Author Topic: Here I go again - '77 CB550F Rebuild #2 (Read 4918 times)

psykod · « **on:** April 05, 2010, 12:56:21 PM »

A little over a year ago I decided to tear down my motor to replace the primary chain on my CB550F.

I had rebuilt the engine only a about a year prior but didn't replace the primary chain and after 10,000 miles on the rebuild, I could tell it was getting worse.

Here's my original post on the first rebuild: http://forums.sohc4.net/index.php?topic=25455.0

Here's the post about the sloppy primary: http://forums.sohc4.net/index.php?topic=37835.msg401034#msg401034

Since I was taking the bike apart for the Primary Chain, I decided to go ahead and repaint the cases. I also had the head milled slightly. Of course, a fiasco occurred when I took the cases in to be soda blasted and they sand blasted them instead. The sand blasting destroyed the cases and jug and severely damaged the head. I decided to try and save the head by having it shaved(again) at the bare minimum to remove the sand blasting pits (the cam journals weren't damaged): http://forums.sohc4.net/index.php?topic=56798.0

So now that I have a trashed head, trashed jugs, and trashed cases, I ordered a new set off ebay from a '75 CB550F. Now I had a new (to me) set of cases and jugs so I decided to go ahead a do the rest of the engine.

So I ordered a new cam and springs from WebCam and picked up a nice set of 1mm overbore pistons and rings off ebay. I also picked up a sweet set of APE cylinder studs after I destroyed a few of mine during removal.

All of this just because I was a cheapskate and didn't put in a new primary chain when I had the engine apart the first time.

Anyway, here are some pics so far

psykod · « **Reply #1 on:** April 05, 2010, 01:01:16 PM »

Pics of the Head Assembly:

(FYI: I know the small chain tensioner is reversed....haha)

SKTP · « **Reply #2 on:** April 05, 2010, 01:43:44 PM »

It soooooo clean..looks awesome. I am about to rebuild my first engine. This post is very inspiring...did you replace the bearings in the trans too or were you able to clean it with them in?

psykod · « **Reply #3 on:** April 05, 2010, 04:16:59 PM »

I didn't replace any of the transmission bearings. However, I did remove everything prior to cleaning and painting the cases. I inspected and cleaned all the transmission bearings. I also replaced the cush drive rubbers when I replaced the primary chain.

SKTP · « **Reply #4 on:** April 05, 2010, 04:39:27 PM »

How hard are they to take out? Taking wheel bearings out of my mags was extremely difficult and resulted in the destruction of the bearings...

psykod · « **Reply #5 on:** April 05, 2010, 04:48:10 PM »

After installing the engine in the frame, I became worried about piston to valve clearance since I've installed a performance cam and different pistons plus had the head shaved (twice!). I guess I'm glad I did...it looks like my intake valve is less than .017 in from the piston. The exhaust seems fine. I'm going to grind down the piston intake reliefs to make sure I have at least .04 in. This is a bummer but I'm glad I caught it now.

I'll ask for some input from the general section before I start grinding on my pistons.

Pics:

psykod · « **Reply #6 on:** April 05, 2010, 04:51:38 PM »

Pics of Piston to Valve Clearance Check After Valvetrain Rotation:

psykod · « **Reply #7 on:** April 05, 2010, 04:53:42 PM »

Pics of Piston to Valve Clearance Check Results:

psykod · « **Reply #8 on:** April 05, 2010, 04:55:17 PM »

More PTVC Results with Intake and Exhaust Measurements:

psykod · « **Reply #9 on:** April 05, 2010, 04:59:45 PM »

Quote

How hard are they to take out? Taking wheel bearings out of my mags was extremely difficult and resulted in the destruction of the bearings...

They're pretty easy to get out...although they are tight like the wheel bearings, they seem to come out ok. I just lightly tapped around the perimeter with a plastic stick I had lying around and they eventually popped out. One is kind of tricky because it's difficult to get to due to the oil pump area but it's doable.

psykod · « **Reply #10 on:** April 09, 2010, 09:27:22 AM »

As I was trying to figure out the best way to fly cut the intake reliefs on my pistons, I remembered that I had an old head lying around that was damaged so I decided to see if I could use it as a fly cutting jig.

I cleaned it up and trimmed off the intake cover side to allow enough room to attach a drill. I then took some epoxy and filled an old intake valve until the surface was level and attached some 80 grit sandpaper that had a sticky back. I inserted the sandpaper covered valve into the old head and bolted it to the engine.

I measured the height of the installed valve as it touched the piston at TDC (all were between .630 - .650 in). I attached a drill with a 90 deg. adapter on it and began sanding the piston until it read around .030 in less than the original reading. I did this in several steps as I had to change out sand paper discs quite often when the sticky back would no longer adhere to the valve.

After sanding, I re-measured the piston to valve clearance. All were between .050 - .060 clearance so I decided to stop there.

