SOHC.co.uk Forums > CB350/400
My New Project arrives after a 44 year wait!
Laverda Dave:
Did you keep those carbs Ash or did you leave them to dissolve back into the ground!
Amazing to see how people allow personal possessions that cost a lot of money back in the day to sit and rot. I was always taught to save up for things I wanted and when I got them to look after them. This thinking especially applied to my coach trimming tools, they were my living and eventually the same applied to my drawing pens etc when I became a design engineer. I could never leave bits of engines out in the elements or sitting in sheds without some level of protection be it grease or in sealed containers.
AshimotoK0:
--- Quote from: Laverda Dave on July 14, 2024, 01:44:53 PM ---Did you keep those carbs Ash or did you leave them to dissolve back into the ground!
Amazing to see how people allow personal possessions that cost a lot of money back in the day to sit and rot. I was always taught to save up for things I wanted and when I got them to look after them. This thinking especially applied to my coach trimming tools, they were my living and eventually the same applied to my drawing pens etc when I became a design engineer. I could never leave bits of engines out in the elements or sitting in sheds without some level of protection be it grease or in sealed containers.
--- End quote ---
I seem to remember they did actually yield some decent bits like brassware, piston slides and some rubber parts etc . After all only 600 odd miles from what I could gather. Mick Taylor (kettle738) actually got the engine that the carbs were from, which the guy had kept inside of his house and from memory it was just covered in fluff and dust with no plugs in it. I think Mick sold it to a bloke in Lincolnshire. We found a receipt from the late 1970's from 'The House of Wheels' in London (was it Leyton?) and the guy had bought a lot of stuff off a crashed 400 they had. ... I found the kickstart off it that was pristine and fetched a fair few bob :D and 'Varnish Blue' side panels, which are now on my own 400.
Laverda Dave:
It's been a while since I posted an update on Ratty but now the Triton has been fixed following it's recent drop from the bike lift I have now moved back on trying to get Ratty finished and to sort out the abysmal running/non-starting issues.
When I left it back in August it flatly refused to start. I removed the carbs yet again and checked the float heights, No 3 was 20.5mm and I tweaked the level. Next up check the pilots, I found three were blocked yet again and I cannot understand why considering there is a new filter on the fuel tap and the tank is clean inside and I have used new fuel lines. I reassembled the carbs and checked them on the workbench. No 3 carb leaked as of course it would! Another drain of fuel followed by another adjustment and bench test, all was now well and I installed them and the air box back onto the bike taking particular care with the cables and all the various measurements as per the Haynes manual.
After an age trying to start it it eventually fired and promptly backfired and stopped. This scenario was repeated many times with lots of checks being made of the static ignition timing (I fitted a new Boyer unit), pilot circuits, plugs, caps and connections. Eventually it ran and was running on all four but it wouldn't rev past 1500rpm. The worst thing was the way it would just stop dead, no backfiring, no chugging or erratic running beforehand but it just stops dead. It always restarted straight away but would again stop dead from 1500rpm. I did eventually get it running for a couple of minutes before it stopped. I have given up (again) as I cannot figure out what is causing the problem. I cannot dynamically time the ignition as I can't get it to rev to 4500rpm in order to set it.
Does anyone have any ideas of what the issue may be?
I have a new Boyer, new non resister ND plugs, new resister plug caps, new leads , Ash overhauled the ignition coils, New wiring loom, the carbs have been apart three times, original brassware (cleaned with clock cleaning fluid followed by an ultrasonic bath) new gaskets and felts. There are no air leaks in the system.
I am at a loss as to why it just stops dead and refuses to rev.
To end a really crap afternoon I discovered the exhaust clamps are going rusty already and I haven't even been out on the bike yet! These were supposed to have been creakoted by the guy who did the powder coating >:(.
Sesman:
A couple of things.
Have you checked the valve clearance? Tight clearances can create severe starting problems and also can stop the motor dead as it warms up.
Have you checked fuel flow. Eg allowed the fuel to flow down stream of the filter and measured the l/m?
I’m only mentioning this as you have checked the static timing (which is normally sufficiently accurate) and you have triple checked the carbs, presumably including the passageways downstream of the jets. Have you tried squirting a quality carb cleaner through these systematically. Eg blocking the common routes to ensure the passageways are blown through individually?
Oh and one last thing. I’m unclear on the bikes history, but have you checked the valve timing?
Hope this helps.
K2-K6:
Something worth checking is how the static timing is set on the Boyer.
I helped another forum member a while back on a 400 snd both of us didn't understand/interpret the initial setup correctly.
Its odd because its effectively set at full advance static as its pulse cannot be "advanced" from a static position until the pulse arrives, if that makes sense . that's in comparison to a mechanical advance mech.
What this system does is set at full advance, then as it cranks initially it can see it's low rpm from internal pulse count. From that it retards the low speed ignition event, then works back towards it's fixed total advance in software to run at that level above a set point.
Thing is, I can't remember the wording on their instructions to say how we eventually viewed it to get correct starting setup.
Have you got a picture of Boyer instructions Dave ?
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