85 GPz 750 Cafe Project

I should set the baseline, it has #40 pilot jets and #110 main jets in it.

Is it possible the vacuum caps are missing from the carb holders? I know from personal experience that can keep the engine from running. :blush: Ed

Are the plugs wet with fuel after an unsuccessful starting effort? Which would indicate that the carb pilot circuits are providing fuel that's being sucked into the cylinders.

Here's one cleaning method:


Remember to wear eye protection when spraying carb cleaner, because the spray always backfires. Always.

Good Fortune!

The carb enrichener circuits should also be functional.




And the bowl passage must be clear so as to provide fuel for the choke pick-up tube.






The enrichener circuit (choke circuit) is designed to best function when the throttle is fully closed.
So it's best to not even touch the throttle grip while attempting to start a cold engine.
And it's futile to frantically and repeatedly twist the throttle grip open and closed while cranking over the engine in a attempt to start it.

Good Fortune!

Maybe already covered in this thread, but the two primary terminals on each ignition coil are non-polar, so it makes no difference which terminal gets the battery+ wire (likely red or red/yellow), and the other terminal gets the signal wire of a different color (usually green or black).

The important thing is that the ignition coil with the black wire fires the outside spark plugs, and that the ignition coil with the green wire fires the inside spark plugs. Absent some maligned wiring.

Good Fortune!

ajsfirehawk wrote: Thanks, Baldy, I'm hoping you are referencing the orange one. . Removed and blew apart the carbs today. Reset the float levels to spec. Also found a large glob of black sticky crap in the #1 emulsion tube and main jet. It was completely blocked while the rest of the carbs are pristine as you would expect after a rebuild. I have to believe it was a chunk of that damnable black paint that made its way inside. I'll never paint another set of carbs. One would be wiser to house his 16 year old daughter in a Frat house than paint carbs.
I've got a set of carb wires for cleaning small passages. Removed and checked all pilot jets, clear and squeaky clean. Same with the main jets. All but #1 perfectly clean. Ran a wire (gently) down each brass air pipe. Reassembled and installed them. ZERO change in the symptoms. Screams on starter fluid, but won't stay running. Two quick bursts with the starter fluid, I"ll not get crazy with that stuff or I'll roast the rubber diaphragms.
As a bonus, I yanked the gas filled tuning bottle off its hook and a quart of gas hit the workbench and splattered everywhere. Landed on the front fender and effed that up, now needs repainted. :pinch: A bit flummoxed at the moment.

Yes I was referring to the Orange abomination not yours. Yours is done very classy and well thought out.

Ed, yes, all four are plugged as the petcock will be manual and the air injection has been removed. SO I did cap all four. Looked at them again today with the same line of thinking you are poking at. When you think everything is perfect, you missed something, correct? SO I have to go back and verify my assumptions.

Patton: Many thanks, with the same spirit as my previous statement in this post I may have to remove the carbs and blow them completely apart again to verify all the passages are clear. On the KZ650.info site a gentlemen suggested CV carbs aren't fond of being run without air cleaners installed. My attempt today was without the pods installed and they don't provide the resistance to airflow that a stock airbox does.

Where did you buy that rear fender?

It is a Paughco. 5" wide rear flat fender. We actually bought a 6" wide which matched the outside dimensions of the tire but it didn't look right. The struts I fabbed. I used a 77 KZ650 front fender strut, cut the ends off, shaped them a bit, and added 1/4 steel rod painted silver. The Paughco blank was a bit rough and in the right light you can see some tooling marks meaning it isn't perfectly flat. I don't have a power planishing hammer or english wheel to work metal, so I cleaned up the edges, cut it to size, reinforced it where I mounted it to the swingarm and sanded it down. It is workable but certainly can't be 'show level finished' without some metal working tools IMO.

Patton: a follow up to your post and very helpful diagrams. I've removed and blown the carbs completely apart as shown in the pics below. All fuel bowl passages are clean. I pulled the choke plungers out as well, all of which have new boots on them. I shot carb cleaner into each brass pipe that goes to the starter jet. EDIT - When I properly plugged the holes with my fingers as your diagram describes, I do get carb cleaner into the carb body via the starter jet. Also of note there are three similar holes in the carb body to the starter jet, but they are back where the throttle blades meet the carb bore. Most of these were clogged. Those little dickens are very hard to see and look like they may get clogged when someone shoots carb cleaner into assembled carbs, the gunk runs off the throttle blades and fills them.
Item last: I do NOT have plugs over the pilot adjustment screws. Since I don't know if it needs them or not, I'll get them to eliminate the potential issue.

Should the pilot jets on the bowl side be plugged? They are not. The more I think about it, that has got to be it. Holy cats. Who was it who said "Its got to be something stupid simple" ... egads.

That was me!

Are you talking about the small peg with a O-ring in it (92066-1087/92055-1059) that is held in place by the bowl? Mine has those but it's not showing on the diagram for the 85 gpz carb... weird.