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Topics - MrDavo
46
« on: September 30, 2016, 11:26:51 AM »
You know that sticker that tells you not to dick around with the standard exhaust system or else? (well not in so many words but that's the gist of it) I don't see it at all in my K1 parts book, but I have one on the chainguard. I don't see it there on any other bike (someone had gone a bit mad with a sticker kit, the bike came with the 'Helmet Lock' sticker where the K1 doesn't have a helmet lock  ), I have seen it on the RHS of the swinging arm on some bikes, or not at all on others. Can anyone satisfy my OCD and tell me where, or if, it should be stuck?
47
« on: September 28, 2016, 06:01:49 PM »
My 1971 CB750 qualifies for 'Historic Vehicle' free road tax, when I check it on the DVLA it says it is due on 1st November.
When it is up for renewal do I have to do anything, fill in forms and apply even though there's no fee payable?
The MOT is due in October, its debatable at the moment whether it will be back in one piece by then - if not do I have to SORN it?
48
« on: August 23, 2016, 04:25:13 PM »
This may be pretty basic stuff, but bear with me, I was raised on British twins and other primitive technology.
I can see the point of the set rings in the gearbox, to stop things moving sideways, but is there just one per bearing? Does it go half in each case, or doesn't it matter?
I seem to be missing a couple, but before I go on a parts hunt I need to be sure of what there should be.
49
« on: July 22, 2016, 11:31:27 AM »
One of the little things that has always bugged me, though noone has ever mentioned it, is the lack of a black stripe on the trim along the bottom of my tank. Whether my trim is off a K0, or the stripe got tatty and was polished or stripped off, I don't know. I did buy a NOS trim a while back from DSS, but there was only one side available, and I haven't found another.Browsing through D Silver's website the other day I spotted that he has had some made, so I ordered a pair, £19, plus VAT & P&P. The postman was puzzled to deliver a large box that weighed nothing - as these strips are easily damaged, they were packed in a lot of fresh air! https://www.davidsilverspares.co.uk/CB750K1-FOUR-1971/part_125409/The finish is good, the main difference with my one NOS one is that that is covered in that same yellowed (with age?) plastic that I often see on Honda alloy levers (not mine), these aren't. After struggling to clip them on from below I took the tank off, and slid them on from the rear:  I think the result looks very good, even if I am the only one that notices. 
50
« on: July 13, 2016, 04:26:21 PM »
The good news is Candy runs well, looks wonderful, getting compliments from everyone who sees her, and has won best Japanese Classic at 2 of the 3 bike shows she has been entered in. However, it looks like she's about to be pulled apart. She has been restored at some point while in South Africa, but I've no idea what engine work, if any, was done until I get inside. Fault 1: While Candy runs ever so sweetly, with very little mechanical clatter, when she gets proper hot, such as after a run 2 up with the camping gear on board, I am sorry to say there is a definite low 'knock' which I can feel as well as hear. Pulling the clutch in makes no difference, so I don't think its the clutch basket rattle that some have suggested. Also, the oil light comes on at low revs, to be expected I know, the manual says it is normal, however the hotter it gets the higher the revs needed to make it go out again. Fault 2: This has only happened twice to me, but she is 45 years old, so who knows how many times it has ever happened. 200 yards from my house, (the same piece of road both times) the oil light comes on solid, not flickering, whatever the revs, and a clatter - as fast as I can pull over it goes as quickly as it happened and doesn't reoccur. I suspect that fault 1 (the knock) was caused by fault 2 (oil starvation), and was already there when I bought her - coming back from the MOT (my first ride) I had issues with the oil light coming on at idle and being reluctant to go out again as I revved. I have replaced the oil pump 'O' rings, oil pressure light sender, and tried heavier (20/50) oil. An experienced race mechanic I spoke to at Classic Le Mans last weekend suggested I could try over filling, with thinner oil, he suspects the thick cold oil just isn't flowing fast enough to keep up until it gets warm, leaving the oil pump trying to pump fresh air, he agrees it may have done for the main bearing shells over time. He also told me about classic Bugatti race mechanics having to warm rear axles with blowlamps, the lubricant they use solidifies to something like candle wax at normal temperatures! I'm going to try pulling the oil supply line at the motor, to see what the flow is like when the engine is cold - maybe it's partly the viscosity, but perhaps there's a partial blockage or collapsed rubber inner in the oil feed line (every other bit of rubber on the bike was shot due to a combination of age and long term storage in a hot climate). Even if I can stop it happening again, the bottom end won't fix itself, and I am reading up about using plastiguage to measure running clearances. I wanted to take the motor out anyway to polish the cam cover. D'oh! 
