Topic: Total Rebuild Thread

[bunghole]

Here are some pics of the rocker arm contacts.  Not sure if you can tell anything from the pics.  What should I look for as a sign to indicate replacement?

1&2 Intake:



1&2 Exhaust:



3&4 Intake:



3&4 Exhaust:



The lobe with the pitting was the second from last on the cam on the right side of bike (#4 exhaust I believe).

Engine serial is CB750E-2700110

The combustion chambers look similar to me, but I'm not a trained eye.  Would it be very obvious?  I measured the depth from deck to between the valve seats and it was 15mm on both the existing and new heads.  Here are pics:





Pistons:

[rhos1355]

Next step was to pull the engine and begin the engine rebuild.  I disconnected the relevant parts and laid the bike on its side:



I forgot to remove the drive chain before laying the bike on its side.  Since the chain will be replaced anyway, I just cut it off with a cutoff tool.

I got the engine out and then realized that it was too heavy to lift by myself as I have a herniated disk.  So I went to Harbor Freight and bought a chain hoist for $50.  Here's a pic:



I should also mention that I bought an engine stand from Harbor Freight as well and modified it to hold a motorcycle engine:



Here is the engine in the stand waiting for teardown:

I just LOVE your workshop, man. Are you sure you're not and official mechanic in disguise? Moreover, the hoist, how did you make sure that the anchoring would take the sort of weights involved in a bike tear-down.
And then I saw your engine stand! Jeepers, that made me GREEN with envy. Where did you get it?

[martino1972]

yeah,by looking at your rocker arms,you DONT want to use them the way they are...!!!
that #4 exhaust looks really bad,and WILL eat up your camshaft in 5 seconds flat.....
but again,i'm not sure if you can get them machined to spec's or if you have to find different onces,but i'm sure with all the expers on this forum you will get an answer to that soon....
nice project though,looks like your doing a great job,and i love your work space,very neat...lokking forward to the rest of the project...

[bunghole]

Thanks guys!

I love my garage.  I've found that lighting is the single best investment you can make.  One of the first things I did when I bought this house was to get an electrician out to install 10 4' double fluorescent fixtures.

The engine stand is from Harbor Freight.  You guys across the pond probably don't have that chain, but I'm sure there is someone over there selling cheap Chinese stuff.  I think it cost me $40 and then I modified it to hold the engine from the mounts.

As far as the hoist.  I need to revisit that mount.  It is actually a heavy bag mount and I tested it by hanging from it.  I weigh about 200lbs, so I figured it would work.  I know how stupid that sounds, but I got through it with my toes intact.  I will definitely build a stronger anchor point in the future.

So I need to get some new rocker arms huh?  Anyone have a source?  For cams too?  Also, any recommendations on what will be a good cam for me.  I want a good reliable bike that I ride the hell out of.  Keep in mind that I am going to put Wiseco 836 pistons in.  I should also probably get the head ported.

[Jerry Rxman Griffin aka MuthaF'er]

That serial number indicates a very early K7 engine. Started at 2700000. In order to improve the performance of the 77/78 K models they used the 75/76 F engine improvements. I couldn't say for sure when they started casting the 392 into the head. The -392 part numbers indicates the 75/76 F models. My 75 F and my 78 K engine both have the 392 with the 78 K also having K hand stamped which indicated different springs, valves, and keepers that were used in the F2/F3. The earlier heads had more raised shrouding around the plug holes while the 392 was a smoother hemi shape. The clean head definitely looks like a 392 but I can't see the other carboned up picture well enough from this computer.

If you're going with a new cam I'd definitely replace those 2 rockers at the least. This is more for a long term higher mileage solution rather than a short term thing. They will work as they have already but if you want to do it "right".............

Also, I'd highly recommend high performance valve springs to go along with a high performance cam for high rpm performance if thats applicable. I missed 2nd gear on a power shift, floated the valve probably above 11,000 rpm and destroyed my top end when the valve didn't close fast enough and kissed the piston.

[JAG]

Looks great B.H. And your garage does look A-Mazing!

Looks like I'll be following along with you while doing my rebuild, as I'd like to go up to the 836 myself..

Great pictures.

By the way, just my opinion, but you may want to try to go deeper with those indents on the gas tank. When you add bondo to smooth out the bumps, you'll be left with not a lot of "indent", if that makes any since...

I went rather deep with mine, to actually make my indents functional more over having just the asthetic appeal.

Just my .02 cents bud..  Keep up the good work!

[bunghole]

Looks great B.H. And your garage does look A-Mazing!

Looks like I'll be following along with you while doing my rebuild, as I'd like to go up to the 836 myself..

Great pictures.

By the way, just my opinion, but you may want to try to go deeper with those indents on the gas tank. When you add bondo to smooth out the bumps, you'll be left with not a lot of "indent", if that makes any since...

I went rather deep with mine, to actually make my indents functional more over having just the asthetic appeal.

Just my .02 cents bud..  Keep up the good work!

Hey Jag,

Thanks.  I was thinking the same thing on the indents.  I just don't know how far is too far.  I always end up going too far.  I imagine if I overdid it, no harm no foul as I can just build up the bondo a bit.

Did you post anything about your process for the indents?  I seem to remember something along those lines.

Did you get the flange welded in yet?

[JAG]

Yeah, here it is... There's a lengthy description, but not very good pictures..
http://forums.sohc4.net/index.php?topic=31144.0

I haven't got the flanges in yet. I'm still trying to figure out if I should go to the 836 (boring) or stay the same (honing) the cylinders..  I think I'll get a more bang for my buck if I go ahead and bore it out, and I thinking you are thinking the same thing.

