Possible cold-weather starting issues?

[aaronsfen9821]

Hi all, Mia here, first time posting to the forum.

I recently bought a 2000 ZG1000 that has been rather erratic in when she decides to start. The previous owner had the bike under covered outdoor storage for the last eight years, with no draining of the carbs or tanks for the entire time it sat, not running. I installed a fresh battery and am waiting on the engine to run long enough to ride it and warm up the fluids (oil, coolant, final drive) for draining/replacing. I replaced the spark plugs while waiting for my carb rebuild kits to come in the mail.

I damaged the #1 carb body when I over seated the idle mixture screw while taking apart the carburetors for a clean/rebuild. Unable to find a replacement #1 carb body with the additional diaphragm on the side of it (pilot/idle boost circuit maybe?), I ordered a complete set of carburetors with "new carburetor kits installed" from an '89 ZG1000 from marksvintageparts on Ebay that do not appear to have the diaphragm on the side of the #1 carb body. Another unknown is the state of carburetor synchronization; I haven't had it running long enough to be able hook up a manometer to check. Also assuming that the idle mixtures are set properly.

I drained the old fuel from the tank and discovered the petcock assembly to be highly corroded and leaking from the fuel port, vacuum port, and the PRI-ON-RES selector. Until I get the petcock replaced, I am running a 1L bottle as a fuel cell to the carburetors with an in-line shutoff to prevent chance of hydrolocking while the bike sits. The bottle contains clear gas with Seafoam at 2-3oz/gallon. Initially the Seafoam seemed to create leaks in the fuel rails between #1-2 and #3-4, but any fuel leaks have since stopped.

Frustrated with the tightness of the intake side of the engine, wrestling with 24-year-old rubber boots, I ordered dreaded pod filters and removed the cumbersome airbox. I have taken the advice of another pod-user on here and wrapped half of the filter media of each filter with aluminum tape to restrict airflow some and keep the mixture from going too lean. I have the PAIR intake hose blocked off and the crankcase is venting to the atmosphere.

Attempting to start the bike is uneventful with the choke engaged and throttle closed. I can run the starter, 5 secs on 10 secs off, until the battery dies and maybe get 2-3 putters out of her at most. I think I have noticed slightly more response when the temperatures are warmer, with her running for even a minute or two before dying out. Not sure if there's something I can do differently, or if I should just hold out for 60 plus degree weather to get her started?

 

[Bud]

Unless you're a carb tuning kinda guy, I would stay with the stock air box. Be careful with carb cleaner in the gas. If you're not careful it can cause some grief. I've never fixed plugged carbs with something you put in the gas. Hoping you didn't run a bunch of ancient gas through clean carbs. They also don't start easily with a weak battery. Just because it turns over doesn't mean it is getting a good hot spark.

 

[SethInIllinois]

The "choke" circuit on these carbs is actually a bypass enricher circuit that feeds extra fuel and air around the butterflies and slides. If it won't start on them, then you probably need to disassemble the carbs and do a full clean and check if all the circuits, especially the idle and enricher circuits, which are the smallest and usually clog first.

A couple members here have parts stashes and could probably get you a replacement #1 body. Stasch may be one.

Pod filters introduce a lot more problems than they solve, unfortunately, but mostly with running and riding performance. They're unlikely to cause the starting issue you're having. These should start up fine on the enricher circuit with nothing behind the carbs.

New soft airbox boots make carb installation MUUUUUCH easier. A set from murphkits is under $100 and we'll worth it. Unless they are really hard, you are probably fine with the existing carb holders on the head side. They're stiffer to start with, and don't get as hard over time. The trick to carb installation is lubing up the boots with silicone oil or spray, shoving the carbs in, popping them onto the head-side holders, then using a large pick/radiator hose tool to get the airbox boots over the carbs. It's not a fun job, but with new airbox boots, isn't bad.

 

[aaronsfen9821]

I appreciate the advice on places to start with my starting issues. Going to stick with the pods for now, I'm fine with a little tuning to get the most out of them. I spent the evening digging into things for a once over while the weather was nice.

Popped the carbs off the intake boots, pulled the bowls and GEEZ that was a lot of crud. The fuel in the bowls was almost orange with quite a bit of sediment. While I had the bowls removed I installed the new jets from my rebuild kit and cleaned out the orifices with a can of B12. Threw new gaskets on the bowls too for good measure. I did not do anything to the diaphragm side of the carbs FWIW.

Next up-- spark! All the new spark plugs were black and wet, so they got a little brake cleaner to them. While removing the #2 plug I discovered a small spring lodged in the plug well! Probably wasn't getting very good spark with that in there. After cleaning each spark plug and checking for a .65mm gap, I checked for spark. All cylinders are getting good spark, and I made sure the plug wires got a good seat on the plugs.