51
« on: April 25, 2016, 12:11:15 PM »
I have just fixed a horrible misfire that has been driving me nuts, more by accident than expertise. When I first bought the bike, I had noticed occasional spitting from number 2 exhaust, and the first ride was very disappointing as I was riding a very flat Honda 3! Suddenly a spit, a bang and all was well. A couple of weeks ago, out for a ride in the country I suddenly had a bad misfire, but it went as soon as it came. I did think at the time that it can't be anything good, and would inevitably come back to haunt me. Last week I changed the pilot jets for new ones, as a couple were partly restricted by crud, and the finest wire on my carb cleaning set wouldn't go through. To my disappointment when I put everything back together the result was a bike on 3.5 cylinders, with occasional forays to 3 or 4 pots. I spent ages b*ggering about with the carbs, to no avail, but did convince myself that number 3 pot was the culprit. I changed that plug, burned my hand on the exhaust ( then put a glove on) and all seemed Ok for a few miles. Then back to the misfire!  Saturday, I pulled the plug cap from number 3, resistance seemed Ok, so I unscrewed number 2 cap to compare it to. Both were the original 'full metal jacket' caps, the outer two were already the plastic type when I got the bike. Got my multimeter out, er, shouldn't number 2 cap at least conduct electricity? Down the local bikeshop, where after a hunt they found me a new NGK straight plugcap, cost £2.84. Went home, fitted it and started the bike. A huge bang as unburned fuel in the exhaust lit, if you have rusty or weak silencers I guess this could do damage. But the misfire is gone and a lesson learned. I have ordered a new cap for number 3 as well, Ash you can have the metal one if it floats your 'originality' boat.
52
« on: February 15, 2016, 06:23:35 PM »
53
« on: February 07, 2016, 08:12:18 PM »
When I was getting ready for my K1's MOT I found that years of standing had seized the clutch plates together, and it wouldn't disengage.
When I stripped the clutch, I pulled the plates apart, and each steel plate had a 'photo' of the friction plate it had been in close company with for god knows how long. I cleaned up the steel plates, and oiled everything before reassembly, as per the manual. Maybe I over oiled, I don't know.
The clutch has worked fine since, but on a ride out today, I gave it full beans to pass a car, going uphill, and the clutch suddenly slipped. backing off a touch got the drive back, but I got it to do it again later, same thing, WOT and a high gear.
It seems to me that if this happens solo, then 2 up with camping gear is going to be a problem.
Do you think my plates are shot, or could cleaning the plates or adjusting the springs get me my drive back 100%?
54
« on: January 29, 2016, 01:15:59 PM »
I was looking for good K1 photos when I came across this site: http://all-moto-brands.com/1971-honda-cb-750/It started off OK if a bit vague: 1971 honda cb 750 motorcycles are considered the most excellent touring bikes in the world. These motorcycles offer the riders the matchless comfortable, influential, balanced ride on different road conditions and they are the completely featured machines, which have been suitably designed for every journey. The superior design and the dynamic styling of these motorcycles from 1971 honda cb 750 make them an aerodynamically sophisticated touring powerhouse Then it goes completely bonkers: With the warmest, taking the sting further than even the longest winter journeys, the 5-position heated grips, autonomously adaptable heated seats and foot-warming system and an adequate luggage capacity create touring a year-round prospect. The six-speaker, SRS surround-echo system with adequate output, and iPhone, iPod or USB stick connectivity and fully incorporated airbag makes your journey pleasant and safe.
