Topic: Suddenly cutting out & surging during long trip

[RAFster122s]

A lot or carnage with a light dive in...I would not feel comfortable or confidant in the motor without a full teardown.
Appears she was abused or sorely neglected for a long time.

[HondaMan]

I have washed out debris before (when college kid in similar situation couldn't afford a teardown) by opening the nice, large oil drain plug and pouring kerosene (about 2 quarts, one pint at a time) into the oil-add hole while the plug was open, then examined the grits coming out. I did it 1 pint at a time so I would have 4 "tries" at it, and by the 3rd time it was pretty clean. That one's tensioner slipper was in better condition than yours, though! Afterward I used straight 30W oil for 100 miles and then went back to the 10-40W Castrol. That one had a chunked-out roller like yours and the slipper was worn to the steel in the front and it got new ones, but he went on 2 years to graduate with the same bike, so I guess it was "fixed" enough?

[grcamna2]

I've seen aftermarket steel replacement rollers on Ebay before:I believe they're sold as a set.

[RAFster122s]

Definitely must clean the oil pump intake screen

[maxheadflow]

Anyone have experience with 350s and have a thought whether I should split the cases or not?I really would rather not lol.

I've done a few but it was 50 years ago. I remember them being pretty easy.  I would split the cases just to clean out the crap and toss on a new cam chain. Just have to make sure all the pins or rings on the bearings are seated properly before assembly.  Use a good case sealer. Torque to spec. If you have any case bolts sticking, use a little heat and penetrant. If a bolt comes out hard work it back and forth until it loosens.

[jakec]

Unfortunately the abuse is all my fault. I was using a CB250/350 manual from 1968 and it says the cam chain tensioner is hydraulic operation. So even though I was doing scheduled maintenance I was skipping the tensioner every time. It is pretty obvious in retrospect that you can adjust it at the back of the cylinders, but I didn't think about it. So that's about 8k miles without adjusting the tensioner. LOL

I guess I will split the cases cause I do want to replace the cam chain tensioner. I just don't want to have the rebuild snowball in time and money. I really just want to put it back together in a stock condition and go back to riding. I did watch a couple videos and it does seem way easier than the other engine I have rebuild which was a 400F.

[HondaMan]

Unfortunately the abuse is all my fault. I was using a CB250/350 manual from 1968 and it says the cam chain tensioner is hydraulic operation. So even though I was doing scheduled maintenance I was skipping the tensioner every time.

There must have been one old engineer at Honda who kept thinking that gadget was a good idea. I wonder if his last name was Dracula-san?

It first came out in about 1965 (I can't remember the bike, it was a single) and failed: Honda quietly sent out replacement tensioners and told everyone to install them for free, or on new bikes.

Then in 1968 it re-debuted on the CB350 twin. It failed there, too, and we did the same dance.

Then it appeared AGAIN on the CB350F! It failed there, too, in less than 1000 miles, typically. I think the first road test I read of the bike had a noisy tensioner, which the dealer changed for the magazine even before the test rider was done with it! I replaced several of those myself.

I don't know if it ever came back to life again...

[maxheadflow]

Unfortunately the abuse is all my fault. I was using a CB250/350 manual from 1968 and it says the cam chain tensioner is hydraulic operation. So even though I was doing scheduled maintenance I was skipping the tensioner every time.

There must have been one old engineer at Honda who kept thinking that gadget was a good idea. I wonder if his last name was Dracula-san?

It first came out in about 1965 (I can't remember the bike, it was a single) and failed: Honda quietly sent out replacement tensioners and told everyone to install them for free, or on new bikes.

Then in 1968 it re-debuted on the CB350 twin. It failed there, too, and we did the same dance.

Then it appeared AGAIN on the CB350F! It failed there, too, in less than 1000 miles, typically. I think the first road test I read of the bike had a noisy tensioner, which the dealer changed for the magazine even before the test rider was done with it! I replaced several of those myself.

I don't know if it ever came back to life again...

  Interesting that it failed on the CB350f.  I did not see one when they came out but would expect that it could have worked. The problem with the singles and CB350 twins was that they had a plunder type oil pump. Pressure was never constant in the system and was low. I would think that the CB350f with the gerotor higher pressure pump would work well if designed reasonable. 

Add: The singles seemed to have gerotor or gear drive pumps but were still low pressure.. 

[jakec]

What should I use to wash plastic and metal debris out of the transmission? I have an ultrasonic cleaner so that is my first thought, but then I need to clean all the water off. Should I ultra sonic and then soak in solvent? Or just solvent?

No damage found to the lower end, just lots of plastic. It's amazing how simple this engine is compared to a 4... I love it

[RAFster122s]

Times like those a parts washer tank would be very handy...

[jakec]

I dropped it at the machine shop and they said to come back with 0.5 over pistons and 4 new valves so that's the plan. Ordering some other new parts as well like full new chain tensioner and chain, gaskets, etc. Need to test my starter motor to see if the problem was the motor or the clutch. Clutch seemed to work fine when I removed the rotor last week.