Very little fuel coming out the main jets..., why?

makenzie71 · 02-13-2005

She'll start up...reluctantly...but will NOT rev above 1000rpm. Carbs are spotless inside. Fuel just barely sputters from the main-jets, though. I tried lifting the needles completely out to see if more fuel would flow and now deal...same sputtering at any throttle position. At no-throttle she also doesn't want to idle but I don't want to adjust that just yet because I feel it might be linked to the main jet's problem. I'm going to try and raise the floats up a bit and see if maybe the fuel isn't high enough in the bowls to get the syphon effect (but I don't really see how that's not possible).

Any ideas?

It's an EX500, 126 mains, needle is on 3rd notch (of 6 I think), and idle screws are 2.5 turns out...which made no difference from when they were about 15 turns out opn the left and 9 on the right when I picked the bike up.

***

With some finagling she'll start up and run at 750~1000rpm all day, so she's getting fuel, just not the right amounts at the right time.

just hooked fuel to the carbs oof the bike with the bowls off...bowls are definitely filling and def high enough that the jets should be getting they're fuel. Any ideas? I've tried covering the intakes with my hand and some oem paper filter material to see if that'd work and got nothing. I'm trying to get the bike to work with two K&N pods.

**Freakinout** · 02-13-2005

Does it have aftermarket exhaust?

makenzie71 · 02-13-2005

full yosh

**Freakinout** · 02-13-2005

Full exhaust + K&N air pods on my '01 ex500 has to have a 140 main jet to run well. Since you aren't all that far away you should need a very similar setup.

I'm not sure about why it doesn't seem to pickup more fuel than it does, but a 126 main is too small for your setup.

makenzie71 · 02-13-2005

Yeah with what I'm wanting to run I will need larger jets, no doubt, but the bike should run as is..."not well" at worst.

What do you have your idle/mix screws turned to?

makenzie71 · 02-13-2005

Anyone know the actual size of a 130 jet? I have about a dozen 120 jets that will fit and a mill. I'm going to experiment with some various sizes but would like to know how they're actually measured. Are they measured by size or by flow capacity?

**Freakinout** · 02-13-2005

I'm not sure about my air/fuel mixture screws, but it seems I'm at 2.25 turns out or so.

No idea on the jet sizes.

makenzie71 · 02-13-2005

That kind of seems the norm...I've never had to pull out more than2 to 2.5 turns. They were seriously at like 8~12 turns out when I got the bike.

**Freakinout** · 02-13-2005

8-12? ****, somebody really didn't know what they were doing when they rejetted that bike. Hope you can get it running.

makenzie71 · 02-13-2005

Yeah tehy were way the **** out there and were like 1 or 2 turns seperate from one another.

What I think I'm going to do is use some thicker needles made for another application (if they'll fit appropriately) and bore out a set of 120 mains to the 130~135 area. I'm hoping that the problem is vacuum related and that increasing the fuel flow capabillity will solve it. I've been trying to get her to run without the airbox or a filter on her so I think that the total lack of vacuum is just hindering the main-jet syphon process. I'm wanting to tune her to use two K&N pods instead of an air-box, if possible.

Any opinions on pod filters?

**Freakinout** · 02-13-2005

I like the pods, going from the stock airbox to pods + full exhaust + stage 3 rejetting did the trick for me. Plenty of tuneability.

makenzie71 · 02-13-2005

Cool. Did you cut up your airbox to retain the stock battery holder or carve out just one side of the airbox or something? On ours the airbox and batt. box are one piece.

Also, out of curiosity...you're running a 140 main? Where are you on the needle and did you have to change the idle jet?

QKENUF4U · 02-13-2005

before you go playing with drilling jets etc. put your needle in the FULL UP postion (bottom notch) , put the air/fuel screws at 2.5 turns out (thats a full revolution not a half turn)
jets are # by either the hole size or flow. all depends on WHO makes them and WHAT carb they are going into.

**Freakinout** · 02-13-2005

Quote:

Originally Posted by makenzie71

Cool. Did you cut up your airbox to retain the stock battery holder or carve out just one side of the airbox or something? On ours the airbox and batt. box are one piece.

Also, out of curiosity...you're running a 140 main? Where are you on the needle and did you have to change the idle jet?

