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Messages - Martin6
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31
« on: December 27, 2023, 11:10:40 PM »
I put the David Silver seat on my 750k6 today. Disappointed. It doesn't rock, but it was not sitting straight on the bike. The front was too far left and the rear too far right. So much so that the front of the left trim strip scratched my tank on first close.  I fiddled with it. I found bending the hinge brackets, in a vice with careful persuasion, improved things. I'm now at the limit of what I'm comfortable with for the seat lock alignment. It's still wrong, almost straight, not too obvious, unless you know. But it's not rocking and looks better than the old one. I suppose, at £100, you get what you pay for. Annoyed at myself for not thinking it might scratch my tank. Only small and inconspicuous, but it will need repairing, to avoid rust. The vinyl paint has arrived and the stencil should be here in a few days.
32
« on: December 24, 2023, 10:49:14 PM »
Hopeful. Well done. Let me know if you fancy meeting for a coffee locally in the new year  .
33
« on: December 21, 2023, 04:26:43 PM »
OK. I'm only an hour from DS, so I'll give it a go and take it back if I don't like the fit. If I recover the seat pan, I'll definitely need new foam too, then also a new trim strip, which is damaged. A new seat solves those issues, but not if it doesn't fit well.
34
« on: December 21, 2023, 01:00:35 PM »
What would we do without you? Thanks, again. 👍
35
« on: December 21, 2023, 12:15:33 PM »
My seat has a couple of repairs, all along the outside edge of the top squares moulded seat pad. Another split has just opened up. I could repair it, but I think it will be a losing battle. I see a replacement at David Silver. Has anyone tried it? Is it comfortable? Does anyone sell stencils to add the 'Honda' on the back face? Lipstick on a pig, maybe 
36
« on: December 19, 2023, 10:33:20 PM »
David Silver has them in stock Maybe Julie has some?
37
« on: December 19, 2023, 02:57:02 PM »
Thank you Julie.
The frame number was left unpowdercoated, just clear lacquer.
38
« on: December 19, 2023, 01:50:31 PM »
Hi,
Having restored my frame I have some finishing touches. This black and silver sticker goes on the frame's steering head tube somewhere. Does anyone know the correct position for a UK 750K6?
39
« on: December 18, 2023, 09:33:32 PM »
Thanks @Skoti. You may have already seen this, I use it on the Norton, it enables emptying the sump with the small drain plug, without wearing the threads in the crankcase: https://andover-norton.co.uk/en/shop-details/16995/magnetic-crankcase-sump-filter-kitYes, 3.5 Litres would also take me over max with the CB750. Not surprising I guess, as we'll never get all the old oil out, without a strip down. My factory manual suggests 2.9Litres as a start point for an oil change, run the engine for 2 minutes, then check the level. I did this and it was fine. I'm sure I'll get there. I've really enjoyed my post rebuild rides, so I have every incentive to get it sorted. 👍 I'm in my late 50s. These 70s bikes were what I saw as 'the ultimate' as I was growing up, with no prospect of riding them at the time. The Norton and the Honda are still ideal bikes. Both quick enough, but in very different ways, so each is a different riding experience. At least, what I lose in the cost of parts, I save in depreciation and hopefully, at least one of them will be in working order at any one moment!
40
« on: December 18, 2023, 05:13:52 PM »
OK, thank you.
I will have another look at the carbs. I used a carb refurb kit when I first got the bike (as it was non-running) from David Silver. I kept the needles, jets and screws the carbs came to me with, so I'll clean them and the carbs and try the old ones again. No idea whether they're original Keihin brass though. I suppose it's possible, but unlike,y after 47 years and 42,000 miles!
I will monitor the oil level carefully. I think it's not wet sumping. I filled the engine about a week before the first run and it stayed at a constant level in the garage. I'd put 1/2 Litre of oil each side of the head (through the rocker covers) and 2L in the tank. The low dipstick reading was the first check, on the first ride after putting the engine back together. So, I just assumed it was low due to the pump filling all the remaining oilways, plus filter. So, it was surprising to see it back to nearly full when I next stopped. That struck me as odd. On the oil change I did yesterday, after filling the tank (2.9L) , it dropped a little when I ran it for 2 minutes, to 75% on the dipstick. I'd guess that was oil filling the filter and sump. I ran it again and it stayed at 75%. So far, so good. Just that first reading on the first ride that's throwing me. I'll keep checking.
