Xj550 engine mods

hi every1 I'm new and tried to search before asking, I know some may get upset when u ask with out trying first. But with 275 threads sorry not reading them all so forgive me if this has been covered. Looking for info on engine mods for xj550. Seen a Video of a cafe version and didn't sound stock so are there cam, choices , heads , valves ect. And who has done them and what's your parts source if so. Any info is appreciated.

 

if it is a maxim motor you can put a seca 550 cams set (head swap) and rejet to seca carb specs
which can be found here
http://xjbikes.wikidot.com/carb-specs
basic carb differences in pilot air jet and slide needles.

they did make adjustable cam kits where the sprocket was adjustable.
air shifters are out there. convert to full led lighting system will add a little to the bike.

you could polish the intake exhaust ports go to oversized pistons.

my advice would be to buy a bigger bike if you are not happy with the performance of a 550

13 second 1/4 mile is not to shabby red line in 20 seconds.

move up in tire height for more top end. if it is a maxim put a seca rim on the back

we have a member who converted to a 600 jug head set up

you can also wrap the exhaust it will also give you a little more hp

go to electronic tach remove the drag from motor from tach cable close off port

 

The 750 Seca does the 1/4 mile in 11 seconds. It might be easier to swap bikes, cuz the engine swap won't happen. Shaft vs. chain drive. Only the 550s have the chain.

 

yup thats why I said
"my advice would be to buy a bigger bike if you are not happy with the performance of a 550"

would cost less in the long run and I do need something to keep the others company

 

I'm half-way through an engine build that will use 600 (58.5mm) pistons and an FJ/XJ600 head on a 550 bottom end. Kickaha on here has already done this. It ups the cc to about 556 from 528 and you get bigger valves. Not sure on how you would carburate in yet but that's all part of the fun right ?

 

He can swap cams without pulling the head. Carbs will need to be rejetted to take advantage of the cam swap.

 

I only used the pistons on the first one, head and pistons are for the next one, might be using bigger pistons too if we can find something off the shelf

I used stock jetting with the first one and it ran mint but nothing else other than the pistons was done to it, bike two I have a set of 26mm Keihin CR carbs for

 

Thanks it's a great running bike and in good shape, yes it is a maxim. It's a 550 so it is what it is just a gear head at heart and no matter what u have there's always tricks to get a little more

 

would the radian cams work in the 550??

 

http://www.megacyclecams.com/catalog/Page64.pdf after looking at this i think you could fit the radian cams in the 550 for better mid range?

 

Interesting. Note that the Radian and FJ/FZ 600 cams will not have the tacho drive on the exhaust cam..

 

Regarding buying a bigger bike, not sure i agree with that.
the xj550 is a great little bike, light and agile.
personally, i converted mine to run Microsquirt for management (Ignition and Fuel) and plan on turboing it with a small turbo for a more "linear" feel.
i know, its not easy to modify an engine to run engine management system, but if you have the fabrication skills, go for it.
as i see it -
58.5mm pistons,
32mm throttle bodies.
4-2-1 stainless exhaust system (soon to be modified for boost)

other than that, i would leave the engine modifications for last.
on my bike, i have an R6 front suspension that i manage to get the original 19" wheel on, with twin 320mm floating disk brakes,
Rear suspension went through a complete rebuild and are great.

remove some weight from the bike, treat it well , and you will enjoy it.

 

But will removing weight get you 2 seconds in a quarter mile? If so, I'm going on a diet! Easiest weight to remove from my bike is that pesky spare tire.

 

Actually lightness is a big contributing factor to performance. The first-year GSXR750 was revolutionary not because of the engine, but because of how much lighter it was compared to the competition, and the competition took note.

 

I know lightness is a big factor. Colin Chapman of Lotus fame said "The easiest thing to add to a machine to make it faster is lightness." In car drag racing, the claim is for every 100 lbs you lose, you gain a tenth of a second. I feel that to gain the difference from 550 to 750 (13 seconds to 11 seconds) you'd have to trim quite a bit. That's why I say if more speed is what he's searching for, more power will provide easier gains. Not sure what 1/4 mile times are for 900 or 1100, but if anyone wants to lend me theirs, I'll find out! Anyone? I'll give you a million hugs!

 

it is the collective of what he can do that will shave the 2 seconds, seca cams and carbs. = .5
convert to led all around light weight housings for the directionals and tail light less drag on alt.
switch on head light to turn it off
mac 4 to 1 exhaust is 16 lbs, oem exhaust 29 lbs
shop around for tires by weight. go to plastic seca chain guard seca plastic rear fender. cut the front fender down. cut the seat in half,loose the chain box, tool tray.
smaller battery.

strip it like old school bobber

taller rear tire will add top end ( but if it top end you want bigger bike)

 

Have we seen a picture of this middle-eastern masterpiece yet ? If not I would like !