I disassembled part of the airbox, that way it retains the battery holder, but doesn't get in the way of the pods or their air supply.

140 main. (I believe, its been a long time, but I think its the one I used. The largest main in the kit ran the best, and I have a 122, 126, and 136 sets of main jets that I didn't use. I'm trying to find all the stuff I wrote down for it, but I don't remember where I put it.)

I have the needle on the 3rd notch from the top, and no modification to the idle jets.

makenzie71 · 02-13-2005

These that I have are labelled by size...my 105's, 115's, 120's, and 125's are all scale to one another in size. If they were labelled by flow the increase in port sizing would exponential.

Bottom notch won't do anything for me. When I get the bike to her "barely running at 1000rpm" condition I can reach in and lift the needles full out and no change.

makenzie71 · 02-13-2005

Quote:

Originally Posted by Freakinout

I disassembled part of the airbox, that way it retains the battery holder, but doesn't get in the way of the pods or their air supply.

140 main. (I believe, its been a long time, but I think its the one I used. The largest main in the kit ran the best, and I have a 122, 126, and 136 sets of main jets that I didn't use. I'm trying to find all the stuff I wrote down for it, but I don't remember where I put it.)

I have the needle on the 3rd notch from the top, and no modification to the idle jets.

Now that I picture it in my mind it does have the screws holding sections together I hadn't messed with.

Thanks man! After I get this bike going and get the girl comfortable on it we'll all have to go hit all of Lubbock's twisties...

makenzie71 · 02-14-2005

Different needles, larger main jet...no change. Absolutely none. It's almost like I didn't do anything.

So, again, she'll idle IF I hold her at WOT. If I let off the throttle she dies. Instantly. Any ideas?

**Freakinout** · 02-14-2005

Quote:

Originally Posted by makenzie71

Thanks man! After I get this bike going and get the girl comfortable on it we'll all have to go hit all of Lubbock's twisties...

..... there are only 2 corners in lubbock. Gotta ride off the caprock to get decent roads.

02-13-2005	#1 (permalink)
makenzie71 Uncle Bob's Love Child BTK Intermediate Join Date: Feb 2005 Posts: 257	Very little fuel coming out the main jets..., why? She'll start up...reluctantly...but will NOT rev above 1000rpm. Carbs are spotless inside. Fuel just barely sputters from the main-jets, though. I tried lifting the needles completely out to see if more fuel would flow and now deal...same sputtering at any throttle position. At no-throttle she also doesn't want to idle but I don't want to adjust that just yet because I feel it might be linked to the main jet's problem. I'm going to try and raise the floats up a bit and see if maybe the fuel isn't high enough in the bowls to get the syphon effect (but I don't really see how that's not possible). Any ideas? It's an EX500, 126 mains, needle is on 3rd notch (of 6 I think), and idle screws are 2.5 turns out...which made no difference from when they were about 15 turns out opn the left and 9 on the right when I picked the bike up. *** With some finagling she'll start up and run at 750~1000rpm all day, so she's getting fuel, just not the right amounts at the right time. just hooked fuel to the carbs oof the bike with the bowls off...bowls are definitely filling and def high enough that the jets should be getting they're fuel. Any ideas? I've tried covering the intakes with my hand and some oem paper filter material to see if that'd work and got nothing. I'm trying to get the bike to work with two K&N pods.

02-13-2005	#2 (permalink)
Freakinout The Absentee Forum Supporter Join Date: Nov 2003 Location: Texas Posts: 7,099	Does it have aftermarket exhaust? __________________ Support Self Defense Freakinout

02-13-2005	#4 (permalink)
Freakinout The Absentee Forum Supporter Join Date: Nov 2003 Location: Texas Posts: 7,099	Full exhaust + K&N air pods on my '01 ex500 has to have a 140 main jet to run well. Since you aren't all that far away you should need a very similar setup. I'm not sure about why it doesn't seem to pickup more fuel than it does, but a 126 main is too small for your setup. __________________ Support Self Defense Freakinout

02-13-2005	#7 (permalink)
Freakinout The Absentee Forum Supporter Join Date: Nov 2003 Location: Texas Posts: 7,099	I'm not sure about my air/fuel mixture screws, but it seems I'm at 2.25 turns out or so. No idea on the jet sizes. __________________ Support Self Defense Freakinout

