« previous next »
Pages: [1]   Go Down

Author Topic: How badly did I just F*$# this up?  (Read 4234 times)

0 Members and 1 Guest are viewing this topic.

Offline JPcb750

  • 77 CB750K
  • Full Member
  • *
  • Posts: 5
How badly did I just F*$# this up?
« on: March 22, 2012, 04:40:00 PM »
Hi everyone,

New member and complete novice here hoping for a little bit of help answering a couple questions.  I'm concerned that I just made an insanely boneheaded mistake on my first rebuild.  Here's the story along with some photos...

Several months ago, I got my cover, heads and jugs glass bead blasted so I could do a repaint.  Once I got them back, I went through it with the air compressor twice to remove any particles, then prepped and primed it with Duplicolor Engine Enamel. 

For a reason that escapes me now (when I finally got back around to the project), I didn't tape off the top of the head when it was blasted and primed.  I'm looking at it now- horrified- and wondering how badly I've just screwed this up.  So my questions:

1.  When I took the engine apart, there was paint (from the factory) on the inside of the head and cover.  Trying to piece together my logic, this is the only reason why I would think it would be ok to blast and repaint the inside.  Is this ok? Or am I f*$#'d?

2.  While I meticulously taped over the lower mating surfaces and covered the combustion chambers, I did not tape over the mating surface of the cover and top of the head (once again, I'm claiming temporary insanity). They're smooth but nowhere near as smooth as they were previously.  Is this going to be ok or will I need to have it resurfaced?

3.  If the answers to both of the questions above are "Hell no, you idiot!", what are my options now?  The more I search the site for answers, I'm becoming increasingly paranoid that I may have primed over fine particulate dust as well... Is there any hope???

Any answers or suggestions would be appreciated before I set fire to the garage and commit insurance fraud.

Many thanks,
JP
« Last Edit: March 22, 2012, 07:39:06 PM by JPcb750 »
Logged

Offline JPcb750

  • 77 CB750K
  • Full Member
  • *
  • Posts: 5
Re: How bad did I just F*$# this up?
« Reply #1 on: March 22, 2012, 04:41:11 PM »
more photos
Logged

Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,717
Re: How bad did I just F*$# this up?
« Reply #2 on: March 22, 2012, 04:49:45 PM »
As long as you painted the inside of the valve cover with the proper paint you should be ok.

If it was me I would re- bead blast the inside of the valve cover just so no paint could get loose inside the engine.

Same thing with the inside of the head. Is the paint high temp?

BTW... If you got paint inside of the spark plug threads you had better use anti sieze on the spark plug threads. DO NOT try to re tap the spark plug threads!!!
You do not have the experience to do that.

Not a serious mistake- and still correctable.
« Last Edit: March 22, 2012, 04:53:16 PM by lucky »
Logged

Offline JPcb750

  • 77 CB750K
  • Full Member
  • *
  • Posts: 5
Re: How bad did I just F*$# this up?
« Reply #3 on: March 22, 2012, 04:54:48 PM »
Hi Lucky,

Thanks for the quick response!  Yes, the primer is Duplicolor's Hi-temp Engine Enamel.  What about the mating surfaces?  Resurfacing required?

So if I re-blast the head and cover, do I coat it with anything or just leave it bare?

Thanks,
JP
« Last Edit: March 22, 2012, 04:56:43 PM by JPcb750 »
Logged

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,810
Re: How bad did I just F*$# this up?
« Reply #4 on: March 22, 2012, 07:19:52 PM »
Before you blast anything............I would apply brake cleaner with a cloth and a brush to all of the threaded areas, the valve-guide carriers and the valve-cover contact surface.......that should effectively remove the paint................now chase the threads with more brake cleaner on the actual plugs and case screws to remove any residue.

It looks very dull........unless that is what you want........if you used the wrong color, do a chemical strip and start over with the CORRECT tape method..............lots of sample photos on the subject.
Logged
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2020 ROYAL ENFIELD Himalayan

Offline JPcb750

  • 77 CB750K
  • Full Member
  • *
  • Posts: 5
Re: How bad did I just F*$# this up?
« Reply #5 on: March 22, 2012, 07:26:45 PM »
That's actually just the color of the Primer- I hadn't painted it yet.  I was going to go with the Duplicolor Cast Iron Hi-Temp Engine Enamel.

I can definitely brush all the threaded areas with brake cleaner.  In your opinion, is the rest of the area (the inside of the cover and head) ok to leave as is?

