Honda-SOHC
SOHC.co.uk Forums => CB650 => Topic started by: Clunker on July 07, 2017, 11:44:48 PM
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I got a bit carried away prattling on about my CB650C in the New Members section when I first joined so I think it's about time I put it in the right place. I picked this bike up as having a "tick over problem", probably clean the carbs out and service it and she'd be good to go.......ha!. First job strip the carbs, found the problem, inside float chamber on carb 4 the casting where the brass jet screws in had been snapped and repaired (bodged) with some kind of resin. It took ages before a no.4 carb body came up for sale. So in the meantime I set about tidying the bike up, polishing, more polishing and yet more polishing. Also, the chrome on the original spoke wheels was totally shot but the budget of bugger all wouldn't stretch to a rebuild so a decent pair of Comstars were obtained through ebay for £75, that included the postage and really good tyres. The wheels have now been fitted along with new chain and sprockets, the exhausts are back on. Jobs left to do are free off the clutch, ultrasonic clean and rebuild the carbs and tidy up the switch gear, then it should be good to go! The last pic is of the greatest invention known to Mankind since the beginning of Time, an arse shaped upturned bucket, yes I really do sit on a bucket polishing my nuts!
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The head and valve cover were covered in four layers of really thick, crazed paint that took three days to remove, that's how the bucket and my arse became best mates. The frame had hardly any decent paint left on it so I removed what I could then got the Humbrol Gloss black and a very small brush in hand, its not perfect but its a 100% improvement. A replacement seat and chain guard add to its appearance as do the homemade side panel decals, they'll do until I can find some original badges. The new rear shocks were included with the bike but not fitted, stainless washers were needed to beef these up as they were a lot thinner at the top and wider at the bottom. Overall I'm really happy with the old girl but the best part is that my Wife absolutely loves her and can't wait for me to get her on the road.
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Very nice,enjoy mate
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the Honda really is looking good,
keep on the hard work
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Nice looking bike there Clunker, what remains to be done to get it all road legal?
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Thanks for your comments guys, hopefully not too long before another Honda SOHC is on the road.........then on to the Nighthawk :D. Mike, as far as I know it should be just a matter of sorting the carbs and clutch, the good news is that Santa came today, he looked a bit like the Postman but he brought me a clutch cover gasket and the long awaited carb rebuild kits from Taiwan. I hope I can find the time next week to get the last jobs done then see Mr MOT man. Be nice if it passes without any problems, all electrics work, tyres and brakes good, new chain and sprockets, fork seals good, no pitting on the stanchions, exhausts solid. R-clips on brake torque arm and rear wheel nut. Can't think of anything else that it could fail on but if you guys come up with anything then please let me know.
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That's looking very nice ;D
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Thanks Julie, hopefully you will get to see her in the flesh (er...metal) at some point. I'm hoping to take her to Matlock Bath the first chance I get, I haven't been there for years.
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She will look well good cruising up and down the High Street. Went there a few months ago for the first time, in the car unfortunately, very nice place.
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She will look well good cruising up and down the High Street. Went there a few months ago for the first time, in the car unfortunately, very nice place.
You do know that it is only about 4 or 5 miles from the Chrich Tramway Museum? Did you go on a Sunday? It used to be rammed with bikes.
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I think it was a Saturday but still plenty of bikes around. I did work out it was close to Crich as saw the signpost.
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When I left Crich I was tempted to take a cruise through there just to see what was occurring but my belly was getting the better of me, see if it was still busy. If its nice tomorrow afternoon (Sunday) I might just fire up the Zephyr and take a ride up there. I'll have my camera with me if I can get there so if there is owt worth looking at I'll post some pics in Out and About.
