Persistent vacuum leaks and cold #1&4

[60ratrod]

Man, ordered parts are never there when you want them.

I know right? at least when I order from partzilla, the parts are always at my house in 2-3 days. when I get around to swapping the parts on the other hand, is another story. ejether, what I did for replacement butterfly plate screws is I took one of the least buggered screws to my local ace (I usually do all my random hardware runs at ace since they have the best selection of fasteners IMHO) and got a full set of 8 that were the same thread pattern as what came out of the throttle shafts. the ones I used were countersunk allen flat head screws and installed them with blue Loctite(the second time around. the first I used red because I didn't think i'd have to do them so soon). to get the old ones out, I carefully ground off the bulged tip of the original screws, then carefully applied enough pressure to removed them. they are going to be a PITA, because when they bulge the tip of the screw to peen it in place, part of the shank also expands, making them very tough to remove. if you are careful and take your time, you more than likely will not screw up the threads on the throttle shaft.

once you have the carb bodies separated, make sure to label/isolate all of your throttle linkage parts to which carb body they came out of. the linkage parts, throttle shafts, throttle shaft springs, and white end seals all matter where they go back to. but once done, you will not have to worry about those seals for probably another 15-20 years.

I suggest using the aforementioned allen screws since the JIS fasteners are really easy to bugger up when installing or removing.

[ejether]

I know right? at least when I order from partzilla, the parts are always at my house in 2-3 days. when I get around to swapping the parts on the other hand, is another story. ejether, what I did for replacement butterfly plate screws is I took one of the least buggered screws to my local ace (I usually do all my random hardware runs at ace since they have the best selection of fasteners IMHO) and got a full set of 8 that were the same thread pattern as what came out of the throttle shafts. the ones I used were countersunk allen flat head screws and installed them with blue Loctite(the second time around. the first I used red because I didn't think i'd have to do them so soon). to get the old ones out, I carefully ground off the bulged tip of the original screws, then carefully applied enough pressure to removed them. they are going to be a PITA, because when they bulge the tip of the screw to peen it in place, part of the shank also expands, making them very tough to remove. if you are careful and take your time, you more than likely will not screw up the threads on the throttle shaft.

once you have the carb bodies separated, make sure to label/isolate all of your throttle linkage parts to which carb body they came out of. the linkage parts, throttle shafts, throttle shaft springs, and white end seals all matter where they go back to. but once done, you will not have to worry about those seals for probably another 15-20 years.

I suggest using the aforementioned allen screws since the JIS fasteners are really easy to bugger up when installing or removing.

I always find that Partzilla is SLOOOW but maybe its just that I'm always ordering the hard to find parts that only come from Japan.
In any case, I've already got the carbs apart, screws out and all. I use the coin trays from a cash register to sort parts. Work really well and the curved up edges make getting the last tiny part out easy, just like a coin.

Parts arrive on Thursday and I leave on vacation Friday AM so I better get it done before I leave or my friend will be mad!

Thanks!



ThaI've already gotten the

[ejether]

HEEEELLLLLLP!

Throttle shaft seals replaced, orings all replaced, air box boots and carb boots replaced...
and it's still got vacuum leaks between the carbs.

How I'm testing:
starting fluid through a red straw on specific places.

Repeat:
HEEEELLLP!

[chef1366]

Possible pinched intake o-ring.

[ejether]

Possible pinched intake o-ring.

Do you mean the o-rings between the carb boots and the head? I don't think thats it, when I sprayed starting fluid directly in that area, it doesn't rev. Only whey I spray on the throttle shafts between the carbs.

??

[ejether]

So, I'm still pretty stumped here.

Quick recap:
Bike came in running lean on all cylinders with hesitation and surging.

I have replaced:
Carb boots and o-rings
Airbox boots
All o-rings on the fuel tees, a/f screws (cycle o rings kit)
Butterfly shaft seals

And there are still major vacuum leaks between carbs 2&3

I'm testing with starting fluid sprayed through a red straw directly onto different parts of the carbs and have ruled out intake boots as the cause.
It only revs up whenI spray fluid between 2&3 on the butterfly shaft and this is supported by how hot cylinders 2&3 are running.

I'm really at my wits end here and I can only think of a cracked carb body at this point?

[Big T]

EJ

Can you post up some pictures of the problem area? Do one with the straw in it for reference

I hate it when carbs kick my ass

[60ratrod]

Possibly worn throttle shaft bushings in the carbs. I think i have the same issue with my kz. I wanna see what you find before i rip into my kz's carbs again

[60ratrod]

Hey ejether, did you doa vacuum sync on those carbs? I just redid the sync on my kz and my lean issues went away.