XJ900F '91 brat style rebuild

So i thought i got myself a winterbike. You know one that would not survive this winterbecause i would ride it even when they poured that nasty salty stuff on the roads. I wanted a tourer and well they say that this bike should/would be indestructible and it was cheap so there it is.

First of let me show you what i got for 600euro, say 650 dollar.


Yeah a '91 XJ900F with 50sum thousand miles on it. Engine and framenumbers match. It came with a top and one side case which (specially the top-case) was quite usefull but absolutely awfull. Also am able to grab the lower fairing from the seller which i will soon although i dont really need it.

I bought the bike on a rainy day and it was almost dark. Cant say its the best situation to try and test a bike when you want to buy one. But i didnt want to wait and eventually i bought it and drove it back home.

Was it all fine and dandy? No it was not. I cant say i liked front headlight. Not the brightest headlight in the world. Also the front suspension is quite soft and felt a bit wobbly. Specially when compared against my other bike (Z1000)

So the first day i went to work which is somewhere near 40miles and when i arrived i noticed that the right blinker did not work anymore. Actually it was hanging by just one cable, so i knew i had to change that.



First i thought about keeping it original. But i thought about it a little longer and i decided to make a bratbike out of it.

i made the first step in cutting off the back and tear apart the old seat.



i modified the airfilterbox to add airpods to it. I wanted to keep the original airbox so i would not need to hassle with the carbs.

more to come...

 

You need to redo your photo embedding. Did you click the picture tool in the editing bar to link the files?

 

unfortunately i did not, i just used bbtags clicked on submit and called it a night. I have to ask a mod to change it since there is no edit post button.

 

well i had no problems with the images as well.. but @k-moe mentioned there was something wrong. It does look fine on my phone and mac as well.

small update on my side.

I started removing the paint from my gastank. which is quite some work. Im not using any chemicals i'm just using a sander.



Im not sanding the spot in the middle more than i already did.

as mentioned in the previous post i have modified the airbox. I removed the part where the airfilter normally sits and closed it up.



i need to remove the excess glue so it looks more natural, might even paint it if i feel like it.
I've created two holes, 2 50mm pvc tubes will be glued to them where i will put the pod airfilters. This way i hope the airflow remains somewhat the same so i do not need to get into carbs troubles.

Unfortunately when i removed the exhaust pipes from the engine, 1 of the studs snapped. I've seen some solutions for this problem and will try them this weekend.



I have also received my handlebars, unfortunately they shipped 2 different sizes. They will ship the correct size as well.. its just another 2 weeks waiting.

 

The pics from the first post are showing up now. Thanks Mr. Sheriff sir.

 

Why would you keep the air box but modify it for pods!? Does not make sense at all...please help clarify.

 

To help smooth the airflow and keep some of the other advantages of having an air box, but eliminate some of the bulk. Others have built mini-airboxes (essentially the wide part of the airbox where the carb boots are) and used a flat filter at the rear of it.

 

Exactly what @k-moe said. There was another bike online where they did this. I didn't think of this myself

 

What bulk? The air box is still therein its entirety...Anyhoo, thanks for clarification. Seems like way too much work for little to no gain at all. Lets see a video when its all done if poss.

 

It's not for any gain except the visual part. At least that's why I did it. I do not expect any performance gain.

Once I have it up and running I will post a video.

 

I'm curious to see the final result. Being an owner of three Seca900s, my first eraction was a bit negative when I saw the hacked frame, and I'd think that the fuel tank doesn't fit the brat style, but I'll try to keep my mind opened !

 

He cut off the part that resides under the seat. Switch to a LiPo battery that has been relocated and you get that "empty middle" look so many people seem to like.
Hh gets the aesthetics, without the downside of totally eliminating the airbox.

 

Yeah, he explained it to me the first time. Thanks K-moe.

 

Sorry for the thread jacking, not my intention...but I am truly curious. Another way to create restriction and have pods would be a perforated tube inside the pod. How much is trial and 'air'....or measure the volume inside air box in stock perimeters and find the flow rate of air and try to reverse engineer flow to said pods that would be directly on the carbs.

I understand keeping the air box make tuning a breeze and maintenance on say valves and other internal parts, less. Much less because most people will ignore basic maintenance. There will be a loss on bottom end torque. A gain on the top end horse power. If tuned right, which is a bit more difficult. Its not a race bike so doing pods is usually not the best way, especially for people just getting into 4 cyl motos and relativity no experience (I was one too, and the XJ happened to be my first carburetor fixer-upper bike.). This is why all the people that have been posting here a while say not to take off the air box, and adjust your valves then make sure your carburetor is clean. I've seen certain people, hypocritically give this advice, then in another post, say something completely different just for sake of argument. It's not that they're wrong or right; its that they're wavering, for whatever reason.

