1981 XJ 550 Seca -- Engine Rebuild

It happened, a couple of months ago, I am coming home from work and I noticed that beyond 60 mph, acceleration was pretty sluggish and at there was a constant metallic sound. With the help of some forum members determined that one of the connecting rod bearings was spun out.
My question: does someone have some guidance, experience and suggestion in doing the engine rebuild? What things do I need to replace, is it almost cheaper to buy a different engine.
I have never done anything like that and I am quite nervous with this project.
Your help is seriously appreciated.

 

My vote would be to find a different engine. The parts are not cheap and if you go through all the tear down and not replace chain guides and starter clutch parts because of the expense it's all for nothing unless you plan on keeping forever then go for it. I seem to see many bikes parted out and engines are plentiful.

 

Thank you.
I will do both because this is my first bike and I have some sentimental value attached to that.

 

Can I put a newer engine in the frame, like a Seca II engine?

 

It should bolt up. Same cases IIRC, but there may be some fitment differences.

 

Replace the engine, ebay is full of them from bike junkyards. Keep the old one and rebuild it as a project if you like, but be prepared to put at least $5-800 in parts not including labor.

 

No Seca II (Diversion in Europe) won't fit. Entirely different top end with 'downdraught carbs' and inclined cylinders. Radian/FJ600/FZ600 will fit but if you intend to use teh bigger carbs of these engines then be prepared for some 'fun' with the rubber parts..

 

IIRC the Seca 2 engines were tilted due to the frame design, but had the same cylinder base angle.

XJ550


Seca 2



The intake runners are different to fit the downdraft carbs, but they should have the same bolt spacing ant port size as the 550 intakes.



EDIT. Looking closer the Seca 2 does have a slightly wider cylinder base angle.

 

If nothing else I think carbs will be the problem. Fit seca 2 carbs and it won't fit in the frame. Fit XJ550 head/carbs (if indeed possible) and the incline will screw-up the levels etc.. IMHO that is

 

+1.

Also +1.

Way too much trouble for the end result. I'd fit another 550 mill and be done with it. Varoom, varoom!

Gary H.

 

Actually....all this talk is making me want a Seca 2 again. It's been 20 years since I've even considered one.

 

Thank you very much guys.
Sounds like I need to get a 'new' engine.

 

There are always those garage queens with low miles that got stuffed away because it was too much money to get the carbs cleaned and the valves set by the dealer.

 

if yoouo feel so inclined you could fit an yx600 engine in it if you cant find a 550 for some reason