Topic: Maine 78 cb750K Build - Time to get 'er back on the street!

[Blitzburgh207]

Guess it's time to start a build thread as this is my first engine rebuild and I know I'm going to need some advice and foresight.  I have a 1978 cb750K with about 32k on the clock.  I'm rebuilding the top end (plus primary chains) because it had a leaky head gasket and ruined a couple pairs of pants over time.   ...And obviously it makes more sense to rebuild the motor than to buy new pants 

I bought her down in Southern Maine in April of last year and put about 5k on her last season.  But now the snow is flying and it's time for some off-season love.

Here's a little timeline from the craigslist ad when I bought it, to how it was when I took it off the road for the winter:







More to come, but I've got to go to class!

[Blitzburgh207]

Well I pulled the motor last weekend - it worked pretty slick.  Took about 5 minutes, maybe.



Maybe three minutes, I don't remember 





But that's all the progress for now.. Ill probably get into it Thursday into this weekend.

I received a nice box of goodies from CycleX on Friday.  Nothing performance really this year, just for reliability.  Got the full gasket/oil seal set, cam chain slider tensioner etc, valve guides (for the pre 76 valve swap), HD studs, oil pressure guage, ...and something else I can't remember right now...

Member SOHC Digger hooked me up with some custom piston rings a week or so ago. THANKS AGAIN!!

Also, waiting on primary chains and tensioner from servicehonda.

Looks like I'll probably be getting some CycleX superflow valves (does that count as performance?    because the ones from my spare K4 motor i was planning on using are in worse shape than I thought.

But anyways,  next step is to get that head pulled.  I'm rreeeeeaaalllyyy hoping that the cylinders are within spec and I don't need to go down that road... but it's going to the machine shop to get it bead blasted, valve seats cut, and cylinders honed.  I'm not sure if I should have them press out the guides or do it myself... I'm scared they'll mess up my head not heating it or something.  ...but then again, maybe I will too! 

That's all the news for now I think  I might throw up some pics of the valves for a second opinion.  I'll report back w/ more pics and the like when I have them!

Later.

[sopo400f]

Good luck!

[lucky]

You need a machinist that does motorcycles and knows Honda.
A motorcycle machine shop

Ask them if they have the HONDA valve seat cutting tool. Or order one.
Just 1.5 turns and that all.

If you just take it to a car machinist who knows what will happen. I would not do it.

Make sure you put a valve in the head and check to see of the valve is a good fit in the guide.

Personally I would just ship the head to Cycle-X and let them do the head.
They charge about $325 I believe.  I would ask about it.

[Blitzburgh207]

I can't post pics right now but I pulled and stripped the head - ready for the blaster, and my seats look really good.  No pitting or corrosion, not even a scratch on any of them.  ...do I still need to cut for the cyclex valves or do you think I can get away with lapping them in?  Will post pics.

...I guess I'll just wait for them to get here (Tuesday) and see how they seal with some liquid.

Thanks!

[Blitzburgh207]

Nevermind....  I have to swap the guides first! 

[lucky]

I can't post pics right now but I pulled and stripped the head - ready for the blaster, and my seats look really good.  No pitting or corrosion, not even a scratch on any of them.  ...do I still need to cut for the cyclex valves or do you think I can get away with lapping them in?  Will post pics.

...I guess I'll just wait for them to get here (Tuesday) and see how they seal with some liquid.

Thanks!

You cannot make valves fit right by lapping. Lapping is just the finishing touches.
The valves have angles on them. Those SAME angles must match on the seat.
You can use blue dykem on the seat then take some lapping compound and turn them by hand with the suction cup tool and see if the surfaces match up.
THEN decide if they need to be recut.

Once the material is gone- its gone.

Sometimes car people just cut valves and seats to 40º.

But Honda valves can have 3 different angles on them, and the exhaust valves are sodium filled to deal with the heat. Just like aircraft engines.

