SOHC.co.uk Forums > The Black Bomber Board
1969 CL450 US Barn Find Restoration
MrDavo:
Hmm, having a couple of teething problems but I have put 8 miles on the trip meter.
First the indicators work fine in the garage but barely at all on the road. Either there’s a loose connection somewhere or the generic relay isn’t happy about something.
Secondly and more importantly I’m dammned if I can get a reliable tickover. I end up revving her like a race bike (mine never had tickovers, deliberately) at the lights. I have had her ticking over, see the YouTube video above, but on the road she died when the revs dropped. Today I set the float levels properly as per the book, so I can rule fuel levels out, but I buggered up the carb syncing- I had them working fine together but after I put the tank back on I realised I’d pulled the cable ends out of the junction box. I may have to do the whole palaver of taking the side panels and air boxes off again just to correct things. I’ve tried adjusting the cables so they are both taking up the slack at the same time but it’s not right. The right carb is very sensitive to the throttle screw while the other isn’t, something wrong there.
In the end I gave up as everything had got very hot, so I was worried I’d do some damage or not get it right anyway. I’m sure I’ll get there in the end, but it was easier to get her running than getting a reliable tickover.
The dry break I put in the balance pipe between the two halves of the tank has made life so much easier, if I was still having to drain the tank every time I took it off I’d be tearing my hair out by now.
MrDavo:
It’s still not right, I resynched the carbs, checked the float levels, put some sealant on the inlet stubs and put it all together only to find it still wants to die or surge, rather than tick over.
Knowing now that it’s not flooding, when the revs suddenly skyrocket I think I must have an air leak, I suspect the inlet stubs. Rock hard with age when I got the bike, Ashley kindly softened them with magic chemistry, but I’ve bitten the bullet and ordered a new pair from Silvers, very uncheap. The Cb750 had a leak on one cylinder when I got it, that was turning the header yellow, despite nothing appearing wrong other than hardened rubbers, new inlet stubs cured the problem completely.
The only way I’m going to get to the bottom of this bad slow running is to be methodical and eliminate all the possible causes. It will all be worth it in the end though.
royhall:
First thing I look for these days is new inlet rubbers, had the same issue too many times.
Don't know if he has any left, but Ash was selling genuine jet kits and needles for the 450.
Have you checked the floats themselves as the soldered joints can go bad on these. A tiny amount of petrol inside the float will mess it up. Cruzinimage sell good quality reproductions.
I'm sure you will have checked all the above as you have done a top job with the rest of the bike. Good luck with finding the problem, there's nothing quite as frustrating as carbs. I'm fairly sure the new inlet rubbers will do the trick.
I send mine to Matt Harper to be done these days, and never had a problem since. Matt Harper - New inlet rubbers - Job done.
MrDavo:
All the jets are new, plus the float needles, seats and pilot screws. I had to use after market ones as the real thing was nowhere to be found.
The floats are new and genuine - one original was bent, the other fell apart, to my horror, when I used heat to unstick the float spindle - the solder melted instantly!
I couldn’t get the screws out that hold the needles in the slides, so they are still original, I hope they are in the original ( or at least the same) groove, but that’s farther up the rev range to be affecting my low rev problems.
I await my inlet rubbers, hopefully this will be the last time I have to take the carbs and air cleaners off for now.
MrDavo:
The new inlet stubs have come, and I'll replace them as soon as I make the time, however if that doesn't solve my problems, reading on the twins forum makes me wonder about air leaks at the felt seals on the throttle valve shafts, which I haven't been anywhere near.
They aren't listed in my parts book, they included in the whole carb body part number, but I've found them on eBay, complete with a video on how to change them.
https://www.ebay.co.uk/itm/Honda-CB450-and-CB500-Twin-Improved-Carburetor-Throttle-Shaft-Felt-Seals/261900707837
It's stuff like this that probably got many of these bikes banished to the back of the barn in the first place, but I'm a stubborn so and so, and won't give up anytime soon. We'll see what the new stubs do, they don't feel a lot softer than Ashley got my originals to be, but at least I can eliminate them and still have a plan if that doesn't work, other than to go and pour myself a large drink.
Does anyone here have any experience of these seals causing an air leak?
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version