First post/engine rebuild question

Hello everyone,

I've had two '82 Seca 550's since June of '16. I've worked on cars for almost my whole 22 years on this planet but this is my first venture into the world of motorcycles. This site has been a great resource for me so far and I am very grateful for all of the advice that you guys have posted here.

I had one of my Seca's running pretty well, but as you know with any machine of this age, sh!t happens here and there. I've had to replace several parts from wear, or due to my own mistakes... But I've put about 3000 miles on my running Seca and it's been a great learning experience so far.

Now for my latest debacle... Toward the end of last season, I was having a little too much fun on an empty road, giving it all she had, shifting without the clutch. So I was cooking, going from 3rd to 4th or 4th to 5th, the bike hung up between gears, almost like neutral, and I revved it a considerable amount past redline... It seemed ok for about a mile, and then it started running like dog sh!t and really hasn't been the same since. I only rode it once or twice after, and it wasn't really happy, so I inspected the top end, rebuilt the carbs, and put it away for the winter.

So the other day, I got a hold of a compression tester and figured I'd check it out. I got super excited when #1 was making 120, but then 2, 3, and 4 were making about 60, 90, and 60 respectively. I squirted some oil in those cylinders and all of my numbers came up, so it looks like I'm doing my rings.

I see that the rings for sale here are quite expensive, and I've looked around eBay and even Yamaha at #15E-11610-00-00 and it doesn't look like I'm getting away without paying $30+ a piston. This is a little painful on the wallet, especially since I just helped a buddy rebuild his '74 CB550 and he got 4 sets of rings for $40! I guess I'm wondering if anyone has any recommendations for aftermarket?

I've always been one to not cheap out and do things right the first time, but I can't imagine I couldn't spec another set of standard size rings that would give me similar performance without breaking the bank.

If not, well, I've learned my lesson. Luckily it doesn't seem like I've done permanent damage. I guess I'll just have to be a little easier on the next set and use the clutch every time!

 

550 motors are plentiful.


yamaha parts nation

Piston Ringset Std (Std)

15E-11610-00-00 4GA-11603-00-00

$31.58

partzilla
PISTON RINGSET STD
15E-11610-00-00

$29.30

 

Yeah unfortunately rings for these engines aren't as cheap as popular models for other manufacturers. The cheapest I've been able to find is from the links XJ550H has provided. Considering that a new rings will set you back approx $130 and a top end gasket kit will probably be another $80, it may be worth it to find a whole new engine or better yet get yamaha fz/fj/yx 600 engine and stuff that in for a nice boost of power. Before you go out and buy standard rings be sure to check the bore dimensions to make sure that its not excessively worn past spec, if it is an overbore is required and that will be far more expensive then just buying a new engine.

 

Tore the thing down last night, definitely had blowby on the low-reading cylinders. Looks like rings at the minimum Cylinders looked ok, but I'll measure them for sure before I buy anything.
Tried to post a picture, but it doesn't seem like the forum will let me do that yet!

What year range are we talking about for compatible motors? I'd definitely consider it. I'm looking at my roommate's 2008 FZ600 and that thing definitely would not fit. Are we talking late 80's, early 90's FZ/FJ/YX 600?

I have a spare 550 on the parts bike which I haven't ran yet, it apparently doesn't have spark, but it was actually on the road in 2015. I stole some things off it but I figure I'll put it back together and throw it in for now, figure out the spark issue, then potentially build a cafe racer out of the parts bike with the bigger motor.

 

Set-up the valve clearances and compression test the spare engine on the bench. If it looks half decent then run with that. Diddling about with YX/FZ engines will cost you time and more money when you find you also need matching carbs, intake rubbers, matching TCI etc..

 

I'll definitely do that for now. Maybe I'll get around to putting this blown motor back together, but I'm thinking in the long run, I'll probably want to upgrade. I want my regular bike to stay stock and maybe take the parts bike in a different direction. I've done a little research on swapping later engines in but haven't really determined the range of years that would make good candidates.

I guess clutchless shifting is no good for these bikes either? I realize these aren't modern race bikes but anyone I talked to about it said it shouldn't be too hard on it. I was doing it fine occasionally, and it's a ton of fun. I never forced it, just give it a blip on the throttle as I lift up my foot. This is the first time it hung up like that, and unfortunately it wasn't at such a good time!

 

Just because you can shift clutchless doesn't mean you should.

 

Good point! By the way, when can I post pictures? I'd like to show you guys how I found my pistons.

 

after 5 posts

 

Five...

 

Hmm.
Doesn't seem like my picture made it here.
Try the link. Piston #1 is the good. 2 is the bad, 3 and 4 were pretty ugly as far as the blowby goes.
https://drive.google.com/file/d/0B3j8z_op9LjIdTdJcGRObmw2MjA/view?usp=drivesdk

 

pistons bad or just rings

 

Yeah the edges of the rings did not look good in a few spots, but I can't photograph it well. I'll clean and measure everything before I buy new parts, I work in the machine shop on my campus and we have all of the tools for that. The bore looks fine aside from a little carbon, I guess from running with bad rings. I gave it a light hone and it's clean now with good crosshatch, just have to check it.

 

Done right, it doesn't do any damage and is often smoother

 

i used to shift without the clutch, then i re-ground the drive dogs for second gear. now i don't do that anymore