Spark plugs are actually read at the base of the porcelain and by doing a plug chop at the rpm that you wish to evaluate. 7000rpm would not be on the main jet. Main jet is when the tach is well and truly in the red zone. http://www.crankshaftcoalition.com/wiki/Reading_spark_plugs
Right so I do have to do a plug chop. Ok well I replaced the main because it wouldn't rev above 5k so now that issue is fixed I probably need not investigate any further then, as I'm not going to getting anywhere near the redline in practical use. You read them at the base of the porcelain? That's at odds with what's described at the website you linked isn't it? Ultimately, can anyone help surmise from those plugs whether I am really lean or just slightly lean at idle? The discolouration of the thread base would have be believe the mixture is ok, but there's no soot on the threads where there is on the porcelain so I'm kind of confused.
I do not see it as at odds with the article. I have never heard of someone setting idle mixture by looking at the spark plugs. I do them by ear https://2fiftycc.com/index.php?threads/setting-pilot-mixture-by-ear.8374/ and there are many other ways to achieve the same thing.
Ok, I was just going by this picture that I could ascertain the idle mixture: http://www.crankshaftcoalition.com/wiki/File:3.jpg
and I was going by your statement "Ok so brand new plugs and the result after a couple of power runs to 7k:" So I assumed you were tuning for main jet. We just had crossed wires. It is very difficult to tune CV carbs for pod filters. Please read this. http://www.litetek.co/docs/InSearchOfFreeLunch.pdf
Right, yes, for mains alone you read the base of the porcelain, we agree on that! I was then seeking some help with determining if the idle circuit was lean/rich/okay. It was painful (in terms of noise levels and emotionally) to rev her to 7k alone so I definitely won't be running off the mains very often I don't expect! Yeah I understand, but it's not impossible - I'm not seeking perfection. Just don't want to run so lean as I damage the engine.
dont worry to much about the idle circuit...really cant hurt if its a little lean or rich..its the high load/rpm lean runs that hurt If the bike idles evenly and is not hunting(rich) or dyeing when you back of on the gas(lean) its should be close...The engine is just sipping the air at idle and carbs are so insufficient (especially when old)anyways
So the main's sound ok, Just make sure the mixture screw's are set up right with no hesitation/stumble off idle, as that can make thing's scary when you're taking off in front of a car or merging in traffic and the bike doesn't want to move
Hi guys, now I've had the bike running ok for a while I'm putting more time into restoring her... cleaning up the frame, new seat, fixing wiring, more painting, etc. Currently rebuilding the carbs and I've found I seem to be missing some o-rings. The manual shows an o-ring on the silver cylinder thingo (4) which both my carbs lack: Manual: My carbs: I can't find it these o-rings depicted on any drawings though. Am I indeed missing required o-rings? If so can anyone help me with a part number? Thanks! PS: I found my engine oil was full of fuel hence the carb rebuild =/
There's a bit of an impression on the gasket from when it has been pressed into place, against that hole. Can't see any residue from a previous o-ring on the gasket. Hmmm I wonder if it's part 22... I was looking at a different drawing which this wasn't present on
Yes, it's 22, but more importantly, what is the point of that O-ring? What's that area linked to that it requires an O-ring to seal it?
If I take out the silver cylinder the hole runs straight into the venturi (venturi?) - the main air tube through the carb. On the bowl is nothing!
That silver disc look's like a plug that cover's the pilot circuit port/s. There might be a hole that run's across the carby body to connect it to the pilot jet? On the inside of the carby bore are there any tiny hole's that line up with the silver plug on the bowl side? If this hole/s is slightly blocked with gum etc it's be hard to get the mixture screw set right, and will be slightly lean off idle
Looks like there may have been something there at some stage. It looks like it's squashed into the bowl.
Well I've ordered part 22, whether it makes a difference or not will be found out shortly. Dont think it could be causing a rich condition safe to say. Found my needle valve o-rings were leaking so gotta replace those too.
Yeah looking at it again I see that now. Bike was running fine(ish) without it but will try a couple of 13374-35C00 anyway!