Fresh fuel in the 1L bottle, charged battery, anddd.... nothing. Not even a sputter. Choke on, choke off, closed throttle, slightly open throttle. She just won't start. Not sure where to go from here.

 

[SethInIllinois]

I appreciate the advice on places to start with my starting issues. Going to stick with the pods for now, I'm fine with a little tuning to get the most out of them. I spent the evening digging into things for a once over while the weather was nice.

Popped the carbs off the intake boots, pulled the bowls and GEEZ that was a lot of crud. The fuel in the bowls was almost orange with quite a bit of sediment. While I had the bowls removed I installed the new jets from my rebuild kit and cleaned out the orifices with a can of B12. Threw new gaskets on the bowls too for good measure. I did not do anything to the diaphragm side of the carbs FWIW.

Next up-- spark! All the new spark plugs were black and wet, so they got a little brake cleaner to them. While removing the #2 plug I discovered a small spring lodged in the plug well! Probably wasn't getting very good spark with that in there. After cleaning each spark plug and checking for a .65mm gap, I checked for spark. All cylinders are getting good spark, and I made sure the plug wires got a good seat on the plugs.

Fresh fuel in the 1L bottle, charged battery, anddd.... nothing. Not even a sputter. Choke on, choke off, closed throttle, slightly open throttle. She just won't start. Not sure where to go from here.

When you had the carbs off, did you confirm you could spray cleaner through all the jets and passages, especially the pilot jets, through the idle jets and needle screw adjusters (did you see cleaner coming out all the teensy ports right at and in front of the butterflies)? enricher air and fuel circuits all clear, and plungers moving smoothly?

Try a squirt of gas or ether into the carbs to confirm that you've got the other elements working together (compression and spark), so you can isolate it as a carb issue.

These carbs are really sensitive to plugged idle and pilot circuits. I can't emphasize how tiny they are. I gather you may have already replaced them with new ones, though? Did you remove the idle mixture screws and clean them and the passages inside, and then reassemble with the microscopic O-ring, steel washer, and spring?

If the idle/pilot and enricher circuits aren't all fully reporting for duty, starting is not likely to happen. The main jets don't do anything at that point.

As long as the slides all move up and down freely and the needles look OK, everything up top is probably fine. Even the main jets are generally fine unless things were really horrible inside.

 

[Bud]

Hoping no B12 made it's way to the diaphragms on the slides or any other rubber bits.

 

[Stasch]

I have a #1 carb body. All its parts have been removed except the butterfly valve but you can reuse parts from the old carb, or out of the 'new' set you bought.

I also have an air cut diaphram valve and an air cut valve cover if needed.

If you end up with left over carbs, I would be interested in taking them off your hands, even if not a complete set.

It would help keep my little carb parts inventory going which has helped a lot of C10 owners over the years.

 

[greenie]

Hoping no B12 made it's way to the diaphragms on the slides or any other rubber bits.

Why, Paul? I used Seafoam as an additive for years without issue but saw SISF's comment about Seaform swelling or damaging o-rings and non metallic parts and then migrated to Techron or Berryman as a routine additive. Again, no adverse issues.... What does B12 do to damage the carburetors?

 

[Bud]

Why, Paul? I used Seafoam as an additive for years without issue but saw SISF's comment about Seaform swelling or damaging o-rings and non metallic parts and then migrated to Techron or Berryman as a routine additive. Again, no adverse issues.... What does B12 do to damage the carburetors?

My concern is that if he didn't remove the slides before he sprayed cleaner through the passages, that the diaphragms would get a big dose of straight carb cleaner. Then it just lays there. Dosing a tank of gas and immediately running it out is a much lower concentration than spraying cleaner from a can. Hope he pulled the slides.

 

[aaronsfen9821]

I pulled the top off the #1 carb to see what damage the B12 may have done to the diaphragm. It feels a little slimy, like it's starting to break down. Going to go ahead and replace them all. Did a compression test, got 160-170 psi across all four cylinders. It's definitely an issue with carburetion. Next step is taking them off the bike and giving them a good cleaning, make sure I get every little orifice cleaned out.

Pulling the #1 slide out, I found something rather interesting. The slide from the '89 carb (currently on the bike) is significantly larger than the slide from the original 2000 carb. Also the needle on the '89 is adjustable (universal maybe?) whereas the needle on the 2000 is fixed. Not sure if there's any adjustments I need to make to the adjustable needles in the bike or if I can just put the needles from the 2000 carbs in the bike. This bike keeps throwing stumpers at me.