« Last Edit: March 22, 2012, 07:28:16 PM by JPcb750 »
Logged

Offline knowsnothing

  • Hot Shot
  • ***
  • Posts: 643
Re: How badly did I just F*$# this up?
« Reply #6 on: March 22, 2012, 08:20:02 PM »
If it were me, i would get rid of it all.  I would worry about a peice peeling off and getting stuck in some oil passage which could fry the engine....
« Last Edit: March 23, 2012, 06:22:34 AM by knowsnothing »
Logged
1978 CB750k Green - 811 engine
1978 CB750k Blue - for sale
1974 CB375F Faded Black - had to have that 6th gear
1976 CB400F Red - in many pieces
1973 CB350F TBD - in many pieces

Offline Milkman666

  • Full Member
  • *
  • Posts: 65
  • It's not junk, Honey - it's a classic!
Re: How badly did I just F*$# this up?
« Reply #7 on: March 22, 2012, 09:48:52 PM »
Is there a missing oil jet there? I do believe I see one on the right, but not the left.
Logged
Milkman
"Everything works if you let it." - Travis W. Redfish
1975 CB750F
2006 VTX 1300C

Offline LesterPiglet

  • Old Timer
  • ******
  • Posts: 4,046
  • 1977 CB550F2
Re: How badly did I just F*$# this up?
« Reply #8 on: March 23, 2012, 02:12:24 AM »
Quote from: knowsnothing on March 22, 2012, 08:20:02 PM
If it were me, i would get rid of it all.  I would worry about a peice peeling off and getting stuck in some oil passage which could fry to engine....

+1 Take no chances.
Logged
'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


Les Ross.            Certified by a Professional

Offline seanbarney41

  • not really that much younger than an
  • Really Old Timer ...
  • *******
  • Posts: 10,849
Re: How badly did I just F*$# this up?
« Reply #9 on: March 23, 2012, 03:12:14 AM »
paint is the least of your worries...one single glass bead and cam bearings are toast...at least imo
Logged
If it works good, it looks good...

Offline Toxic

  • Expert
  • ****
  • Posts: 1,200
Re: How badly did I just F*$# this up?
« Reply #10 on: March 23, 2012, 03:54:00 AM »
This is the part that concerns me " I didn't tape off the top of the head when it was blasted and primed. "

If you glass beaded the head without taping it off properly I would be concerned you have left over residue hiding in the many tiny little crevices.

If when you say "I didn't tape off the top of the head when it was blasted and primed. " and you are only referring to blasting the head with paint I would still be concerned with the paint coming off and as mentioned plugging an oil galley.

Either way, I would say you need to redo it.  I  would have zero confidence in that engine knowing it was put together that way.

Also and this is probably just me but ... a couple of passes with an air gun to remove blast media is not going to do it.  That stuff gets everywhere.  It needs to be washed thoroughly and a pressure washer taken to it.   If you don't have a pressure washer take it to a do it yourself car wash and be prepared to get drenched.

About brake cleaner, if you are going to use it wear eye protection.  It will ricochet  off the surface and get in your eyes.  It burns like crazy, made that mistake once, now I always wear eye protection.

Sorry to be the bearer of bad news but I wouldn't take a chance the way it is
Logged

Offline trueblue

  • A person who has had many interesting experiences, some of which are true, is known as an
  • Old Timer
  • ******
  • Posts: 3,124
Re: How badly did I just F*$# this up?
« Reply #11 on: March 23, 2012, 05:09:34 AM »
It is actually amazing how many engines are painted inside, I would have to say at least 3/4 of the engines I see inside of are painted inside, but also most of the engines I work on are slightly larger than these bike engines and as such have larger oil galleries that don't get clogged as easily as these little engines. If it was me and I wanted to remove the paint I would wash it out with gun wash thinners, damn near as good as paint stripper ;)
Logged
1979 CB650Z
Nothing can be idiot proofed, the world keeps producing better idiots.
Electronic Guages for your SOHC 4

Offline Music City Metalcraft

  • Full Member
  • *
  • Posts: 64
    • My Facebook page
Re: How badly did I just F*$# this up?
« Reply #12 on: March 23, 2012, 06:21:04 AM »
Some old engines and other oil containing drivetrain parts are painted (special paint for that application, never use normal outside engine paint) inside cause of porous castings. The Honda castings are good enough to not seep oil. So, no paint on the inside, it will only give you and your engine headaches!!!
Logged
The part that needs the most upgrading is the nut holding the handlebars

