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DRZ400E Carb Question

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Ok, so I have had my DRZ for over 16 years now but for the last 2 years its been hell keeping it alive.  I think its the carb.. but not totally for sure.  I have rebuilt it three times in the last 2 years and keep finding junk in my bowl and jets.  I have cleaned the tank, put in fuel filters and fuel lines.. I dont know if its coincidental but after getting my new tank from IMS its been down.. I asked them if the tank needed to be cleaned out prior but never got an answer.  Its weird tho, each time I rebuild it I have to replace the pilot jet and the float valve and seat.  It seems like it runs like new for one day.. but then its back to crap and not idling again. Just pops and dies.. then my pipe is glowing red hot.. I am about to give up on this thing. I purchased it in 2001 right from the dealer it had Calif License Plates and street legal. Love the bike when its running.  So I have people telling me its my carb still.. I just took it out the other day blew it out with carb cleaner removed the jets and made sure all looks good. The carb is not leaking fuel so the float valve and seat are still good.  I am thinking about buying a refurbished/rebuilt carb for 525$ is the best deal I have found.. But dang.. if that is not it I am really beating myself up good.  Then someone from Kiehn said it was my Mid gaskets.. I am just really frustrated.  If the replacement carb works I am going to tear this one down and replace the mid gaskets and go from there and test it.. if its good. then it will go on ebay and try to recoup my money back.. What do you all think?  2 years now if pulling that thing off and on and 3 full rebuilds.. Also I found this link on "How to DRZ400.." it shows a flat side like mine going on an SM model to swap out the mikuni carb.. I noticed one of the pics (see attached) shows to remove the Pilot air jet on the intake side of the carb.. why is that?  Why do I still have mine(which I replaced every jet on the carb just back in November again).  

 

Also included is a link to it running and what it does, even with choke on its not as smooth as it used to be,

DRZ Running

 

Thanks in advance for any input.

9d6df145_vbattach7980.jpg

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So Jets shouldn't need replacing unless they are so corroded you can't clean them.

We used to use drillbits turned by hand but that's when we didn't know better.

Bits of wire should help.  Have you identified what you're removing/cleaning from it?  The plastic tanks often have plastic shavings in them but now that you have a filter, that shouldn't be an issue.

What does rebuild mean to you?  New jets or take it all apart, soak/ultrasonic, etc.?

The fact that opening the carb does something to help is interesting and leads away from gaskets.  A red hot header could be a lean condition or bad exhaust timing or both but since opening the carb fixes it, it makes sense that your issue is in the carb/fuel system.  It could also be because you tested it in the garage with no airflow.  

Here's a long thread on the PAJ - 

 

Edited by trc.Rhubarb

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Rebuilt like take completely apart except mid gaskets, replace ALL JETS, as they were all green colored. Don't know why they have corrosion on them as I run the carb dry each time I put it away after a ride. I see some slimey stuff in the bowl and some stuff in the jets that are hard and breaks up as I run the jet wire through it. I have jet cleaner kit with all sizes but when they are corroded I just toss them. Seems like they corrode fast. It's just strange that I am having so much problem with the carb. I have a 2003 LTZ400 with the makuni carb and it sits a lot longer than my bike and I can take it out and it starts right up.

Edited by Suzuki_DR650SE

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Man that sounds awful!  Are you somewhere where gas sits a long time?  I was in a bad accident in November and haven't really ridden the drz in 7+ months now but when I opened it up, not a hint of green but the same ethanol laden gas.

Was it still dry when you opened it up?  I could see a constant small amount of gas trickling in, then evaporating causing the buildup.

I wonder if it could be related to the mid-gasket.  There are quite a people with failing mid-gaskets that somehow come loose in bits and plug the jets.  If you were to have a jet that passed very little fuel, the heat could cause the gas to evaporate on it and cause build up.

I think with as old as your bike is, the gaskets are available but some aren't, so find them before you take it apart if you go that route.  Looks like a cheap part if it's the right one for your carb: https://www.jdjetting.com/xcart/home.php?cat=5

There has to be a reason gas is evaporating in the jets and very slow movement/low quantities passing through seems to be all I can come up with.

 

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My E model did something strange this past month. It generally liked to run with a 45 pilot, but one time it decided it didn't want to idle and wanted a whole 4 turns of fuel screw. Dropped a 48 pilot in and it ran pretty good at one turn out. Left it like that for a few days then one night it wanted a whole nother 2 turns to be happy again. Carbs are weird man.

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Carbs are easy, they are very simple devices compared to tuning EFI... especially when you are also tuning an ignition curve to go with it :goofy:

Something has to be going wrong to need first more fuel, then more air... 

I notice a lot of people messing with the mixture for 1/2 throttle+ issues, which it should really have little to no effect on.

I wonder if this helps...

http://www.keihin-na.com/assets/1/7/slide_valve.pdf

 

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Leave the paj in. Removing it was bad advice repeated countless times.

I have 2 ideas.

1st, buy some Yamalube carb dip and soak the carb over night. If you have already blasted everything with auto zone carb cleaner you might as well go ahead and order a new vacuum release seal.

2nd. I don't know where you're located but it sounds like the gas is especially shit. Either stop buying from the Arab gas station or start treating it with Star-tron or similar fuel treatment.

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