Engine nube - need CB350 help

C

cbkid

New Member
Hey folks,
I am rebuilding my engine for the first time and have been doing some research and whatnot but still have a few questions. Its an engine off a 1973 Honda CB350G. I took the thing on a sweet 6K trip through the SW a couple years ago but then it started leaking oil out the gaskets so i figured i needed to give an overhaul. The time has come and here i am.. I'm sure some of these are basic questions but I'm a total nube and have nobody to ask so any help would be much appreciated. Thanks!

1) What is the best way to clean and touch up the case parts? I dont want to put a ton of money into powder coating (unless its cheap, im actually not sure). Are they other ways to like power wash the pieces or something to get them clean and get the crusted gas and chems off?

2) i have a new gasket set. i know most of these are one-time use paper gaskets. when putting them in should i use any extra glue to seal it up?

3) whats a good way to not waste the paper gasket but reassemble the engine to make sure it works right? maybe that is a dumb question. but seems like id waste the whole set if i got something wrong and had to disassemble again..

4) What do I use to seal the two halves of the lower end of the engine? I imagine there is some special glue...

5) I'm getting a new cam roller assembly. Also read that putting new rings on the pistons is a good idea while i am in there. Any other good things to do while i have the thing apart?

6) when do i know its time to re-bore the cylinders? if they show wear? or is it a measurement thing?

7)how do i remove the valves? do i need to get that special spring compression tool or is there some other trick?

8) i have the top end apart and the sides all dissasembled. anything i should know before opening the bottom half (other than open it upside down).

Thanks so much in advance!
 
Hey welcome to DTT.

Here are some answers I can give you:

1) De-greaser and a pressure wash will clean your engine parts. It wont remove any corrosion though. To remove corrosion they will need to be blasted or scrubbed with a scotchbrite or fine sandpaper.

2) Shouldn't be necessary (provided your mating surfaces are clean and undamaged).

3) Follow the instructions in the service manual closely. If you do need to take something off again you'll find the paper gaskets are perfectly ok to use again (I mean freshly installed ones), just be careful not to tear them if you take them off.

4) Do you have a service manual? If not get one! It will tell you in there. Usually cases are sealed with a liquid gasket (Threebond is a good brand) someone else might be able to tell you what one to use because I've never done a 4-stroke bottom end.

5) Best to get info from someone who has worked on 350's or similar.

6) They need to be measured and compared with the maximum wear limit stated in the service manual. A friendly bike shop might do this for you for free.

7) A valve spring compressor tool or make your own (do a google search).

Sorry I don't know more about these engines to give you more specific advice. But the number one thing I will say (and anyone else for that matter) is get a service manual!

Good luck with the rebuild.
 
Several questions suggest that you either don't have a service manual, or you haven't read it, yet you say you "have done your research."
 
sounds like you have looked at pictures of someones rebuild... but didnt read anything
get the manual...and read it.

1. mine went in the Kenmore...the wife was delighted.

kenmoreclean.jpg
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2 whats the manual say? probably no.

3 read the manual... lessen the chance of something going wrong.

4 360 manual, refers to a sealing agent...Hondabond.

5 the manual will have you check things for wear specs as you go.

6 manual

7 do they use a tool in the manual? probably yes...does the manual give shortcuts, probably no.
 
Thanks everyone. I do have the 2 service manuals and have been working with them. But the questions I asked were more meant to be in the vain of seeking tricks and tips. I guess I figure the manual will recommend routes that will cost more and I was looking for insider tips that might save me money and stress. I have looked at and read thru a few rebuilds but I just want to be super clear on what I am doing so I dont mess it up! Again, thanks for the help!
 
The cylinder bores last real well, unless it's run with real dirty oil they should be fine for 40,000 miles or more. Rings are a different matter, if your over 15,000 miles hone bore then fit new rings
You only use sealer on the cam box to head joint, everything else has gaskets
The gaskets are heat/pressure activated, if motor hasn't been run there generally isn't a problem re-using them
.
DO NOT USE SILICON SEALER, the correct stuff is relatively expensive but much cheaper than a screwed up engine
 
+1 on not using silicone..,it clogs the oil passages & will cook your camshaft,etc. :o I've used Indian Head before when absolutely necessary.
 
