Author Topic: My CB350 has died. So close and yet so far.....  (Read 4297 times)

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Offline Raul CB750K1

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My CB350 has died. So close and yet so far.....
« on: June 22, 2008, 07:32:01 AM »
Next month it will be three years since I bought it as a resto project. I have gone through every single washer on that bike. Have it painted. New seals, pistons, rings, valves refaced etc. I even had to endure all the red tape to register it in the spanish DMV.

I even dismantled the clocks to paint the cases and put the odometer at 0. Didn't want to plug the tacho cable until the bike was road-ready, to start counting from it. I took it running to the DMV station and everywhere, and got the plates a couple of weeks ago. Did a couple of outings with it, everything was fine but that annoying front weave.


Today it was a classic bike rally, so I thought it was a good chance to make it first "public appearance". I received a lot of compliments. The rally started, and about 16 miles the bike starts to stutter and stops. "Big deal", said to myself. This annoying carb that refuses to work. I will remove the filter and make it suck. The organization' van offered to load the bike. "No thanks, it will either run or I will call roadside assistance and go back home". Then i notice the choke was on for no apparent reason. Put it off, and it starts right away!!. Time to make for lost time, the guy in the back of the rally was waiting for me, we hurry to meet the rest of the group. Three friends from the Sanglas club had been waiting for me until I told them not to wait, it was pointless that they miss the group.

So we meet the group that was waiting a couple miles away. We are ready to start again and suddenly my bike does something like "THUMP" and dies. I new this time it was something more serious. The kickstart was frozen, and the starter motor didn't even spin. The guys in the van, with a grin, tell me to swallow my pride and load the bike. I knew the rally was done for me, but even worst, the bike had something serious. I thanked the guys in the van but told them I would call roadside assistance, this time it couldn't be fixed at the roadside.

Removed a plug and it had compression, as now the kickstarter worked. But there was no spark. My friend tells me it is an electrical problem. I told him it was not. Just by opening the point's cover I could see the camshaft didn't rotate when I kickstarted it. Prognosis? Broken camchain or loose camchain sprocket. And the clock it still showing 0 km...... How can a bike die even before it is born?

Camchain was new, but aftermarket. I rather have a broken camchain than a loose sprocket. Why? Because I KNEW that it was important that the sprocket bolts be tight, and I thoroughfully cleaned them, used the strongest loctite there was and tightened them. If the bolts came loose after that, I cant' think of another way to tighten them.

In any case, the engine must be removed, and I don't feel like doing it again now. I'm afraid this bike will have to wait at least one year until I finish my other two bikes.


You know the only good thing about it? The guys in the van told me it was a pity: they all had agreed that my bike deserved the "best restoration" trophy. Unfortunately, it went to somebody else, but at least it made my work worthwile....

jsaab2748

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Re: My CB350 has died. So close and yet so far.....
« Reply #1 on: June 22, 2008, 08:31:39 AM »
I don't know if this will help you, but I have seen/had a 350 twin that had the cam chain adjuster lock bolt strip out. The adjuster then allows constant movement of the plunger while the engine is running. Eventually, the cam chain jumped time, and valves hit the pistons.
Maybe yours only skipped a tooth or two? My sl 350 bent valves when it happened. Hope you have better luck than I did >:(

Offline kghost

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Re: My CB350 has died. So close and yet so far.....
« Reply #2 on: June 22, 2008, 09:22:50 AM »
Que Mal Suerte Amigo.

That really sucks Raul sorry to hear.  :'(
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Offline Raul CB750K1

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Re: My CB350 has died. So close and yet so far.....
« Reply #3 on: June 22, 2008, 12:47:03 PM »
Que Mal Suerte Amigo.

That really sucks Raul sorry to hear.  :'(

It sucks big time. Specially the feeling of failure. I have done everything myself, and I have been very conscietous. But it seems I have failed somewhere.


Guess the annoyance of removing and repairing the engine will become a -expensive- lesson to be learnt.

Offline kghost

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Re: My CB350 has died. So close and yet so far.....
« Reply #4 on: June 22, 2008, 04:28:36 PM »
Ah yes.....but you'll be an expert when your done....

People will seek you out...