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Carbs went in the ultrasonic cleaner this morning, rebuilt this afternoon. The Taiwanese rebuild kits were a bit of a joke, the gaskets for the carb tops didn't fit very well plus a hole for the locating peg was in the wrong place so I had to modify them with a hole punch. There are plenty of O-rings in the sets that don't fit anywhere on the carbs. In the end I decided not to risk using the jets or float needles as I'm pretty sure they'd have caused problems later on. Luckily I bought a partial set of carbs from a CB650Z a couple of months ago so I robbed bits from them to get the job done. I also had to figure out the choke mechanism worked as I hadn't noticed before that it didn't actually work, looks like a PO didn't have a clue either so he just chucked the parts on anyhow. First pic is me operating the choke pulley but nothings moving. Second pic is the top gasket fix and the third is the job done.
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The only parts that I did use from the rebuild kit were the top gaskets, the float bowl gaskets and the mixture screws, springs, o-rings and washers as this bike was a US import, the mixture screws had blank tops that had a slot sawn into each one. When I first stripped the carbs only one screw had the o-ring two others only had the spring and the last one was just the screw. I still have to make an o-ring for the number 1 carb air cut off valve chamber, I figure a tap washer and my hole punch should fix that. Forgot to mention in pic 1 above, can you spot the missing part????
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Carbs took about 15 minutes to put on with the ratchet strap method. Bike fired up straight away but petrol poured out of number one carb overflow, a sharp tap with a screwdriver handle to the float bowl cured that. Petrol dripping from accelerator pump, B*&^%$*£! as the little girl says in the VW advert! There weren't no sodding o-ring in there when I stripped em! I'm really surprised that this bike ran at all when I got it, there were stains on top of the engine case where fuel had been dripping for years. Anyways, back to the story, too lazy to be taking the carbs off (big idle mistake) I opted for a bit of keyhole surgery with my 90 degree screwdriver and loads of enthusiasm (beer). Figured if I could just lower the bowl a bit I could slide an O-ring in with the tip of my finger, I just happened to forget how thick my sausage like fingers actually are. I was trying to not disturb the diaphragm......................well I got the o-ring in and got the bowl back on, slight drip from accelerator pump, think I dislodged the you know what (not spelling it again). Carbs are gonna have to come off again but at this moment in time I just CBA!
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Well I got back on the bucket and pulled the carbs off again, I had managed to dislodge the diaphragm on the accelerator pump. When I removed the float bowl on no.2 carb I noticed a snot like substance in the bowl so I gave it a wipe out. Then I removed the other bowls and found the same crap in them as well.
The PO told me when I bought the bike that he had put clean fuel in the tank, he didn't mention that he hadn't drained the old fuel out first though. I emptied the tank into a bucket...............I have never seen fuel look as bad as that before! In the bottom of the bucket was a load of what looked like black silt with green snot mixed in, with a layer of really dirty petrol floating on top.
I had some clean but old petrol in the shed so I poured a couple of pints in the tank and gave it a right good swilling around then emptied it out, still dirty so I did it again and I think I got most of it out.
I put fresh fuel in and put the tank back on the bike, tried to start her up but the choke lever won't move, not even a bit ??? Took the tank back off and operated the choke pulley by finger tip underneath the carbs, it moved very freely, thought I'd pinched the cable somewhere but couldn't see anything obvious. With the carbs in place on the bike you can't actually see the choke pulley where the cable locates so I traced along the cable with my fingertip, it wasn't connected to the pulley but was trapped inside the airbox rubber.
When I refitted the carbs it must have slipped out of the pulley and hung loose until it got in the way of me connecting up the airbox rubbers ::)
I freed the cable and put it back on the pulley then tried to start her up again, choke worked fine, bike started but something didn't sound right, 1+4 headers were cold and 2+3 were hot.
This is the part where I love having two of the same bikes (or very similar) at the same time.
I borrowed the left coil from my Nighthawk and put it on the Custom, still the same, no spark on 1+4 so I moved on to the spark igniters, swapped both of them just to save splitting them, sparks on all 4 plugs ;D.
I put the plugs in, tank on, fired her up, all headers getting warm, let her run till she no longer needed choke. Switched her off then started her again, did this a couple more times just to check for any problems.
