Topic: CB 350F cafe build with 400f engine swap, looking for help and advice

[Rushmore]

Hello, everyone this is my first post here.  I am taking the task of rebuilding my 1973 CB350F, despite the fact that I have really never worked on a bike before.  This is my first time working on a bike, but I want to learn, so any advice would be great.  I am a 28yo medical student so time and money are short, but I have scavenged some parts over the last couple of years and I am just now getting some time to put into working on it.  I am going to be posting my progress so any advice or suggestions will be appreciated.  I am also going to be posting at www.dotheton.com and keeping a blog at http://rushincafe.blogspot.com/

[Rushmore]

http://www.dotheton.com/forum/index.php?topic=18373.0 is the link to the other thread.

[Rushmore]

[Rushmore]

I did not think to take a picture until after I removed the tank and seat. so here is a picture of the bike before I start.  Below is a pic of the seat and tank.  I'll be putting the old seat, tank and side covers up for sale at some point.

[Rushmore]

Today I started to take apart the 400F engine.  Here is what it looked like before starting.




So that was the tag that was on the engine, its a 1975, and it had "70% Leak" written on the tag, but over the top of the 70% was written 30%.  The guy I got it from said that the result of a leak down test was 30%.  I figured either way that was too much, and I wanted to learn something so I was going to take it apart. Any comments about what the condition of the motor looks like to you guys?

[Rushmore]

Ok so I started by removing the 10mm bolts on the top of the cylinder head cover, including removing the breather cover and the four 10mm bolts beneath it.  i am organizing the parts by labeling cardboard and pushing the bolts through them, and laying out some labeled paper towels in the order that I removed the parts.

[Rushmore]

Here is a look under the cylinder head cover.


 For some reason I thought that it would be a little dirtier than it was.
Next I removed the oil jet tubes on both sides and the cam chain tensioner, and the one of the cam retention bolts.  In order to get the last cam retention bolt off, I removed the contact breaker cover on the right (retained by two screws) and
turned the engine by clamping onto the large hexagonal washer, This allowed me to remove the last cam retention bolt and move the cam sprocket to the left.  I tied a small length of fishing line to the cam chain so that it would not fall down the tunnel, and then removed the cam chain from the cam sprocket.  Next I removed the cam shaft and the cam sprocket, by removing to the right hand side.















So there are some pics of the cam shaft and the cylinder head camshaft bearing surfaces (which seem a little scratched to me).  What do you guys think about the condition of everything?  Also I'm not entirely sure how or what I am supposed to be looking for when checking the rocker arm-to-rocker arm shaft clearance?  Any help on either of these topics?

[Rushmore]

The next step I took was removing the cylinder head, which was attached by 12 nuts two of which were close to the spark plugs (I removed all four spark plugs as well).  After removing all of the nuts I bumped the bottom of the cylinder head with a rubber mallet and then lifted it off, and then removed the cylinder head gasket.  Once removed, the pistons looked very dirty, Whats next?  Here are some pictures let me know what the condition of everything looks like to you?  the cylinder studs looked a little rusty? (I think the Cylinders are numbered from 1-4 from left to right, Correct me if I'm wrong.  So that makes the pictures below cylinder numbers 4,3,2,1 from top to bottom)

[fasturd]

Good luck on the build. I have to look up my numbers but I think your 400 engine is a fairly early unit.

[Rushmore]

Good luck on the build. I have to look up my numbers but I think your 400 engine is a fairly early unit.

Thanks man, yeah let me know.

[Rushmore]

Ok, so I am having trouble removing the cylinder block, it just does not seem to be moving at all, I sprayed some penetrating oil but that has not helped, anything I could have missed?

[1980cm400t]

A screwdriver and a deadblow hammer will do the trick just don't gouge the head or block if you can help it, assuming you have removed all the head bolts and other hardware.

[Owned]

Rushmore!  I'm currently going through the SAME project as you.  However, we're at different stages.  My 350 frame is currently getting a few mods done to accept a new tank and custom seat.  I've completely rebuilt the engine/carbs and am looking forward to bike reassembly.  I don't want to high jack your thread, so I'll stop now

If you haven't removed the cylinder block yet, give it a few good taps with a heavy rubber mallet.  It should break free.  Sometimes, those old gaskets can make things a little sticky.

