Horrible rebuild results!?

I'm thinking it is to rich and you may be fouling a plug or two. The step up in the pilot jet will cause a lot more fuel to be sucked through the low speed circuit, as you let go of the throttle at higher rpm you get huge manifold vacuum pulling through the slow circuit. Just think about dropping these jets back down and limiting your riding to below 1/2 throttle, then check your plugs, if there is no lean hesitation and the plugs are now just a light brown move onto the next circuit. Read the tuning manual even if your carb's are different, the tuning process is the same.

Old Man Rock, I will read that!

Motorhead, I didn't do anything with the pilot circuit. Left the stock jets in and 2 turns out. Seems to idle just fine.

The biggest of the problems is the rev up that won't drop back. Happens anytime I rev it up past 1500rpms or so. I have watched the linkage as this happens, and the linkage is returning to idle when I release the throttle, yet the rpm stays up. I have traced the cable and no kinks found, works smooth. I also inspected the carb boots and could see no external air leaks. Caps are where they should be and so on. It was mentioned that a carb diaphram might be torn? Would that result in a racing idle? I agree that it is running a tad rich and I may have to rejet, but it runs quite smooth now and then, so I think this is something else.

Sorry but read in the fist post that #60 went up to #72? You called all of the jets "Mains". I believe that if a slide had a torn diaphragm, that the slide would be very slow to lift up, not return. Now you may have 1 binding up in the carb bore, that could cause a poor take off for sure, but the high Idle most likely not as the main butterfly should still be shut. Try the well known method of checking for air/ vacuum leaks around the intakes, and make sure that your ignition advance is returning smoothly. Post up some pic's of the spark plugs so we all can see the color.

Old Man Rock wrote:

:whistle: :huh: :dry: :whistle:

kzrider.com/index.php?option=com_docman&...d&gid=461&Itemid=108

That pdf has the Keihin carbs covered too. He just highlighted Mikuni

I'm not familiar with it happening every other time....but that horrible take off (boggging down and no power) and the high idle, was what happened to my kz400 when it had a torn diaphram (same CV34 carbs). If you run out of stuff to look for you might take a stubby phillips head screw driver and a mirror to see if you can look at the diaphrams without pulling the carbs. Check especially around the seal, splits like to hide there.

Good luck!

Motor Head, right. The Keihin CV34's have two main jets, the primary and secondary. The pilot jet is a third jet, which I have not changed. So you think that a torn diaphram would have a limited idle rev effect, and Link14 says it had a strong effect on his. Makes deciding what to do a bit confusing, but I think a carb rebuild is probably in order.

The ignition advance is working fine, and spraying around the intakes had no effect, so if it's a vacuum leak, I haven't found it yet. I'll post a plug pic shortly.

Doug... there's a whole slew of good information there...
Wasn't truly implying you weren't reading it... more for that big lug of a Canadian who refuses to learn the correct way.... :blush:

Then again, he only got through the 5th grade so big words are hard for him..... :whistle:

You have carb theory 101 that is just what it is. Each manufacturer may accomplish mechanically a little different but the principles are the same...

The trouble shooting guide informs you of the symptoms and most likely cause. Again, regardless of the exact name or part, the principle still applies whether it's a Mikuni or Keihin carb.

Regardless of manufacturer, jetting for the most part is the same... Pilots or slow jets, Needle and clip positions and Mains... Pretty much all carbs have them and they cover the same principles of operations...

Now the best info there is what was given to me from Larry... "How to Red Spark Plugs Correctly".... That tells you a whole slew of information from those 3 little reviews...

Good luck keep us informed how it turns out for you....

I am wondering if your float jet isn't getting suck or not flowing enough fuel. Something that would cause the float bowl to fill too slowly. That would cause you to be starved for fuel but only after long steady runs. Just a thought.

check your throttle cable make sure the idle screw is returning to position, if the cable is in a bind or catching this could be an issue,

your running way too fat on your jetting for just pods and a header and a stock motor.
on the plus side, you will never have a mosquito problem when you start the bike :laugh:

did you seal the intakes at all?
there cheap enough to replace from z1.you should do that first.
old intakes may look good but i have seen them have a vacuum leak way too many times.
cheap fix is get some right stuff rtv and skim coat them. put them on and let them set overnight.
check every vacuum plug on the intake boots and carbs as well.
old brittle ass boots always leak.

btw, did them rings work?
you have good compression with them?

Yes, the idle screw and linkage is fully returning when I let the grip loose. No binds and seems very smooth.

kawsakiman, I ended up only using about three of the rings. One to replace the second ring on #3 that I broke, and two others to replace rings that I didn't like the look of. Also honed the cylinders. Haven't seen any smoke (except for a few minutes at the very first startup), but because of the above problem I haven't been able to run it very long either.

Yea, I had this rev problem before, so I sealed the carb boots with Moto 1, both at the head flange and around the throats of the carbs, and while idling and running in the garage (before the initial street run) I did NOT have the rev problem anymore! So that worked...at least for a while. It only returned during the initial street run where I encountered the above problems (almost as if maybe some of the sealant had cracked-but I can't see that anywhere).

I have noticed that cylinder #4 has a wet plug and is wet inside. Doesn't smell like gas or oil, but is probably oil. Of course the rings haven't seated yet, but that plug may be fouled. Still doesn't explain the rev problem though. I'll be pulling the carbs back off tomorrow, and checking diaprams and possible dirt or leaks.

Here's the bike by the way.....

Well, I read Old Man Rock's carb pages. Very interesting, but didn't see anything that related to the revving problem. Started taking the carbs apart today. Checked the float bowl levels and all are good. The diaphrams are all good (no holes), and the carbs are surprisingly clean inside. Will fully clean them anyway, and try again.

Yes, I had sealed the carb to head boots, and I don't think they were leaking.
??