Topic: CB350 cam chain tensioner Help needed

[schmors]

I have a 1970 Honda CB350 twin and it started making a little bit of noise, so I figured I'd tighten the cam chain. I'm new to bikes and haven't done it before, but I have the manual so no big deal. I followed the directions in the book but now the bike makes way more noise than it ever did before.

How I did it was take the tappet cover off the left cylinder intake valve and turn over the engine until it was open and started to close, then put it to the LT mark under the alternator cover and loosened the cam chain tensioner bolt and it is supposed to automatically take up the slack.

I put the alt to LT and took the tensioner all the way off to look at the plunger and everything and put it back on and its still making noise.  I don't know what it would be..

Well if anyone knows what I, or the bike did wrong, any help would be appreciated. Thank you!

[Alan F.]

Personally I have no answer for you, except maybe to try looking on forums specifically suited to honda twins.   http://hondatwins.com/resources.html

Good Luck and ride well!

[Short Round]

Somtimes the tensioner screws will get corroded in the cylinder.  Try turning the tensioner screw counter clockwise intil it turns no longer and releasing it.  if it does not auto-tension then there is a burr in the tensioner itself which means it will need to be removed and cleaned or replaced.  Another thing to try is turning the screw clockwise until you feel tension and them tighten the locknut, start engine and see if it helps. 

I'm not sure with about the 350s but with the 550s you have to make sure you find TDC then turn engine a bit more so engine is 15 degrees past TDC so all the slack is at the back of the motor, that way the tensioner can work properly.  Post the procedure on her that your manual has so I can give it a read over.

[Bill Vaughan]

There are several parts to the tensioner system to include the tensioner, guide, roller, push bar and spring.  If any one or combination of these is worn beyond spec. or the chain is stretched, you will not be able to obtain proper adjustment.

How many miles are on the engine?  Did the push bar have free movement when you removed/inspected it?  Can you pinpoint from where the noise is coming?

[schmors]

Okay, so the manual says to take the alt. cover and the left cylinder intake valve tappet cover off.  Then rotate the engine untill the valve opens and starts to close. Then move it to the LT mark which is under the alternator cover.  Then loosen the tensioner bolt and locknut and retighten them as they should automatically tighten it.

I posted on advrider.com and it looks that it might be the small roller that you can see with the tensioner off is too worn.  The tensioner seems to be working right and the push rod thing moves freely and locks into place when I tighten the bolt.  Here's a picture of the roller:

well the picture is not working, but here's the link to that other thread that has a picture of it:  http://advrider.com/forums/showthread.php?t=414703

This sucks because in order to replace that roller, you have to pull the whole engine.  The bike has between 19-20k on it and the noise definitely sounds like a chain coming from where the cam chain is.  I don't understand why it made the noise so much worse after I tried tightening it than it was before..

Thanks for the help!

[bryanj]

I have looked at the picture and that engine needs to come out NOW and be totaly stripped and cleaned with the following parts:-

Cam chain
tensioner COMPLETE (NOT THE ADJUSTER)
Gaskets
Seals

pay particular attention to the centrifugal oil filter on the RH side of the crank and NO gasket goo on reassembly ANYWHERE except crankcase halves.

If you dont pull it you are risking cam and bearing wrecked plus bent valves

[schmors]

Why will it do all of that if I don't pull it now?

And what is the difference between gaskets and seals exactly?  I'm still new to all of this stuff, and I'm a little scared 

[tbpmusic]

And what is the difference between gaskets and seals exactly?  I'm still new to all of this stuff, and I'm a little scared 

Then you might want to enlist the aid of someone experienced to walk you through things.
There are older guys around who would be happy to let you watch while they fix it, and explain things as they go.

bill2

[mark]

Why will it do all of that if I don't pull it now?

And what is the difference between gaskets and seals exactly?  I'm still new to all of this stuff, and I'm a little scared 

my 2¢.....

First... all of the rubber that your roller has lost is now most likely packed into the screen on the oil pump, reducing flow.

Second... the cam and bearings are the last items to receive oil - after crank and mainshaft bearings.

The slipper chain guide and inner roller are probably just as bad as the part you can see. more rubber bits. This all adds up to a possible serious reduction of oil flow, and the top end gets torn up first.


The gasket set includes gaskets - flat paper things. Oil seals are sold separately and you want to change them while it's apart.

Oil changes and valve adjustments are about all that can be done to the 350 without pulling the engine.


Happy trails.


 

[Bill Vaughan]

Well, unfortunately, the photo confirms what was suspected - the tensioner system is shot.  Heed the advice you're receiving here and do not run that engine until you tear it down and replace the worn parts.

Now for the good news.  You couldn't have a better engine on which to hone your repair skills.  The 350 twin is relatively compact and simple in design.  You really wouldn't want to be doing this for the first time on a 450, 550 or 750.

If you haven't done so already, invest in a Honda factory manual for your model.  They are available online at Helm, Inc. (www.helminc.com).  The manual will walk you through the various procedures step by step.