[Blitzburgh207]

Ok gotcha.  I need to slow down and take my time on this....  I Think I'm going to go to any/all of the shops in my area and talk to them - go with whoever I'm most confident in.   Any suggestions on where I can buy this "Blue dyekem"?

[Blitzburgh207]

Well, I backed all the studs out....15 of them anyways  I snapped the last one off rushing to get to the GD superbowl party.  But on the bright side, there's about 1/4" of it sticking up above the case so I should be able to weld a nut on there and turn it out.

In other news: The head and jugs are going to the machine shop this afternoon for blasting, cutting the seats, and honing the cylinders.  Turns out this guy rides year round and loves working on bikes  He's also owned several sohc fours and seems excited to work on one.  He also suggested reaming my existing guides rather than replacing them with the pre 77 guides because he said sometimes the new ones will go in a little crooked and then you'll be hard pressed to ever get the valve to seat right no matter how many times you cut it.  What do you guys think?

[lucky]

Ok gotcha.  I need to slow down and take my time on this....  I Think I'm going to go to any/all of the shops in my area and talk to them - go with whoever I'm most confident in.   Any suggestions on where I can buy this "Blue dyekem"?

You should be able to get it online or at an auto parts store.
In a pinch you can use a magic marker.

[Blitzburgh207]

Well I had some photos for you guys but my cameras data card is lost deep inside of my laptop somehow (don't ask  ) But anyways, jugs and head are with machinist.

Time to start on the lower end... I'm not really familiar with this at all.  Top end is easy enough but i've never looked twice at lower end stuff...guess it's time to stick my nose in the manual.  From what I understand I have to remove the crank to get the new continuous cam chain on there right?  Would it be a good idea to strip down the case and clean everything up anyways?  ...not sure if I want to tackle that.

Also in the meantime, spare tank from the 74 parts bike is going to be stretched 5 inches or so, and I need to order a seat so I can start relocating the electrics.
I want a custom oil tank too and I've found a guy to do it butwhere can I find oil lines?

Oh yeah, and the rotors are going out to ElCheapo sometime this week!

Phew,  I've got more to do than I thought! 

[lucky]

Well, I backed all the studs out....15 of them anyways  I snapped the last one off rushing to get to the GD superbowl party.  But on the bright side, there's about 1/4" of it sticking up above the case so I should be able to weld a nut on there and turn it out.

In other news: The head and jugs are going to the machine shop this afternoon for blasting, cutting the seats, and honing the cylinders.  Turns out this guy rides year round and loves working on bikes  He's also owned several sohc fours and seems excited to work on one.  He also suggested reaming my existing guides rather than replacing them with the pre 77 guides because he said sometimes the new ones will go in a little crooked and then you'll be hard pressed to ever get the valve to seat right no matter how many times you cut it.  What do you guys think?

Part of this makes no sense.
You said the machinist said" to ream the existing guides rather than replacing them.
If you ream the existing guides then how will they fit properly?
The valve stem is much harder than the guide.
As far as putting in new guides and them getting crooked, I do not know how the guide could get crooked. Maybe he meant off center?  Never heard of that either.
Maybe he meant that when the reaming of the new guide takes place that is when it could get off center.
But I do not think you can get valves that have oversize stems to fit worn out guides. And worn out guides may be off center too.
If the head is warmed up, the guide should come right out.
Then with the head warmed up, the guide which (should be chilled) can just push right down the hole.

Also... If you put in a new guide you can then put in the valve cutting tool into the brand new guide and cut your seat. That is what keeps the valve seat in alignment
 with the center of the guide.

Don't go for knurling the inside of the guide. That is a cheap way to fix a head.

You want all new guides if they are worn or out of spec.
You put the valve in the guide and check for wobble. It shows the procedure in the Clymer workshop manual.

[lucky]

Well I had some photos for you guys but my cameras data card is lost deep inside of my laptop somehow (don't ask  ) But anyways, jugs and head are with machinist.

