Author Topic: CB466f  (Read 20940 times)

Offline Erwin83

  • SOHC Member
  • Posts: 228
    • View Profile
Re: CB350f (400) - big bore time
« Reply #45 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.
CB466f - KTM 1190 advR

Offline Erwin83

  • SOHC Member
  • Posts: 228
    • View Profile
Re: CB350f (400) - big bore time
« Reply #46 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).
« Last Edit: November 11, 2019, 02:24:03 PM by Erwin83 »
CB466f - KTM 1190 advR

Offline taysidedragon

  • SOHC Master
  • Posts: 1318
    • View Profile
Re: CB350f (400) - big bore time
« Reply #47 on: November 11, 2019, 02:26:54 PM »
Use valve grinding paste to get a good seal. I've always done mine by hand by rotating back and forth, never used a drill.
Gareth

1977 CB400F
1965 T100SS

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
  • Grogu
  • *
  • Posts: 8206
    • View Profile
Re: CB350f (400) - big bore time
« Reply #48 on: November 11, 2019, 02:33:05 PM »
You are doing the leak down test the wrong way round. You need to put the fuel in the inlet and outlet ports, with the springs on, as it is the springs that close the valves, not gravity, and then observe for leaks. And you need proper valve grinding paste to do the lapping in.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Erwin83

  • SOHC Member
  • Posts: 228
    • View Profile
Re: CB350f (400) - big bore time
« Reply #49 on: November 11, 2019, 03:01:38 PM »
OK, so you would advice cutting/lapping the valve anyways (now that we're here)?
Obviously, I was only cleaning so far. The engine ran well, and there were no signs of leaking or burned valves. (the old 'if it aint broken, don't fix it' idea)

I guess that you're also saying that installing the springs and applying pressure to the seal, the results of the leak-down tests may differ.
I don't see the difference (technically) between adding the fuel in the ports, against in the combustion room. Apart from the the latter is less messy...
CB466f - KTM 1190 advR

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
  • Grogu
  • *
  • Posts: 8206
    • View Profile
Re: CB350f (400) - big bore time
« Reply #50 on: November 11, 2019, 04:11:36 PM »
Yes, fit the springs and you may not have a leak. If the bike was running fine before you took it apart, just lapping in will  be OK I'm sure. I'm also assuming you don't have the correct equipment to grind the valve seats and re face the valves anyway. 
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Erwin83

  • SOHC Member
  • Posts: 228
    • View Profile
Re: CB350f (400) - big bore time
« Reply #51 on: November 11, 2019, 04:40:29 PM »
I certainly don't. Completely resurfacing the valves and seats would be a machinist job for sure.

Just to be more sure and don't run the risk of screwing up my one bigbore head gasket, I just ordered a can of Chemico valve cutting paste and one of those suction-thingies-on-a-wooden-stick. Hope the smallest one will fit the exhaust valves.

The valve lapping should be a bit better with that, and I'll be doing a leak-test with the valves in place to check results afterwards.


Thanks for the advice once again.
CB466f - KTM 1190 advR

Offline Moorey

  • SOHC Master
  • Posts: 1666
    • View Profile
Re: CB350f (400) - big bore time
« Reply #52 on: November 11, 2019, 04:52:16 PM »
I always do valves with a drill if i can get one on. It takes a fraction of the time. Valve grinding suckers must be one of the most frustrating tools in the box.

Offline paul G

  • SOHC Master
  • Posts: 1748
  • No room left in the garage what now !
    • View Profile
Re: CB350f (400) - big bore time
« Reply #53 on: November 11, 2019, 04:55:44 PM »
Get yourself some velcro with adhesive on both sides stick it to the valve  and sucker or that rubber sucker will drive you mad  :o :o :o
Honda CB400 4
Honda CB550 K3 (sold)
Honda CB750 UK K1
Kawasaki Z650 C2
Kawasaki Z650 cafe racer (Sold)
Honda CD175 sloper

Offline Erwin83

  • SOHC Member
  • Posts: 228
    • View Profile
Re: CB350f (400) - big bore time
« Reply #54 on: November 11, 2019, 07:30:06 PM »
Great advice gents.
The sucker was only 7,50 euro. So if frustrates me, even with some double sided tape to help, it will end up somewhere in the garden.