The manual, parts, some tools and the good advice provided by the members of this forum should be all you need to get that engine back in shape.

[bryanj]

That roller should have a ridge in the middle sticking out, so where has all that rubber gone and why?

Answer somewhere inside the engine trying to stop oil going round!!


THATS why it needs doing NOW before you total all the expensive innards , some of which are not easy to get now.

[schmors]

Thanks for the advice everyone, I can use it for sure.  I just bought the chain and the rubber rollers on ebay, so they should be here in not too long.  Also on www.davidsilverspares.co.uk I can get the oil seals and gaskets for a little over $60 or so.  I may be inexperienced, but chewed up rubber and lack of oil flow like Mark is talking about is no bueno.  I won't be running this bike any time soon.

And like you said Bill, I'm for sure glad it's a 350 not a 750   I also have a 1966(ish) Suzuki 120cc B105P that I'm working on with a buddy who knows more.  We have the engine out of that sitting in his garage right now, so that should be a good warm up for this one!  I'm keeping this guy at my house so should get some good experience out of it!

I do have the Clymer manual for this bike, sure is handy.

Thanks for all the help!

[Bill Vaughan]

One last suggestion:  David Silver Spares is a great parts source, particularly for out of production NOS items, but they are located in the UK.  Between the exchange rate and shipping charges, parts can be expensive.  You might do better on price with one of the following domestic dealers:

www.servicehonda.com

www.babbittsonline.com

www.westernhillshonda.com

They all have exploded parts views/lists on their websites.

[schmors]

Thanks for the links!  I've had good luck with the davidsilver, but if I can find it cheaper and in the US, even better.  On the western hills one, is it an actual site or just a search thing? Click on the link and look..  Thanks again Bill!

[Bill Vaughan]

Forgot that they changed their site address:

www.westernhillshondayamaha.com

[schmors]

There we go. That looks much better.
I emailed service Honda and they no longer make the gasket set or seals, so I guess that one's out. So we shall see.

I started taking the bike apart today.  Just took of the seat, tank, exhaust, loosened some bolts and such.  Think I'm going to paint her while I'm at it. My buddy works for a custom hot rod paint/body shop, so I can have a professional job for the cost of materials.  Should be pretty awesome.  Anyway, wish me luck pulling that engine.

[mark]

Most of the seals and some of the gaskets are still available separately from Honda.

I ended up with aftermarket stuff anyway.

You should be able to find a factory manual here.

Good luck.

[schmors]

Ah you are awesome Mark! Thanks a lot, that should be really helpful!

[schmors]

Well, I have the engine out, head and cylinder off. The tensioner is off, but is the only way I can get the cam chain out by splitting the case and slidding it of the crankshaft? Thats a pain. The chain doesn't look bad, but can you really tell if the chain is bad?? The rubber rollers were for sure and the braket with the rollers in it was worn on one side like the chain was rubbing on it.

It was easier than I thought pulling it out and apart as far as I am now. What should I do with it like this? I scrapped the carbon off the pison heads with a screwdriver. Now just wait till the gaskets come in the mail and put it back together?

[Bill Vaughan]

If there is any evidence that the chain was rubbing against anything, it should be replaced.  While some Honda cam chains, like that of the 450, used a joint link (master link of sorts), I don't believe that the 350 was one of them.  That said, you'll need to split the cases for removal.  Not a bad job as long as you have a manual. 

You could replace the tensioner parts, chain and put it back together with new gaskets and seals, but you've probably had bits of metal and plastic running through the lubrication system for quite some time.  You'd be best served performing a thorough cleaning and checking everything against spec.  Some parts, like valves seals, are likely bad due to age alone.  Again, follow the disassembly/inspection procedures in the factory manual.  They'll guide you through the process.

[schmors]

Yeah the chain was definitely rubbing on the bracket, so I'll be replacing it. And ya, it is an endless chain. I guess you don't have to worry about it coming apart in the engine, but a rivet or masterlink would have been nice if you ask me.
What would you say to be the best way to throughly clean the motor and get all the junk off of everything, and make it look pretty?

Oh, and the valve seals, do I have to take the valves off to check that or? Thanks for having patients with a noob like me, you've all be very helpful!

[tbpmusic]

350's don't have valve seals,

bill2

[schmors]

350's don't have valve seals,

bill2

Sounds good to me  Thanks

[tbpmusic]

350's don't have valve seals,

bill2

Sounds good to me  Thanks

Go here, you can get a gasket kit. This is a good supplier, I use and trust them.

http://www.crc2onlinecatalog.com/Index_Main_Frame.htm

bill2

[schmors]

Thanks Bill, butt I already got the gaskets and oil seals. Ended up being around $55 for the oil and gasket sets including shipping from http://www.davidsilverspares.co.uk/ which was the best price I found despite them being in the UK.  The dealer sites didn't have them either cause they don't make the sets anymore, so these are after market. I'll save that link for sure. Thank you