TOPIC:

Edit : Changed the subject of this thread because the valve clearance question has been answered, but I also brought up some other issues and wanted to stay with this thread because of the good info so far.

You can probably just start reading at post #604401, that's the 12th post in this thread. That will get you past all the valve stuff.

Ok guys, time for me to check the valve clearances on my bike for the first time since I have owned it. Bike has 11,650 miles, 1977 KZ1000 LTD.

Readings are in MM (shim size present)....

#1 Intake .08 (2.70) Exhaust .15 (2.45)
#2 Intake .11 (2.55) Exhaust .15 (2.65)
#3 Intake .08 (2.65) Exhaust .17 (2.65)
#4 Intake .08 (2.60) Exhaust .13 (2.65)

Book says .05-.10 is spec. But from searches I find a lot of guys seem to be comfortable with the exhaust set to .15, so that only leaves #3 exhaust outside those specs. Opinions? Should I run it like it is or go by the book and get all my clearances between .05-.10? Pipe #3 does take longer to get to temp then the others. 1,2 and 4 are too hot to touch almost right away, 3 stays cool enough to touch for considerably longer.

Bike is on stock airbox with one size over stock on main and pilot jets. (I live at sea level) Mileage is 33+ on this setup over the last 2 tanks. Bike will idle at 500rpm when warm, starts very easily. Has a bad hesitation when going from idle to WOT quickly. Will bog down and just go completely flat until I let off a little and then will jump to life. Still have to do some messing around to get that problem solved but want to be sure valve clearances are good before going further. Carbs have been cleaned and bench synced only, dont have a set of vacuum gauges yet. New carb holders/boots installed. Still on points, coils powered with relay.

Seems to be running great besides that huge bog if I twist the throttle too fast from a 1/4 or less throttle position to WOT. I don't know how much of that is a problem or if that's a normal thing for slide carbs? This is my first bike so I don't really have any reference to compare it to.

But first things first....valve clearances....?

Set all those clearances as close to 0.15mm as possible.
0.5 to 0.10 was quoted for the early 900s but was soon widened across the range to 0.15mm

Oh! and your 0.17mm on number 3 shouldn't be a problem as it's common to run as wide as 0.18 on fast motors you just might notice a touch more ticking till it gets hot.

Stock airbox + stock pipes = stock jetting, no matter what altitude you are living. Drop down a size on the mains and pilots. Check the heights on the needles.

74ullc wrote: Ok guys, time for me to check the valve clearances on my bike for the first time since I have owned it. Bike has 11,650 miles, 1977 KZ1000 LTD.

Readings are in MM (shim size present)....

#1 Intake .08 (2.70) Exhaust .15 (2.45)
#2 Intake .11 (2.55) Exhaust .15 (2.65)
#3 Intake .08 (2.65) Exhaust .17 (2.65)
#4 Intake .08 (2.60) Exhaust .13 (2.65)

Book says .05-.10 is spec. But from searches I find a lot of guys seem to be comfortable with the exhaust set to .15, so that only leaves #3 exhaust outside those specs. Opinions? Should I run it like it is or go by the book and get all my clearances between .05-.10? Pipe #3 does take longer to get to temp then the others. 1,2 and 4 are too hot to touch almost right away, 3 stays cool enough to touch for considerably longer.

Bike is on stock airbox with one size over stock on main and pilot jets. (I live at sea level) Mileage is 33+ on this setup over the last 2 tanks. Bike will idle at 500rpm when warm, starts very easily. Has a bad hesitation when going from idle to WOT quickly. Will bog down and just go completely flat until I let off a little and then will jump to life. Still have to do some messing around to get that problem solved but want to be sure valve clearances are good before going further. Carbs have been cleaned and bench synced only, dont have a set of vacuum gauges yet. New carb holders/boots installed. Still on points, coils powered with relay.

Seems to be running great besides that huge bog if I twist the throttle too fast from a 1/4 or less throttle position to WOT. I don't know how much of that is a problem or if that's a normal thing for slide carbs? This is my first bike so I don't really have any reference to compare it to.

But first things first....valve clearances....?

Would go to 2.70 shim in #3 exhaust valve, and ride.

The .17 mm #3 exhaust valve clearance isn't causing the combustion issue in #3 cylinder, imo.

