Let's get SERIOUS.

OK- I've had a chance to browse through most of the threads here; lots of really great info! But I haven't found the one thing I've been looking for. Maybe some of you can either point me in the right direction to existing threads or help me out here.
My '81 Seca 550 is basically stock, with the exception of the Gemini exhaust system. I've got 42K on the Odometer, but the engine has good compression and runs well (when it feels like starting without some, er...assistance). But the bike does not have the "oomph" I crave. It really doesn't start to wake up until I'm above 7K on the tach, and below that it makes a lot of noise but doesn't impress me much. Keeping the tach up gives me the throttle response, but drinks gas like nobody's business. With the high mileage on the engine, someday soon I'll be tearing into it. Here's the dilema; I have found nothing in my years of ownership relating to performance on this engine/chassis with the exception of K&N's and exhaust. I'd like to access some info regarding;
1) Carb mods (I see Dyno Jet makes a (rather expensive) kit for this bike. Anybody used it, and your thoughts? Dyno run sheets, etc? Throttle response is poor compared to a Mikuni flat-slide.
2) Ignition upgrades. The stock ignition sucks-plain & simple. Dyna Tek does not make an upgrade for this model XJ and doesn't plan to. Can anybody recommend a better ignition system (perhaps with a tuneable advance curve)? Dyno sheets, etc.
Since I'll be looking at top end work, for sure, any swaps, like Seca 650 cylinders, higher compression pistons, etc that might fit or interchange from other XJ bikes that might build more HP? I have no idea what will interchange with what.
3) Cams. Does anybody grind aftermarket cams for this engine? Which grind would be recommended for better lower end grunt (say, in the 4 to 7K range?)
4) Headwork, etc.-porting, polishing, etc
5) Better suspension and handling. This bike needs help big-time in this area. Brakes are marginal-to-inadequate. Steering is wobbly, not firmly "planted" and I get head shake at higher speeds at times. Rear suspension is too cushy and the swingarm has a dangerously "floaty" feel; not firmly planted. I'm running Metzeler ME33's that have seen better days and I'm planing on replacing them. Recommendations?
I guess what I'm looking for is someone who has race-prepped or done a lot of work to one of these and might have some inside info. (Or maybe some URL's to info of this nature) Thanks in advance!

 

Sounds bold Kirk! Don't have any suggestions but I hope you find some good answers. Be sure to spread the wealth when you pick up any info!

 

sounds like you need a new bike....

 

I'm with Foximus.

All of the things you commented on could be improved, but you're talking a fair ammount of money, and with the way you wrote the post it doesn't seem likely that you'd be satisfied with the results.

Just remember that it is a 550 and that it is 25 years old... you do get what you pay for.

 

Alright, the 550 is an oddball motor for the XJ family. The 650/750/900's are all very similar, and many parts interchange, but the 550 was smaller (in physical size, not just cc's). But, from what I've seen the 550 will interchange with the FZ600's and the Radian 600's. Both of those have a bit more aftermarket support. I actually saw a Seca 550 on Ebay a while back with a Radian 600 swapped into it.

As far as brakes go, there was a member here that swapped on a dual disc Seca front end onto his 550. He also said his handling improved a lot too. But making sure that things are in good shape is a good place to start. You can get progressive fork springs for the front, there's several places you can get new shocks/springs for the rear.

Go to: http://www.megacyclecams.com/ for some cam choices for ya. They have everything from mild to wild. However, I think it's gonna be hard to get more low-end grunt out of such a small motor. You might have to comprimise and sacrifice a bit of low end (up to 5k or so) to have a fatter high-rpm powerband. Would go nice with some port work, but don't go overboard or you'll lose even more low-end.

Carbs I'm not sure on, maybe check around for FZ600 stuff and you might find some flat-slides somewhere.

Main thing is to go through your bike and fix the basic maintenence stuff. Sounds like your current suspension is pretty worn. I'd replace the steering head bearings and swingarm bearings, then put progressive springs in the front, and some replacement of your choice in the rear.

Yes, it is a 20+ year old bike, but it can be made better than it is. The response is typical "if you want a better bike, buy a new one", but some of us (like myself) can't afford a newer one, and even if I could, there's not too many new bikes that I actually like. So, you do what you can within your budget to make your bike what you want it to be. Sure, you'll probably end up with more in the bike than what you can sell it for, but if it's for your enjoyment, who cares???

Good luck, and keep us updated with it. I've always loved the Seca 550's.

 

Joel, you're right in many ways. I guess the point I was trying to make was that he could sink a few hundred in... or many quite a few hundred in and still not be satisfied.

I don't mean that it being 25 is a bad thing - but no matter how much he acheives he's got 25 years of progress to combat if he wants to compare it to some of the newer better setup bikes. To do that will take more money, or more willingness to compromise than I think is reasonable to expect in this situation.