But pods sounds so dope!!! And it looks dope!!! Think air cooled Porsche ripping around Laguna Seca (Yeah, the same SECA you're thinking.).

 

Pods (on their own) are not able to maintian the smooth airflow required for constant Velocity carbs to meter fuel correctly. At the very least the air box to carb boots (or other velocity stack) should be used in order to smooth the airflow.

Restriction speaks to reducing the increased air volume once the airbox is removed, and would be a fine (if somewhat tedious) way of avoiding the need to rejet. Of course it would also negate the airflow gained by removing the airbox; so in my way of thinking, tackling the problem that would only be done for asthetics.

Then there is the whole issue of efficiency losses when the scavenging benefits of an engineered airbox are eliminated...... Everything is a compromise. What compromises you choose will depend on the end-goal.

 

I wouldn't say members that don't remove the air box on their bike(s) but try to help members that insist on running pods is being hypocritical.

@k-moe: good explanation.

To synch the mill is to have each cylinder make equal (preferably peak) hp throughout the rpm range. Although the carbs are designed the same the intake air at each pod is so erratic that a restrictor within each pod would still be a metering nightmare. As k-moe stated the air box and boots are designed to eliminate all that.

Gary H.

 

WOW...please re-read what I wrote.

 

@eurosnap53: My apologies...maybe I mis-understood. I still think trying to reverse engineer the perimeters of the air box for pods would be a nightmare. Well...for me anyway cause I'm not that smart. I digress.

Gary H.

 

And since im not that smart either I chose not to go through that same nightmare.

Maybe when I'm older wiser..

 

I would gladly remove my stock airbox to replace it with something that makes pulling the carbs off the bike and putting them back on less of an hassle and that doesn't affect performance negatively at the same time, or doesn't require any rejetting. It would have to be cheap in addition.

I haven't seen such a thing here yet.

 

If you love beer and want to have a unique bike then this is the mod for you!
http://www.xjbikes.com/forums/threads/link-to-my-beer-can-rat-bike-video.25418/

 

I just did a kind of a proof of concept on a different bike, not an XJ. I think it worked successfully. I'd try an XJ, if the airbox wasn't such a godawful PITA to pull out and put back in.

Might give it a go on the FJ600, whenever I get the carbs back together...

 

I do wonder what is the easy way to get the airbox out. I had to kill mine to get it out.

 

Everything out (side covers, battery, batt box, disconnect/ move wiring aside, carbs, air boots on box. any other BS I forgot in that space) including the starter...its still tight; its a puzzle for sure. There may be different ways tho...I have only done a complete tear down, which is a pain and is commitment to its fullest. . I took the motor out, but you don't need too. From a frame up it goes Frame, rear brake pivot, swing arm, air box, motor. Then everything else can go in at your leisure I believe. Haynes or OEM service manual is nice too.

 

WIth enough practice it takes about 5 minutes to pull a rack of carbs from an XJ, and maybe 10 to reinstall.

 

Remove the starter and battery box first.

 

+1. Let's see...

1.Remove the seat.
2.Remove the tank mounting bolt, jack the tank in the rear and remove the vac hose and fuel feed.
3.Remove air box top and side mount bolts.
4.Free and clear ec, throttle and clutch cables from the rack.
5.Loosen manifold and air boot clamps.
6.Slide air box to the rear and remove air boots (or shove them into the air box).
7.Strattle the bike, grab the carb rack on either end and pull it straight back. It should pop out.
8. Done. Rack out in 20 minutes but who's counting?

Gary H.

 

It sounds a bit optimistic, actually I'm not sure I want to practice that much.

 

After stripping the gas tank from paint i noticed that the tank is leaking. I now have the option searching for a replacement or fixing this one.

I was wondering. Does a xj550 tank or 750 fit or are there others that fit with few modifications?

 

@k-moe: what's the link to the aircraft tank liner you posted in another thread that's better than por15 and can be used as a welding option? I was meaning to save that link.

Gary H.

 

Caswell Tank Sealer

 

Today i was cleaning some parts that i removed from the bike. Like the electronics on the handle bars and also the break and clutch levers.
I already noticed that the clutch lever was a little loose or well it didnt feel quite stable.

i found out why that was the case. On the hunt for a new break and clutch lever.

 

Uh, come again?

 

Crazy typo mistake !