I forgot to mention that when I rebuilt the carbs I replaced the slide and needle in number 4 carb as the original slide had some deep scratching and the needle was distorted, probably due to the resin bodge on the carb body. The replacement slide and needle came from some CB650Z carbs but were exactly the same as far as I could tell.
Due to the PO's rather fanciful stories about he "did this" and "checked that" :-\ my next steps are going to be to free off the clutch while changing the oil and filter which he said he had done, check the valves like he said he had done....then balance the carbs and adjust the mixtures with my glass spark plug. So that is how she stands at the moment. I didn't take any pics of the above stuff as I just pulled up a bucket and started fiddling and one thing just led to another. :)
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Good bit of fault-finding going on there, glad it all works. How do you get on with the glass spark plug?
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To be honest Mike, I've never used one on a Honda before but they helped set up my kwaks a treat, made them purr like kittens on tickover and roar like lions on the road. Have you used one? anything I should look out for?
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Never used one. I like the theory of them; adjusting the mixture to the right colour for most efficient burn, just like a gas boiler. Some things are more trouble than they are worth, I wondered what they're like to use.
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I've used them many years ago on cars with SU or Zenith Stromberg CV type carbs and they were okay, but not much use on fixed jet carbs other than to adjust the idle mixture. Mine was a "Colourtune" made by Gunson, but proved pointless on most bike carbs, as to sort the mixture above idle meant dismantling to adjust needle height or jet sizes.
Sent from my X6pro using Tapatalk
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I will let you know how it works out with these carbs. When I used it on the kwaks I balanced the carbs first then used the Colortune then balanced the carbs again. Both bikes ticked over superbly and went like excrement off a digging implement. Both bikes were carb strip jobs that had been stood for years.
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I would have thought the colourtune would be useful for setting the air mixture screw because the existing advice is a bit hit and miss. Not something I play around with, if the bike starts and runs ok then I don't adjust anything but I wouldn't mind checking.
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It was after I first balanced the kwak carbs, then tried adjusting the mixture screws according to the Books and plug condition, with less than satisfactory results that I invested in the Colortune. With the Colortune I could actually see how different the settings for each cylinder were, even though they were adjusted as much as possible to proper specs. I set out at plug 1 with the tank off and a motorcycle cover over myself and the bike, engine running of course, screwed in the mixture screw all the way then backed it out until the "bunsen blue flame" appeared then carried on going until I lost it, then backed it in again until "bunsen blue" again. Did this for each plug, also opened the throttle about a quarter on each cylinder to observe colour change in the chamber, got each mixture screw set so that the response was as close as I could get with each cylinder. I figured that if each mixture screw was set as closely as possible to the rest then that wasn't going to be a bad thing and balancing the carbs again afterwards was going to be as close as I could possibly get by myself without expensive equipment. Anyway, it sure did improve throttle response and performance. I'll just have to try it with the CB carbs, it's not gonna cost me anything to give it a go as I've already got the gear. Watch this space! ;)
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Today I freed off the clutch plates, lubricated the extremely stiff clutch cable, changed the oil and filter. While the clutch cover was off I got the polishing tackle out, 400 + 800 + 1200 grit wet & dry, fine wire wool, toothbrushes, tube of Solvol and bucket of warm soapy water. The clutch cover now matches the rest of the casings, just need to do the black circle with Humbrol Satin black. Rain stopped play! >:( Clutch works great though! 8)
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Yesterday I set the valves, PO told me he had set them. He must have used a shovel for feeler gauges cos they all had way too big settings. :o
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I won't be posting anymore updates to this thread as CB650's seem to be a non subject on this site. Regards Clunker, signing off.
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Nooooo, don't go away. I'm sure its only because no one else on here owns one (I think) It is a SOHC so still an important bike on here. I have read all your posts but know diddly squat about them so can never comment.
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Keep 'em coming Clunker, we like our success stories on here and the photos. And when you're scratching your head we all chip in with advice it becomes a team effort.
One word of advice though: upgrade the the bucket to a mechanics stool so you can scoot it around with your feet.