Yeah I know what you mean but I didn't get any rpm response at all the last time I tried. A couple of possibilities pop up, #1 was that I didn't have the tach/speedo assembly hooked up so I had no clue what my idle speed was and being I had the multimeter tach hooked up to the neg side of the coil rather than the tach lead, I couldn't tell what exactly the engine was idling at either. #2 I didn't have the air box/filter assembly on either, whether that played a role I don't know yet. However the engine was responding to the pilot screw adj, it just didn't do it in a way I expected it to. The reason I could tell was how snappy or lack of it the throttle was. The initial 1 1/2 turns out which is what the manual says you should start at (at least that's what mine says) was lean and 2 turns was too rich but the 1 3/4 that I left then at the last time seems pretty close. Also the manual says nothing about using a vacuum gauge to set the pilot screws but I have a nephew that has worked on bikes all his life and is currently a shop manager for a Honda shop so he knows CBR's like the back of his hand. Problem is he's very hard to get a hold of and doesn't reply to text messages very often. I asked him about the procedure and the way he described it was for a seasoned pro and not for a week end warrior doityourselfer like me and his method relied soley on his ears listening to what the engine was doing along with a vacuum gauge. He's actually never used a tach for tuning pilot screws which is why he didn't have an answer for me when I asked him about how to hook up the multimeter tach because he's never used one. Not what I wanted to hear.

When I try it again this weekend I'm going to stick with the procedure described in the manual using the tach/multimeter but I'm going to have a vacuum gauge hooked up on the carb I'm adjusting to see that if I notice a change in the vacuum reading, will I also see a change in the tach or visa versa. Yeah I'm not crazy either for spending $60 for a tool I may not have needed but it is a good multimeter and I've got 2 other bikes I can use it on.

 

For pilot screws you need a tachometer, you can use your vacuum gauge to sync the carbs.

 

Ok, guys, there are several picture posts on carb syncing in the how-to's.
Ya'll sound like you're having a hard time with this. It's not hard if you follow
the correct procedure and use the right tools.

If you have re-built/cleaned your carbs, you set all of the mains to 1 1/2 to 2
turns out, after GENTLY seating them. Put them back on the bike. Be sure
that they are properly seated in the boots and that the clamps are tight to both the carbs and head. You don't want air leaks any where.

After mounting the carbs, COMPLETELY assemble all hoses, ducting and airbox.
If it isn't drawing air the way the bike will be driven, the results are meaningless.

The first tools you use next are a vacume guage and a long reach phillips screwdriver.
You use that to reach between the carbs to get to the adjusting screws. There won't be a screw for the base carberator, there will only be 3 adjusters.

If I remember correctly, the #2 is the carb that you sync to. The cylinders are numbered, left to right, 1-2-3-4. Hook up the guages to all of the cylinders. All of
the adjustment is to bring 1-2-4 to match 3. Be sure to snap the throttle as you are
making the adjustments to be sure it is stable.

If you have a F3, the #1 cylinder has a 5mmx10 screw instead of a vacume port.
Don't ask me why, I think Honda screwed the call on that one (imo). You'll have
to get one for $3.88 at your dealer, if the adapter doesn't come with your guages.

Once you have done that, THEN you adjust the main jets/idle. That is where you use
the tach and a long-shafted right-angle adjuster with the proper tip for your main jets.
Be sure the bike is at normal operating temperature when you do this part.

Look up pilot screw adjustment/ idle adjustment to get you throught the rest.

I hope this helps, Ern

 

No offense but you're not getting what I'm saying. At the moment no rpm response is happening when adjusting the pilot screws so the tach isn't serving it's purpose and I'm in the process of figuring out why. Now that I know how to hook the tach/multimeter correctly to get an accurate rpm reading I now will be able to set my idle speed correctly and maybe that's why it didn't respond the last time because I was simply guessing the idle rpm and I'll find out this weekend. I agree that using a vacuum gauge may be a waste of time but I still want one handy to maybe try the method my nephew described. He is a professional at this so I tend to listen and at least consider what he's saying because I'm open to all opinions.

 

Bingo, I didn't have the airbox/filter in place plus double checking to make sure the boots are sealed wouldn't hurt. Oh and it's the #3 carb that you sync the others to not the #2.

Don't us newbies drive you crazy? Thanks for the input.

 

I think the point that Ern is making here is you have to have everything else done first, then the idle mixture adjustment is the last thing you do. Now, that being said, you really have to be patient when making these adjustments. 50 RPM is really hard to see. What I mean by that is your engine is going to be fluctuating up and down a bit just sitting there. The challenge is being able to see the increase or decrease in engine speed as an average of the fluctuations. Once you see it happening on the tachometer, you'll know what I mean. Good luck with your adjustments and let us know how it goes.

 

That's fantastic info because I think that's where I'm screwing up. My kids previous vf500 was very responsive to its idle when adjusting the pilot screws and the rpm drop or increase was easy to notice so naturally I was expecting a similar response from the cbr. However I'm beginning to realize that even though the carbs on the cbr and vf500 are both CV carbs, that's where the similarity ends and the response I'm used to expecting is much more subtle on the cbr. I think I'm also going to wait till I get the special 90 deg adj tool as well because the one I have is an old snap-on tool that I've had for about 25 years used for tuning idle mixture screws on cars and it's 90 deg bend has too much of a radius to work as well as I'd like it to and just isn't compact enough for tuning motorcycle carbs. Thanks to you experienced guys for being patient with us newbs.

 

I also just ordered a right angle screw driver so I can do the job correctly, might as well do it right the first time. Tach comes in the mail tomorrow.

 

A lot of Gd info in this thread. I'll def be purchasing that harmonizer tool.

 

Ok now, today I'm going to start build my own manometer, but I'm confused.

Now I have these parts;

30' .170 clear tube, 2 T connector, 3'x1' wood and automatic transmission fluid. And I think I need an adapter. Is that good for that? Motion Pro Vacuum Adapter Intake 5mm Neck 08-0218 Honda | eBay

Do I need something else?