Here are a few pics. Sorry I didn't get of pic of the sanding action on the bike so I took a shot of how it was attached while sitting on my workbench.

psykod · « **Reply #11 on:** April 09, 2010, 09:30:27 AM »

Here are the results of the sanding (The first pic is a before shot):

So after losing 2 days to this issue, I can finally get back to putting it all back together without worrying about the engine blowing up when I first start it.

psykod · « **Reply #12 on:** April 22, 2010, 08:41:53 PM »

Holy Cow...I'm finished and it runs. More Pics and Video to follow.

psykod · « **Reply #13 on:** April 25, 2010, 09:26:17 PM »

Here are the final assembly pics. No Leaks!

I'm thinking of adding some cafe stuff to it now that she's running ok.

traveler · « **Reply #14 on:** April 25, 2010, 09:37:27 PM »

Nice looking bike!

What is the thumb button on the side of #1 carb for??

(My '77 550K dosen't have that!)

~Joe

psykod · « **Reply #15 on:** April 25, 2010, 10:17:47 PM »

The '77 F models still had the previous style carbs that used a manual choke switch on the side of the carb...

psykod · « **Reply #16 on:** April 25, 2010, 10:35:42 PM »

And finally a quick video from where I was checking the brakes.

http://s826.photobucket.com/albums/zz184/tvdenning/MGW%20Shifter/?action=view&current=MotorcyclePicsandVideo008.flv

lordwhimsey · « **Reply #17 on:** April 26, 2010, 12:41:23 AM »

Genius! Thanks for all this Psykod; I’ve been worrying about valve clearances with my over bore pistons and 650 cam but now I know what to do!

TyMatthews · « **Reply #18 on:** April 26, 2010, 12:46:14 AM »

That bike looks beautiful just the way it is! No need to do anything at all to her, except ride!

psykod · « **Reply #19 on:** May 01, 2010, 02:37:07 PM »

Dyno Run Today to Verify A/F. Had pickup problems on the dyno and only went to around 8k rpms but looks like I'm making around 44 hp at 8500. You can really feel it liven up at around 5000 rpms now.
First dyno run is stock. Second dyno run is after rebuild. Third image is an overlay of the stock and modified runs.

fastbroshi · « **Reply #20 on:** May 01, 2010, 10:15:23 PM »

Wow, that cam really does make a difference. I wonder what the difference would be with the stock bore. What exhaust is that?

psykod · « **Reply #21 on:** May 02, 2010, 08:18:29 AM »

Quote

What exhaust is that?

You know, I'm not even sure what kind of exhaust it is. It was just an ebay special that I found similar to this one:
http://cgi.ebay.com/ebaymotors/Honda-CB500-CB550-F-4-2-Exhaust-System-Pipes-Header-_W0QQcmdZViewItemQQhashZitem53e0f1ee6fQQitemZ360256237167QQptZMotorcyclesQ5fPartsQ5fAccessories.

I only paid $299 for mine though.

I believe a couple of other guys on the forum here have it as well.

psykod · « **Reply #22 on:** May 12, 2010, 06:55:02 PM »

Alas, I've had a setback. I decided to do a compression check the other day and the results were not good:

1 - 145
2 - 145
3 - 105 !
4 - 145

Man was I bummed. I ran down to Harbor Freight and bought a Leak Down Tester and the results were:

1 - 7%
2 - 7%
3 - 35% !
4 - 7%

So I hooked up 80psi to the #3 cylinder (at TDC):

No air sound from the exhaust.
Perhaps some air (and gas smell) coming from the Carb Intake.
Lots of air coming out of the valve cover. I'm not talking about the little cap on top of the valve cover that contains the crankcase vent (it was quiet with no (or very little) air). I'm talking about the valve cover itself.

The only thing I can think of is that my intake valve isn't seating properly and air is leaking up thru the valve stem and out the valve stem seal. Both the valve and the seal are brand new.

I would hate to have to remove the head and re-lap the intake valve but it looks like I might have to. Any suggestions would be appreciated!

I'll post in the main section as well in case noone looks at this.

psykod · « **Reply #23 on:** May 13, 2010, 06:00:06 AM »

A new hint:

If I pull a spark plug while the engine is running at idle on cylinders 1, 2, and 4, the engine dies. However, when I pull the plug on #3, then engine doesn't skip a beat.

The exhaust is hot on #3 and the plug looks good (tan) so I know it's firing.

I don't know if that means anything or not...

traveler · « **Reply #24 on:** May 13, 2010, 01:00:24 PM »

yeah....it means you have a dead cylinder.....you made 44 hp on 3 cylinders!

Sorry to say, but the head is going to have to come off! The rings are sealing, but one of the valves has a "buggered up" surface.

Damn bad luck, bud.

~Joe

News:

Author Topic: Here I go again - '77 CB550F Rebuild #2 (Read 4918 times)

traveler

traveler