I got one of those tap wrenches! Might give that a try as well.
With the household cleaning agent, I used a fuel pipe on the valve stem and on a bit- holder.
The only downside is/was that any pressure has to come from the combustion chamber side, press too hard and the fuel line will slip.

Once my chemico paste is in, i’ll pick this back up.
« Last Edit: November 11, 2019, 07:32:21 PM by Erwin83 »
CB466f - KTM 1190 advR

Offline MCTID

  • SOHC Pro
  • Posts: 608
    • View Profile
Re: CB350f (400) - big bore time
« Reply #55 on: November 11, 2019, 08:00:52 PM »
Stick the Valve in an electric drill (cordless or mains) with a light spring behind it (between the valve guide and the reverse head of the valve) and 'Bobs yer Uncle' - done in no time and with minimal effort.
Now: 2008 CB1300S, CB750K4, 1970 Bonneville. Various other 1960's 650 Triumph T120's/ TR6's/ TR6C's (all in bits...many, many bits unfortunately). Previous: 2007 CB600FA, 1976 CB500 Four. BMW F800ST. GS750E. ZZR1100. CB1300 (2). ZXR1200S. VFR800. CB750 Nighthawk. CX500. XS500 Yam. Suzuki GT500. BSA A10. Various Lambrettas. Zundapp Bella (honest).

Offline K2-K6

  • Grogu
  • *
  • Posts: 5234
    • View Profile
Re: CB350f (400) - big bore time
« Reply #56 on: November 11, 2019, 09:08:01 PM »
I was taught when in training never to use an electric drill as it could ruin the valve face, long time ago now but I think it was due to the speed it went at and how it was easy to cut too much off as a result. Might be wrong but eleccy drill was a big no no back in the day

Same here,  taught that to run it continuous in one direction risked putting "tram tracks" in both components as the cutting particals weren't moved out of line. 
Method taught was oscillations with a lift out occasionally to redistribute the cut, resulting in smooth lapped surface.

You could get those drill driven oscillating gearbox with sucker on then to convert drill rotation into the right movement to facilitate if you had a lot to complete too.

Offline paul G

  • SOHC Master
  • Posts: 1748
  • No room left in the garage what now !
    • View Profile
Re: CB350f (400) - big bore time
« Reply #57 on: November 12, 2019, 08:07:22 AM »
I was taught when in training never to use an electric drill as it could ruin the valve face, long time ago now but I think it was due to the speed it went at and how it was easy to cut too much off as a result. Might be wrong but eleccy drill was a big no no back in the day

Same here,  taught that to run it continuous in one direction risked putting "tram tracks" in both components as the cutting particals weren't moved out of line. 
Method taught was oscillations with a lift out occasionally to redistribute the cut, resulting in smooth lapped surface.

You could get those drill driven oscillating gearbox with sucker on then to convert drill rotation into the right movement to facilitate if you had a lot to complete too.

This is what I use but the velcro still needed  ;D
Honda CB400 4
Honda CB550 K3 (sold)
Honda CB750 UK K1
Kawasaki Z650 C2
Kawasaki Z650 cafe racer (Sold)
Honda CD175 sloper

Offline Trigger

  • Grogu
  • *
  • Posts: 8434
  • Engines built on reputation, not advertising.
    • View Profile
Re: CB350f (400) - big bore time
« Reply #58 on: November 12, 2019, 09:31:56 AM »
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).

Was the wire brush you used Brass or steel that is copper colour ? If it is steel then you may have damaged the faces. Easy way to clean valves is drop them in thinners for 24hr and the carbon will wipe off.

Lapping in valves is a final process after you are sure the seats have no pitting and the valve face is good and the valve is not bent. If a valve doesn't lap in after the first grind ( a minute ) then something is wong. A valve can appear to be seated on a leak test but, turn the valve 90, 180 degrees and it could leak.

I re grind the seats and re face the valves and it will only take me a couple of minutes to lap in as, I already have a good matching surfaces.

Offline Erwin83

  • SOHC Member
  • Posts: 228
    • View Profile
Re: CB350f (400) - big bore time
« Reply #59 on: November 12, 2019, 10:24:31 PM »
They're brass. Nothing got damaged fortunately.
CB466f - KTM 1190 advR

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal