cb350 winter maintenance

R

Rimmy

Been Around the Block
Hello all,

So I've got a 73 CB350. I bought a ton of parts for it and just wanted to slap them on and call it a cafe racer. After I came to my senses and realized that the only thing that would leave me with was an uncomfortable, unsafe bike I've decided to slow things down....

Currently I have the bike in pieces. I want to polish and paint everything and make sure everything is mechanically sound. And I'm giving myself all of this winter to do so.

Since I have basically a bare frame and can access nearly any part on the bike, what should I replace or be cautious of? I already know from the wisdom of others (and the search function!) to replace the steering bearings, cam chain tensioner and do something about the shocks. Does anyone know of any other parts that I may want to look into to make sure I have a safe and reliable ride?

Any and all advice would be appreciated.

-jordan
 
If you're doing the tensioner then you might as well replace the cam chain as well. Go for a Tsubaki. Keep in mind you have to split the cases to do this. Good true rims with good rubber on them is also a safe bet.

keep in mind that while you have the motor apart there are quite a few things you can do. Kibblewhite Valves and guides are nice, as well as Barrnett friction disks, alloys, springs for the clutch (of course you can do the clutch stuff anytime really). You also may want to consider some mild porting on the head. It all depends how deep down the rabbit hole you want to go.

Have fun and enjoy your build. No matter what your level of experience, you'll always walk away learning something.
 
valves and guides are pointless unless if your doing a port job, as well as a cam, and much other work.
 
I'd say get the camellia cam chain from boretech, and a rivet master link, that way if you're careful you can replace the old one without splitting the cases. the cam chain tensioner is crap stock, and probably shedding chewed bits of 40 year old rubber into your oil screen or soon will be, replace it with a KA slipper tensioner, will probably last longer than you or me. stock valves are a good start, if they're in good shape, they'll do just as nicely as stainless if you're not racing. get a lapping kit from goodson and reseal them into the seats and you'll be tickled pink. replacing the valve guides with bronze is again not needed unless you're racing and its quite the job, you really need to replace the valve seats with the guides or you'll likely never have a good alignment of the valve face and seat. so that becomes a huge job that nets you 1% improvement where you'll be running the bike. replace the rings and hone the cylinders, inspect them for unusual wear (pitting or vertical scoring) take to a machinist to bore .25 or .50 over if needed and fit with oversize piston kits, they're available for good prices (<$100). your motor will be much happier. while you have the block off, pull the wristpins out and check the conrod and wrist pin surfaces for unusual wear. check the cam and rockers for unusual wear (again, pitting or scratching), replace if needed, there are lots of spare parts available for this motor. go through your oiling system and make sure there are no obstructions, clean the oil filter and pickup screen, inspect the pump innerds for unusual wear (scoring), you'll have to remove the clutch basket to do this. that should keep you busy for a while and get your motor running like the day it left the factory
 
Thanks for the replies! I am hoping to have quite a productive winter ahead of me. Hopefully I'm going to be able to strip and repaint the frame this weekend. And, I just finished my makeshift workbench so I can work on the motor!

Looking at the boretech website, it looks as though most of these products are within my budget too. Though I have a follow-up question. If I'm going to make these modifications to my motor, would it be worth it to toss in a more aggressive cam? I know I'm not going to get massive amounts of power from this bike, but would dropping a couple hundred on a cam be a waste of money?

-jordan
 
running a hotter cam in the 350 isn't going to improve things without some other modifications, if you're in the mood to play, get a copper head gasket from lani at copper gaskets unlimited, and some spray copper gasket sealer, that way you can pull the engine without throwing it away, and it's a lot easier to clean off copper residue than baked on gasket. file the bolt holes in the cam sprocket and get a degree wheel so you can play with that, get some tools and play with the engine and get comfortable taking things apart and putting back together, play with cam timing, use solder to check valve to pocket clearances, learn how cam timing affects the powerband. after you ride your good running stocker for a season, play with things like the cam over the winter, there's not much point in starting out shooting for the moon and maybe getting a few extra horsepower that you really won't notice because you haven't ridden the bike in good stock running order yet. it's a lot more fun to play with the motor and learn how to make it faster as you go

my blog is at http://roccitycafe.blogspot.com I'm keeping up to date on rebuilding a 350 motor for a customer's bike that was burned through and through, as well as a 350 race backup motor built basically as a refurbishment (going through and making it as new or better) and a 350 motor punched out to 362cc and running my bearing modifications to the head. so keep it in your bookmarks and you'll probably get some pointers - Sean
 
Since you already have several conflicting opinions to your very appropriate questions, I thought I'd add a couple more.