41
« on: December 18, 2023, 11:40:31 AM »
Thanks. I have a dry sump system on my 850 Commando, so I know about 'sumping' This was variations whilst still hot. I'll watch it, but I think it's probably fine. The thing I'm most nervous about is still having signs of the sooty plug on no.1 and a bit on no.2 and not taking off when i more aggressively whack on the throttle. I think that suggests it's too rich, but not sure about that? Along with the bad oil leak, this was one of the reasons i took on the engine refurb. The carbs were cleaned out thoroughly with carb cleaner and compressed air. Needles on middle grooves, bench synch'd to get reasonably close, using a drill bit method. Air screws initially at 1 turn out. Float heights double checked with a vernier guage on the inner flat area of the bowl edge. New rubber seals on the carb tops. No sign of splits in the rubber manifolds. Can timing is fine and points / ignition timing (also no.4 is running clean). Tappets were set carefully when the cover was off. Not sure where to go on this? It's a pain cleaning the plug every 200 miles, which is what I was doing. I've had one thought, I didn't clean out the exhaust headers, which were sooty on 1 and 2. Is it possible the sooty plugs could be due to transfer from the headers? But that wouldn't explain the bogging down. All a bit confusing...
42
« on: December 18, 2023, 08:12:56 AM »
No cannister, it's only a removable paper filter onnthe 750s. Just cut the ends off with a Stanley and unravel. Do it over the catch can though Edit: it's not diligence, more like lack of confidence I could have got it right 1st time!
43
« on: December 17, 2023, 10:45:24 PM »
Great news Martin! So impressed you managed out this time of year for a “shakedown” run. Wouldn’t be too concerned about the oil level, I’ve had that on my 750, after all the engine is where you want the oil to be not the tank. Well not all of it anyway. Bit of syncing and tuning to do by the sounds of it but plenty of winter ahead yet!🥶
I'd guess it's a little bit warmer and a lot dryer down here! I'm able to pick my days and ride all year with a few mates. Bacon and eggs are a great winter warmer! Although, some of the winter runs, I stick to a modern bike with a big enough alternator for a heated jacket. I was out again today, warmed the engine through and up to nearly 100 miles, so I could change the oil. I'm really pleased, it was lovely and clean and I dissected the filter, which was also clean. I'd also unwound the air screw on carb no.1 by 1/8th of a turn. Initial impressions are it is better, but forgot to check the plug before restarting the bike to check new oil level. Still so far, so good 👍
44
« on: December 15, 2023, 11:07:45 PM »
78 miles. Ran almost faultlessly, after I tightened the rocker caps! No other oil leaks. The bike is definitely punchier and the suspension feels good, much better at absorbing bumps and no bottoming out. Perhaps a little underdamped at the front, but I'm not complaining. It was a very enjoyable ride.
A friend saw no smoke, except at one point when I opened up to accelerate hard, producing a whiff of black smoke. Running rich maybe?
Couple of questions:
I've a slight hesitation applying the throttle from tickover and a bigger hesitation if I rapidly whack the throttle on whilst riding (c.3500rpm). It's fine if I just roll the throttle on in a more measured way. Are these symptoms of running too rich?
I seem to have a wandering oil level on the dipstick. Was at 80% when I started out. Was just above the minimum 40 miles later, then at 75% when I got home. All readings were taken on the centre stand,.on level ground. Oil return looks consistent when I check in the tank. For the last of the readings, I put it on the sidestand before lifting it onto the centre stand. Can't see how that would affect the tank level though? In your experience, is this odd, or usual behaviour?
Minor observations:
I'm not convinced the tacho is calibrated correctly. 1400rpm sounds and feels like a nice gentle tickover. Below that just feels too slow. I'm yet to do a running carb balance though. The speedo is definitely reading fast by more than I'm used to. I'd say indicated 60mph is really a tad over 50mph. A local radar speed awareness sign shows 30mph when I have 36 on the speedo! I'll live with that.
Thank you for encouraging me to give the rebuild a go. I have a huge sense of achievement and feel like this is now my Honda CB750, my 'pride & joy'! The manuals (Haynes and Honda) were good start points, but a bit tricky on model variations over the years. Most problems I stumbled into were solved without too much drama, via searches here and on SOHC4 forum. Only a little blood was shed in the process!
I'm looking forward to next year with my bike, although with my fingers crossed for now.
👍 Best,
Martin.
45
« on: December 14, 2023, 11:07:42 PM »
Everything is back together. Bike started 2nd attempt. Oil light out within a couple of seconds. I warmed it up, varying the revs. No oil leaks so far. I still need to balance the carbs, I spent time getting them as close as I could before mounting them on the bike. It seemed OK at 1400rpm, but not especially smooth below that. I didn't idle it for long though.
I replaced a lot of the head nuts, bolts and screws and engine mount hardware, repainted the engine and had the frame and brackets powder coated, whilst the engine was out. I also found the cause of my stiff front suspension, a slight bend in one of the stanchions. So I replaced that and the fork oil seal. New Hagons on the rear.
It's looking quite tidy. Fingers crossed it will run well. I'm aiming to go for a run tomorrow in the sunshine. Maybe get 30 miles on it and check it over a few times. I'm thinking I'll change the oil and filter at 100 miles. Does that seem sensible?
Martin
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