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DRZ400 SM turns off when pressing the clutch to brake

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Last week i changed the petcock on my 2015 DRZ400SM because it was leaking fuel and it was working fine for five days and then on the way home I was going in third gear and the bike made a loud pop from the exhaust and when i pulled in the clutch to brake it shut off. I test rode it today and it turned off again when attempting to brake. If anyone can help please respond.

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...changed the petcock..now have a problem = problem with petcock.

Lots of folks have observed that the exhaust will pop when the bike is running out of fuel (going on reserve etc.).  Further, if you are slowing (closed throttle) and the engine is starved for fuel, you won't really know if the engine is powering itself at idle or has died, as the wheel rotation will continue to turn the engine over and give you the desired engine braking.....until you pull in the clutch, at which point the engine will either continue to idle, or will stop as it was not running anyway.

So: assuming you put an OEM petcock back on,

1. try running the bike in "pri" setting, which provides fuel whether or not vacuum is present to the petcock.  If the issue disappears, then you have a problem with the vacuum line to the petcock. 

2. If the problem continues (an I am assuming you have a full fuel tank......) then check the fuel line to the carb for kinks. 

3. If all good, then with the petcock in PRI, put a small tube on the drain nipple on the bottom of the carb and open the Drain screw a few turns: fuel should continuously flow out the tube.  If not, then there is an issue with the carb float that is preventing the float bowl from filling correctly.  

4. If fuel flows freely, then the carb is getting fuel fine, so the issue may be a bit of gunk in the idle jet.  To check this, start the bike with the choke on.  Does it run fine/rev right up?  If so, what happens when you put the choke off?  Note that the choke is not a traditional choke (which restricts airflow to an engine to force it to suck harder, and thus get more gas) it is more like a continuous primer: when you pull it on, it opens a separate passage to allow more fuel to flow to the carb body and thus the engine...in other words fuel passes through two places: the idle jet and the "choke" passageway.  If it runs with choke on, but dies when choke is put off....then it is not getting fuel through the idle jet, which may be blocked by something you dislodged when changing the petcock.

So, that is enough for you to run with for the moment....please post your results.  Lluck

 

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Thank you so much for such a detailed answer. I forgot to mention that I put the other kind of petcock, a non-vacuum OEM Yamaha Raptor, which is recommended by DRZ owners. I closed the vacuum line with a screw and that worked fine for couple of days. I also used an old fuel line which was a tiny bit short with new petcock installed, but it seemed to fit ok. Now I'm thinking it might have gotten slightly deformed (bent) over couple of days when it worked fine and now it doesn't allow for full gas flow. I will change it first and will keep you posted on results.

EDIT: Ok turns out when we were switching the petcock, we adjusted it the wrong way so the gas was not getting in the fuel line when the tank is half empty. I switched on the reservoir setting and the bike is running just fine now but i still plan to take out the petcock and adjust it the right way. Again, thank you for your help.

Edited by Marko Mario

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I too have swapped for a raptor, and you need to know that the reserve standpipe is pretty short...and gives a very tiny reserve.  See my earlier post in another thread, that I have repeated below: 

The OEM petcock allows fuel to flow, without any vacuum being present, at all times in the PRI (prime) position.  This was intended to allow one to fill the float bowl after a carb job, to get the engine to run, and thus to provide the vacuum needed for fuel flow in the ON or RES position.  Note that the PRI position uses the reserve fuel inlet, so will let fuel flow until the tank is dry (other than the right lobe..).  I have a clarke 3.9 gal tank on my S, and just installed a Raptor petcock.  The tank installs cleanly and mounts over my rad guards without issue.  The Raptor petcock fits on perfectly, and does not need the pedestal (spacer) that comes between the OEM petcock and the tank.

The raptor petcock has a very small standpipe, and thus has virtually NO RESERVE.  I got some 7mm brass tube at a model store, twisted the old reserve standpipe out (it is a press fit) , cut a 4.5 inch length of the new tube,  used a hacksaw to carefully make a kerf around the end of the replacement pipe to hold the lip of the OEM fuel filter on, rounded and emery clothed the end I was inserting into the petcock, froze the tube, and inserted it into the new raptor petcock.  This was superb, and resulted in a standpipe that is 4.1 inches above the flat mount face of the raptor petcock.  It gives me a 1.5 Litre (30km) reserve.

By the way, the Clarke 3.9 US gal tank is an honest measure: the tank dispenses 14.7L (3.9US gal) of fuel to dry tank......but still has 1.7L of fuel in the right lobe. (tank actually holds 16.5L of fuel)  If you lay the bike on the left side, pick up the front wheel and tip it to past level, this fuel crosses and is useable.  So: with a 4inch standpipe on the raptor petcock on the Clarke 3.9US Gal tank, you get 13.2L in the ON, 1.5L in RES, and a further 1.7L avail in the right lobe.  Between the reserve and the right lobe, even when I am flogging it like a rental, this gives me 70km once I go on reserve.

Have fun 

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Good thing is that it seems you can adjust volume of the reserve. There is a transparent rubber gas line over the inlet/filter for fuel position. I pulled it too high and thus made the reserve quite big. Half a tank. You can move it up and down and depending on the position you leave it on, your reserve has certain volume. Funny but works. I will however put it back into right position soon.

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Yes, I had that transparent plastic/rubber thing over the reserve standpipe and filter too.....but I believe it is a protective sleeve only...ie meant to protect the standpipe and filter in transit to you...and not for use as you have described.

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