Women will swoon.  ;)
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Offline Johnie

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Re: My CB350 has died. So close and yet so far.....
« Reply #5 on: June 22, 2008, 06:09:55 PM »
Yah Man, that is the pits for sure.  I can not fathom spending that much time and be so up for the bike show - then have that happen.  Well, just look forward to next year.  It will happen and all this will be behind you.  And yes, you will even be more of an expert!!!  Best of luck to you and that 350...
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Offline DarkRider

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Re: My CB350 has died. So close and yet so far.....
« Reply #6 on: June 22, 2008, 07:15:06 PM »
Patience Grasshopper...your time at being a Master of the 350 will come..
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Offline bryanj

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Re: My CB350 has died. So close and yet so far.....
« Reply #7 on: June 22, 2008, 09:41:06 PM »
Raul, Before you condem the camchain is it just the auto advance not rotating, i seem to remember that the tiny drive pin would give trouble sometimes---hope it is cos thats an easy fix
Hang in there mate
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Offline Raul CB750K1

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Re: My CB350 has died. So close and yet so far.....
« Reply #8 on: June 23, 2008, 12:14:55 AM »
Raul, Before you condem the camchain is it just the auto advance not rotating, i seem to remember that the tiny drive pin would give trouble sometimes---hope it is cos thats an easy fix
Hang in there mate

For a moment you gave me some hope, but come to think of it, not even the auto advance retaining bolt was turning. That bolt is bolted to the camshaft itself.

Offline bryanj

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Re: My CB350 has died. So close and yet so far.....
« Reply #9 on: June 23, 2008, 06:44:58 AM »
Sorry mate, i tried, commence the inspection slowly and methodically, I'm sure that any problem is a bad part not your workmanship as youve shown me/us most of it and you are meticulous.

I seem to remember that i once got the top plate off without taking engine out just to look, doesnt help much as to go any farther it has to come out
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Raul CB750K1

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Re: My CB350 has died. So close and yet so far.....
« Reply #10 on: June 23, 2008, 07:32:49 AM »
Sorry mate, i tried, commence the inspection slowly and methodically, I'm sure that any problem is a bad part not your workmanship as youve shown me/us most of it and you are meticulous.

I seem to remember that i once got the top plate off without taking engine out just to look, doesnt help much as to go any farther it has to come out

"Meticulous" That was the word I was looking for in my brain when I wrote "conscietous". Don't know if they are synonyms but I meant "meticulous".

I too took the plate out before removing the engine when I bough the bike. That should be enough to see whether it is a broken camchain or a loose camshaft sprocket.

But there is something, even before opening the engine, that got me startled. First, the kicstarter was frozen. And by clicking the starter engine I could hear the relay clicking but the engine didn't spin. That seemed like a broken camchain stuck in the crankshaft sprocket.

Put it into gear and rocked the bike back and forth. Then the kicstarter loosened, but by kicking it it was much weak than ever. First I blamed on the gearbox not engaging the crankshaft. I removed a plug -the engine was hot- but I could feel the air going out when kickstarting it. My friend touched the spark body against the engine and that's when he diagnosed no ignition - but I knew it was something more serious, so I removed the points cover and didn't see the camshaft turning. This would make perfect sense: broken camchain, tangled in the crankshaft sprocket, that falls in the oil pan, the crankshaft turns and the kickstarter is weak because it doesn't have to overcome the valve springs.

But then, why would the starter motor remain frozen?

I have always been very keen of quality and "measuring twice to cut once". Haven't cut any corner with this bike, and haven't done any work if I was not 100% confident it was well done. That's why it would piss me off big time it I commited some blunder, but hey, I'm human after all.

One thing is clear: I will take this bike from the ashes and on the road again, whatever it takes.

Offline bryanj

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Re: My CB350 has died. So close and yet so far.....
« Reply #11 on: June 23, 2008, 09:26:33 AM »
Unfortunately Raul there will be bent valves but no way of knowing how many.

Engine would lock if camchain broke and fell into crank gear then rolling backwards could easily loosen it to fall into the sump so that kickstart would turn it again.

From what you have said i would suspect  a chain more than a loose sprocket and that would suggest a faulty chain, can you remember what make and where it came from?
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Offline Raul CB750K1

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Re: My CB350 has died. So close and yet so far.....
« Reply #12 on: June 23, 2008, 01:25:34 PM »
As always, you are spot on Bryan. The camchain snapped.


This afternoon I removed the alternator cover. By kickstarting the bike, the rotor turned, but not the camshaft. Tried again the starter motor, and seemed locked. But wait a minute, the light seems dim.... the battery was flat. Remember the thread I opened about the battery draining with the H4? I thought it was fixed after I found the lamp was a 90W unit but seems that the battery was flat. Jumpstarted the bike with a car battery and the starter motor spun the crankshaft with ease.

Removed the spark plugs, and by closing the gap with my thumb, there was suck and blow in both cylinders. Good news, seems that the valves are closed. With a torch -flashlight- I could barely see there was no damage to the pistons, only carbon. Opened a rocker inspection cover and saw that it didn't rock when the starter motor cranked.