Good luck.  I'll be posting more of my reassembly once I get the frame back from my fabricator and it's in powder coat.  Final product will have close similarities to the link in my signature...just a little more aggressive as this one's for me and not my wife.

[Rushmore]

@Owned, awesome man looking forward to seeing it, I'll be sending my frame to the fabricator for some adjustments to accommodate my new tank and  seat, but not till I finish this.  I did finally get the cylinder block off, you guys were right it just took a few more bangs with the rubber mallet, and a baby flat-head.  So here is my progress form the other day, I did not get much done today, because I painted the ceiling in the bedroom and replaced a door in our townhouse, but tomorrow should be more fruitful.

Alright, well the cylinder block was harder to remove than what I thought it would be.  First I removed the cam chain guide, and the cam chain adjuster lock nut and the bolt beneath that, then turned the engine some to line up all the pistons and tried to lift the cylinder block off of the studs.



  Eventually I was able to remove it, it took some penetrating oil and a small screwdriver and a rubber mallet.


After removing the cylinder head, I started to remove the pistons by removing the innermost or outermost circlip (whichever was easiest to get to) and then pushing out each gudgeon pin using a small flat-head screwdriver.  I lined the pistons up in order and attempted to remove the two piston rings and the three-piece oil control ring that is on each piston.  That was going well until I got to piston 3, where I snapped the 2nd ring, due to my impatience (looks like I have just incurred my first cost other than new gaskets).  There are some pictures here, any suggestions for how everything looks as far as ware goes?  But I am just going to replace all of the rings anyway, so that's fine.




piston 1 (above), Piston 2-4 sequentially below




here you can see the broken 2nd piston ring on piston #3

So I'm not sure what to do next?  Should I pull the clutch and take the bottom end apart or is that not necessary?  I have never run this engine, I just bought it from some dude, and it was sitting in a store house for a while behind a cabinet on a pallet wrapped in plastic, what are the suggestions for the next step on this, I obviously need to order a set of gaskets and some piston rings, should I bring the the block to a shop to see if it needs to be honed?  what about the cam chain and the valves?  Oh yeah can i just use some simple green and a wire brush to clean those pistons?

[Owned]

Rushmore,

Your next step depends on how far you're willing to go.  It's up to you.  I completely disassembled my 400 by splitting the cases.  You've came this far, it's really not hard to do and reassembly isn't difficult at all.  Personally, I wanted to split them so I could have the cases blasted clean (soda blasting set me back about 50 bucks and came back ready to paint).  You may want to consider replacing the cam chain and ensuring the cam chain tensioner mechanism moves freely.  They can be prone to gumming up and getting sticky.  I can help you along the way if you get stuck in reassembly.  You seem to have the aptitude thus far.  As for the cylinder bore, I'd drop the jugs off to be measured and honed.  Bring your pistons and give them the new rings.  My guy installed the rings on the pistons for nothing.  I'd have them deck the cylinder bore and take a little off the head, for a tad more compression and to ensure all is 'true'.  This is also a great time to replace the valve stem seals.  I'm assuming that you've bought a full engine gasket set and oil seal kit?

[Rushmore]

ok so I cleaned the piston heads, and wiped out the block.  I then placed the clean pistons in the cylinders and measured the gap (front to back) between the piston and the cylinder wall, 0.003 slid between, but 0.004 and 0.005 would not fit. (below piston 1-4 in order)






today, I was going to go over to Werks Engineering in Virginia Beach to bring the cylinder block to be honed, because its still within spec right?  Now I think I just need some advice on where to get rings and what to do about the valves, I am still thinking about taking the bottom apart and replacing the cam chain at least, because like I said I have never heard this engine run at all, it supposedly has about 27k on it though.  Any advice for the machine shop or anything else?

[Owned]

I picked up my rings from Metric-Cycle-Parts.com.  They shipped fast, and for some reason sent 5 complete sets.  Concerning your head, I'd have your machine shop check the valve guides for wear.  If there is any, now is the time to replace.  Odds are that your valves are in good shape, but they can tell you when they are inspected.  When you reassemble, get a set of new wrist pin clips.  It's cheap insurance against a possible catastrophe by using your old ones.