Topic: Redundancy: Big-bore plans for a 550...

[n9viw]

I know it's been covered ad nauseum here, but I've just been through at least seven or eight pages of old posts, and I still find myself with questions... maybe MORE questions now than before I logged in tonight!
Subject is a '76 CB550k, about 25k on the clock, and some REALLY bad engine abuse, most at my hands.  It's started spitting oil out the exhausts, so I figured a bore job is the bare minimum I'm like to get away with. That, of course, starts the old wheels turning down the slippery slope... something about the word 'bore' automatically begs for the word 'big' to be inserted before it!
After having gone through the 500/550 big bore posts for the last hour, here's a few questions I have- purely subjective, of course. I know the hardships coming down this road, from excessive heat to some crazy expensive work, but I wanted to get some opinions:
* Big bore kit, or home-brew? IOW, is it better to get the ART "605cc" kit from ClassicCycle on ebay, which comes with sleeves and head gasket but incipient extra milling costs to the case and block as well as the cylinders, or do the CB750 pistons in stock CB550 sleeves, get a custom head gasket and just have the 550 sleeves bored, which means dealing with thinner sleeve walls- and how bad is that? Is the thinner-walled stock sleeve issue really an issue?
* Rob Lloyd suggested 650 parts, but I rather prefer the look of the 550 rocker cover, and just got some sweet finned tappet covers for it. As I mentioned in volzfsu's "836cc pistons in 550cc engine" post, would it be possible to create a weirdness comprised of a 550 rocker cover, 550 cam, 650 head, and 550 block with 750 or 605 kit pistons in it? What would be the potential advantages or drawbacks of such a creation?
* Should I just do a stock overbore, but then have Mrieck do some snazzy flow work on the stock head and toss in a Megacycles mild street cam to wake up what the factory provided, and leave the big bore business to those more daring?

I do plan to keep this bike for a good long time- it makes a really nice commuter- more power and presence than my 250, but not so clunky in traffic as my 750. I'll need to save a bit to do these mods, but that's not a big concern as I have other bikes to ride in the meantime- heck, the 550's no slouch even when drooling its lifeblood out its exhaust! I may take it out when needs require it, provided it's not a bad idea to do that- continue to ride on bad rings, I mean...

[Terry in Australia]

Vroom, Vroom, KA-BOOM! Ha ha, sorry, i just like the sound of that.................. (I gotta stop drinking)

[Chris in Ramsey]

I bought one of those ART 605 kits a few years ago and used it in a worn-out 550. I believe that the actual displacement ends up at 593cc. The liners that come with the kit are needed for a 500 engine, but the stock liners in a 550 are fine for this kit.
If you use a 650 head with other than 650 pistons the compression ratio will drop due to the increased dome shape of the 650.
Doing some flow work and matching the intake runners will help the breathing alot! This with a stock over-bore and a cam and carb work will yeild nearly the results of the big-bore route.
HTH

[n9viw]

Okay, how about a 650 head with 750F pistons shaped to match?
Terry, you shush with that 'kaboom' stuff. I'll be coming to you sooner or later for one of those fancy cooler kits, maybe two, so you be nice!

[Terry in Australia]

Okay, how about a 650 head with 750F pistons shaped to match?
Terry, you shush with that 'kaboom' stuff. I'll be coming to you sooner or later for one of those fancy cooler kits, maybe two, so you be nice!

Roger, wilco!

[n9viw]

Well, I think I answered my own questions. Got the pistons, pins, and clips for FREE (thanks Digurchop at HC.com!). I can get a set of Dixie stock rings for $40 from Ricepaddy.com. At $50 a hole for the bore job, plus another $25 a piston to flycut them for valve clearance, and $100 for a custom head gasket, and it caps off at about $450 total outlay (not including various taxes).
Contrast that to the 605 kit: $177 shipped for the kit, $50 to have the upper case bored, $200 to have the old cylinders pressed out and have the block rebored for the new sleeves and new sleeves pressed in, another $200 to have the cylinders finish-bored for the new pistons. Grand total: $630 (not including various taxes), for what amounts to the same thing.
Now, to patiently wait while my 'toy' fund replenishes enough so I can actually pull this off, AND do the $75 for the Megacycle cam, AND the $200 for head work by MRieck, AND AND AND....

