Honda-SOHC

That part would never have been available as a spare, but i know i have a crap set of those carbs somewhere and it might have the bits you need, will not be able to look till next saturday unless i wake up real early one afternoon

That'd be great if you could help, its such a frustrating little spring and its all thats stopping my carbs going back on now arghh!

Thanks Bryan, im 90% sure its a plastic shim that fits onto the slider mechanism on carb *2. As theres no sync adjustment on this carb, the linkage which mounts to the throttle spindle is thinner and requires this shim (it fits perfectly, but might just be a big coincidence!)

Hi guys,

Dissasembling the PD46A carbs off my 550K3 and this plastic shim fell out from somewhere. Im not sure how it was fitted or where it came from exactly, can someone help?



Thanks in advance, apologies for the silly question!

Looks like a nice little bike not keen on the pipe though 

Mick

Im 90% sure its a stock exhaust with the silencer chopped off, the tip on the exhaust is held on with 3 self tappers! Not really my cuppa either but does sound quite good in my opinion!

Is it actually a K as on the sidepanel? If it is, and the carbs are original, you're in for a fun time getting them sorted! And they are the most likely cause of the problematic running you described.

Those are indeed 550K3 carbs...

The carbs are PD46A according to the stampings on the body. Are these the right ones for the model year? I've been doing some reading and heard these are the more troublesome carbs due to the emissions targets of the late 70's. Still the same principles though eh, so should be a bit of fun getting it all running proper!

Had some time to play with the bike, started by checking the mixture screws, which were ALL set differently, ranging from 1/4 of a turn out to 3-1/2 turns out! I set them all at 2 turns out and the bike was instantly running smoother, i was able to lower the idle a bit after this, much better!

Got a video of it starting well and running a bit smoother.

https://youtu.be/5ZcM3FnMFEA

A bit more satisfied with that, i decided to take the carbs off and inspect everything, for cleaning and a bit of learning. Not to mention piece of mind after finding all the mixture screws set different.













As you can see, all in need of a good clean up. One of the float covers was held on with sealant, all the floats were different heights and out of spec carb *1 was totally wrong which might explain the fuel flowing out of the airbox drain before.

The needle sliders looked pretty uniform heights bar carb *3 which was quite high in comparison.

So with a deep clean and proper calibration hopefully the bike will be nice and smooth under load!



Invested in a synchroniser, im sure it'll come in handy in the future!



110 and 115 mains, not sure what ones to try first, i think i'll start with the 115's first and work down from that if too rich.

Some individual pod filters are on there way at the moment, that will be fitted when the carbs go back on, so thought id make some jet adjustments while the carbs apart, to give me a starting point! From what i've read so far:

- Start with a high main jet size that pulls strong at WOT, lower the size until WOT becomes too lean, then go up a main jet size
- Adjust needle clip/height setting to imrpove part-throttle performance
- Raise pilot jet size if required
- Plug chops

Does that sound about right? Im learning, and enjoying it so far! I know the pod filters vs. airbox is a trivial topic, i understand that the R&D that went into the box means that its engineered perfectly and pod filters are therefore pointless. Im solely fitting pod filters for aesthetic reasons! If i wanted a fast/high performance bike i wouldnt have bought a 70's Honda! I've read some heated conversations on this subject and just think its pointless to argue, all personal preference really. It'll be quite satisfying to find the right settings and get the bike running as well as it can do.

Cheers

Thanks for the fast response! Appreciated.

Thats good i dont have to split the engine then, it starts great off the starter motor anyway. I think i'll ride it as-is until winter when i'll be taking the engine out to powdercoat the frame, will fix the mechanism with the engine on the bench

Thanks again!