1971 honda cb 750 feature a slow-pace, electric reverse system that provides the ease of general maneuvering in taut spaces and parking lots. The frivolous electronic tour-control system is a pleasure for the rider on those long distance freeway rides. I look forward to toasty feet as I listen to my iPod on the stereo (very forward thinking of Honda in 1971), but will watch out for the airbag going off as I slip into slow pace electric reverse....
55
« on: November 13, 2015, 11:31:13 AM »
Well after 4 months I finally went for my first legal ride on Candy, with the new black and silver plate that had turned up in the post from Chestnut. It all seemed a bit (/lot) gutless, after wondering if I had expected too much I took her for a short spin to Stockport on the M60, to find the top speed flat out was, er, 75mph.  The expression 'wouldn't pull the skin off a rice pudding' sprang to mind - who the hell would do that using a motorbike anyway? On the way back, approaching the lights by the Blue Pyramid, there was a backfire, and I nearly lost it as the missing cylinder kicked in!! The clue's in the badge on the sidepanel, '750 Four'. I can only think that a carb passageway was blocked with crud somewhere, or I'd wet a plug starting up - I did clean the float bowls out and spray brake cleaner through the jets, but you cant get everywhere doing that. I may put some fuel injector cleaner in the tank before my next ride. After that she flew, and the HM300s made a glorious din! On the way back on the motorway I was able to go fast enough to remind myself of what the CB750 speed wobble feels like - only mild, I used to make it much worse on my old K1 in my youth by loading up the carrier at the back with full camping gear, or all my worldly goods when I went off to Uni. It never chucked me off, but scared me silly a few times. I got used to shifting my weight over the bars, if it got bad the trick was to open the throttle. That bike had suspiciously long looking Girling shocks, which probably didn't help the steering head angle any, but I never measured them, as I wasn't really aware of such things then, I just rode it like I stole it (and still do!). Anyhow, the 'hot breath' refers to the tacho - despite putting in a new oil seal in the cam cover, which stopped the oil leak it had before, the engine is breathing down the tacho cable and fogging the glass on the tacho - I've never seen that before! I think I need to find and check the breather tube from the engine, but is there a seal at the tacho end that I could check or replace? I cant see anything in my parts book, but the tacho is just sold as a single unit, no parts are listed. has anyone any tips on checking the breather?
56
« on: November 04, 2015, 12:30:26 PM »
You may recall I bought a restored CB750 K1, which although looking very fresh and new is not very shiny - the engine cases and fork lowers that should be polished, have had the same aqua jet (or vapour blasting, IDK) treatment as the engine - it all looks new but doesn't shine.  The fork lowers I will remove and polish during the winter, and the cam cover can just stay there for now, I'm not taking the motor out just to polish or replace it, until I really have to. However, I was excited this morning to get a box delivered, which contained 3 NOS parts - the alternator cover, gearcase cover ('crankcase mission cover') and clutch outer housing. The gearcase cover alone is £405 at David Silver, the clutch cover £114, and the alternator one is out of stock - so £200 for the lot on Fleabay is a definite result!    The gearcase cover has a couple of small marks, which were mentioned in the eBay ad, fair play, I'm torn between leaving the lovely 'new' slightly brushed finish alone or trying to sympathetically polish them out. I have ordered new kickstart and gearshaft seals, I'll post 'after' pics once the cases are fitted, I'm sure there will be a definite improvement, The removed bits will be for sale once they are off, vgc, but not shiny enough for a 'as new' restoration. I'm still after the polished cover over the drive sprocket 11351-300-050, btw.
57
« on: October 26, 2015, 11:32:19 AM »
This is related to my other thread in this section, re polishing a vapour blasted alloy surface which should be gloss, but this topic is how to keep my engine clean? - vapour blasted and looking like new is all very fine, but sooner or later my CB750 is going to be used in typical filthy British weather, ridden accross muddy fields at rallies etc.
