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Just installed KRS-002 30mm stacks in place of KRS-004 70mm length which I was running for a couple years.
Also went rich with jetting, after my recent Pilot Jet bump got things moving a bit quicker...

Then:
15 Pilot Jets
.07 Air Jets
115 Main Jets
2nd Needle Slot

Now:
17.5 Pilot Jets
.06 Air Jets
120 Main Jets
2nd Needle Slot



Shorter velocity stacks have made a significant performance improvement. That has me wondering if KRS-007 15mm might be even better.
During break-in last year, I ran air filters with no stacks. Throttle response was noticeably better than before, but I attributed that to the MTC piston upgrade.



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It is my understanding that the best stack length is determined by the power curve the engine produces, but can also slightly influence the curve. Basically, the long stacks are for broad mid-range power. The shorter stacks are for higher rpm peak power.
Based on what I remember of your build, I would guess that you may have just hit the sweet spot, but there i suspect the only way to know for sure is to give the shorties a try. Would you still be able to use the air box with them?

TexasKZ wrote: It is my understanding that the best stack length is determined by the power curve the engine produces, but can also slightly influence the curve. Basically, the long stacks are for broad mid-range power. The shorter stacks are for higher rpm peak power.
Based on what I remember of your build, I would guess that you may have just hit the sweet spot, but there i suspect the only way to know for sure is to give the shorties a try. Would you still be able to use the air box with them?

Shortened RamAir MS-006 filters make it into the air box with the 30mm stacks. Un-modded filters will work with 15mm stacks, but they may not like the remote idle adjuster.
Changing appearance somewhat with air filters protruding, but the air box still works good.



Update same day: Installed the un-modified RamAir filters tight to the stack flange, where the "shorties" would have them. Hmmm.


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hey there my friend, im new here but i really like your kz. Can you tell me what alls been done to it. I have a 1977 kz1000a. And Im thinking of upgrading the carbs. to mikuni carbs. Not trying to make a race bike out of it, but the stock carbs seem a little sluggish. slow response. Im wondering if I do install mikuni carbs will I always be turning screws on the carbs. And all so which ones would you recommend, they make so many. Thanks Mitch

The 1977 KZ1000-A1 came from the factory with Mikuni VM26SS carbs; if yours has something different someone already made a change. So saying you would be "upgrading" to Mikuni is a bit confusing to me.

The stock 1977 KZ1000 ran the 1/4 mile in less than 13 seconds, and even though there are newer bikes quicker than that at the time that was a very fast bike. Ed

www.motorcyclespecs.co.za/model/kawasaki...asaki_z1000%2076.htm

Mitch`s KZ wrote: hey there my friend, im new here but i really like your kz. Can you tell me what alls been done to it. I have a 1977 kz1000a. And Im thinking of upgrading the carbs. to mikuni carbs. Not trying to make a race bike out of it, but the stock carbs seem a little sluggish. slow response. Im wondering if I do install mikuni carbs will I always be turning screws on the carbs. And all so which ones would you recommend, they make so many. Thanks Mitch

If they are sluggish, they are probably in need of cleaning and tuning. They certainly were not sluggish when new.

Jumped again to size 20 Pilot Jets, which necessitated changing to leaner Air Jets. Went two steps to .08 since the plugs were quite dark with the .06's. May need .09's, but time will tell.
Last check the base ring on plug 1 was black all the way around, after around 60 miles. Will post plug pic soon, after a hundred miles or so.

The engine fires up now with barely a click of the starter, whether the engine is cold or hot.

Also have a set of the KRS-007 15mm "shorty" stacks coming in a week or so. Then we'll see where we're at with cool weather jetting.




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daveo wrote: Jumped again to size 20 Pilot Jets, which necessitated changing to leaner Air Jets. Went two steps to .08 since the plugs were quite dark with the .06's. May need .09's, but time will tell.
Last check the base ring on plug 1 was black all the way around, after around 60 miles. Will post plug pic soon, after a hundred miles or so.

The engine fires up now with barely a click of the starter, whether the engine is cold or hot.

Also have a set of the KRS-007 15mm "shorty" stacks coming in a week or so. Then we'll see where we're at with cool weather jetting.

I've put a great 400 miles on the "shorty" stacks and the plugs pictured below, with 22.5 Pilots and 122.5 Mains.
.08 Air Jets seem ideal, and idle is calm and steady.

Will try #25 Pilot Jets next...