Jetting: Part 1 - Page 7

**jonathan180iq** · 08-15-2014, 05:37 PM

Drilling holes in the exhaust is kind of a waste. Just wait and save up for a real slip-on muffler at least.

If you're only going with the K&n filter, you won't need a 140 main jet.
Stock is 122.5 or something close. Start with a 125. Maybe a 128 or 130 should cover the intake.

EDIT: (Second thought, just slap a 130-135 on there. Worst case, you'll be a tad rich but that just helps the bike run a little cooler.)

Be sure to order the K&N filter for the GS500. That's the one you want.

Everyone, even stock, should do the needle shim. So go ahead and plan on that too. It's not hard at all.

http://www.gz250bike.com/forum/showthread.php?t=16

Etsola · 08-28-2014, 09:51 PM

Hey thanks for the reply ! I had thought I would've had an email notification, but I didn't.

I will probably go for an aftermarket exhaust in a bit, but in the meantime I just wanted it to at least sound better

And yeah, in Canada, stock main jet is #120. So, since we get colder weather, I'll definitely get 130-135-140's to test.

Looking at part #'s, what type of carb is it ? It says MIKUNI BSR32SS, but for jets it only says something like SR ... only 2 letters and there seem to be 2 types of very similar jets. Any idea ?

I already have a small pod filter that I tried to use on my Bandit GSF400 ... but tuning 4 jetted carbs is not that easy at all

So I'll reuse it with the GZ ...

I'll probably create a thread with my bobber build.

Also, thanks for the link for the needle

Cheers

mainlinecoffee · 08-29-2014, 12:16 AM

For what it's worth I run a 140 just to be cautious,with a pod and slip on you can't be too safe. Plus more fuel never hurt,itl get burnt just the same

raul10141964 · 08-29-2014, 12:31 PM

carb modding

1) main jet control the maximum amount off fuel available to the engine (part#16) factory 120 upgrade to 140 (I found my at my local motorcycle dealer , look for small mikuni main jet or take the old one with you)

2)needle shine control the fuel at mid range move the washer (part# 9)from the top of the E-ring (part# 10) to under the e-ring to improve the mid range

3) Pilot jet (part#26) control the fuel from idle to about 1/8 of Throttle factory set under 2 turns from the close position new set 2.5 to 3 turns, you may need to remove the plug (part#26A) to gain access, improve idle and reduce the fluctuation be twin col and hot idle

4) Upgrade air filter (I modify the factory filter see second picture)

http://www.gz250bike.com/forum/attac...9&d=1408145033

http://www.gz250bike.com/forum/attac...0&d=1408147180

pfaffe1 · 12-25-2016, 02:57 PM

Hi, will it gain power to jet the carb and change the airfilter to GS 500 ( without tube inside ) with the original exhaust ?

Can i use the bigger jets from the S40 with 8mm top N100604 ? I have got some in 125, 130, 135

Thanks

pfaffe1 · 06-25-2017, 01:22 PM

130 Jet instead of 118, PilotScrew 1 3/4, and this airfilter from GS 500 WITH large Tube inside. Not annoying loud and Drives perfekt with much power in all ranges, Floatlevel 13 mm

kilo0195 · 07-02-2017, 10:52 PM

I ported, repiped the exhaust to 1.5, installed an emgo shorty glasspack, k&n filter, and rejetted to 147.5. I shimmed the needle by moving the silver washer to the bottom and made some more washer shims by drilling and cutting some pieces of a coke can. I also did the 16t sprocket and it will get up and move with the mods.

spldart · 07-12-2017, 07:06 PM

Unless your gonna bend the heck outta the inlet tube you need to remove the two 10mm bolts either side the airbox and shift it rearward about a centimeter to clear the carbs removal.

spldart · 07-12-2017, 07:07 PM

Oh! And I anxiously await your jet test results mr. 180.
I have found whenever I through some K&Ns on a bike I had to go up 2 or 3 jets.
But I haven't done any mod like that on this bike... yet...

kilo0195 · 07-20-2017, 07:12 PM

After I put the k&n in it I actually decided to take the air box out. The rubber connector from the carb to box I found actually fits around the top opening of the filter almost perfectly. I them decided to just epoxy the tube directly to the filter and it fits nicely. I was also running a tad rich according to my plug and after this my plug is reading just fine.