So I emptied the carb bowls in order to let the bike sit for some months until I'm done with my Sanglas bikes, when I notice the camchain tensioner. Can't wait until the engine is out to know what happened. Removed the tensioner, and with an inspection mirror, I could see one end of the camchain hangin, and the other side of the chain in the front end of the engine. It is the only consolation I had: it was a chain failure, not an installation failure.

Remember I told you I didn't cut corners? In fact I did. Honda chain had a price tag about 70 euros. siriusconinc in eBay had a non-OEM chain at $20. I genuinely believed there should be not much difference in a chain. I refused to reuse the original one, even when it looked fine and it was only about 10.000 km. Now I will have to pay tenfold in sweat what I saved in money, and will have to buy the Honda camchain after all. And all this praying that the valves were closed when the camchain snapped.

But, come to think of it, how come that one of the camchain ends is at the rear? If the chain snapped at the rear, the crankshaft should have turned the camshaft, if only with the tight side, until the chain left the camshaft sprocket if you catch my drift. Unless I was lucky enough that the camchain snapped right at the crankshaft sprocket, in such a way that the crankshaft pulled the chain until it just tangled and the crankshaft stopped dead, and with the same luck, the valves were closed in that exact moment.


Well, live and learn. I think it won't be before october or november that I will have the time to tackle this rebuild. Lesson learned: BUY OEM!!!!!

Offline bryanj

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Re: My CB350 has died. So close and yet so far.....
« Reply #13 on: June 25, 2008, 05:40:33 AM »
Raul, I think you just had a bad chain, Honda normaly use DID chain so just get one of those, dont have to be Honda. Mr Silver seems to have lots of parts so try him i would offfer to be postbox but that would mean double shipping charge and he dont rip you off on that anyway.

Any help i can be please ask
Bryan
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Offline Green550F

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Re: My CB350 has died. So close and yet so far.....
« Reply #14 on: June 26, 2008, 06:19:31 PM »
Did you use the origional bolts on the cam sprocket?(they are high strength bolts)
I sheared one and am still looking for suitable replacements.
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Offline bryanj

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Re: My CB350 has died. So close and yet so far.....
« Reply #15 on: June 27, 2008, 02:40:42 AM »
Raul, I just posted the following in a different post, may be of help when you are searching. concerning cam sprocket bolts
Regards Bryan

These bolts:-

90081-312-000 is listed as "knock bolt" and is the same bolt as that securing the tensioner "horseshoe" to the crankcases on a 350/400 four---Also NOT listed as discontinued but maybe NONTHELESS there are enough 350/400 fours out there to rob.

90085-312-000 Is listed as discontinued BUT is a simple 6 x 14 High tensile bolt available anywhere.

Now no offence but this took me 5 minutes to find out at

http://www.motogrid.com/pages/parts/viewbybrand/7/default.aspx

A link I have posted MANY times in relation to parts searching
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Raul CB750K1

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Re: My CB350 has died. So close and yet so far.....
« Reply #16 on: June 27, 2008, 03:05:26 AM »
Thanks for the tip Bryan, I will copy it to my personal data file in case I need it in the future, but it was not me asking for the bolts; it was Green550F....  ;D

The sprocket bolts are not the issue. I reused the original ones. Haven't removed the cover but, after seeing the snapped chain, I doubt the bolts came loose.

I remember I wrote about the camshaft bolts a while ago. It is in this thread

http://forums.sohc4.net/index.php?topic=28347.15

Quote
Let me share my experience with CB350 with you guys.

Before I rebuilt the engine I got all the possible info I could, Honda and Haynes manuals, and also several articles from Classic & Motorcycle Mechanics (Glenn have now them all if you are interested). Well, in one of the articles of CMM, they said that the official shop manual was wrong with regard to the camshaft bolts, they should be installed the other way round.

Camshaft bolts, not only are high tensile, but also are different. One is threaded all the way, the other has a "pan", a part of the bolt not threaded from the head. Since I read that I wrote down a mental note to myself: "never forget this when the time comes".

Several months later came the time, and I didn't forget about it, and even when I tried to install the bolts opposite to what the Honda manual said, there was no way. If one went in, the other was out of alignment. I was positive I should be doing something wrong, because if the skilled people at CMM found the mistake and published it, there should be a mistake. But the fact is that it was impossible to install the bolts that way. BUT, if I turned the camshaft sprocket 180º, they would go just fine. The way to know which bolt goes where was that the bolt with the "pan" had to go on the sprocket hole that was not threaded, and vice versa. Seems that the bolts are not 180º apart but a different angle -say 177º-, so if you put them wrong they will never align. That is, Honda designed them in such a way that you can not install them wrong even if you want, that whay the "TOP" mark on the sprocket will set the lobes in the right position.


