StewC

Why is my Drz-400s still running completely fine after leaving the pet cock on PRIME for 3 weeks?

12 posts in this topic

So I'm pretty new to carb bikes, I used to have a CBR-600rr and decided I wanted a supermoto. I have read the repetitive topics concerning leaving your bike on prime but no answer as to why my bike is ok, everyone seems to have problems. 

One day I was in the trails and my bike tipped over and wouldn't start, so I set the pet cock to prime and it started fine and I rode/left it sitting like that for 3 weeks because I went to Florida. When I came back I shit myself when I noticed I left it on prime, the bike wouldn't start but was cranking. Eventually I killed the battery trying different choke settings and decided to try to push start it and it started right up. It wasn't idling high like the choke setting was set to but after riding it around for the day it was fine. I let it cool and it started fine.

Why does my bike seem ok after what is supposed to be a horrible mess up? Does anyone know the science behind why it wouldn't start at all choked but started fine when I pushed it? 

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The carburetor has an automatic shut off valve (needle and seat). The needle is attached to the float. If everything is set correctly (float level) fuel cannot continue to enter once it reaches the desired operation level and everything is fine. The problem occurs when the needle and seat begin to leak, the float level is too high, or the o-ring in the seat body fails.

Choke is only used for cold weather. I suspect you flooded the engine using improper technique trying to start it. As a general rule, carburated 4 stroke bikes don't need any throttle to start if tuned correctly.

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2 minutes ago, ohiodrz400sm said:

The carburetor has an automatic shut off valve (needle and seat). The needle is attached to the float. If everything is set correctly (float level) fuel cannot continue to enter once it reaches the desired operation level and everything is fine. The problem occurs when the needle and seat begin to leak, the float level is too high, or the o-ring in the seat body fails.

Choke is only used for cold weather. I suspect you flooded the engine using improper technique trying to start it. As a general rule, carburated 4 stroke bikes don't need any throttle to start if tuned correctly.

If I flooded my engine did it continue to un-flood when I bump started it/rode it around? I just dont understand how it went from not starting at all to running fine now. Or the alternative in which I pray is not the case - the bike is waiting to have an issue. 

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While you were pushing it, did you notice if you were holding the throttle open? Maybe without even realizing it? The correct way to clear a flooded engine is to hold the throttle wide open and turn the engine over.

By bump starting it, the engine was simply turned over enough to allow it to finally clear and start. The faster speed the engine was likely turning help as well.

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4 minutes ago, ohiodrz400sm said:

While you were pushing it, did you notice if you were holding the throttle open? Maybe without even realizing it? The correct way to clear a flooded engine is to hold the throttle wide open and turn the engine over.

By bump starting it, the engine was simply turned over enough to allow it to finally clear and start. The faster speed the engine was likely turning help as well.

No, I definitely was not holding the throttle open but the second it turned over I revved it up high to make sure it didn't die. The bike was definitely idling odd because I had it on high idle and it was not idling high. 

I assume it ran rough off the start because it was un-flooding itself?

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all that is happening when an engine is "flooded" is that an amount of  fuel is forced into the cylinder.  Liquid gasoline has a higher flash point than

atomized fuel so the wet OR flooded spark plug does not ignite the fuel air mixture.  Once the engine is running it is "unflooded".  


 

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Stew......I'd check your oil and see if you smell gas. When I had that issue it was exactly like you describe.....no start using the button, at least it took upteen attempts and finally started. Out on trail I stopped to take a picture and it wouldn't start back up. wtf??? so I started pushing and came to a hill and bumped it going down hill. Took it in and low and behold, gas in the oil. Like I say, check it.............;)

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25 minutes ago, Signman606 said:

Stew......I'd check your oil and see if you smell gas. When I had that issue it was exactly like you describe.....no start using the button, at least it took upteen attempts and finally started. Out on trail I stopped to take a picture and it wouldn't start back up. wtf??? so I started pushing and came to a hill and bumped it going down hill. Took it in and low and behold, gas in the oil. Like I say, check it.............;)

I did check for that, I don't have a good nose when it comes to gas/ oil smells, it all smells the same to me, same with my Dad. I'm just going to change it regardless to fully get my mind off of it. 

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4 minutes ago, StewC said:

I did check for that, I don't have a good nose when it comes to gas/ oil smells, it all smells the same to me, same with my Dad. I'm just going to change it regardless to fully get my mind off of it. 

Great idea!!!! You really can't go wrong, and it's only a few bucks worth of oil for peace of mind. (If you did smell gas in the oil, don't put good oil in the first time. Use something cheap and run it for a bit, then drain it and then put the good stuff in. That gas goes into the whole bottom end and I'm sure it isn't good for the clutch plates.)

My issue was a leaking petcock, so I bought a new Raptor that requires you to shut it off. OEM petcocks will fail at some point, so might as well fix the problem before it fixes you....jmo :thumbsup:

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58 minutes ago, Signman606 said:

Great idea!!!! You really can't go wrong, and it's only a few bucks worth of oil for peace of mind. (If you did smell gas in the oil, don't put good oil in the first time. Use something cheap and run it for a bit, then drain it and then put the good stuff in. That gas goes into the whole bottom end and I'm sure it isn't good for the clutch plates.)

My issue was a leaking petcock, so I bought a new Raptor that requires you to shut it off. OEM petcocks will fail at some point, so might as well fix the problem before it fixes you....jmo :thumbsup:

thats not really fixing the problem though, thats putting a petcock not designed for the system on the bike and hoping you remember to turn it off AND on, i guess when your young your sharper, im sure not lol ... oem petcocks may fail at some point, my 17 year old one never has, i think alot has to do with actually turning it sometimes, personal theory ...

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23 minutes ago, cowpie said:

thats not really fixing the problem though, thats putting a petcock not designed for the system on the bike and hoping you remember to turn it off AND on, i guess when your young your sharper, im sure not lol ... oem petcocks may fail at some point, my 17 year old one never has, i think alot has to do with actually turning it sometimes, personal theory ...

totally right on this, but,   having had this happen out on trail, and fortunate enough to find a hill to jump it.....believe me, I NEVER forgot to turn it off when I got back.......oh, and for the record, I'm a longggggg way from being younger and sharper, hahahahahaha

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