Topic: 1975 CBB550 build- very first bike and first build

[madmtnmotors]

I happy to drop past tomorrow late afternoon and have a look now that I'm in FL for the week.

Damn! How did I miss that post? I'd have rode up just to bust your chops! 

you;; have another chance, I'll be in Orlando (again) 9/8-9/12. Between the 3 of us, we should be able to coax at least 60HP out of this little monster and get it running in about 6 hours?  I'll plop my 500 motor in it, bring my extra MotoGadget m-gear and we'll have some fun!

And I'll bring the cutting torch and sawzall!     

[CBertels]

After checking the valves, most were WAY too tight and I couldn't even get my smallest feeler gauge in there.  I was hoping this was the issue.  I adjusted all valves, kicked it a few and rechecked.  Checked compression again and no change.  Oh well, it looks like I'll be tearing the top end off. 

I'm torn between having the head checked out vs simply getting a new one given the PO's claimed P&P job and valve/spring upgrades on it.

In terms of pistons/cylinders, I'm hoping I can simply hone the cylinders and replace the rings on the stock pistons.  Hoping to avoid boring and new pistons.  Any thoughts?

[madmtnmotors]

Are you checking the compression with the throttle wide open? The throttle slides (when closed) can restrict the intake enough to have a negative impact on your compression test readings.

[CBertels]

Yea, throttle is wide open and without filters. Choke is open as well. Two cylinders have almost no compression. What meeting how much of that is rings and how much is PO destroying the head.

[madmtnmotors]

Yea, throttle is wide open and without filters. Choke is open as well. Two cylinders have almost no compression.

Well, once you've got the head off it should be pretty easy to tell from there. If the valves are leaking it might be a good idea to at least hone the cylinders and re-ring the pistons at the very least.

Overbores are more fun though!  There's no replacement for displacement! 

[CBertels]

Thanks for the help.  The overbore stuff is certainly tempting but I worry how deep the rabbit hole goes on the small 550.  My initial plan was really just to get a fun driver to cruise around on a bit.  I have 750 basket case that I intended to all out with on a longer-term project and pass the 550 down to the GF.

I don't want to cut corners on the 550 but didn't want to go ape on the thing either.  Do you think I could get away with new rings, a cylinder hone and have the head looked at?  I'd like to get a machine shop to check the head to make sure the PO didn't wreck it too.  If I'm pulling it that far apart, I'd like to do it once and right the first time.

[madmtnmotors]

As for the head, you can turn it upside down once it's removed and fill the combustion chambers with alcohol or acetone to check the valve sealing. NO SMOKING/PILOT LIGHTS/OR ANY OTHER IGNITION SOURCE NEARBY (including air compressor or other electrical motors).

As for rings, you'll have to measure the pistons and bores for wear to determine whether just a hone and rings will work.

cruzinimage has pistons with rings and head gasket on ebay for $120:

http://www.ebay.com/itm/Honda-CB550F-CB550K-600cc-Bigbore-Piston-Kits-Head-Gasket-CB550FBB-/161744449539?vxp=mtr&hash=item25a8b87003

CycleX or A.P.E. should be able to do the re-bore for $150 to $200. Just have to call to confirm and then ship the cyls and pistons.

[CBertels]

Thanks for the info!  I might go bored after all.    That was FAR less than I expected, although I admittedly hadn't investigated thoroughly yet.

I'll post some photos once its torn down and see whats what.

[SOHC4 Cafe Racer Fan]

You can also select a minor .5 or 1mm oversized piston from cruzinimage to reduce the cost of boring.  If you cylinders check out, you may only need to hone the sleeves and get new rings.

[madmtnmotors]

Didn't see the .5mm or 1mm at the cruzinimage ebay store. DSS has .25mm oversize which would run just over $230 plus shipping:

http://www.davidsilverspares.co.uk/CB550K1-1975-USA/part_70607/

[SOHC4 Cafe Racer Fan]

Didn't see the .5mm or 1mm at the cruzinimage ebay store. DSS has .25mm oversize which would run just over $230 plus shipping:

http://www.davidsilverspares.co.uk/CB550K1-1975-USA/part_70607/

The DSS pistons sound like a good option if upping performance is not a priority versus keeping it as stock as possible.

[madmtnmotors]

Didn't see the .5mm or 1mm at the cruzinimage ebay store. DSS has .25mm oversize which would run just over $230 plus shipping:

http://www.davidsilverspares.co.uk/CB550K1-1975-USA/part_70607/

The DSS pistons sound like a good option if upping performance is not a priority versus keeping it as stock as possible.

Plus, it still leaves room for a future overbore. There are at least two threads here that I stumbled across:

http://forums.sohc4.net/index.php/topic,151007.msg1725064/topicseen.html#msg1725064

http://forums.sohc4.net/index.php/topic,112346.125.html

[Bootsey]

If you want to go +0.5mm, you can buy CB500 +3mm pistons - that brings the bore to 59mm, which is +0.5mm from stock 550.

http://www.ebay.com.au/itm/Honda-CB500K-CB500F-553cc-Bigbore-Pistons-Kit-59mm-W-Head-Gasket-CI-CB500KBB-/131238402760?hash=item1e8e6b1ac8

[CBertels]

Thanks for all the input. I'll get some estimates from the show suggested on the condition of the cylinders and recommendations. I like the 600cc idea given that the piston/rings/etc. seem to be a bit less than the .5 or .25 kits offsetting the cost of machining.

