Topic: 1973 CB350F "Freakshow Build" completed! Stay tuned for updates...

[Spikeybike]

o- 75 ft-lbs .. and i just looked it up and now it's 30 bucks

http://www.sears.com/shc/s/p_10153_12605_00944978000P?vName=Tools&cName=MechanicsTools&sName=Torque%20Wrenches&psid=FROOGLE01&sid=IDx20070921x00003a

[Tim in Ohio]

Thanks Spikey.  That'll be the one for me.

[Tim in Ohio]

Today's Progress:
Got the cylinder head removed (with my son's help):


Took Spikey's advice and said the obligatory off color joke to my son about the head...


He just gave me that:  'I'm calling Child Protective Services' look.





Cylinder #1:


Cylinder #2


Cylinder #3


Cylinder #4


By the way, Matt...  There wasn't a bolt in the middle back side of the head.  Just a hole where maybe a bolt should go?

OK Guys.  Review the pics, what is to be done at this stage of the game?

[kghost]

Take the barrels off...get them to the machine shop. (along with the new pistons)

Send head to Mike.

Flip it over and split the cases. 

[Tim in Ohio]

Are new pistons a must?  Scunny, Matt, Spikey, Hoodelly, are you guys gonna weigh in?

[kghost]

Are new pistons a must?  Scunny, Matt, Spikey, Hoodelly, are you guys gonna weigh in?

At least one of the bores has a pretty good scratch in it that will need to be machined oversize.

[martino1972]

a machine shop can measure your cylinders to see if they are still within spec's....
that will determent if you need an overbore,or not...
also a visual inspection of the pistons(and measuring by machine shop) can tell you if it would be wise to go to new pistons...
piston rings new is a absolute must...overbore or not...
if cylinders and pistons are good enough to be reused,then deglaze cylinder walls,clean pistons,put new rings on and reassemble...
see,over time a cylinder wall wears out mostly on the top 1/3 of the walls,making the bore's bigger in size there..
they can look nice and shiny,but only measuring will tell you what shape they really are...

[Tim in Ohio]

Thanks Martino.
I have never taken something like this to a machine shop,  Do I need to provide them with what the specs should be from the manual?  Do I take the head / valves in too?  What else should I know?

[martino1972]

yeah,i would let the head looked at for sure...valve leak,a valve guide out of place/spec can cause lot's of trouble you really don't wanne have..
any self respecting machine shop can give you good advise on the cylinder/piston shape,when they see it...
but before i talk you into spending a million bucks,make sure to ask the shop what it's all costing,so that you don't get unwanted suprices...
see,it all depence on how "anal" your taking this rebuild...if it's like you just want it to run halve decent with not too much smoke and rattling,or that you want a perfectly good dependable engine..
that is something you can discuss with the machine shop,they should be able to give you some options on ..well oke,let's deglaze the cylinders,slap some rings on,seat the valves a bit and your oke,or like,...well sir,if you don't do this or this ,it will blow up soon...

[scunny]

+1 on what martino said. give the machine shop the specs as well

[mattcb350f]

New pistons are a must if they're worn beyond the tolerance. There are specs for ring to piston clearance etc. in the manual which will tell you what you need.

On my build, I was able to use the old pistons but with new rings and honed cylinders. The way I determined if I needed new/oversized pistons is that my machinist honed the cylinders until they were fit for assembly. Then, we took a cylinder bore micrometer and checked each of the bores.

My bores were just under the wear limit for the 350F (which is 47.1 mm) so I went ahead and stuck with the stock bore. My pistons were in good shape so I used them too.

Like everyone else has said, a good machine shop will tell you if you need new or oversized pistons and what size to get. The machine shop will need all the wear specs listed in the manual to do this, so take them all the info you can.

I would also advise you to do some shopping to find out if and where you can get stock and oversized pistons/rings. I've heard of people having a hard time finding (0.75mm) oversized pistons/rings even though certain websites listed them. There are more sizes but I know that one is hard to find.