I'd leave the frame paint until last. That may sound odd, but until you build the bike, you don't know where you want the footpegs or brackets to mount teh exhausts or seat and so on. The "right" way to do this is to dry build the bike. In other words, you build it first without paint. When the inevitable happens and you want to cut something off or weld something on, it is not an issue.

When you have it built and running, then you strip it again and get it painted and powder coated. With a clean bike, a full strip takes less than an hour and full build is less than one day - because there are no surprises. Everything will fit perfectly. I cannot tell you how many times I thought I had all the frame mods worked out and sent it to powdercoat only to realize later that I want to change something.

As for teh motor, a good mild cam will help and as the lads already intimated, a port job will bring out the best in a cam, but a simple cam change can be worthwhile. My suggestion would be a very mild Megacycle cam. Stay away from race cams which lose power at most revs. A valve job is always worth doing. Get your local import auto engine shoip with s SERDI to clean the valves and seats up with a nice 3 angle valve job.

Race valve springs are a good idea but titanium or alloy caps really come into their own at race speeds, so if you don't plan on thrashing it, they aren't mandatory.

Cleaning up obvious bumps in the ports is a good idea but don't try to open them up unless youhave read and understood AG Bell's book on 4 stroke performance first. If the stock valves are OK use them.

Check the pistons and bores and if necessary get a rebore and fresh slugs. New cam chain is a good cheap insurance. Stock rubber cam wheel is OK on the street as long as it's new. Slightly higher compression would help performance, so measure all the head/piston/valve clearances and machine the block to suit. A better solution is machining the head and squish bands, but that starts to get complicated real fast.

If you get a great Xmas bonus, you could always fit 67.5mm pistons from THR, Boretech or Les Barker's small engine shop. Les is teh best guy to get this stuff from IMHO. http://www.vintageadvantagemotorcycles.com/vintage%20advantage%20website%20photos%20350.jpg

One list of suppliers: http://www.groupwracing.com/suppliers.html



Obviously tires and barkes and cables and other roadworthy stuff have to be taken care of.
 
teazer said:
I'd leave the frame paint until last. That may sound odd, but until you build the bike, you don't know where you want the footpegs or brackets to mount teh exhausts or seat and so on. The "right" way to do this is to dry build the bike. In other words, you build it first without paint. When the inevitable happens and you want to cut something off or weld something on, it is not an issue.
Click to expand...

take that good advice even one step further and put 1000 miles on it before you powdercoat it... you'll quickly figure out how a 1" change in a footpeg makes a world of difference on a motorcycle
 
thanks for the replies! A few weeks ago the bike was running, and all put together already. I had put all of the cafe pieces on (rearsets, clip-ons etc) and new tires already so the geometries and ergonomics are all set.

As for the motor, I think I'll not dive too far down the rabbit hole this winter. I'll heed the advice given here and will definitely put some significant mileage on after winter before I decide to do anything radical to the motor.

From the advice above I think it looks like I'll be replacing the cam chain and tensioner for certain. As far as the motor, I'll probably end up with new pistons and decide what to do with the valves once I have everything opened up and can see whats going on.

Once again thanks for the advice, though I'm sure I'll be asking more once I have the motor all ripped apart. Now to start that build thread....

-jordan
 
djelliott said:
Um, no they're not.
Click to expand...

yes, they are. well, unless if they are trashed or otherwise and REQUIRE replacement, then its worth it to change them out for good stuff.

but really... no point in changing stock valves unless if they are trashed.

also dont bother with race springs with titanium tops etc on a stock cam; unless if you constantly wind the motor out to 10,000 rpm. otherwise you are just putting additional stress on the cam, rockers etc, for no gain. high rate valve springs are for high rpm applications to reduce or eliminate valve float.
 
