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Messages - stoutgoose

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1
CB750 / Re: David Silver Daytona Electronic Ignition Kit
« on: December 29, 2023, 04:29:34 PM »
Thanks all, very much appreciated. I’m validating the wiring diagram I have produced and the 12v supply (oxymoron deleted 🤓) to the electronic ignition was the final piece I was scratching my head over.


2
CB750 / Re: David Silver Daytona Electronic Ignition Kit
« on: December 29, 2023, 04:22:20 AM »
Excellent! Many thanks.
The blue and yellow wires from the ignition plate route to each of the coils; I assume there is a 12v supply running from the kill switch to the other side of each coil?
The reason I ask is that I need to build a loom from scratch for a track bike using a basic wiring circuit. No lights, starter, etc.

3
CB750 / David Silver Daytona Electronic Ignition Kit
« on: December 28, 2023, 07:16:42 PM »
Hello all. Before I go back to Silver’s and ask for clarification, has anyone else fitted the Daytona ignition kit? The reason I ask is that it states in the instructions that on set up, you should connect the black wire to the rear brake switch feed. I’m assuming this is to provide a 12v earthed supply.
However it didn’t state whether this needs to be disconnected and then connected to an earth or something else.
Any ideas?

4
Desperately Seeking!! / Keihin PD41 Float Bowl - CB750 K7 or F2
« on: November 22, 2023, 01:31:05 PM »
I’m looking for a single float bowl, ideally number 3/4, for my 1977 CB750 K7.

Fitted to Keihin PD41 carbs (and possibly others) fitted to the K7 and F2.

Many thanks.


5
CB750 / Re: 1978 CB750 SOHC F2 Sump Capacity
« on: October 31, 2023, 08:10:14 PM »
Many thanks. Any suggestions of stopper seal suppliers?

6
CB750 / 1978 CB750 SOHC F2 Sump Capacity
« on: October 31, 2023, 07:35:17 PM »
I'm wondering if I have a wet-sumping issue.

The bike emits a reasonable puff of oil smoke when revved reasonably hard (over 4000 rpm) on the stand. Friends also mention they can smell oil when trailing me, with a small puff visible, but no oil smoke on overrun.

I rebuilt the engine about 5000 miles ago, which included new valve guides, valves, and valve stem oil seals. The bores were in spec, as were the pistons and ring end gaps, so I honed the barrels but nothing more.

I did not replace the oil return stopper in the oil pump because I couldn't find a seal kit, and now I am beginning to wonder if it is this that could be contributing to the oil smoke.

The oil tank level doesn't deplete significantly, however when I drained the sump today, over 1.5 litres of oil came out from just the sump. I started and ran the bike and then measured the oil level which was now at the bottom of the dipstick, so I added another 1.5 litres and this brought it halfway up the dipstick.

I took the bike for a good blast with some hard acceleration and WOT at times. Back home, the oil level remained at halfway, and when I drained the sump again about 3 hours later, 1.5 litres of oil was again extracted.

Is this a normal amount to be expected to be contained in the sump of a '78 750?

7
CB750 / Re: 1978 CB 750 F2 - Oil pouring from above head gasket
« on: May 22, 2020, 08:56:17 PM »
Many thanks.

8
CB750 / Re: 1978 CB 750 F2 - Oil pouring from above head gasket
« on: May 19, 2020, 09:00:13 AM »
Update to close the thread. I removed the engine and stripped the valve gear to take a look at the studs. I located the copper sealing washers which weren't in the correct place (my manual made no mention of sealing washers and cap nuts). I removed the Kibblewhite nuts on studs 5-8, annealed the sealing washers and put them on studs 5-8 along with the correct cap nuts, and reassembled the bike.

Problem solved. The engine is now leak-free. It is rather surprising just how much oil can find its way down a stud thread and under a standard steel washer.

I'm now off to burn my 'Honda' manual and the Haynes version, and locate a real one. Many thanks for all your replies.


9
CB750 / Re: 1978 CB 750 F2 - Oil pouring from above head gasket
« on: May 10, 2020, 08:10:10 AM »
I used HT Howard in Slough who use equipment that detects the metal type and adjusts the cut accordingly; in this case it accounted for the alloy head and steel liners without the need to remove the liners and the associated work you mention. The cut is excellent.

The original oval fire-ring gasket for the F2 is obsolete from Honda; do Vesrah make the oval type? Anyhow, the cost of the skim was reasonable and with the reduced leak potential promised by the MLS gasket I thought it a good idea, but time will tell.

Thanks for the information.

10
CB750 / Re: 1978 CB 750 F2 - Oil pouring from above head gasket
« on: May 09, 2020, 04:15:02 PM »
Thanks that’s a useful tip; I’ll check the bolt lengths when I get the engine out again.

Out of interest, what’s the issue with decking the block and using a thicker base gasket to compensate? What’s the alternative?
(When I say decked, .006" was taken off to smooth the surface and remove some dinks in order to make a perfect surface for a MLS gasket).

11
CB750 / Re: 1978 CB 750 F2 - Oil pouring from above head gasket
« on: May 09, 2020, 02:45:09 PM »
Thanks all. I performed a complete rebuild on the engine, so it was completely stripped, chemically cleaned, the head skimmed and block decked, new guides and seats ground, repainted/powder-coated and reassembled using new seals and gaskets.

