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Bigger jets for open exhaust?

  • TheForumTroll
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20 Jul 2021 12:03 - 20 Jul 2021 23:21 #852130 by TheForumTroll
Bigger jets for open exhaust? was created by TheForumTroll
Im getting my carbs cleaned tomorrow and I was thinking if I should get some bigger jets put in as the bike is running lean and got what is closer to magaphones than actual exhausts

It got stock everything else. What does the experts think? Bigger? and by how much in first try?

-[ KZ700-A1 '84 ]-
Last edit: 20 Jul 2021 23:21 by TheForumTroll. Reason: Changed title to stop the pitchfork crowd storming the gates
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  • SWest
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20 Jul 2021 19:37 #852173 by SWest
Replied by SWest on topic Bigger jets for open exhaust?
No baffle? Jets won't keep it from falling on it's face at WOT.
Steve

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20 Jul 2021 20:39 #852176 by ghostdive
Replied by ghostdive on topic Bigger jets for open exhaust?
I've run without the baffle in my 4-1 a few times, and once I had the entire cone off for non-fun reasons. I never noticed a significant change in performance or anything, but my jetting is a little rich as-is. 

A helpful person might respond to your thread with the standard rigamarole of "do plug chops at varying throttle openings to determine jetting" but some people don't like loud exhausts...anyway, I would personally not really worry about it beyond going up a size or two in the main jet and maybe a half turn out on the idle mixture. It'll be fine.

1982 KZ750 Spectre - 6 speed swap, BS34s, 18" rear wheel

2001 ZX-6R
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20 Jul 2021 21:31 #852179 by SWest
Replied by SWest on topic Bigger jets for open exhaust?
These engines start making the most power at 7-9000 RPM. Back pressure is your friend.
Steve

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20 Jul 2021 23:09 - 20 Jul 2021 23:11 #852181 by TheForumTroll
Replied by TheForumTroll on topic Bigger jets for open exhaust?
Well now, sure hit a sore spot there huh?

They do have baffles and they are installed, so no need to be mad. There's even a little stuffing inside too. Still they are open enough to make it run lean, even compared to stock. And besides, it's less loud than 90% of Harleys (99?) even if I pull out all the interior of the exhausts so please calm down 

*backs slowly away making calming gestures*

-[ KZ700-A1 '84 ]-
Last edit: 20 Jul 2021 23:11 by TheForumTroll.

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20 Jul 2021 23:27 #852182 by daveo
Replied by daveo on topic Bigger jets for open exhaust?

Im getting my carbs cleaned tomorrow and I was thinking if I should get some bigger jets put in as the bike is running lean and got what is closer to magaphones than actual exhausts

It got stock everything else. What does the experts think? Bigger? and by how much in first try?
 

Reading your post brought back some really "great" memories of better times for me.

1982 KZ1100-A2

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20 Jul 2021 23:53 #852183 by TheForumTroll
Replied by TheForumTroll on topic Bigger jets for open exhaust?
Magaphones? Oh now I have really stepped in it. I'll let myself out

-[ KZ700-A1 '84 ]-

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21 Jul 2021 06:19 - 21 Jul 2021 06:19 #852191 by TexasKZ
Replied by TexasKZ on topic Bigger jets for open exhaust?
As always, the answer depends on the specifics. You may only need to shim the needles a bit or you may need to go up a size or two on the mains. Dynojet may still sell a Stage 1 kit that worked well for many aftermarket systems. There are several ways to check the jetting. The most precise would be to hook up a wide band sniffer to the pipe that can record engine data and go ride the thing under real world conditions.

A less tech and expense intensive method that will get you close is this——

www.factorypro.com/tech/tech_tuning_proc...igh_rpm_engines.html

1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

www.kzrider.com/11-projects/620336-anoth...uild-thread?start=24
Last edit: 21 Jul 2021 06:19 by TexasKZ.
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