Offline 1974cb550k

  • Enthusiast
  • **
  • Posts: 133
Re: How badly did I just F*$# this up?
« Reply #13 on: March 23, 2012, 06:31:19 AM »
FYI you are going to need to chase all those tapped holes to remove the sand. I use a thread restoring kit i bought from snap on. Just blowing compressed air across it ain't gonna do #$%*e. I just blasted the head on my 750k4, i spent roughly 4 hours on sand removal. Either do it right now and spend the time or you re gonna do it later. Be sure to get ALL the sand from the spark plug holes, run a plug down through and make sure there is no grit, and don't attempt to re-thread as another member suggested
Logged

Offline nayto550

  • Hot Shot
  • ***
  • Posts: 277
Re: How badly did I just F*$# this up?
« Reply #14 on: March 23, 2012, 07:18:00 AM »
Quote from: seanbarney41 on March 23, 2012, 03:12:14 AM
paint is the least of your worries...one single glass bead and cam bearings are toast...at least imo

This is exactly why I refuse to use glass/sand/coal slag media on my engines.  If I'm going to blast something with tiny oil passages and lots of little crevasses for junk to hung up in I always use soda blasting media, such as sodium bicarbonate (baking soda) or magnesium sulphate (kieserite).  They both work pretty good (kieserite is a bit more aggressive) and they are both water soluble!
Logged
1976 CB550F
1976 CB750F - in resurrection process
1988 HD FLHS

Offline Gonzowerke

  • I burn asses like a Bhut Jolokia, 'cause I'm a real
  • Hot Shot
  • ***
  • Posts: 360
  • Member #106, Owner of the ORIGINAL Frankenbike!
Re: How bad did I just F*$# this up?
« Reply #15 on: March 23, 2012, 05:48:41 PM »
Quote from: Old Scrambler on March 22, 2012, 07:19:52 PM
Before you blast anything............I would apply brake cleaner with a cloth and a brush to all of the threaded areas, the valve-guide carriers and the valve-cover contact surface.......that should effectively remove the paint................now chase the threads with more brake cleaner on the actual plugs and case screws to remove any residue.

+1
If brake cleaner doesn't do it, use some good old fashioned Gum Cutter, and it will come right off with no damage to the sealing surface
Logged
1977 F2 "Highway Star"
1977 F2 "Bike-In-A-Box"
1978 K8 "Frankenbike"
1991 CRX Si "Buzz Bomb"
2000 Jeep Wrangler "UBoat"
2011 BMW S1000RR "TIE Fighter"

Offline dawdish

  • Enthusiast
  • **
  • Posts: 142
  • Life's better with bugs in your teeth!
Re: How badly did I just F*$# this up?
« Reply #16 on: March 23, 2012, 06:36:10 PM »
Quote from: seanbarney41 on March 23, 2012, 03:12:14 AM
paint is the least of your worries...one single glass bead and cam bearings are toast...at least imo

I agree whole heatedly. As a master tech, I see the bead blasting of the inside of the engine as a total disaster. I'm sorry for the bad news but the engine is toast...
Logged
'75 CB400F
'72 CB500 Four
1 CB550 Chappa (barn find)
1 '75 CB550 (barn find)
'81 Guzzi V1000( I couldn't help myself)

Offline LesterPiglet

  • Old Timer
  • ******
  • Posts: 4,046
  • 1977 CB550F2
Re: How badly did I just F*$# this up?
« Reply #17 on: March 23, 2012, 08:17:56 PM »
Quote from: dawdish on March 23, 2012, 06:36:10 PM
Quote from: seanbarney41 on March 23, 2012, 03:12:14 AM
paint is the least of your worries...one single glass bead and cam bearings are toast...at least imo

I agree whole heatedly. As a master tech, I see the bead blasting of the inside of the engine as a total disaster. I'm sorry for the bad news but the engine is toast...

From what I read it was only the head that was blasted inside, I hope it will be recoverable. Though there are bearing surfaces involved.   :(
Logged
'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


Les Ross.            Certified by a Professional

Offline BeSeeingYou

  • Old Timer
  • ******
  • Posts: 3,913
Re: How badly did I just F*$# this up?
« Reply #18 on: March 23, 2012, 09:05:38 PM »
Quote from: seanbarney41 on March 23, 2012, 03:12:14 AM
paint is the least of your worries...one single glass bead and cam bearings are toast...at least imo

Check out pages 9 and 10 on this thread and then clean out all those passages again and again.
http://forums.sohc4.net/index.php?topic=79515.200
« Last Edit: March 23, 2012, 09:12:11 PM by srust58 »
Logged
Pages: [1]   Go Up
« previous next »