Time to start on the lower end... I'm not really familiar with this at all.  Top end is easy enough but i've never looked twice at lower end stuff...guess it's time to stick my nose in the manual.  From what I understand I have to remove the crank to get the new continuous cam chain on there right?  Would it be a good idea to strip down the case and clean everything up anyways?  ...not sure if I want to tackle that.

Also in the meantime, spare tank from the 74 parts bike is going to be stretched 5 inches or so, and I need to order a seat so I can start relocating the electrics.
I want a custom oil tank too and I've found a guy to do it butwhere can I find oil lines?

Oh yeah, and the rotors are going out to ElCheapo sometime this week!

Phew,  I've got more to do than I thought! 

The oil lines and parts to make it work can be ordered from Cycle X. They do that all the time. You just replace the two fittings on the engine. Then if the new oil tank is steel you can cut the fittings off of the old oil tank (do not use a torch).
Or if the new tank is aluminum you can get those fittings too.
Check on the Honda chopper website because the chopper people do that all the time also.

Make up the hoses after you have the fittings on the engine and on the tank.
Matter of fact if you got two sets of fittings from Cycle X for the engine you could have one set welded or bolted to the oil tank.
Ask CycleX, or check with the Honda Chopper website.

[Blitzburgh207]

Thanks Lucky, I really appreciate your help in this.

First of all.... not sure what I was thinking but I was under the impression that the earlier valves (the ones I'm installing) had a larger stem than the later valves that I have removed.  That is the only reason why I bought new valve guides.  I will have the shop check my existing guides to see if they're out of spec. but judging by the overall shape of the head, I doubt it.  Maybe I can get a $70 credit from cyclex? 

Second, thanks for the advice on the oil lines. I'll check out the hondachopper site...not sure why I didn't think of that before!  But, that's pretty much the last mod on my list, so I think I'll be a little while on that.

I'm just going to keep bouncing my plans off everyone on here - need you guys to keep me in check haha!

p.s. it's about 30 degrees where I am right now! T shirt weather! Wish I could ride!

[MRieck]

Well, I backed all the studs out....15 of them anyways  I snapped the last one off rushing to get to the GD superbowl party.  But on the bright side, there's about 1/4" of it sticking up above the case so I should be able to weld a nut on there and turn it out.

In other news: The head and jugs are going to the machine shop this afternoon for blasting, cutting the seats, and honing the cylinders.  Turns out this guy rides year round and loves working on bikes  He's also owned several sohc fours and seems excited to work on one.  He also suggested reaming my existing guides rather than replacing them with the pre 77 guides because he said sometimes the new ones will go in a little crooked and then you'll be hard pressed to ever get the valve to seat right no matter how many times you cut it.  What do you guys think?

I have removed and installed hundreds upon hundreds of valve guides on all sorts of heads. Yes...the valve center will change a bit BUT that is why you have to perform a valve job after installation. I have no idea about the reamimg and pre 77 guides stuff As an aside....I believe in honing guides...not reaming them. You can control the ID of the guide better and it leaves a better finish that helps retain oil.

[Blitzburgh207]

Ya I definitely made that difference in stem size thing up.... idk.  My CycleX supaflow valves came in the mail today 

So I brought them to the shop - they slid right into the guides no prob with no play  He said he would hone the guides for oiling purposes anyways...

Also, carb gasket sets plus float valves arrived today. Here's the status on that:

Bedroom TV stand/work bench haha

I'm going to give the bodies a two day soak in simple green and clean them up more from there. I did this once last summer while I was waiting for parts, with good results.  So I think I should be able to get them to really look good now. And no gas drips on the freshly painted case!

[Blitzburgh207]

WOW JUST GOT A CALL FROM THE MACHINE SHOP ON FINAL PRICING!!! 