Cheers

James

 

I will be posting pics soon, on vacation at the moment

 

Ok I have a lot of great ideas, but I ask this: I ordered the Mac 4:1 exhaust, it has removable silencer, if I remove it and get a different air breather I know it should be jetted. Will the specs for the seca 650 jetting shown in the link work for these two mods?

 

Of course your's too but also the Microsquirted one in Israel..

 

no read this link in it you will find a formula for rejetting based on the mods you do BE aware it is just a place to start
The Information Overload Hour

if you go to the jetting sales company they will sell you a kit they think will work for you.

read this this is what you will have to go through to tune carbs for your bike
http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

read this too it may help you
http://www.dansmc.com/carbs2.htm


before you start to modify the bike make sure it is running correctly

 

Bike is in great shape and runs perfect as is. Fantastic read on carb adjustment. I'm no carb guru but when I looked at ur other link with the carb specs it shows a main jet and pilot air/fuel jet. The tuneing link never mentioned anything about the pilot jets?

 

well, in order to not hijack this thread, ill just leave a couple of pics .
still a long way to go, need to conclude the wiring and bodywork.

but the engine runs perfectly, managed by MS.
different front with new brakes on original wheels.
4-2-1 SS exhaust system, designed and built for performance.

 

More please

 

Better start a new thread - we need details !

 

pilot jet is idle to 2500-3500 rpm adjusted with mixture screw using a color tune or by pipe temp or by ear. barely comes into the picture to go through plug chops when you can color tune it
if you need to change it the color tune will tell you

edit on a 550in first gear 10 mph =2500 rpm 15 mph=3500 rpm which is all happening in a few yards trying to go slow below a normal start from light or stop sign, would be more like moving up to stop sign after the person in front of you went.

my understanding of the pilot circuit it is to idle bike and make it pass epa emissions testing of the era

 

Ok peoples, I have some Spec II 5730 grind cams. Problem is no one makes valve springs for them any more. Everyone says, " send us the head and cams AND $700 we will make some for you. Does any one have any ideas?

 

Whats so special about the cams that you need different springs?

If you have a the OD, ID, wire diameter and overall length you should be able to match something up

what about someone like Kibblewhite?

 

I can't give official #'s, but CAN tell you that I can pull my 900 out of my neighbors drive just a couple houses down, and pass my house at 100mph. Carb clinic people can attest.....

 

With a healthy engine a 900 should be a tick faster than a 750 in the 1/4. The 750 can run 11.99 with the right rider on it (and the sport fairing). I figure the 900 should be good for 11.8 even with a normal guy on board.

The magazines ran the 550 in the mid 13's when new.

 

special cams need special springs in one of the other threads someone posted a link to cams on the list some of the cams needed different spring sets

it was this thread and link
http://www.megacyclecams.com/catalog/Page64.pdf

when you change the lift you push the valves deeper into the cylinder stock springs may bind fighting the extra lift (may not be able to compress that much)

 

i believe its the same concept as cutting the springs in your forks so that you can use a spacer to make them stiffer. you have to figure out how much gap you are replacing so that the springs dont bottom out before the rest of the contraption

 

what about unipod air filters, heard good and bad, anyone have experience. I've heard a lot of complaints about removing carbs. Seems they would help olongapo with cleaning up engine bay.

 

CV carbs and pods do not play well together. You can put them into a "get-along shirt," but they will only pretend to be friends (see link below, particularly page 5).

 

oem is a uni pod
it is not about the filter it is about the configuration with velocity stacks if you used a i piece filter on stacks it may get closer to where you need to be.

 

I'm well aware of that but they dont always, case in point the Yoshi cams in my sidecar motor can use stock springs

Spring bind is to do with insufficent installed height for the cam lift you're running so the coils end up stacked hard against each other, this can happen regardless of what spring you use and comes down to poor assembly and checking

 

Make your bike running well with stock airbox...you can add a k&n filter. Pods can be a pain to make work properly , and you have to fabricate a braket to support carbs...the boots will be under a load and can crack if carbs are not supported. You will have to rejet carbs , bike might have power at high rpm and stumble at low rpm or vise vs verse. Mikuni and Hitachi carbs on the 550 and 650/ 750 just don' t like this . High velocity causes problem. I know some will disagree with me on what I stated some claim how great their bike runs with pods, but my xj750 seca runs sooo smooth at 85 mph I still have throttle left and I have stock airbox.

 

i have tried pods on the 550 its not easy it can be done but not worth it you wont notice a power increase if you some how manage to tune them perfectly for the pods. theres just not enough back pressure and the carbs dont like to work right. not to say it cant be done but the stock air box works so much better its worth the hassle of pulling them out and putting them back in each time