Carbs Carbs Carbs and more Carb... all I want to do is ride

Ok, just got off the phone with dad talking about my carbs. He worked for GM for 33 years mostly with carbs and though they are for cars the principles are the same. I was telling him about my plans to re-jet and why (plugs are very white due to pods and Bub pipes) when I brought up drilling out the adjusting screws to fine tune the mixture. His question to me was why mess with them when they only effect the lower rpm's (idle) and not when the bike is at speed. His thought was if it idles well at 1100 rpm why change the settings? A lean idle setting should not harm the motor, it's running lean at the higher rpm's that causes the harm.

I have my jets from chacal size 24...going to install them today. My thought is after they are in if the plugs are still too white (lean) then I'll go up a size but if they are getting black (rich) then I'll go down a size. According to dad that is all I should do.

Is he correct in this? Makes sense to me though I am not a carb expert by any means.
Could someone please tell me why I would need to go through drilling out the adjustment screw caps and mess with the idle mixture? And why did I buy a colortune plug if all it can do is give me a picture of the air fuel mixture at idle and not under load at higher rpm's?

Thanks

 

You bought the ColorTune so you could adjust the Pilot screws under those pesky caps that you will now be drilling.
As soon as the bit just touches thru, you stop!! so go slow!! Then you pick the cap out with a nail or (gee) a pick.
You have to remove the Pilot screws to completely clean the carbs anyway.
The 124 jets should make it rich enough unless you have Absolutely No muffler.

 

I think the best thing to do from what I gather is to do a Plug Chop. The color tune is to only set your idle if its off a bit. Like, after rejetting! After you get new jets the airflow thereafter changes. So you gotta fine tune your carbs with the engine after rejetting. Use the colortune, and then go on to a plug chop to find out what your plugs are doing at a high RPM
-SLKid

 

Have trust in the old man. He's right. If you're bike not fouling the plugs at idle and idles fine for ages then don't mess with the idle mixture. Maybe at one day you will realize that she's running hot at idle and you will think to change the idle mixture but if she's fine, then leave it alone and concentrate on the main jets (along with the main air jets) only.

 

The valve clearances in an engine affect the fuel-air draw and combustion process in the cylinders, which affects the amount of vacuum draw, which loops back and affects all the above issues.

Your valve clearances are not and will never again be exactly the same as when the bike left the factory----never mind all the other wear issues (rings, pistons, carbon deposits on the combustion chamber surfaces, etc.) and it doesn't even matter if you check and adjust your valve clearances back to within the specified RANGES (which you should do!), the clearances will never be the same, on all 8 valves, as when the bike was new. AND THE MIXTURE SCREWS WERE ADJUSTED TO THOSE ORIGINAL CLEARANCES (and other characteristics) which have now changed, and thus, so do the mixture screw settings.

If you want your bike to perform properly, that is.

By the way, all of the above is why you don't "SYNCH THE CARBS", you "SYNCH" the entire engine to run properly to itself. It's just that the carb butterfly valve openings is the only EASY (but not "the only") way to synch the power output of each cylinder to all the rest.

Although the pilot circuit is involved primarily in idle and off-idle conditions, it's influence is felt all the way up to about 2,500-3,000 rpms. You can't build a skyscraper straight if the foundation is crooked.

Some people sometimes get all caught up, unknowingly, in doing things the hard way----and here, just to clarify, the "hard way" is to IGNORE THE FUNDAMENTAL BASICS AND MOVE STRAIGHT INTO ALL THE "FANCY" HIGH-FALUTIN STUFF FIRST.

To those people, I guess tinkering is more fun than having a well-running bike.......but I think most people would prefer the riding!

1) Check and adjust your valve clearances.
2) Make sure your carbs and intake system is leak-free an "zestfully clean".
3) Synch, adjust the mixture screws, synch again, adjust screws again, etc. 2-4 times.

Your engine now runs as good as it's going to. If your insulators are white, only now do you start re-jetting and plug chopping and etc.

 

Best piece of advice I have read in a while! ^^^