Sooty spark plug readings would tend to confirm suspected over-rich (for whatever reason) carb pilot circuit as possible cause for the reported hesitation and bog-down.

Carb sync might have a minor influence on the hesitation and bog, but usually relates mostly to achieving smooth performance at lower rpm and helping to produce a smooth strong normal pull-away from idle.

Would perform the clear tube test on each carb to assure that fuel levels are within spec (especially on #3 carbn).

Would also adjust the pilot mixture screw in #3 carb to provide a slightly leaner air-fuel mixture -- say 1/2 turn IN, and then test run.

What are the spark plug readings?

Is the air filter clean and unobstructed?

What exhaust system is fitted?

Good Fortune!

Mcdroid wrote: Stock airbox + stock pipes = stock jetting, no matter what altitude you are living. Drop down a size on the mains and pilots. Check the heights on the needles.

+1

It's possible that larger jets were fitted in the past along with a freer flowing exhaust system, and stock exhaust later re-fitted without returning to the stock jet sizes.

Good Fortune!

Bike has stock exhaust and now finally stock airbox, but I am missing the silencer. Bike had pods when I got it.

I went back to the stock airbox but went one size over stock jets in the carbs. Running 17.5 pilot and 107.5 main now. Needles in middle (stock) position. Fuel screws set to highest idle as per shop manual.

Air filter is bran new from Z1E.

NGK B7ES spark plugs installed, just checked the book and it says NGK B8ES so looks like I have the wrong plugs. I'm kicking myself right now for not checking the plugs. PO told me he had just installed them when I was buying he bike. Every single thing he touched on the bike was wrong, I mean EVERY single thing, so I'm not surprised, just disappointed in myself for not checking them sooner.

Cylinders 2,3,4 have stock plug boots installed, #1 has one that says Nichiwa LB05F.

I did do the clear tube method to set the fuel level but it wouldn't hurt to recheck if I end up pulling the carbs back off.

Do you want to see the spark plugs after idling (with a strong fan on the motor) for about 5 minutes? Not sure I'm up for a 3-5 minute run at WOT on this bike for a throttle chop. Too fast for me!

Mcdroid wrote: Stock airbox + stock pipes = stock jetting, no matter what altitude you are living. Drop down a size on the mains and pilots. Check the heights on the needles.

I have to say you know what you're talking about since you only live 30 miles from me. I live in Richwood.

Any chance, when I get my KZ back on the road, of making a trip over to see those GPz's? I ride thru Danbury all the time. The ride between Liverpool and Danbury is my favorite around here.

Missing air box silencer won't matter insofar as engine performance is concerned.

Could defer spark plug reading until after a tankful of normal riding with NGKB8ES spark plugs.

Would visually inspect spark quality on the new plugs, looking for fat blue spark when cranking over the engine.
Acceptable spark quality provides some indication that the caps and wires are probably okay.

Clear tube tests may be performed with carbs installed in normal position on fully assembled bike on center stand or balanced upright.

Good Fortune!

As suggested by Mcdroid, would assure the jet needle clips are in stock position, which for the carbs at hand is the middle clip position.

A previous owner may have ill-advisedly lowered the clip (raised the needle), which could in and of itself contribute to the hesitation and bogging.

Good Fortune!

Jet needle clips are in stock (middle) position.

I got some of the correct plugs, NGKB8ES, and will check for a fat blue spark with these new plugs.

I previously set the fuel level to 1/8" below the carb body using the clear tube method but will recheck. I'll also recheck the mix screws once the valve cover is back on and bike is running. I will try going 1/2 turn in (leaner) on carb #3 first and see how it runs.

Bike is up and running again. I completely forgot to check the spark with the new plugs before riding it, I'll check after the first tank full when I pull them to check color.

I checked my fuel screws and they were #1 1.5 turns, #2 1.75 turns, #3 2.5 turns, #4 2.5 turns. I put them all back to 1 turn, book says 1 +- 1/4 turn. I'm not really sure if I set them there or if they moved. The springs are in place, they are new fuel screws from Z1 as my originals had been bent/broken by the PO. I set them using the highest idle method but my buddy was sitting on the bike and I was not watching the tach, he was. Maybe he misunderstood what was going on as I was adjusting the screws.