I made sure all oilways and journals were cleaned and used a MLS head gasket to assist with eradicating the oil leaks associated with the seal height issues.

The rocker gasket is on correctly and there are no leaks (yet) from the head gasket. The pucks were installed using Hondabond. I ground the four head dowels to compensate for the decking and skim and used a larger base gasket to ensure pison clearances were maintained.

I know for sure that at least one of the copper washers is on the wrong stud because I can see it on the one exposed studs at the front of the head. I also did not use domed nuts on studs 5-8 because the manual I posess omitted this crucial information.

The oil seepage is coming from the areas surrounding suspect studs 5-8, but the thing that confounds me is the amount of oil that came out; as per the description quote in my initial post, the oil dribbled out quickly whilst the engine was running. It's alarming how much oil is leaking down the threads of studs-5-8 and past the (non-sealing) washers.

Thanks for all of your comments.

12
CB750 / Re: 1978 CB 750 F2 - Oil pouring from above head gasket
« on: May 07, 2020, 08:44:41 PM »
Many thanks for this. My 'original' Honda workshop manual and the Haynes manual both omit this information. I'm just amazed at the volume of oil that was discharged, although the location from where the oil is coming (upper fins between cylinders 1 and 2 and 3 and 4 suggest this is the issue). Pucks were replaced and sealed in with Honda Bond. Rocker gasket is good, and the cam tower studs were never removed. I want to make sure this is the only cause of the issue before the engine goes back in again.

Thanks all for your replies.


Below is a copy from official workshop manual for your engine.

(Attachment Link)

Shows location of special capped nuts and sealing washers to prevent oil leaks.

For sealing they mean the copper type.  If you're unfamiliar with copper annealing,  just heat to red on a gas ring and quench in water to soften the material and they'll seal properly.

Hope it helps your rebuild.

13
CB750 / 1978 CB 750 F2 - Oil pouring from above head gasket
« on: May 07, 2020, 09:35:55 AM »
First start since rebuild and within a a couple of minutes running oil starts dribbling from the head above the gasket line from between cylinders 2 and 3. A small pool had formed within a few seconds.

Scanning the forum, I found a old post below that mentions using the domed nuts and copper washers on studs 5-8. During the rebuild I put in ARP studs and the nuts that came with them which were for the F2 yet didn't have domed ones. Also, I don't recall any of the washers being copper. Irritatingly, there was no mention in the manual about either copper washers or the import of the domed nuts.

My question is this; how can so much oil come from this area, and has anyone else experienced this? I'll be removing the engine to rectify this but am worried it may be something else as well.

Old thread:


"hya there serge, to help you understand, look at your f3 head, there are only four oil return holes...
Each "pair" of  valves share one hole, whereas on the k series heads,there is a return oil hole next to EVERY valve.....
Be VERY VERY carefull that you do TWO THINGS RIGHT. Down at the crankcases BEFORE you put the barrels on, make sure you have installed the four tiny   "o" rings on the studs that do not have the knock pins, I believe from memory these are labelled 5,6,7and 8 in the tightening sequence, but NOT IN EVERY MANUAL!! ( I have two manuals that show different tightening sequences!)
The purpose of these "O" rings on the studs is two-fold, the stop oil rising up the way AND believe it or not (BUT ITS ABSOLUTELY TRUE!!) they stop water and weather from entering down the way so to speak, this can be proved by looking at your cylinder head in a moment!

IF, you take a screwdriver or other probing device (but not your personal tool so to speak) and poke it down "those" (5,6,7and8) stud HOLes ON YOUR CYLINDER HEAD, AND LOOK through the fins, "OH MY GOD" YOU MAY WELL EXCLAIM, "why can i see my screwdriver?"
You will then be in the enviable position of being in the f2/3 "know" This is because "those" holes are not fully enclosed like in the k series, and should you forget OR neglect to replace those copper washers and domed nuts with new copper washers OR put the domed nuts on the wrong studs, you WILL get oil pissing out between the fins when the motor is started.........MORE THAN ONE person has experienced this! ( including me!) and I now have a mission to stop other people from the pain this causes!!
If ever you get the chance to see UNDERNEATH the barrells of a k and an f2/3 side by side, DO IT!
If ever you get the chance to see a k series AND f2/3 series head side by side DO IT!
Only close inspection reveals the differences and its well worth the looking and then the knowing!
kindest of regards,
kaceyf2"

14
CB750 / Head skimming and gasket thickness
« on: February 23, 2020, 06:45:30 PM »
1978 CB750 F2.

I am rebuilding the engine and having the head and cylinder block lightly skimmed by approximately .005" in order to ensure they are totally flat and prepare them for a MLS gasket.

My question; standard Honda head gasket is .040", and the base gasket .010".

The replacement gaskets I have are from CycleX and are of the same dimensions as above. I plan to add an additional .010" base gasket and reduce the head dowels as necessary in order to maintain the standard Honda specs of .050" total, however can anyone tell me what the minimum clearance that can be used is? Must it be .050" or can I use the single .010" base and .040" head gaskets?

I have posted this on the SOHC 4 forum as well.

Many thanks.

15
CB750 / Steering lock key
« on: December 18, 2019, 10:40:29 PM »
I have a nice looking steering lock but no key. Is there any way of determining the key number?

Failing that, what is the process for replacing a steering lock sans key?

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