Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Winterfield on June 01, 2020, 07:17:34 PM
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Hi all,
I've managed to get my 400 up and running after much work on the body, repainting etc.
Today was a mixed bag. I just couldn't get the bike to start and idle. It would start very briefly with full choke and some throttle, then it would die. It turns out you need a fair old whack of fuel in the tank to fill the floats, and they just weren't filling up.
Once I got the fuel situation sorted, I managed to get it to start and idle with full choke (very smokey), then if I turn the choke off, it shoots up the RPM (without any throttle input) at which point I hit the kill switch. The idle screw is all the way out, and I don't -think- there are any obvious air leaks, because I tested with some squirts of carb cleaner around the place. What I suspect is that the slides are too high, and are letting in too much air at idle. If I understand it, it's probably best to use the balancing screws to have the carbs quite low (but equal), then use the idle screw to lift them if it idles too low?
Once it got a little late to be rev bombing the neighbourhood, I turned my attention to a spare set of carbs I have. While dismantling, I may have used a tiny little bit too much force trying to get the main jet out.
I managed to create a couple of hairline cracks in the carrier for the main jet. They don't go down too far, maybe 2-3mm. Is this likely to cause any issues?
(https://i.imgur.com/cdWPqas.jpg)
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So after finally figuring out the right Google search terms, it looks like this is a solved problem: http://forums.sohc4.net/index.php/topic,100144.msg1117373.html#msg1117373
Now to solve the next problem: it turns out that finding .45 bullet casings for this repair is not as simple in the UK as it is in the US.
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Small brass interference fit sleeve over it would sort it provided it didn’t interfere with float movement, if you knew somebody with a lathe. Otherwise replace carb body.
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Interesting solution there for the damaged casting ;D
For your high tickover problem http://www.sohc.co.uk/index.php/topic,17769.0.html should help you as it appears you've got the slides positioned too high relative to the lifter mechanism.
That would stop you completing a setup so worth checking through.
Edit;- microbore plumbing copper olives may give you a scource of material to reinforce the casting cracks.
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Check the fast idle screw on the choke side of the carbs. There should be about 0.2mm gap when the choke lever if off. When you put the choke on it lifts the slides. Could be set wrong holding the slides up all the time.
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Deano, the fast idle was adjusted to have a huge gap, so I don't think it was even affecting the throttle.
I suspect that K2's post is exactly what's happening, and I saw a similar post.
Will report back with details on how to recognize and fix the issue (assuming I manage to fix it).
Nice idea on the plumbing olive. I could only find 12mm microbore tubing, but the olives will be slightly larger diameter, and pliable.
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Try here for .45ACP cartridge
https://www.flecktarn.co.uk/spobc5nx.html
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Now to solve the next problem: it turns out that finding .45 bullet casings for this repair is not as simple in the UK as it is in the US.
Just in case it helps, a .375 rifle cartridge will also work.
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