To be even shorter, the options I can see:

1 - status quo
2 - some fixes for a small cost
3 - alot of fixes for a lot of money
4 - a newer bike (for less money than option 3 likely) with the fixes already done.

I personally really enjoyed working with the xj... it's a beautiful machine. The difference I feel is that I connected with the machine and appreciated it for what it was - rather than the feeling I'm getting (maybe unfairly) from the original poster that they don't appreciate it for what it is and want it to be something else. Some people at this point do wonders and recreate the bike, whereas other people might be better served to find a better starting point.

 

You're right on the money woot. If it's a matter of wanting sportbike performance out of the old XJ, you're definetly better off buying a newer bike. And like you said, if you're unhappy with it as is, it might be time to think about selling and getting something newer.

But if you're like me, I just can't leave anything alone. I always see room for improvement from the way the vehicle left the factory. While we can't make our XJ's accelerate, handle, and stop like a sportbike, we can get some pretty exhilirating performance out of them, and have the satisfaction of knowing that it's unlike anything else on the road.

So, I guess the question is, speed costs money, how fast do you want to go?? :lol:

 

Well guys I’m in an agreement too. Look there’s many things on this bike that are upgradeable from the way it was delivered 25 years ago. A lot of them are safety related brake lines, sealed head bearings…some offer marginally improved performance, Dynatek coils new wires, progressive springs. But if you’re looking for much more than that you should just find a newer sports bike. IMHO an XJ is never going to be a Hayabusa nor would I want it to be.

 

Think of your bike as your first girl friend. The relationship is just great because you two can have fun ... within the limits she imposes on you.

550'ing is OK. But, you've been together for awhile and wish she'd give you some 650. She can't; so you break-up and get a bike that will 650 you all the time.

Then, pretty soon after you start getting 650'ed ... you're going to want to know what it's like to get 750'ed. All your friends are getting 750'ed and you'd like to try getting 750'ed; too!

Well then ... why don't you just go 750 yourself! : )

"Say Goodnight; Gracie"

 

LOL - it's true... then one day, you remember the old 50 you dated growing up, and wonder what she's up to... that's when all hell breaks loose.

 

Thanks for all your insight.......especially for the suggestions regarding buying a new bike! That is, in fact, excactly what I did four years ago! Maybe that's the root of the problem; transitioning from one to the other is such a shock factor. Still, I love the Seca and the point here is to make it all it can be; maybe I'm wrong, but I feel there is a lot of room for improvement here. I've already spent more on the bike than it's value (and it shows!) but I know there's untapped potential here. I certainly don't expect it to be something it's not, but I don't see throttle wheelies being an unreasonable expectation. Or am I dreaming?
And, yes, I know the swingarm bushings and axle are worn, and the steering head bearings need changing. I'll probably get to all that over the winter and keep you posted. Anyway, keep the suggestions coming!!!!

 

First thing: you MUST rebuild the engine.. that means new: bores, pistons & valve guides .. no if's or buts. Gotta have a fresh solid engine to add power to. You may even find that a fresh unit has all the power you need.
The Cyl head can benefit from a decent port job and a competent performance valve and seat job... the Guides are Bronze hydural and are usually well worn by 30 k.. yer on borrowed time.
Cams are easily added after a rebuild, no rush.. and you really do NOT want a regrind effort on a unit that turns 10,000 rpms. they must be Billet types.. which are V pricey
Ohh... Before you start all this, suggest you get price quotes on the Needed parts you may not want to continue after that little shocker.

 

Well, as long as it's running well for now (and it is) I'm not gonna break into the motor at this point. I found a decent cam set on the link provided (Thanks!) but that can wait until the motor gets torn into.
For now, I'd like to spruce up the suspension, put new tires on, upgrade the ignition and maybe do the Dyno Jet carb kit with K&Ns and see how it responds. Like I said, compression is good and it runs strong in the higher RPM range.
I'm not expecting miracles, just improvement; especially in the handling dept.

 

Hey Captain,
I'm on the exact same bike and yours looks in way better shape than mine is and I'm putting tons of work into what I've got mainly because, I don't have any choice. I'm broke and it's the only motorized wheels I've got. I know my bike wouldn't be running today if it wasn't for XJ Chat and having Robert close by to help out. I'd say go for it and see what happens over the winter. Robert has been helping me out with a list of everything I need to repair and it's a long list but, it's been fun working on it and feeling satisfied when I'm going down the road. I've got all the power I need to stay out of trouble in LA traffic and my Kerker is loud enough to let them know I'm coming. The handling sucks as low speeds but, I'm getting new progressive springs up front so hopefully that'll help out and I already put in new steering bearings. Have fun with what ever you decide. Good luck.