[cb(r)]

if you want to go big than more power to ya.  that is awesome, but I bought the 500 big bore to make it a 555cc for my 550.  I have not done the bore yet but the kit cost like $90 bucks on ebay.  pistons rings clips pins and gasket.  I do not remember the actual oversize bore of the 550 is maybe  .025 of an inch?  still thick walls.

this might be the cheap and easy fix.  if you dont like it beat the hell out of the motor and then pour the money into a real big bore kit for your 550.

good luck with whatever you do.

[n9viw]

I figure it this way- even if I just go with a mild overbore, I'm looking at a minimum of about $300- Sirius lists four sets of S1 rings for the 550 at $76 shipped, plus $200 for cylinder rebore. Another $150 for 48 extra CC's isn't SO bad, and it'd net me a pretty nice gain in volume. I've heard the overbore really doesn't have much effect until some substantial headwork is done, but I can run the bike with the overbore for a while, then once I've saved for the headwork I can take it off and send it to MRieck at that point.

[cb(r)]

that is not a bad Idea either.  I completely understand building on a budget.  just a little bit more wrenching. 

[bwaller]

I follow your plan with great interest.  I have a set of 61mm slugs in the wings. I'll do the engine when I finish the "roller". I wonder though about the $75 cam, it's a little less than I've seen listed on the Megacycle site. You must know something I don't, and that would not be a first!

Keep us informed.

[Chris in Ramsey]

Again...I think that you CAN do the 605 kit with the stock 550 liners so the cost of pressing and opening the cases for larger liners can be applied to Mr. Rieck's bill.

[volz1fsu]

Well, I think I answered my own questions. Got the pistons, pins, and clips for FREE (thanks Digurchop at HC.com!). I can get a set of Dixie stock rings for $40 from Ricepaddy.com. At $50 a hole for the bore job, plus another $25 a piston to flycut them for valve clearance, and $100 for a custom head gasket, and it caps off at about $450 total outlay (not including various taxes).
Contrast that to the 605 kit: $177 shipped for the kit, $50 to have the upper case bored, $200 to have the old cylinders pressed out and have the block rebored for the new sleeves and new sleeves pressed in, another $200 to have the cylinders finish-bored for the new pistons. Grand total: $630 (not including various taxes), for what amounts to the same thing.
Now, to patiently wait while my 'toy' fund replenishes enough so I can actually pull this off, AND do the $75 for the Megacycle cam, AND the $200 for head work by MRieck, AND AND AND....

Let me just say WOW!!!!!!!! 
Where did you get those prices?  I just about had a heart attack.  You need to do some more looking around because they want you to bend over and take it hard.  $50 a hole is ridicules, actually you shouldn't pay more than $100 total for the boring and honing.  I used to work in a machine shop and it was $15-20 a hole. You can get a V8 bored for $120.

Here is a bit of info that everyone should know about the sleeves and cylinders.  They are press fit but you don't have to press them in and out.  I would actually recommend staying away from this because it could damage the gasket surfaces.  In place of pressing them in, you can do the job yourself with an oven.  Heat the assembly to 400 degrees and let it sit in there for at least 15 minutes or so.  Take the thing out and the sleeves will literally fall right out.  Do the same to put them back in.  That should save you some money since all they have to do is bore the cylinder block to accept the sleeves.  Just make sure they bore it with the same press fit, give them the old sleeves and new ones to make sure.

I would recommend you go with the 605 kit and then all you have to get bored is the cylinder block.  If the head gasket is included, you saved another $100.  I wouldn't get to fancy with mixing parts and custom work, like I am going to, unless you have a lot of cash to burn.  The gains won't be worth it unless you race the thing.  I have access to maching equipment so I don't have to worry about it.  If I didn't, the money would be a big issue.

[Big Jay]

Couple of things.
First those old Abby kits, ( would say HAINDs or something like thay up inside) the 605 and the 890 for the 750 use odd ring packs. If you can't get replacement rings from who ever you get the kit from, chances you won't find any that work when yoiu need to re-ring, or, heaven forbid, you break one during assembly.

As for installing your own sleeves, you need to press them after the block cools and then surface it before you can use it.

Jay