Get the right stuff. Hondabond or the company that makes it, threebond. 1184, 1104, 1194....they are similar, they formulation is slightly different in each....California has some restrictions on the chemicals, so Threebond made a California specific formulation, but they all do the same thing as the Hondabond

41QJUDsLkNL.jpg


Amazon carries it as well as most Motorcycle online shops and local motorcycle shops.

It is specifically made to work on the cases and rocker box where a gasket is NOT used.
 
Thanks everyone!
I got the hondabond for the lower end. There isnt a gasket for those two main casing pieces (dont know the right terms here). but i have a new gasket set for everything else. I took the top end in to my friends shop and got it sand blasted at a low psi. now it looks like crap but it got off the 40+ years of grime. I guess ill get those bits powdered coated.

the lower end could use some good cleaning and buffing. any good tips? the guy was saying to use a buffing wheel. but at this point i just want to get the thing back together and looking nice but finally ride the thing (its been 3 years).

the cylinders are below spec (!) so im going to hone them and put a new ring set on just to be safe.

cleaned the valves but am wondering if i should clean the top of the combustion chamber with a wire brush. im guessing not messing with the smoothness of the shape is a good idea but i figured it coated in carbon and not smooth already.. thoughts?

i ordered my cam chain roller from thailand (i know the rubber is suspect but i cant shoot for the more expensive KA or cappellini aftermarket parts). got a steel bolt set too. excited.

more help would kick ass! thanks!
 
Top and bottom cases are just top and bottom cases, it's assumed everyone knows your talking about crankcase set ;)
Generally you find anything with 'precision bearings' doesn't use a gasket as the bearing size will change if one was fitted as it could crush by different amounts even on production line assembly
If you have a thin even layer of carbon, leave it alone, it helps insulate the head slightly which improves performance (keep the heat in combustion chamber without direct conduction into head)
 
I always bead-blast the combustion chamber. Of course, then you have to be really, really meticulous about cleaning every nook and cranny.
 
Hey folks,
So I did the rebuild-ish doing the following:
  • honed the jugs
    lapped the vales
    replaced the rings at 120º spacing
    fixed the broken cam pieces
    cleaned the lower end and honda-bonded the halves back together
    cleaned off the old gaskets
    replaced the top end gaskets (put them on dry)

Now I have the following issue: when I go to set the tappets and points timing, i can't get the rotor to "LF".. its stops hard just before it. Ideas? There is no oil or fuel in it yet in case I have to take it back apart. Its in neutral as well.

Also, I didn't think to replace the seals around the kickstarter or chain sprocket rod. Then I heard it might leak there if they were the originals. Is there anything I can do to make them not leak. Can I put hondabond around the outer perimeter of the seals?

I am so close! Please help if you can. I haven't fired this thing up in over 2 years.

Also:
cleaned the carbs & air filters
new battery, plugs, oil, fuel filters, fuel lines, and fuel.
 
Seals are cheap. Replace them.
Follow the instructions in the service manual on how to time the cam. Pistion hitting valve can bend the valve, then you are fucked.
 
im back in the top and pulled the side covers and rockers. now when i sync the cam sprocket to the L mark and horizontal line to the LT mark on the stator, i can't get one of the the left rockers on. its too tight as the rocker is being fully engaged and pressing down on the left exhaust valve. i thought maybe i have the sprocket off 180º, but i read that the sprocket bolts are designed to only go on in one orientation.

is the exhaust valve supposed to be open at TDC? doesn't make sense to me.. also, i dont seem to have a hole for the "governor pin" on the points side of the camshaft. looks like the bump that holds and moves the spark advancer is just built in to the campshaft. is this right? i have a 73 cb350G.
 
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