00 Left / 89 Right

2000 Slide/Needle

1989 Slide/Needle

 

[SethInIllinois]

The slide from the 2000 carb does not look familiar. Every one of these (and other Keihin CVK32 carbs on other Kawasaki's) that I've worked on has a slide that looks like the 1989 one in your photos (longer taper on the flat part). Does the 2000 slide fill the slot width in the carb body? Do the two interchange between each other in the respective carbs? I wonder if the carbs on your 2000 were swapped from something else. It's possible that there are some variations in production, but every year C10 I've looked up lists the same Kawasaki 16126-1160 part number for the slide.

The one-piece needle is a stock Keihin CVK needle, and the one with grooves and clips is an aftermarket adjustable needle (likely a Dynojet, but could be another brand).

I would check your jet and needle sizes throughout to make sure they're consistent and at (or near) stock sizes. The main jets should be 125 for typical US models. Needles should be stamped N52M. Pilot jets should be 35.

I suspect that one or both of your sets of carbs have a bit of mix-and-match parts. These Keihin CV carburetors were used in a ton of different bikes (everything from Kawasaki's to Harleys), in various sizes and other tweaks (racking and linkage for various number of cylinders, with/without decel air cutoff, etc. So there is a lot of opportunity for parts availability, but also the risk of mixing up the wrong stuff. Given the importance of cylinder balance on an application like this, it's pretty important that all four carbs have the same parts and jets/needles.

Of course, even with a completely mismatched set of carbs, you should still be able to get it fired up and running, so that is the first order of business.

 

[aaronsfen9821]

The slide from the 2000 carb does not look familiar. Every one of these (and other Keihin CVK32 carbs on other Kawasaki's) that I've worked on has a slide that looks like the 1989 one in your photos (longer taper on the flat part). Does the 2000 slide fill the slot width in the carb body? Do the two interchange between each other in the respective carbs? I wonder if the carbs on your 2000 were swapped from something else. It's possible that there are some variations in production, but every year C10 I've looked up lists the same Kawasaki 16126-1160 part number for the slide.

The one-piece needle is a stock Keihin CVK needle, and the one with grooves and clips is an aftermarket adjustable needle (likely a Dynojet, but could be another brand).

I would check your jet and needle sizes throughout to make sure they're consistent and at (or near) stock sizes. The main jets should be 125 for typical US models. Needles should be stamped N52M. Pilot jets should be 35.

I suspect that one or both of your sets of carbs have a bit of mix-and-match parts. These Keihin CV carburetors were used in a ton of different bikes (everything from Kawasaki's to Harleys), in various sizes and other tweaks (racking and linkage for various number of cylinders, with/without decel air cutoff, etc. So there is a lot of opportunity for parts availability, but also the risk of mixing up the wrong stuff. Given the importance of cylinder balance on an application like this, it's pretty important that all four carbs have the same parts and jets/needles.

Of course, even with a completely mismatched set of carbs, you should still be able to get it fired up and running, so that is the first order of business.

Seth,

Thank you for your expertise on these carbs. The 2000 slide does not fit the slot in the 89 carb body, it's a bit narrower. The stock needle is stamped N52M, I'll pull those from 2000 carbs and run those instead of the aftermarket needles. The current jetting on the bike is 130 main, 40 pilot. The 40 pilot jets came with the rebuild kits I bought, using those to help correct for the extra air from the pods.

If both sets of carbs weren't mixed and matched before, they sure are now! Just wanted to be sure the parts in the carbs on the bike are as close to original as possible. Thank you again for your help, I think I have enough info to get her running now.

Ride safe everyone!

 

[SethInIllinois]

Seth,

Thank you for your expertise on these carbs. The 2000 slide does not fit the slot in the 89 carb body, it's a bit narrower. The stock needle is stamped N52M, I'll pull those from 2000 carbs and run those instead of the aftermarket needles. The current jetting on the bike is 130 main, 40 pilot. The 40 pilot jets came with the rebuild kits I bought, using those to help correct for the extra air from the pods.

If both sets of carbs weren't mixed and matched before, they sure are now! Just wanted to be sure the parts in the carbs on the bike are as close to original as possible. Thank you again for your help, I think I have enough info to get her running now.

Ride safe everyone!

Sounds good.

BTW, a 130 main jet was the stock size for California models. I'm not sure why they came with bigger jets.

I have 128s in mine, but it's got aftermarket slip-ons and a K&N filter in the stock airbox. I'm honestly not sure if you can notice one or two sizes in the main jet unless you are tuning it on a dyno. The midrange response is all going to be dominated by the pilot jet, and to a lesser extent, the needle.

You can also shim under the stock needles if you need to enrichen the midrange. That lifts the needles sooner, opening up the main jet fuel supply more before the slides are fully open.