Topic: '71 CB500K jetting for pods and stock 4 into 1?

[Snoefy]

I have a '72 CB500K, which came with a 4 into 1 exhaust and some paper/mesh pods (Emgo?)... And, yes, I'm looking to replace with K&N or UNI's.
Current jetting is 42 and 110 secondary.

Let me know your thoughts.

[calj737]

110 sounds large. What 4:1 exhaust? If its a Mac brand, these typically don't offer much improvement or need for tuning changes. The pods will. Many find 105 with a needle clip change to richer by 1 slot and some air screw changes perform the "best" for this type of change. It will always be less than ideal compared to the stock airbox though.

[Snoefy]

What 4:1 exhaust?

Not sure, doesn't look to be a Mac. I haven't had any luck identifying the exhaust.
Here's a link to view the exhaust side of the motorcycle: https://drive.google.com/open?id=1oyL6c9BtnorGbltlMdRuyBC91Nr3v-Cn

Thank you for pointing out the 110 may be too high, I'll buy one size down.
Are 42's the correct mains? (or as close as it gets with pods).

[calj737]

I'd say Kerker off the top of my head. Hard to know exactly.

For the pilots, normally folks run stock sizes (which depending upon model of carb and country could be as low as 38s). Typically, stock idle is on the rich side for warming up the engine and dealing with "cold starts". Pods don't heavily influence idle mixtures because there's not yet enough vacuum to generate a lot of difference. Once you get into the throttle range, that's where they lean out the mixture noticeably.

The downside of too large a pilot is fouled plugs and bad stumbles off idle. Check your carb model, and the parts fiche for your country code, and go from there is my recommendation.

[Bankerdanny]

If it is a Kerker then the name will be engraved/stamped on the bracket that attaches it to the peg loop.

[Gurp]

I would go 38 and 105.
As previously mentioned pods are not a huge difference at idle. Although you will notice differences starting the bike and warming up. 110 is a bit large for mains.

[seanbarney41]

That is a MAC exhaust system

[Snoefy]

Went with #40 and #105 and stock setting mixture screws.. but now I'm getting a really big exhaust blow back and popping noise when trying to start (I haven't been able to start her up yet). The blow back startled me quite a bit and now I'm a bit confused on why it's happening. Rather now keep trying and risk breaking something.
Does it mean the mixture is too lean?

[calj737]

Sounds like you might have reversed the coil wires/plug wires? LH coil serves 1/4 cylinder with BLUE ignition wire, RH coil 2/3 with YELLOW wire.

[Snoefy]

Sounds like you might have reversed the coil wires/plug wires

Hmm, I think you may be right. Without looking at my motorcycle I think I did 1/3 and 2/4 - Hopefully no permanent damage! And hopefully you're right and this solves everything 

[Snoefy]

Thanks again for that suggestion, my green-self didn't check them after taking them off to check the valves.

Now, I'm back to square one as the idle dies without throttle.

[TwoTired]

Are all the head pipes getting equally hot?

Cheers,

[Snoefy]

Not sure, haven't checked the pipes since rejetting down from #42 to #40.
Is it to make sure all 4 carbs are functioning properly?

[TwoTired]

Checking head pipe temp (relational) tells you which cylinders are firing and how even they are among them.  If  unevenness is caused by carbs, the throttle position determines which jet is dominant for mixture control. This can also be a slide position issue related to carb balance.

Head pipe temps are another informational tool to help diagnose the proplem cause.  If you had enough information, you'd know just what to fix, right?

Have you bench synced or vacuum balanced the carbs?
Have you accomplished the entire tune up procedure prior to carb meddling?
Have you looked at spark plug deposits to determine what's happening in the combustion chambers?

Cheers,

[Scott S]

 How are you using the choke lever?

[Snoefy]

The further I open the choke the faster she dies off. I was unable to move the needle height as the screws were stripped, I was able to open a single one that had the needle placed on the 4th ring (highest/top) setting.

I bench synced prior to this last mount.
I can't remove the spark plugs as I don't have the tool for it, unfortunately.

[calj737]

Until such time as you can remedy the spark plug removal and stripped screws, you would be wise to measure the fuel level in the carbs with the Clear Tube level to verify what is actually going on.

[Scott S]

 By open, do you mean move the lever horizontally or push down on it?

[Snoefy]

Drain holes are impossible to unscrew - I'm stripping the screw trying to remove it, which may make it impossible to place back in..

Choke - by open I mean pulling it up horizontal to apply the choke, it's closed (not being used) when it is vertical on mine.

[TwoTired]

Look closely on the markings on the lever.

Lever up, choke on/ closed.  Lever down choke off/ open.

The throat butterflies are mounted at a 90 degree angle from lever angle.

For the drain screws, you'll need to fit the proper size driver to get good screw head engagement.  That's why they make different screw driver sizes.

Cheers,