SOHC.co.uk Forums > CB500/550
CB550 K3 custom project
thomaspigeon:
Hello everyone,
I bought this 550 K3 in parts and putted it back together.
I’ve redone the wiring, got a spark (electronic ignition). But I guess I can have the timing wrong.
I’ve got the carbs ultrasonic cleaned, I change most of the bits inside apart of the needle. Carbs were overflowing with the float at 22mm so I putted them at 24mm (weird?!). Also those carbs are from a 550 f1 weirdly.
The engine was in 1 piece and the previous owner told me it was running.
So I’m guessing the carbs are messing around, how can I be sure some fuel is running into the engine ? Also maybe the spark is not strong enough or wrongly timed...
I’ve got a video that you’ll find below.
https://youtu.be/W0aizX9RmVA
Let me know what your thoughts are.
Thanks
Tom
Nurse Julie:
Hello Tom and welcome to the Forum. You would stand half a chance of it firing up if you fit the air box, air filter etc. These engines need some back pressure to function properly. I'm intreagued at the filter you have on the Breather cover, a rubber tube is what is normally fitted there😁😁😁
Also, the floats need to be set at 22mm.
McCabe-Thiele (Ted):
As has been said put the air box & filter in place - it reduces the fire risk from a backfire.Even if you have the ignition timing 180 deg wrong the plugs will be wet after cranking that will tell you fuel is getting through imho.
I assume you know there is some compression?
Likewise did you test for spark at the plugs?
Fuel, spark, compression ignition timing at the right cylinder - it's got to run in some sort of fashion.
thomaspigeon:
Thanks for your quick reply everyone! I'll have to try all of this tomorrow.
About the height of the float, how do you mesure it? Carb upside down with the float sitting on? It looks like the floats are getting stuck open very easily.
The previous owner took off the airbox and removed the brackets of the bike, so that will run on pods (I know, not ideal). I'm waiting for some K&Ns but I still have the previous cheap chinese pods, that should do for starting it.
I'll test the compression, and I'll have a look if I have a spark on all the plugs. I know that I have a spark on the cylinder #4. Also as I said, the engine should be a runner.
@nurse Julie , the little pod is to avoid the oil to get straight out I believe...
Tom
Nurse Julie:
Here is a guide on how to set float heights on your carbs Tom.
http://www.sohc.co.uk/index.php/topic,23233.0.html
The Breather cover on top of the engine that you have the filter attached to, is just a vent, no oil should come out of it (as there is no oil up that high on the engine) it just let's out fumes from the engine.
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