$250 for the following:

Degrease head and jugs in the "Hot tub"
Bead blast head and jugs
Resurface head and jugs
Hone Cylinders
Install valve guides
3-angle valve job

I was expecting them to take me for at least 500!  I'm so stoked on that shop right now haha.  I've heard from every motorcycle dealership and shop in the area that he does the best work too.  I think he was just excited to get an old honda in there.  He said he hates working on harleys  .  Is that really as cheap as I think it is, or is that pretty standard?  The most expensive item was installing the valve guides at $50!
-That was only for four guides though, he said the the exhaust guides needed to be replaced, but that the intake guides were good.  He said he didn't want to take an unnecessary chance on damaging the head by pulling the intake guides when "they're perfectly fine".

[sopo400f]

What's the name of that place?

[Blitzburgh207]

It's just the carquest on outer Hammond st in Bangor - best shop in the area according to all the bike shops in the area.  There's a guy there Peter I think who does all the motorcycle stuff.  He's pretty cool. Rides a goldwing and a duc I think?  ..Maybe he used to have a Duc I don't remember... Anyway, seems like a stand up guy - I expect he'll do a good job.

There's another carquest machine shop down on main st... the guy quoted me $270 just for the valve seats.  Real weasely guy that looked at you all sideways like with one eye - and didn't know anything about hondas.  I was like "huh, thats about 200 more than I was just quoted on the other side of town. I'm all set" and walked away.

[Blitzburgh207]

So it's been a couple weeks since I've posted anything.... Mostly because it's been a couple weeks since I touched it  .  But I did want to post some pictures of my "home port job".  Just cleaning up the intake ports so far... I'll probably tackle the exhausts tomorrow.

Before:



...they weren't really too bad compared to others I've seen.

After:






I obviously haven't bench flow tested them or anything... I just smoothed out what was there and tried not to take too much off.  I think it ought to make a difference..  We'll see how the exhaust goes tomorrow  It feels good to get back to work.

[Blitzburgh207]

Well it's starting to come back together now  It's going way slower than expected because of work and school but here's some pics of the motor going back together.  I put in new HD studs from ape, shimmed the primary chain tensioner, new primary chains, new cam chain, new cam chain rollers.  I have the head on now too and torqued but ape suggests waiting 24 hrs and re-schecking them so that's where I stopped.






Juggs are black but cases and head are VHT aluminum.  Cam cover and side covers are polished.  I also got the front end back together too.  I'll post more pics this afternoon or tonight.

[lucky]

Ok gotcha.  I need to slow down and take my time on this....  I Think I'm going to go to any/all of the shops in my area and talk to them - go with whoever I'm most confident in.   Any suggestions on where I can buy this "Blue dyekem"?

In a pinch you can use a black or blue magic marker.

[lucky]

Ya I definitely made that difference in stem size thing up.... idk.  My CycleX supaflow valves came in the mail today 

So I brought them to the shop - they slid right into the guides no prob with no play  He said he would hone the guides for oiling purposes anyways...

Also, carb gasket sets plus float valves arrived today. Here's the status on that:

Bedroom TV stand/work bench haha

I'm going to give the bodies a two day soak in simple green and clean them up more from there. I did this once last summer while I was waiting for parts, with good results.  So I think I should be able to get them to really look good now. And no gas drips on the freshly painted case!

There is ALWAYS some play but the question is how much play.
See the workshop manual to see how you measure the play of the valve in the guide.

[Blitzburgh207]

There is ALWAYS some play but the question is how much play.
See the workshop manual to see how you measure the play of the valve in the guide.

Ya the machine shop checked it for me - I don't have the tools needed.  If I were going to rebuild motors regularly I might invest but hopefully this is the last one I'll do for a few years  The intake guides were within spec but the exhausts were replaced.

Finally got an hour to myself earlier tonight and installed the clutch and ignition  Sorry, the picture is a little dark but it's looking pretty trick. I'm liking the black jugs...wasn't sure I would.

I just want a day alone with my bike to finish this damn thing! haha

[Pecantree]

I think this is what you need.
http://www.permatex.com/products/automotive/specialized_maintenance_repair/rebuilder_aids/auto_Permatex_Prussian_Blue.htm
Good Luck
Steve