Any suggestions for jetting

While I have the carbs apart, I figured I would get some recommendations for jetting. I have a 74 Z1. Compression PSI is around 210psi, so it would be safe to assume that it has high compression pistons. Aftermarket cams are installed, but I have no specs on them. I have another thread for that. I'm pods with V&H Sidewinder exhaust.

Still running stock carbs, Mikuni 28's. 17.5 pilots and 125 mains are whats in it now. Stock jets are 20/113. Does this sound like a reasonable starting point? I was a little suprised to find out that the pilot jets in it now are smaller than stock.

OEM Carb Jets:


POD/Exhaust Mods:


Should be a good starting point but will also require some fine tweaking based on carb internal conditions, head component conditions/P&P, camshafts, elevations where you live, temps etc...

OMR

Great info. I think I'll try 20 pilot, 122.5 main, then go from there.

Don't know if this will save you some time but for my 81 C4 KZ1000 I went with 22.5 pilots and 127.5 on the mains. I too have pods but with stock pipes attached to two 9inch glass pack mufflers. There is very little pop on decel when cold and none when warm. The bike idles very well and stable throughout the rev range.

Hope this helps.

Alright. I have pilot size 20 & 22.5, main size 122.5 & 127.5 on the way. Thanks. I'll keep you guys updated.

I installed 20 pilots and 127.5 mains and new float needle and valve assembly. Checking fuel levels today and hopefully my valve shims will arrive so I can put her back together.

Adjusted valve clearance and got everything back together. Made all adjustments according to the manual, regarding carbs, to include sync. When adjusting the air mixture screw, I started all the way in and slowly backed them out, with hardly any change. Hardly an increase in rpm's at about 1/2 turn out. Pilots too big??????

FSM says start air screws at 1½ turns out, and fine tune from there.

Good Fortune!

stock kz 900 kerker 4 into 1, pod air filters can anybody tell me what setup they use with this combination

Check out the info from OMR above. Should give you a pretty good idea.

So, after getting everything back together I was finally able to go for a test ride. Just to reiterate, I installed 20 pilots, 127.5 mains, adjusted float level. During my test ride, it was fair (at best) during low speed cruising. If I grab a fistful of throttle, it breaks traction and screams! I like that part.:woohoo: After riding maybe 3 miles, it started acting up. It would basically only want to run if I was in the throttle. So I took her home. I inspected the plugs and they were black, rich. I was also running b9es plugs. My air mixture screw was set to 1/2 turn out.

Before I started playing with the jets again, I decided to throw a set of b8es plugs in it and set the air mixture screw to 1.5 turns out. Because the idle is so choppy, its really hard to tell where the I get the highest rpm from adjusting the screw. Anyway, I went for another ride. Low speed seemed better, but still not to my liking. Full throttle and she screams. I was worried about fouling the plugs out again so after a few miles I headed home. Checked the plugs and they looked good. Maybe a little lighter than they should be. I may try to ride a little farther tomorrow, just don't want to get stranded. So in order to smooth this thing out, what else do I need to look at?????

I'm definitely making progress.

When turning pilot air screw fails to change rpm, that's evidence of an imperfect pilot circuit.

This cleaning method seems to work pretty well:



Would suspect there's still and issue within the pilot circuit, and not an issue with the main jet or the needle clip position.

Good Fortune!