Any non-obvious pros/cons with going the 600cc route?  Will carb tuning be a nightmare with the larger bore?

[SOHC4 Cafe Racer Fan]

Tuning will not be a nightmare.  If you want to maximize the gains from any big bore kit, add a cam (you can swap in a 650 cam which will be your cheapest option) and port the head to improve flow of gas and air into and out of the head. 

The 600 cruzinimage kit is affordable.  Note: it does not increase the compression, so higher compression/smaller big bore kits like the Wiseco or Dynoman kits will create more power.  That said, you will still get a broad improvement to torque and horsepower from the cruzinimage kit. 

[SOHC4 Cafe Racer Fan]

The stock heads on the 500/550/750 all benefit greatly from porting work.

If budget is a concern, you may want to stick with the 59mm kit.

[CBertels]

Thanks everyone for all the advice.  I'm trying to do as much research as a I can on the forums and elsewhere to avoid asking the same questions you've all seen a million times.  I'm hoping to get the engine out tomorrow and get the top end to the machine shop.  I'll make the decision on bore size once I get an idea what shape the cylinder and head is in.  PO said the head had "work' done already, so I can't wait to see that that exactly entails...

I like the sound of the street beast Cal described    I read through Flatlander's build and its really impressive.  With this build I'm more concerned with simplicity than cost.  I wanted to avoid anything too exotic or difficult to source.

Now, once I dig into the 750 and get thoroughly over my head, I'll be looking and going overboard.

[madmtnmotors]

With this build I'm more concerned with simplicity than cost.  I wanted to avoid anything too exotic or difficult to source.

That's a good plan. The bigger the overbore the more stress on other components. If the 59mm pistons will work that sounds like a sensible performance modification, without breaking the bank, and leaving room for future expansion (61.5mm) if the spirit moves you... 

[Restoration Fan]

you;; have another chance, I'll be in Orlando (again) 9/8-9/12. Between the 3 of us, we should be able to coax at least 60HP out of this little monster and get it running in about 6 hours?  I'll plop my 500 motor in it, bring my extra MotoGadget m-gear and we'll have some fun!

Wait, what?  Atlanta is on the way to Orlando, right???!!!!

I mean, I have TWO 550/500's to do and you didn't offer help with those.  Geesh.  I see how it is now! 

[SOHC4 Cafe Racer Fan]

Cal,

You must log some serious miles in your work. 

[Restoration Fan]

Atlanta is if I drive down 85. I've been taking 95 due to time constraints. I owe Bill and you a visit. I'm heading back down to Orlando M-Th of next week again 

Well, if you're ever looking to break the drive up and not drive the whole thing in one day, you're more than welcome to stop here & spend the night.  I have a pretty big house with an extra guest suite that's got your name on it. 

If you're really nice, I might even let you ride a real motorcycle...errr, I mean a 750 named Stella! 

[Restoration Fan]

Besides your job as an international studmuffin, what else do you do for a living, Cal?

[SOHC4 Cafe Racer Fan]

Shhhh.  Cal is an interstate man of mystery!! 

[CBertels]

inally got some free time and tore down the engine a bit. Lots of strange things on this one so I'll try to go in order.

While removing the carbs and exhaust, the bolts on the exhaust and intake manifold were quite loose, although maybe a blessing.

The cam cover and the rockers all looked pretty good. No noticeable scoring/wear and moved freely without any noticeable side play. The cover, however, had some large holes that appear to be some modification from the PO. Photos below. Two are on one side, one on the other. Is that normal??

In removing the head, this is where stuff got interesting. The alleged port/polish job is concerning. The "football" in both the intake and exhaust ports have been ground down quite a lot compared to photos I've seen of stock. Inspected the ports looking for obvious problem signs. I believe the valves have been replaced and not properly. Two of the intake valves are not completely seated and I can see a flashlight shine behind them. No trouble with the exhaust side that I can see.

The cylinder block looks freshly machined or honed and feels very smooth. Very clean and I could detect few wear marks or grooves. There is a small corner of a fin that broke off that I didn't notice when assembled. Can this be easily repaired?

The piston tops were to very clean. . The tops of two look almost brand new while the others look marginally worse.  A good sign I guess. I did find a broken ring, but I'm not sure if that happened during disassembly or was broken in the cylinder.

 I'm betting whomever did the "rebuild" never got it running once reassembled. The gasket between head/cylinder looked very new and a bit thick (1.25?) while the one between the cylinder crankcase much older and stuck to the cylinder.

I'm gonna check with the recommended machine shops for the cylinders and will have that head looked at as well.

EDIT: Photos are not uploading at the moment, but I'll get some up soon.

[CBertels]

Photos of Cam cover.  Hole are towards the top.  Should these be here?