Once it has got filthy, how best to bring it back like new - solvents, alloy cleaners, Gunk? or what? Any sort of abrasion would ruin the matt silver finish I now have. Leaving crud on to bake I am sure would stain the cases / fins etc forever, no?
I will try and avoid the dreaded road salt, but you can't use a bike and do that forever.
I could even paint it matt silver over the blasted surface, but to spray it properly the engine would need to come out, and that's not going to happen until it definitely has to, I want to ride it first.
58
« on: October 22, 2015, 12:39:10 PM »
That's not the oil pressure relief valve, but relief at having some oil pressure!
Last Friday I had my first ride on the K1, to get an MOT on the frame number (she passed, advisory was one loose spoke at the back, which shows they were thorough). About 5 miles, she ran as sweet as a nut, but on the way back the oil light started to come on idling at traffic lights, then took more and more revs to go out. The nearer home I got the more the light came on, I limped back onto the drive seriously worried, and already trying to work out how and when the motor was coming out.
After some internet research (not a euphemism, for a change), I decided to check the oil pump O-rings, I think the bike was restored years ago, but barely used since (and I started to wonder if low oil pressure was why) and everything rubber on the bike is hard or perished - for safety's sake I changed the inner tubes as well as the tyres, and the cracked fuel lines - I'm waiting for the fuel cap gasket as that leaks now I have a fullish tank. The pump O-rings were Ok, but hard and flat, so I ordered a new set from David Silver at Stafford Show, they came yesterday, and I fitted them last night.
The wife came home late yesterday to find me despondent - O-rings fitted and oil replaced, I fired her up, the oil light went out, then came back on at idle, the warmer she got the higher the revs needed to make it go out. I checked for oil at the number 4 tappet cover, fine, but by I switched off she needed 2,000 rpm plus to extinguish the light. By now I'm thinking mains - the motor all seems freshly rebuilt, but mistakes can be made.
The last throw of the dice today was to try a second hand oil light switch I bought for £4 at Stafford show, mainly because I wanted the rubber boot, which is missing on my bike.
I am here to tell you how releived I am - the light goes out as soon as I fire her up, and stays out until I switch off. Ladies and gentlemen, we have oil pressure!
As I'm waiting for the DVLA to process my registration application (why do I expect that they are going to send the forms back with some new problem?) I can't legally go for a test ride unless I book another MOT, but I may be sneaking out later for a quick test after accidentally fitting the plate off another bike. Don't try his at home.
59
« on: October 08, 2015, 03:05:07 PM »
So how do I 'preserve nature', like my sticker tells me to? Not run over wildlife? Miss the flies? Not go out on the bike? - Wearing a helmet and 'thinking safety' are a bit more obvious.
While we're at it, my CB750 k1's warning sticker is below the filler cap - shouldn't it be above, ie between the filler cap and the forks? - It seems that way in the parts book, but the sticker is missing on most bikes I see on the net. I'm a bit distrustful of the stickers that came on my bike, after noticing yellow 'Helmet Lock' stickers where there aren't any on a K1 - someone obviously felt compelled to use the whole sheet!
60
« on: October 05, 2015, 04:53:47 PM »
All the bolts ansd screws on my bike are new or replated, but at the risk of sounding sad and OCD, many are wrong, ie not original.
Ive replaced all the allen screws with JIS crossheads, but many bolts which should be 'number 8' flange bolts aren't - there's a bolt and washer with modern mumbo jumbo on the head. I want proper 'no 8' bolts, damnit!
When I get to shows and autojumbles I will be rooting around in boxes for these, but eBay only has job lots the same size, as far as I can see. Anyone point me at a good source? I particularly need 6mm x 12 for the airbox, 3 shorter 6mm bolts for the oil tank, and 8mm x 28 for the brake pedal. Then there's the big ones for the rear indicator / frame bracket.
I also need a K1 battery sidepanel in candy blue green (code AZ) - I have a replica that someone is consistently failing to paint for me, if I can bag a factory finish one that would be a result. I have a genuine K0 airbox AND a K0 battery side panel in the same colour to swap.
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