CB350F Rusteration

[andy120t]

Oh  - thanks! I haven't seen those on my 650, but will have a look in the daylight to see if they are there too.

[Andych]

You see plenty of cars have valve seals replaced with the head or heads still on. They basically use a leak down tester to pressurise the combustion chamber and they use a fulcrum to compress the valve springs so they can slip in the collets... worth a try... worst that can happen is the valve wont stay up.. then you will need to drop the head off..
Looks to be in really good condition inside though..

[kevski]

Thread a length of rope into the cylinder bore then raise the piston to compress it against the valve bottom, do the job, lower piston, pull rope out, don't forget to leave enough rope hanging out of spark plug hole to retrieve the rope though.

[Moorey]

Its the rope method I have used. Getting the springs and collets off is easy, just put a socket on top and give it a tap and they jump out, getting them back in will be a bit more awkward. 

[kevski]

I thought the early ones did not have stem seals on the exhaust side, i have not been into mine so unable to verify.

[Moorey]

Mine has and I would say its top end has never been opened up before. I have now got a method of getting the collets back in.

[Moorey]

I thought the early ones did not have stem seals on the exhaust side, i have not been into mnine so unable to verify.

The parts book lists 8 for the F. Unless there is some confusion as the first engine number listed is 1068969.
It does say at the beginning of the book.
If there is a production change to a part, the frame or engine number to which this part become effected will be indicated in the " Serial No " column. However, in the case the part is used from the initial serial number, its applicable serial number is not shown.
I read that as it should have them, But could well be wrong . Hopefully someone more au fait with the Honda parts system will enlighten us.

[royhall]

Moorey. This is what I found whilst rebuilding my 350F. There's no real definitive answer on what is correct here, this was the comment a while back:

Some engines (mine included) had stem seals on the exhaust side and some had unsealed guides that are machined to a point to shed the excess oil. According to some on the internet the excessive wear is due to the stem seals on this engine and the lack of oil on the valve stems, and they should have the other type. Many others disagree and say to fit the 400 type with the seal (which as we know should be designed to leak slightly). I even checked the ones on Yamiya's site for the 400 and if you buy the full set they all have seals, if you buy the exhaust guides separately they don't have seals? All the guides on CMS for the 350 are without seals except for the French bikes. This is all a bit weird.I rang CMS with my engine number and they say the non sealed version so that is what I have gone with (even though seals were fitted in my engine). On top of that there are 4 different versions of unsealed guides so I went with the latest version. Just hope it's the right decision as I have fitted them now.

[Moorey]

My guides a machined to accept stem seals, so when the new one comes we shall see if it cures it.
I guess you pays your money and make your choice then. 

I had read your smokey thread and the one on the US forum and then when I saw this bike was a smoker I just thought "Bollocks." We shall see though.

[Moorey]

The new one came just after my last post  the engine is up and running again now and it looks quite promising. I need to get it registered now and take it for a decent run to burn of all the old crap in the pipes. Quite happy with what I see now out of the headers. 

[royhall]

We need to know? How did you get the collets back on. Sounds promising on the smoke front though.

[Moorey]

Quite easy really I used the end off my spring compressor and used a length of timber between that and the frame to compress the springs. A blob of grease on my finger to hold the split collet and just wiped them onto the valve stem, released the spring and Bobs yer uncle.

[Moorey]

Booked it in for Mot in the morning.  Then send the paperwork off to get it registered.

[Moorey]

Passed its Mot, front brakes must be terrible to fail because these are shite. hopefully they will get better when the bed in. I had my first ride on it and it goes like a gud un, just doesn't stop like one. I don't like the exhausts they look too low so I will raise the back end of them by a good couple of inches either by bending or cutting and welding  as they don't need to clear the wheel spindle with the swing arm having open ends.
Just need a V5 and plate now.

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[Nurse Julie]

Brilliant.