02-13-2005	#9 (permalink)
Freakinout The Absentee Forum Supporter Join Date: Nov 2003 Location: Texas Posts: 7,099	8-12? ****, somebody really didn't know what they were doing when they rejetted that bike. Hope you can get it running. __________________ Support Self Defense Freakinout

02-13-2005	#3 (permalink)
makenzie71 Uncle Bob's Love Child BTK Intermediate Join Date: Feb 2005 Posts: 257	full yosh

02-13-2005	#5 (permalink)
makenzie71 Uncle Bob's Love Child BTK Intermediate Join Date: Feb 2005 Posts: 257	Yeah with what I'm wanting to run I will need larger jets, no doubt, but the bike should run as is..."not well" at worst. What do you have your idle/mix screws turned to?

02-13-2005	#6 (permalink)
makenzie71 Uncle Bob's Love Child BTK Intermediate Join Date: Feb 2005 Posts: 257	Anyone know the actual size of a 130 jet? I have about a dozen 120 jets that will fit and a mill. I'm going to experiment with some various sizes but would like to know how they're actually measured. Are they measured by size or by flow capacity?

02-13-2005	#8 (permalink)
makenzie71 Uncle Bob's Love Child BTK Intermediate Join Date: Feb 2005 Posts: 257	That kind of seems the norm...I've never had to pull out more than2 to 2.5 turns. They were seriously at like 8~12 turns out when I got the bike.

02-13-2005	#10 (permalink)
makenzie71 Uncle Bob's Love Child BTK Intermediate Join Date: Feb 2005 Posts: 257	Yeah tehy were way the **** out there and were like 1 or 2 turns seperate from one another. What I think I'm going to do is use some thicker needles made for another application (if they'll fit appropriately) and bore out a set of 120 mains to the 130~135 area. I'm hoping that the problem is vacuum related and that increasing the fuel flow capabillity will solve it. I've been trying to get her to run without the airbox or a filter on her so I think that the total lack of vacuum is just hindering the main-jet syphon process. I'm wanting to tune her to use two K&N pods instead of an air-box, if possible. Any opinions on pod filters?

02-13-2005	#11 (permalink)
Freakinout The Absentee Forum Supporter Join Date: Nov 2003 Location: Texas Posts: 7,099	I like the pods, going from the stock airbox to pods + full exhaust + stage 3 rejetting did the trick for me. Plenty of tuneability. __________________ Support Self Defense Freakinout

02-13-2005	#12 (permalink)
makenzie71 Uncle Bob's Love Child BTK Intermediate Join Date: Feb 2005 Posts: 257	Cool. Did you cut up your airbox to retain the stock battery holder or carve out just one side of the airbox or something? On ours the airbox and batt. box are one piece. Also, out of curiosity...you're running a 140 main? Where are you on the needle and did you have to change the idle jet?

02-13-2005	#13 (permalink)
QKENUF4U AZ's Official Mechanic BTK Expert Join Date: Sep 2004 Location: phoenix arizona Posts: 3,650	before you go playing with drilling jets etc. put your needle in the FULL UP postion (bottom notch) , put the air/fuel screws at 2.5 turns out (thats a full revolution not a half turn) jets are # by either the hole size or flow. all depends on WHO makes them and WHAT carb they are going into.

02-13-2005	#15 (permalink)
makenzie71 Uncle Bob's Love Child BTK Intermediate Join Date: Feb 2005 Posts: 257	These that I have are labelled by size...my 105's, 115's, 120's, and 125's are all scale to one another in size. If they were labelled by flow the increase in port sizing would exponential. Bottom notch won't do anything for me. When I get the bike to her "barely running at 1000rpm" condition I can reach in and lift the needles full out and no change.

02-14-2005	#17 (permalink)
makenzie71 Uncle Bob's Love Child BTK Intermediate Join Date: Feb 2005 Posts: 257	Different needles, larger main jet...no change. Absolutely none. It's almost like I didn't do anything. So, again, she'll idle IF I hold her at WOT. If I let off the throttle she dies. Instantly. Any ideas?

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