retract in reverse direction. If left alone, when starting the bike, the starter gear would never engage. The assembly is pressed together and is very difficult to remove without distorting the outer plate. I think I'm going to remove the outer plate, flip the inner, and machine a new outer plate.

example:


Next is the cam chain tensioner. With the reversal, the tension and slack sides are reversed. The tensioner will have to be moved to the front side(exhaust) of the engine.

front cam tensioner (hard to see, but it's there underneath the headers)


After all that, The custom shaft coming out of the middle gear for a sprocket can be used. I'll use the middle gear housing and make a longer inner custom shaft that will extend into the oil bath area of the output shaft of the case. The oil paths in/out will need to be plugged and a sealed bearing will replace the open bearing on the middle gear. I think the shaft will extend into the cover with a sealed bearing. Of course, a custom cover will need to be made. There is not much room in there for a sprocket with chain. I think a 13T with chain would be the max diameter allowed, at most 14T.

the (ou28) chain conversion


Output shaft box


proposed mill area for spocket


I'll use the holder, compression spring, driven cam, drive cam, etc.. and replace the inner middle gear with a custom one


I'm not settled on swingarms yet, but I'm close to throughing down on a Ducati 996 single-sided swingarm. It's only 1.5" longer than the maxim swingarm and I'll have roughly a 56" wheelbase.



or a 1098 swingarm, but it's 2" longer than a 996 I think?


This weekend I also prototyped the (OU28) FZ750 alternator conversion. First one outside of the factory. Needs to be refined, but it will work!





I liked the concept of using a cell phone for display gauge on the bike, but ran into issues. Not being able to boot straight to app from startup, automatic boot up & down from ignition and charging in the rain. This is possible, but with a lot of custom programing. I decided to scrap the idea and went with a AIM MXS Display. It is compatible with megasquirt CanBus code and I can customize the data being displayed! It looks sweet too. I made a custom bracket attached to the upper triple tree.




I'll keep you guys up to date as things progress.

 

Sweet

 

Holy cow... I must be learning. I understood at least 40% of the words you used..."if... but... the... a... on... not..." Yep. I understood those words. Beyond that, not so much! I do like the maxim badge on the tank... almost ironic? That thing is NOT a maxim anymore! I may not understand what you say, but the pics look pretty.

 

Wow, this an awesome, inspiring project you are doing - great stuff, well done!
One small question, could you not use some sort of intermediate gear set between the output shaft and the chain drive to get the correct rotation?

 

Simply amazing work sir! Well done! Greetings from the tmioa Yamaha xj650 turbo forum.

I've been working on my 82 seca turbo (LJ) project bike for a while now and always wanted to convert a Vision (xz550) swing arm for monoshock. Clearly the Virago was the way to go!

Questions on turbo conversion.... I'm looking into a 900 turbo engine, but with (a now rather pedestrian looking thanks to you) stock LJ turbo set up on ms3....

I was already worried about too much compression with that set up and stock 900 pistons. You're going full on crazy with larger turbo...How are you going to deal with this?

Water methonal injection (snow performance) and custom thick head gaskets were what we came up with many moons ago.

On the front wheel...what was main reason for not going with 900 front wheel?

On rear, did you have to shim it?

Thanks for your time, wish I had found your posts a few years back man. You are building the ULTIMATE XJ! KEEP UP THE GREAT WORK!

 

crazy price.....but maybe you can keep your swing arm with chain conversion...

http://www.ebay.com/itm/CHAIN-DRIVE...cc1ca35&pid=100033&rk=2&rkt=4&sd=111679892332

 

Wooooooooooooow, and to think, you were gonna scrap it LOL! I'm speechless, truly...

 

Good sir, this is a family site.

 

That swingarm is overpriced. the TR1 had a very long production run, but was just not brought to the US but the one year. Searching overseas is the answer to the question. Just make sure that it gets handed off to the USPS so no duties or tarrifs are charged.

 

skylrk62, could you please post pics of the swingarm frame mount you fabricated? Im starting to gather parts for monoshock conversion. I have a Yamaha Vision, but no access to a Virago for reference. Many thanks in advance. This is an inspiring build!

 

With a compression of 9.6:1 not being ideal like a 8:1, but it's manageable with 93 oct, a good tune, and a knock sensor. Intercooler should drop the intake temps down to safer levels, theoretically.

I'm not sure of the axle diameter on the xj900s wheel and I already had the r6, plus I like it more.

No, fit perfect!

The turbo has a large range that the 900 falls perfect into, theoretically speaking.

Mine is the 313296

here ya go!

concept

installation 920xv swingarm (upper portion)




xj900s rear wheel installation

old tire(maxim 130/90r16)



xj900s wheel with 150/70r17 roadsmart dunlop tire




Hope this helps you out? Axle is original to bike(maxim 17mm)

 

Thanks man!

 

How's it progressing man? Dying to see what you do to it next!

 

And heck, while you're at it....http://www.turbomirage.com/water.html

I mean, you might as well for the price, and to say you've gone as far as inhumanly possible.

Updates, please!

 

1) its another safeguard against detonation (serious concern given the high compression for turbocharging you've got)
2) it could be stand alone, or wired into megasquirt set off the knock sensor or boost sensor.
3) you'd be one of the only people running water/meth injection on a bike...more cool factor points!

 

I thought about incorporating an water/methanol injector , but due to space and not a huge difference at my boot levels, I decided to pass. Maybe down the road, but unlikely.

Sorry for the slow response. I don't get on here as much anymore. I post my updates more frequently on instagram.

link to instagram https://instagram.com/skylrk62/ @ skylrk62 handle name

post some pics of your turbo XJ bike

 

Really liking what you've done so far. Looking AWESOME! so how hard was it to make the mono shock swing arm? Also did you get the chain conversion finished. You might have already mentioned it but I might have missed. Keep up the work.

 

Keep posting on here! Know your roots! I follow you on insta but remember where you started...I hate it when people start jumping around from different forums and such, thus separating the build process. I'm sure I speak for all members on how impressed we are at your technical prowess; you're the first person on here to do a write up on the chain conversion and also a full custom turbo setup without having started with a turbo bike...and your astetic value has jumped up 10-fold since the beginning of the build, i though they were different bikes/people. Absolutely amazing, your exhaust manifold is 'to die for'...cheers!

 

Your bike is over the top awesome. Could you flip over the cams so they would be backwards?

 

Where can mr skylrk62 be found these days?