I don't think there is a position for the advance mechanism. Pistons are 180º apart and so should the lobes on the advance mechanism, so it shouldn't really matter which way it goes in. If memory serves me, there is a slot in the camshaft for the mechanism to go in so there shouldn't be more than one way to install it, but it has been a few months since I did it. I put my mouth -not my money- for crossed coil wires, but considering the experience you have with CB350's, I don't think it is such an obvious mistake.
« Last Edit: June 27, 2008, 03:07:02 AM by Raul CB750K1 »

Offline bryanj

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Re: My CB350 has died. So close and yet so far.....
« Reply #17 on: June 27, 2008, 07:53:26 AM »
No Problem Raul, I hadnt had any sleep for about 26 hours when i posted before! (now had 2 hours) hope the link helps in all your Honda work---they do have a couple of other makes as well on there, i find the cross reference most usefull as it tells me what other used bikes I can go and rob bits off----especially if they are less expensive like 500Twin, you just dont let on at the breakers what the part is for as the price goes up!

I have been thinking about your chain, do you think it was possibly supplied with a "soft" link that had been fitted but not riveted? NOT good practice but just possible and you would naturaly expect an endless chain and fit without looking, I know i would have as all the split chains i have had came with the link seperate.
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Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Raul CB750K1

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Re: My CB350 has died. So close and yet so far.....
« Reply #18 on: June 27, 2008, 03:14:26 PM »
It didn't have a clip pin, that's for sure. I used to take pictures of all the used parts I bought, and I also did a picture of the cam chain besides the old one before assembly. Unfortunately I don't remember which one was the new one, but if memory serves me it was the one below.

The only thing that I can see is something like a rivet in the chain pictured above, but I would say that is the old one....


Offline bryanj

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Re: My CB350 has died. So close and yet so far.....
« Reply #19 on: June 28, 2008, 04:41:38 AM »
Have to wait till you get it out and check mate, its amazing what goea through the mind whilst driving a truck 5-800 Kms a night!
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Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline markjenn

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Re: My CB350 has died. So close and yet so far.....
« Reply #20 on: June 28, 2008, 12:17:22 PM »
Eventually, the cam chain jumped time, and valves hit the pistons.
Maybe yours only skipped a tooth or two? My sl 350 bent valves when it happened. Hope you have better luck than I did >:(

350's are interference engines?  That would be surprising.

To the OP, camchains are about the weakest links in these old engines, especially the tensioners.  Anytime I go into one, I replace everything and us nothing but Honda OEM parts if I can find them.  You'll get this sorted and be back on the road in no time.

- Mark

Offline bryanj

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Re: My CB350 has died. So close and yet so far.....
« Reply #21 on: July 05, 2008, 08:58:27 AM »
Any news yet Raul, and haow did you get on with the Sanglas caliper?
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Raul CB750K1

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Re: My CB350 has died. So close and yet so far.....
« Reply #22 on: July 12, 2008, 02:07:15 PM »
Any news yet Raul, and haow did you get on with the Sanglas caliper?

Thanks for your interest Bryan. I just returned for a 10 day vacation on the beach with the family -hell, I would have never imagined I could have so much fun with my two little kids- and I'm off tomorrow until next friday. No bike work until then.

Regarding the CB350, I have no other remedy than to sidetrack it until I'm done with my Sanglas bikes. Finish the restoration of the 400 thumper, the charging problem on my first 400Y(amaha), and the brake caliper and other issues of my second 400Y(amaha).

I just bought new M6 bleed nipples. They are not the same -the original one is thicker at the top to fit an o-ring- but I think I could make it work as long as I can get the remains of the old one. M6 nipples doesn't seem to be very common, I had a hard time finding them.

Will post on it when I have some news. Now it's time to find left-hand drills -you should see the faces of the hardware store clerks when I ask for that.....-

Offline bryanj

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Re: My CB350 has died. So close and yet so far.....
« Reply #23 on: July 13, 2008, 08:54:42 PM »
Should have asked mate, i got a pack of 5 in my brake parts box, hears an idea tap it out to take the 750 bleed nipple as it has a bigger thread, or a standard car metric one
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Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

jonnycbgood

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Re: My CB350 has died. So close and yet so far.....
« Reply #24 on: July 15, 2008, 03:00:38 AM »
Wow that really sucks I can only imagine what it must be like to work for so long and then have it fail just when you thought you had it.  I have recently started on my own 350f restoration project I am planning on taking a few years to do it and hopefully everything will come together nicely.