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Gas On, PRI, and RES??? What grade gas?

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Hey there

Just picked up my '05 DRZ, but it didn't come with an owner's manual (it is on the way, though).

So, what grade gas should I use? I've owned a lot of bikes over the years and they all took something different. I'm guessing super??? but....

On the gas pitcock, I see On, PRI, and RES, what's PRI? Primary??

Thanks!!

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Hey there

Just picked up my '05 DRZ, but it didn't come with an owner's manual (it is on the way, though).

So, what grade gas should I use? I've owned a lot of bikes over the years and they all took something different. I'm guessing super??? but....

On the gas pitcock, I see On, PRI, and RES, what's PRI? Primary??

Thanks!!

Is it an S or an E? My understanding is that the E requires premium while the S will eat anything, such as unleaded regular, which explains why it weighs more.

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Hey there

Just picked up my '05 DRZ, but it didn't come with an owner's manual (it is on the way, though).

So, what grade gas should I use? I've owned a lot of bikes over the years and they all took something different. I'm guessing super??? but....

On the gas pitcock, I see On, PRI, and RES, what's PRI? Primary??

Thanks!!

The S model petcock is operated by engine vacuum. Normal position - just leave it in ON. If you let the bike sit for a while or drain the float bowl for storage, you may kill the battery before enough vacuum/fuel flow is established to run the bike. Hence the PRIme position, which lets gas flow regardless of engine vacuum. Once started put it back in ON.

RES is reserve.

My S model runs fine on 87 octane regular unleaded. Mid grade around here is 10% ethanol, I'm not running that stuff.

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Ahh... the PRI position...It gave me a little scare one time..

My neighbor thought he was doing me a favor by putting the petcock on PRI (thinking it meant primary). Later that day, I was out riding some rocky trails (far from the truck/trailer) and the bike kept stalling on me when I pulled the clutch in going downhill. It also became very difficult to re-start (presumabley because it was flooding out with the free-flowing gas). This happened over & over. I'm thinking, "great. the bike is dying on me and this is no place to be pushing". I finally figured it out and continued on. 😢

-Mike

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Help me understand,

While the engine is running would somebody explain to be the difference between prime and on. They both provide freeflow, just in the (on) position only provides free flow while running? If flooding out riding on prime the carb isn't cutting off the gravity flow supply, I don't see there would be any difference in the ON position.

((Later that day, I was out riding some rocky trails (far from the truck/trailer) and the bike kept stalling on me when I pulled the clutch in going downhill. It also became very difficult to re-start (presumabley because it was flooding out with the free-flowing gas). )))))

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I think I can explain this. It all has to do with vacuum that's required for fuel flow when in the ON position. No vacuum (provided by engine running), then no fuel flow. It will not free flow in the ON position. The carb only sucks as much fuel as needed based on the amount of throttle applied (more vacuum sucks more fuel into the carb. When in the PRI position, fuel will flow without the vacuum created by the engine (via gravity).

Perhaps it had something to do with the angle of the bike (going down hills when it occurred) and the fact that I'd have the clutch in and no throttle. It may have been that fuel was free flowing, but the engine wasn't revving enough to burn the extra fuel that was flowing due to gravity. 😢 It's also possible that my carb is not set up/adjusted correctly. But I do know that once I flipped the petcock back to ON, the problem went away.

-Mike

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Well, you're certainly more knowledgable on this subject than I am, so I can't really argue. It just seems odd that the problem went away immediately after I switch back to ON.

-Mike

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I had a similar problem. I usually put it on prime for a few seconds if it was sitting a while (a few weeks). It will usually start easier that way. Well, one dAY, I trailered it and forgot the lever on prime. When I got to my destination, the bike would not start and it acted like it was severely flooded!! It sounds like way too many coincidences. Now we have to figure out why it is allowed to flood, when there is a float bowl that is supposed to regulate the flow. I know it doesn't make sense that it should flood, but how can all these coincidences be explained? I was wondering if maybe the float bowl float is bouncing around, letting fuel in with every bump, causing it to flood? Maybe a different than normal design??? What do you guys think? I can't really come up with a better excuse.

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I was wondering if maybe the float bowl float is bouncing around, letting fuel in with every bump, causing it to flood?

Yeah, it was happening to me on bumpy (rocky) downhills, so that may have something to do with it.

-Mike

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😢

Ok,, I give,,,,, But gang keep in mind two things when your proclaiming the PRI position to be the root of all woes.

1: The prime position is no different then the E petcock being in the on position,, On is on.. period. A few hundred thousand E's seem to be doing just fine running that way

😢

2: Many of us,, including me, have been running their bikes in the PRI position during normal use,,,,, I've got more then a year doing it that way now,, and umm My bike might see a bump or tow now and again,, No problems. (oh and to cut short the theory, it;s a CV vs FCR thing,, I ran mine this way with the CV for many months)

ON, is ON, much as Prime is on,, it's just On.. No magic is happening, no back up high pressure fuel pump kicks in when the petcock is placed in the prime position.. it's just on 😢

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Bronco, I agree with you 100%, but that's why I am so confused. Logic says one thing and our track records say another?????? Like I said, I can't come up with any other excuse.

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If both the ON and PRI positions operate the same way, then why the heck did they bother with both? Anyway, no point in arguing over it. I can only go with my own experience. I suppose if I never run it in the PRI position again, then it becomes a non-issue. Problem solved! 😢

-Mike

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Well, one dAY, I trailered it and forgot the lever on prime. When I got to my destination, the bike would not start and it acted like it was severely flooded!!

Actually, this looks like a different symptom than mine. In your case the manual specifically states that you shouldn't leave it in the PRI position with the engine off as the carb may overflow.

I can understand how the engine would run normally in the PRI position. My problem was stalling while bouncing down a hill, which went away as soon as I changed it to ON. Anyway, as I said above, I can fix that by not running in PRI anymore.

-Mike

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I run premium fuel which is 93 I think I think I got 92 at one place though but I just get the premium fuel and run it in my DRZ E I'm partial to Amaco though as I seem to have had the best luck with there gas although the one I know of and go to is out in the middle of nowhere so they jack prices way up so I pay more. I also like Shell ok Exon was ok but seemed to get foulded plugs quickly with it. In my 2-stroke quad I don't know what it needs so I run premium in that too thats what my uncle said he thought it takes anyone know it is a LT250R. In my XR100 I just ran regular though and the S says it will take anything.

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