[bunghole]

Any tips on splitting my cases?  I've got all the bolts out, but it doesn't want to cooperate.  The last thing I want to do is damage anything.

[cleveland]

Why are you splitting the case? 

[bunghole]

Why are you splitting the case? 

Because I want to.  Seriously though, I want to take it down to a pile of parts and rebuild it.  Partly as a learning process.  Partly to make sure it is good or better than new.  And that's just how I am.  I'm going to replace the primary chain and tensioners.  Again 'cause I want to.  I'm anal about things being done right and I want to clean this thing to within an inch of its life and repaint.

Besides...don't you all want to see me do it?

[martino1972]

yeah,would love to see you do that..
and i think your taking the right steps here,better do it right while your at it,then to halve ass finish it,risking a engine blow on you on one of your trip's..

[bunghole]

Sooo,

Any tips from the experts on separating cases?  Like I said, I don't want to bugger up the mating surfaces and piddle oil all over the place.

[Jerry Rxman Griffin aka MuthaF'er]

Last set I split was easier than I anticipated. I took the rubber mallet to the "tit" (for lack of the proper word) on the front upper case half. This "tit" is just a "protrusion" that mates to nothing. Sure wish I had a picture to post considering there are many mental pictures being drawn right now. No prying involved just a small whack and it popped apart. You might take the mallet and pop it lightly all around the perimeter too.

[bunghole]

Thanks Griff!

I ended up gently tapping a thin scraper into a corner and that got the ball rolling:

[JAG]

Besides...don't you all want to see me do it?



yes yes yes! I definitely want to see how you properly gauge the crankshaft. As you already know my problems Bunghole, I wanna see how difficult it is to take that dude outta there, if you DO decide to go that far.

Also may be a dumb question, but how did you separate the piston heads from the rods?

[JAG]

Also, was your head already like that when you bought it or did you have it all blasted later? If so, how much did it set you back?

Isn't there a way to send your cylinder and all that to cycle exchange and have them do that to your stuff? Would it be any cheaper?

Thanks B.H.

Keep up the good work!

[bunghole]

Besides...don't you all want to see me do it?



yes yes yes! I definitely want to see how you properly gauge the crankshaft. As you already know my problems Bunghole, I wanna see how difficult it is to take that dude outta there, if you DO decide to go that far.

Also may be a dumb question, but how did you separate the piston heads from the rods?

Like I know how to gauge a crankshaft!?!?!

There are thin circlip type retainers on either end of the piston.  Just remove from one end and tap the pin out through that end.  Since I was going to an 836, I wasn't too worried about damaging anything as that kit comes with pins and retainers.

So JAG brings up a good question...now that I have the cases open and the crankshaft out, should I spend the time fussing around with plastigauge?  I'm going to because I can't not (remember...anal) but I'm curious to see what is typically done on a rebuild.

By the way, I just pulled the studs out of the case (will be putting APE studs in).  That was a bear of a job.

[bunghole]

Also, was your head already like that when you bought it or did you have it all blasted later? If so, how much did it set you back?

Isn't there a way to send your cylinder and all that to cycle exchange and have them do that to your stuff? Would it be any cheaper?

Thanks B.H.

Keep up the good work!

Hey JAG,

I had the head hot tanked and blasted.  I think it cost about $70 or so.  CycleX will do all of the work for you if you send in your head and cylinder.  I think they even have an exchange deal where they have already bored and ready to go cylinders that they will send once they get yours:

http://www.cyclexchange.net/Engine%20Tech%20Page.htm

[cleveland]

Just asking. 

[bunghole]

Question:

Does one typically replace all the bearings in the case on a rebuild?

[rhos1355]

Ok I'm a bit of a worrywart, but I would, since the case is stripped and opened, spare no expense in getting it into tiptop condition.Which is what I'm doing on my rebuild. The last thing you want to have preying on your mind once the engine has been rebuilt and replaced is "how much life is left in those bearings?" Get it done now and get it done well.

[bunghole]

I'm in agreement on that rhos...so sorry in advance for the following 10 pictures, but I need advice on what to look for.  I found at least two that had fingernail catching grooves.  Should I assume they will need to be replaced.  Here they are...top case left to right and bottom case left to right:





















Phew!

[bunghole]

Holy crap!  My dog and I just got skunked.  I'm stark naked and covered in some sort of skunk smell remover.  Where's my camera?  Seriously, does anyone have any secret weapons in skunk odor removal?

JAG.  Good questions.  I just got my Wiseco 836 pistons in the mail.  I think CycleX has a very good price on them as they come with pistons, rings, pins, and retainers.  They charge $399.  I dropped the cylinders off at a local shop and they are going to call me in the AM with a quote for the bore.  I don't think new valves are necessary, but I understand that a new cam, springs, and studs are the way to go.  I think the stock rods are fine.  If anyone has any opinions either verifying or refuting this, please chime in.

My life is a never ending adventure!

I've been trying to trap these two skunks.  I got one, but the other got his revenge tonight.

[JAG]

Well I removed the thread thinking I was high jacking and started my own topic, but at any rate, thanks for the reply.

Keep me posted on what you find out..


BTW, I've heard tomato juice gets rid of it, but I think the clothes that you are wearing are just going to have to be burned!

Good luck.. I've been close to getting shot at, even aimed at, but never, ever, EVER sprayed!!

Damn varmits!!