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Discussion Starter #1
Just finished putting my motor back together after installing a new transmission. I have a 03 ltz400 and I'm getting gas in my oil. Does anyone have any idea what could be causing it?
 

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Probably a stuck float or needle valve/ valve seat. Take the carb apart and inspect.
 

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Still running a stock petcock?
 

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An off setting would help the problem
 

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What kind of carb do you have?
If the carb is functioning properly, I don't think any gas should be getting into your oil. Even if the petcock is letting it run, the needle valve should shut off the flow assuming your float is closing the needle into the seat. Even with that, the overflow should be leaking the gas out.

I had this issue with mine a while back. My FCR has no overflow though. My needle valve wasn't sealing.
 

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What kind of carb do you have?
If the carb is functioning properly, I don't think any gas should be getting into your oil. Even if the petcock is letting it run, the needle valve should shut off the flow assuming your float is closing the needle into the seat. Even with that, the overflow should be leaking the gas out.

I had this issue with mine a while back. My FCR has no overflow though. My needle valve wasn't sealing.
Same thing last time out to the dunes.
 

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Discussion Starter #10
It's the factory carb. The four-wheeler set for years before I got it. Probably needs replacing. What type of carbs would ya recommend?
 

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What you mean offset it some? Change the intake boot?
He is taking about an off setting on the petcock valve, not an offset.

The stock petcock has no OFF SETTING like so many other quad petcocks do since the fuel flow is controlled by a vacuum line on the Z400.
 

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Discussion Starter #13
Is there a different style of petcock I can buy to offset it? I'm just getting used to all this 4-stroke stuff
 

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What you mean offset it some? Change the intake boot?
If your replying to what jetmech25 said, i think he meant by changing the stock petcock to a 660 raptor petcock, you can turn the fuel off (on, off and reserve). so fuel is not flowing/ flooding into the cylinder.
This will not fix the problem though, just ease it a little.

You more than likely just need a new one of these and the seat it goes into to fix the issue. Or most likely just the little o-ring! (If in doubt change it all).
View attachment 26994

If your after more power then most upgrade to an fcr 39 or bigger.

If you use the search bar at the top, you will find all the info you need on this mod.

I have asked all these questions also :)
 

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The float needle seat dry rots if it sat for a long time with no fuel in it. It dries out and cracks, which lets it weep fuel in the overflow. If the overflow line is pinched or capped off, it can't go anywhere and fills the float bowl, ending up in the cylinder.

A stuck float would cause the same thing, but much more fuel. A petcock with an off position would only allow a little fuel to go by the float rather than having the weight of the entire tank pushing on it. Shutting the petcock off after riding allows only the amount in the bowl to leak into the cylinder, which often evaporates from the residual heat of the piston and isn't noticeable.

If the engine isn't filling with gas, I doubt the float is stuck. Probably the needle seat, but don't trust the petcock since they are garbage. Make sure the overflow line on the carb is open and not capped or clogged with dirt.
 

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Discussion Starter #16
Yall guys are awesome! Thanks so much for all the great advice! What about the vacuum line on the carb coming from the original petcock? Can I just block it off when I change the petcock?
 

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Discussion Starter #18
What years fcr 39 carbs will work? I'll just go ahead and upgrade the carb if it ain't to much work
 

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Its an excellent upgrade. I believe pretty much any will work from what ive read. You will need to do some research though, as you will need a new cable and thumber, intake upgrade?, jetting?,raptor petcock to handle the fuel demand and if you buy something second hand you may need a rebuild kit also?

Not trying to put you off, it will definitely be worth it.

If you post in the wanted section, im sure someone will give you a good deal on everything you need.

Heres some reading material in the meantime to get you started.
http://www.suzukicentral.com/forums/15-performance-parts/85424-fcr-install-dummies.html

http://www.suzukicentral.com/forums/17-maintenance-repairs-tuning/55003-fcr-39-set-up-04-yfz.html

No offence intended on the first link... Lol
 

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FCR List:
2008 CRF450R - 41mm FCR
2003-2007 YZ450F - 39mm FCR
2005-2007 RMZ450 - 40mm FCR
2006-2008 KX450F - 40mm FCR
2005-2012 450SXF - 41mm FCR
2004-2008 YFZ450 - 39mm FCR
2006-2012 TRX450R - 40mm FCR
 
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