08-15-2014, 05:37 PM	#61
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	Drilling holes in the exhaust is kind of a waste. Just wait and save up for a real slip-on muffler at least. If you're only going with the K&n filter, you won't need a 140 main jet. Stock is 122.5 or something close. Start with a 125. Maybe a 128 or 130 should cover the intake. EDIT: (Second thought, just slap a 130-135 on there. Worst case, you'll be a tad rich but that just helps the bike run a little cooler.) Be sure to order the K&N filter for the GS500. That's the one you want. Everyone, even stock, should do the needle shim. So go ahead and plan on that too. It's not hard at all. http://www.gz250bike.com/forum/showthread.php?t=16 Login or Register to Remove Ads
	0

08-29-2014, 12:16 AM	#63
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	For what it's worth I run a 140 just to be cautious,with a pod and slip on you can't be too safe. Plus more fuel never hurt,itl get burnt just the same Login or Register to Remove Ads
	0

12-25-2016, 02:57 PM	#65
pfaffe1 Junior Member Join Date: Dec 2016 Posts: 2	Jetting with original exhaust Hi, will it gain power to jet the carb and change the airfilter to GS 500 ( without tube inside ) with the original exhaust ? Can i use the bigger jets from the S40 with 8mm top N100604 ? I have got some in 125, 130, 135 Thanks Login or Register to Remove Ads
	0

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08-28-2014, 09:51 PM	#62
Etsola Junior Member Join Date: Aug 2014 Posts: 3	Hey thanks for the reply ! I had thought I would've had an email notification, but I didn't. I will probably go for an aftermarket exhaust in a bit, but in the meantime I just wanted it to at least sound better And yeah, in Canada, stock main jet is #120. So, since we get colder weather, I'll definitely get 130-135-140's to test. Looking at part #'s, what type of carb is it ? It says MIKUNI BSR32SS, but for jets it only says something like SR ... only 2 letters and there seem to be 2 types of very similar jets. Any idea ? I already have a small pod filter that I tried to use on my Bandit GSF400 ... but tuning 4 jetted carbs is not that easy at all So I'll reuse it with the GZ ... I'll probably create a thread with my bobber build. Also, thanks for the link for the needle Cheers
	0

08-29-2014, 12:31 PM	#64
raul10141964 Senior Member Join Date: Apr 2012 Location: Elkhart, Indiana Posts: 369	carb modding 1) main jet control the maximum amount off fuel available to the engine (part#16) factory 120 upgrade to 140 (I found my at my local motorcycle dealer , look for small mikuni main jet or take the old one with you) 2)needle shine control the fuel at mid range move the washer (part# 9)from the top of the E-ring (part# 10) to under the e-ring to improve the mid range 3) Pilot jet (part#26) control the fuel from idle to about 1/8 of Throttle factory set under 2 turns from the close position new set 2.5 to 3 turns, you may need to remove the plug (part#26A) to gain access, improve idle and reduce the fluctuation be twin col and hot idle 4) Upgrade air filter (I modify the factory filter see second picture) http://www.gz250bike.com/forum/attac...9&d=1408145033 http://www.gz250bike.com/forum/attac...0&d=1408147180
	0

07-02-2017, 10:52 PM	#67
kilo0195 Member Join Date: Jul 2017 Location: Illinois Posts: 52	I ported, repiped the exhaust to 1.5, installed an emgo shorty glasspack, k&n filter, and rejetted to 147.5. I shimmed the needle by moving the silver washer to the bottom and made some more washer shims by drilling and cutting some pieces of a coke can. I also did the 16t sprocket and it will get up and move with the mods.
	0

07-12-2017, 07:06 PM	#68
spldart Senior Member Join Date: May 2015 Location: Stafford, Texas Posts: 604	Unless your gonna bend the heck outta the inlet tube you need to remove the two 10mm bolts either side the airbox and shift it rearward about a centimeter to clear the carbs removal.
	0

07-12-2017, 07:07 PM	#69
spldart Senior Member Join Date: May 2015 Location: Stafford, Texas Posts: 604	Oh! And I anxiously await your jet test results mr. 180. I have found whenever I through some K&Ns on a bike I had to go up 2 or 3 jets. But I haven't done any mod like that on this bike... yet...
	0

07-20-2017, 07:12 PM	#70
kilo0195 Member Join Date: Jul 2017 Location: Illinois Posts: 52	After I put the k&n in it I actually decided to take the air box out. The rubber connector from the carb to box I found actually fits around the top opening of the filter almost perfectly. I them decided to just epoxy the tube directly to the filter and it fits nicely. I was also running a tad rich according to my plug and after this my plug is reading just fine.
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