 Matt.

[Tim in Ohio]

Team:  Are we in agreement that after getting the cylinders honed/bored if necessary, and new piston rings, we reassemble and start tearing up the streets?
In other words... Kghost, were you kidding about splitting the cases?  I want to get this thing running reliably and with good power and fuel efficiency, but it need not be in concourse shape.  With my job situation, now might not be the time to worry about going all the way with a rebuild.  Top end enough for now?  Give your two cents please.

[martino1972]

the bottom ends are usual pretty good...
also,usually when you start tearing into the bottom,you will end up replacing bearings,seals etc..
if you say,now is not the time to do this,you can "feel" the connecting rods for tightness,and maybe "feel" the crankshaft,by push/pulling up and down on the ends of it,but personally i would'nt be too worried about it..if the rods feel good,you should be fine..
good practice would be to remove the oil pan,and inspect/clean the pan and sump etc...

[Tim in Ohio]

One more noob question for now...
When I take the head in for inspection, do I need to remove the valves, etc first?  (seems kind of tricky) or is it best to hand it off to the machine shop with all of valves in tact for them to examine?

[mattcb350f]

If the bottom end/cases are holding oil and everything worked fine then i say keep it together. Cause once you open up that can o worms you might as well replace every part in it.

How was you cam chain/tensioner before you took it apart. Did the adjuster work well or was the chain loose?

The reason I ask is that my chain had got soo loose that it started to eat the slippers and the cam chain tensioner U bolt inside the cases.

the cases need to be split to totally repair the cam chain and tensioner so better to do it now..... but if they're ok then carry on  


Found this pic burried in my photobucket of the tensioner U bolt thingy which seized from the chain rubbing it:



 Matt.


EDIT: let the machine shop remove the valves - if they'er like my machinist they'd rather have the head in tact then 'screwed' with 

[kghost]

The reason I'm thinking at least one piston is below.

Note the scuffing and grooves in the cylinder....

[mattcb350f]

Worth a better pic......take one with the piston at the bottom of that cylinder Tim, and an angled shot of the area kghost has spotted.

I thought it was just some flaky mystery bits from the head gasket, but it does look suspicious.

 Matt.

[kghost]

Worth a better pic......take one with the piston at the bottom of that cylinder Tim, and an angled shot of the area kghost has spotted.

I thought it was just some flaky mystery bits from the head gasket, but it does look suspicious.

 Matt.

Good shot of all four bores with the piston at BDC (Bottom dead Center) would help.

[Tim in Ohio]

OK guys more pics of the cylinders coming up, I pulled the cylinder block off so the pistons won't be getting in the way of the shot anymore.  But first...  check this out.  I have read in other post what a challenge it is to get the "studs" out for those who are going to replace them.  One of mine was actually not even "finger tight"  I screwed it out with my hand easily...  what do you make of this?

[kghost]

Happens sometimes when taking the nuts off.

Check the threads in the case and if thier all ok...put it back in with some locktite.

[Spikeybike]

could that be the leaky top end ?

[Tim in Ohio]

Guys, sorry, my photography skills will not allow me to get a decent pic of the inside of the cylinders (too shiney).  I can report that on at least one of them, there are a couple of grooves that are deep enough to catch on my fingernail when I run my finger across the surface.  At this point, I guess I will take the head (with valves in tact) and the cylinder block to the machine shop tomorrow.   Matt (or anyone) remember those oiler manifolds on the head that we were talking about?  Since they just sit down in those holes, (and could come off and be lost or damaged if someone at the machine shop was careless...  should I just pull those out and bag 'em here at home first?  (my gut says yes)

[Spikeybike]

trust your gut

[Spikeybike]

i just noticed that your gaskets came apart in one piece , lucky bastard 

[Tim in Ohio]

They did.  I have a new top end gasket set on the way though...  good idea, yes?

Hey, this will show my ignorance, but that is no secret.  Are the rings around the pistons supposed to be loose?  I can move them around freely with my hands.