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Messages - Erwin83

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136
Project Board / Re: CB350f (400) - big bore time
« on: November 11, 2019, 02:21:35 PM »
While I am getting bored, waiting for the cylinders to get bored, (see what I did there... haHAA), a good moment to revamp my cylinder head.

A question about the valves:

First of all, off course I've kept valves very neatly ordered per cylinder.
Next, I've cleaned the valves with the wire brush (brass) and cloth, and the seats as well. Next I cleaned the set (valve and seat) by adding a light rubbing cleaning compound (just household cleaning, this stuff is way too light to actually cut any metal) to the valve and turning the valve in the seat (using a drop of machine oil and a rubber hose on the stem to connect to a drill.
Result is a clean valve seat and uhmm. bum (?). the part that hits the seat at least.

Next, I've checked for leaks by dropping the valves back in the head, and filling the combustion chamber with fuel.
To my surprise, 4/8 are (slowly) leaking fuel. 2 exhaust valves and 2 intake valves.

Is this to be expected? After all, the valves are only closed by gravity, and gravity doesn't affect these teeny tiny valves very much.
Before putting in the time and effort of installing the springs to double check, I'd love to hear from your experiences.

thanks in advance.

(picture is obviously of before the cleaning, there is quite some carbon build-up on the exhaust valves).

137
Project Board / Re: CB350f (400) - big bore time
« on: November 08, 2019, 03:48:53 PM »
Thanks for the responses.
I need to correct myself. The supplier (Forseti), didnt say they are the same material, they said they have no specific advice, which I interpreted to “follow honda spec”.

My machinist also had a good look. At first he wasn’t happy that it was “cheap internet stuff”, instead of Mahle or whatever top notch brand he usually gets to work with, but upon inspection, he was happy with what he saw, quality wise. Size wise it’s a different story. His smallest size is 50mm bore. So only 1 mm under the 400 bore size, and sleave lenght he prefers a minimum of 100mm. The 400 sleave is around 90mm. But he could work with it.

At least, they are not forged pistons, which for him means using the normal manufacturer specs.
We also discussed the thin sleaves after boring and I mentioned that too tight of a fit would potentially cause heat issues. He agreed and told me to leave it to him. Which I intend to do. This machinist has litterally decades of experience. It’s one of those old fashioned shops, with no reception. Walk through the door and you stand right between the heavy machinery. I trust him to make it work.

Once done, I’ll ask or measure what the actual clearance has become and report back to you all.

138
Project Board / Re: CB350f (400) - big bore time
« on: November 07, 2019, 09:27:44 AM »
Baked this cake yesterday. It came out all black...

Got a response from Australia that there is no specific clearance advice. The pistons are of the same material as standard.

I dropped the kit off at a machinist this morning. He was confident he'd deliver a good fit based on the Honda specs.

Keen to see the result  8)

139
Project Board / Re: CB350f (400) - big bore time
« on: November 01, 2019, 02:25:14 PM »
Ok, well you certainly triggered me to do some more research before I tell the machinist what bore diameter I want.

140
Project Board / Re: CB350f (400) - big bore time
« on: November 01, 2019, 01:57:18 PM »
sorry, 54,50 piston 54,54 cylinders  :P

141
Project Board / Re: CB350f (400) - big bore time
« on: November 01, 2019, 01:37:02 PM »
now, please correct me if I'm wrong, but I read cylinder size upon fresh install: 51,00-50,01. Piston diameter 50,97-50,99.
So 0,01-0,04 mm clearance.

I agree that temperature is more critical with less liner material. So (should no advice come with this kit), would the upper limit of the installation spec be the best way forward?
that would mean 54,50 pistons, 54,54 cylinders (EDITED).

142
Project Board / Re: CB350f (400) - big bore time
« on: November 01, 2019, 01:26:08 PM »
Found the info for the 400:

143
Project Board / Re: CB350f (400) - big bore time
« on: November 01, 2019, 12:25:32 PM »
There is no specific installation manual provided for this. I just emailed the people in Australia to find out if they specify anything other than standard.

Standard assembly clearance (as I understand from the service manual: 0,01-0,04 mm piston-cylinder clearance.
Ring gaps 0,1-0,3 mm.