Anyways, the bike is running better with the screws 1 turn out. I noticed that gear changes are smoother and the bike isn't chugging along thru the very low speed turns like it was. Acceleration from a stop is much smoother too.

I do still have the bogging down when I go very quickly to WOT from low RPM's. Betting I'm going to have to go back to stock jetting to get that responsiveness where it should be.

That and a vacuum sync and I bet this bike will finally be right again! I know I'm getting very close, its sure come a LONG way from when I got it.

Ok guys. I am now back to stock jetting in the carbs. 105 mains and 15 pilots. Needle in middle (stock) location. Mix screws 1 turn out and carbs still just bench synced.

The bike still seems to be running rich at WOT. Not as bad as before with 1 size over on jetting, but still seems rich. I am still getting a bog/hesitation in the mid RPM's. When in a high gear at low RPM's (3,000 or so) if the throttle is moved from almost closed to WOT the engine will just bog down. I know the correct thing to do would be to down shift to get up in the RPM's but I don't think it's normal for the engine to bog like that.

Let off the throttle and slowly roll in and it works thru to about 5k or so then it pulls hard. It's not like it's cutting out or anything, its just like you can tell its not giving all it should be. It pulls harder at 1/2 - 3/4 throttle than at WOT in that bad area.

Could this still be a carb problem or do I need to start looking elsewhere?

I have not gone thru a full tank of gas with the stock jets so I cannot report on MPG yet.

Fuel level dead on 3mm confirmed with clear tube method, all 4 carbs are dead even. Tested with carbs on level work bench using 70% isopropyl rubbing alcohol.

The manual says that at full throttle openings an overly rich condition could be caused by clogging of the air jet, its air passage, or the air holes in the bleed pipe; by needle jet or needle wear (increasing clearance); by a loose main jet; or by a loose bleed pipe.

I can rule out the loose jet/bleed pipe for sure. Air holes in bleed pipe are clean. I would like to rule out the clogged air jet/passage but cannot be 100% sure its spotless. I have cleaned it and it seems clean....but how can you ever be 100% sure its spotless. I have followed the diagrams posted on this site, blocking off certain ports and spraying cleaner thru others followed by compressed air and all seems good.

The needles do not show any wear like I have seen photos of, flat spots, rub spots. But what about the needle jet? Can they be removed from the carbs? (VM26SS)

Could it somehow be possible that I need to go a size under stock on the mains? I live at sea level but the density altitude has been 1,800-2,100 ft the times I have ridden it recently. Its very hot/humid here in August.

Do I need to look elsewhere? Ignition system? I still have points, I think the PO installed the complete points plate from Z1E, he told me he did and it all looks new. I have set point gap and timing but its been almost 1,000 miles ago. I do still have stock coils. Plug wires look to be original also.

What about the advancer? I have never taken it off. I did verify it was advancing with a timing light when I set the points. Should I just take it off and verify its clean and arms moving freely? Could the advancer have this affect on performance? Again, once it gets up past 5K RPM's it pulls hard. Should be at full advance by 2,500 RPM's. I did verify this with a timing light but its been almost 1,000 miles ago.

Could exhaust leaks at the motor cause problems like this? I am pretty sure I have exhaust leaks on at least 3 cylinders. I have new gaskets, just haven't installed them yet.

I know I have low voltage to the coils. I am powering them with a relay now. I show under 11 volts to the coils on the stock power wire with battery showing 12.5 volts. I have cleaned most connections and switches. There are a few connections I have not been able to get apart. The white connectors behind the headlight are stuck together. My lights are dim and blinkers are slow to start blinking so I have to get that problem sorted. Battery voltage while running is right on what the book says and battery is new (April) and bike keeps it charged. Getting 14 volts @ 5,000 RPM w/high beam on.

I feel like the bike is almost there but this last bit to get it 100% has been tough. I'm not even sure how much of this is a problem and how much of this is normal for these bikes. Is it true that with slide carbs you can't just open the throttle as fast as possible because you will create a lean condition for a moment until the fuel can catch up? But still, I don't think I should be able to bog the motor down completely by going to WOT while at 3,000 RPM. Plus I think this is a rich condition because the smaller mains seemed to have made the problem a little less severe.

Open to suggestions!