Roc City Cafe said:
I'd say get the camellia cam chain from boretech, and a rivet master link, that way if you're careful you can replace the old one without splitting the cases. the cam chain tensioner is crap stock, and probably shedding chewed bits of 40 year old rubber into your oil screen or soon will be, replace it with a KA slipper tensioner, will probably last longer than you or me. stock valves are a good start, if they're in good shape, they'll do just as nicely as stainless if you're not racing. get a lapping kit from goodson and reseal them into the seats and you'll be tickled pink. replacing the valve guides with bronze is again not needed unless you're racing and its quite the job, you really need to replace the valve seats with the guides or you'll likely never have a good alignment of the valve face and seat. so that becomes a huge job that nets you 1% improvement where you'll be running the bike. replace the rings and hone the cylinders, inspect them for unusual wear (pitting or vertical scoring) take to a machinist to bore .25 or .50 over if needed and fit with oversize piston kits, they're available for good prices (<$100). your motor will be much happier. while you have the block off, pull the wristpins out and check the conrod and wrist pin surfaces for unusual wear. check the cam and rockers for unusual wear (again, pitting or scratching), replace if needed, there are lots of spare parts available for this motor. go through your oiling system and make sure there are no obstructions, clean the oil filter and pickup screen, inspect the pump innerds for unusual wear (scoring), you'll have to remove the clutch basket to do this. that should keep you busy for a while and get your motor running like the day it left the factory
Click to expand...

So many great suggestions here on this thread (perfect for newbies like me)..

Thanks for sharing the knowledge, chaps.

I have a question, touched on in the above post..

I have been getting into my first bike restoration project, and getting assistance from a friend along the way.
We have the CB350 engine apart to replace the broken up cam chain tensioning parts..

My friend called today to say that he was inspecting the pistons and conrods and he is concerned about the wear shown on the small ends where the wrist pins go through.
I think also he was surprised that there is no bearing used on that end (which I think he said his CB750 has in that position).

So, do the connecting rods need to be replaced, or can they be modified or upgraded with a bearing in the small end to repair or even improve reliability in the long run?

Thanks in advance for any light you can shed on this topic.
 
Re: cb350 winter maintenance (conrod pic's)

My conrod ends (pics attached)

My friend feels they look to have been starved of oil flow?
 

Attachments

  • Honda CB350 conrod small end EVAN 002.JPG
    Honda CB350 conrod small end EVAN 002.JPG
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More likely wrong oil was used, probably 20/50 or straight 40wt?
majority will tell you they are trash (they really don't look good)
You'll need a new piston pin to check how much 'rattle' you have, unless you have equipment to measure inside the small end bore?
May be looking for a 'new' crank :(
 
crazypj said:
More likely wrong oil was used, probably 20/50 or straight 40wt?
majority will tell you they are trash (they really don't look good)
You'll need a new piston pin to check how much 'rattle' you have, unless you have equipment to measure inside the small end bore?
May be looking for a 'new' crank :(
Click to expand...

Thanks PJ.

I don't know what oil was used in the bike before I got it recently, and I haven't run it.. I just got it to fix up and (hopefully!) ride soon.
:)

So, easiest solution may be to get a complete replacement crank and just swap the whole lot over, with conrods and the rest?
 
Yep.
It's possible to re-build crank but a used one will probably be cheaper.
I wouldn't toss the old one though, never know if someone else has a worse problem and it could be used for parts
You need at least a 20 ton press to separate the parts and pieces (plus various fittings and adapters)
I've done hundreds (maybe thousands?) of pressed and bolt up cranks, would be a couple of hundred minimum to split, replace and re-true damaged parts, OK if your racing and fitting expensive rods, not so much for a basic build
 
Honda do not bush the small ends of those pressed up cranks and the only lubrication is oil mist. There are no oil jets AFAIK spraying oil up inside the piston which is a design that is used more now. Small ends are never well lubricated but they also don't rotate/oscillate much and are not revolving, so they don't need a lot of oil.

As PJ suggested, while they look "bad", what counts is play. If the pin is a good sliding fit in the rod, they are OK to use. I have had really oval small ends bored out and bushed, but that's a lot of work if it's not needed. I have also had rods bored to take 1mm longer piston pins in a CB160 frankenmotor with CB500 pistons.

More important that the small ends are teh big ends and main bearings. How much play and rock is there in the rod? And how smooth are the mains?
 
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