144
Project Board / Re: CB350f (400) - big bore time
« on: November 01, 2019, 08:11:53 AM »
Well, that escalated quickly:

Apart from finding 2 broken piston rings, sticking oil-scrape rings, 2 hardly torqued down head nuts (the ones in the sparkplug hole), no mayor problems found (yet).

Now, I'll be on the look-out for a company who can bore the cylinders to 54,5+ mm (anyone know the piston clearance and ring gap specs on these?), and in the meantime, I will focus on refurbishing the head.

145
It's been a while since my last update.

After losing 2 cylinders (capacitor blew up) during the last few km's of the Distinguished Gentleman's Ride in 2018, I added one more mod to the CB350 (with 400 engine): Electronic ignition unit.
Ever since, the bike has been running great, though starting to leak more and more oil from valve cover seals and head gasket (O-rings). Up to the point that it wasn't just a drop anymore, and my left shoe got wet.
So, I decided to make the CB my winter project again for season 19-20. Last winter I restored and customized a 1978 Guzzi V35 to a Scrambler, so was in need of new work anyways.

Coming up:
- New cylinder base gasket, new head gasket, new valvecover gasket, etc..
- And whilst everything needs to be taken apart anyways: I ordered a 466 big bore kit from Australia 8). I've been wanting to do such a job for a while and took the chance now.

- Also (already done): new stem bearings and new wheel bearings are installed.
- New throttle cables have been ordered (I was riding with just a pull-cable for the last decade or so)
- New instrument cables have been order. Shorter ones to match better with my set-up: 60cm rpm (of a Honda CB360 G5) and 80cm speedo (of a Honda CB50-J)

I'm just about ready to start pulling the engine apart and will post update every so often.


146
CB350/400 / Re: Tapered bearings leaving little thread for the head top
« on: October 30, 2019, 12:39:41 PM »
Just installed new bearings on my 350f (All-balls kit) last weekend, and this link was very very helpful. Thanks for sharing!

I used the smaller spacer (of the 2 options) at the bottom after measurement of the bearing, spacer and seal stack as described in the link.
At the top, I was able to use the seal, spacer (as All-balls manual describes) and top nut with the curved down cover attached.
Agreed, there is much less thread left than originally, but still a comfortable 1,5-2 full turns. Enough to properly tighten it down.

147
CB350/400 / Re: 400-4 Clutch slip when cold
« on: March 16, 2018, 09:50:48 AM »
Hi,
    Try searching out a set of "race" clutch springs, the standard clutch will handle a yoshi 460cc with road/ track cam fitted, or question the   new friction plate qualities.

Hi. I fitted the "heavy duty" version of Gecko springs and (by feel) checked the compression force on the new springs versus the old. It really seemed quite OK.

So assuming this is all in order, is there another possible thing I'm missing?

148
CB350/400 / Re: 400-4 Clutch slip when cold
« on: March 16, 2018, 08:50:09 AM »
Would adding another steel plate just increase the preloaded pack size?

Have you any way of checking spring length/rate? As all other thing's being equal, then spring loading will control the clamping pressure.

Yes, it's a fairly safe way of increasing preload. Another method is adding rings under the springs. I added rings on my Aprilia Falco after having modded the clutch basket to counter slip...

I installed a new Gecko clutch last spring, with new Gecko clutch springs as well...

I'm a bit lost why I would need more preload, other than I could imagine the steel plates being worn a little... Or maybe something wrong in the clutch lever mechanism integrated in the right cover?

149
CB350/400 / Re: 400-4 Clutch slip when cold
« on: March 14, 2018, 09:08:20 AM »
thanks for the responses!

I changed so many parts on the bike last year that I forgot, but the friction set is a new one, by Gecko. I also changed the clutch springs.

The 10w40 mineral oil is the right spec, so i'm now thinking about adding another steel plate (basket-steel-steel-friction-steel-fric..etc).
If I remember correctly, this is also how I took this 400 clutch apart, although I'd still like to understand why a clutch, with everything in spec, can still slip.

150
CB350/400 / 400-4 Clutch slip when cold
« on: March 12, 2018, 09:36:55 AM »
Hi fellows,
looking for some advice. My 400-4 has a lot of clutch slip when the engine and oil are cold.
When warmed up, everything is fine.

I'm running Bel Rays 10w40 mineral oil, and the clutch isnt worn out.

In what direction should I be looking for a solution?

The fact that the slip disappears when all is warm, is just opposite of what I would expect...

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