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Discussion Starter · #1 ·
I've barely owned this for a year, it has 33,000 miles on it so without knowing it's maintenance history over the winter I decided to remove the carbs, clean and check the float bowls R&R the float needle and seat, which I'm glad I did due to fairly clogged screens on them and put a new bowl gasket on them. Now for some reason I'm getting a vacuum leak from the float bowl vent!! I have rebuilt many different carbs in my life and never heard or seen this before! The simple half cleaning and inspection I did should not have caused this, they were running o.k before. What am I not seeing or figured out about this? I do not see anything wrong with the manifolds, And getting the carbs to fit is a bite for sure! After removing then for a 3rd time I went through with carb cleaner checking the various ports I thought I might have gotten dirty, all seems good. I would appreciate any input! Thanks!
 

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Can you explain a bit more. Which ,"Vent" do you mean ? Each carb has a Vacuum spigot which has a pulse when the engine runs to be used for Carb-Balancing .

Bookmark a parts fiche for your year/model as I find it useful for tracking down faults,

 

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Discussion Starter · #3 ·
Can you explain a bit more. Which ,"Vent" do you mean ? Each carb has a Vacuum spigot which has a pulse when the engine runs to be used for Carb-Balancing .

Bookmark a parts fiche for your year/model as I find it useful for tracking down faults,

I'm sorry , I should have had a clearer post! This is the port that has a breather hose coming from it on both carbs. While running if I block up the port it runs smoother because of vacuum coming from it. No problem on the other carb with any vacuum. these are not vacuum ports.
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'07 SV650S, '05 Ninja 250
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Are you positive that's not the port that goes to the fuel pump? Hard to tell from the fische, but it looks easy to mix up with the breather right above it.
 

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Discussion Starter · #10 ·
Are you positive that's not the port that goes to the fuel pump? Hard to tell from the fische, but it looks easy to mix up with the breather right above it.
Thank you, but It's the front carb that I have issues with, so the only hoses are the fuel input and float bowl vent hose. and the lower vacuum line to hook up with the meter which is capped off until used. On the rear carb the fuel pump vac hose is connected to the rear manifold and other vacuum line is properly connected from the carb.
 

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2000 SV650 N
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This is some weird shit Gearhd. Several times you called the port the "float bowl vent". After readings nicks-sv's post about the choke it got me thinking.
the choke has a rubber sleeve where it screws to the carb. the black caps holding the diaphragm could be loose. there is a small oring under each black cap.
So I dug up my extra carb set. I When I blew into the "float bowl vent" port, I got air coming out where the choke plunger sits. They are obviously connected. I don't know if there is enough vacuum in the choke port to make this happen, but it may be a place to look.

Deductively, if it was running before you messed with the carbs, then stopped afterward, you messed something up.
 
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Discussion Starter · #13 ·
the choke has a rubber sleeve where it screws to the carb. the black caps holding the diaphram could be loose. there is a small oring under each black cap.
Thank you, When you say black caps that are holding the diaphragm, are you referring to the main sliding venturi diaphragm? You just reminded me that I had to replace the o-rings for the choke also, since they were leaking gas.
 

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Discussion Starter · #14 ·
This is some weird shit Gearhd. Several times you called the port the "float bowl vent". After readings nicks-sv's post about the choke it got me thinking.

So I dug up my extra carb set. I When I blew into the "float bowl vent" port, I got air coming out where the choke plunger sits. They are obviously connected. I don't know if there is enough vacuum in the choke port to make this happen, but it may be a place to look.

Deductively, if it was running before you messed with the carbs, then stopped afterward, you messed something up.
Thank you! I see what you're saying, and I just remembered after reading the other post that I had to replace the choke o-rings because they were leaking gas. You got me thinking and I'll be looking in the manual to see if there might be some type of pressure valve inside the body that might cause this.
 

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i replaced the orings did'nt do a thing. my front choke never worked. but i discovered its connected to the bowl and the top black cap. so you can get a vacumn leak. my cap was loose, check all your nuts and bolts.
 

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Discussion Starter · #17 ·
O.K, Mystery solved!! Since I didn't know the maintenance history of this bike and I've been doing maintenance on it, the mistake I made was removing the carbs to check them! I come to find out after replacing the front intake manifold, even though there were no signs of deterioration, but sign of some kind of vacuum leak but not easy to locate with a spray can of carb cleaner, it was the manifold!! I'll be ordering the rear one as well, after all it is 21 yrs old! So I would say to anyone if yours are older than 12 yrs replace them! Thank you all for your help.
 
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