Alright beet, come school me - carbs for dummies

[highsider]

So I suck, and dont have the foggiest clue as to how to work on a carburetor. But it looks like I'd better figure out, because if I dont:

a) beet will continue to pick on me , and

b) my bike will continue to run like a bag of smashed assholes.


Here is the problem: I had a Stage 1 K&N jet kit installed by my mechanic before the July TTD, and ran the bike all day. It ran great, and had a little more power.

I then let it set for about a month before riding it to work one day, at which point the bike would not idle at all, and generally ran like crap (having the choke on seemed to help). So, I brought it back to my mechanic and asked him to fix it. He gave it back running, but the throttle response is not as quick as it once was, and when I ride the bike on the trails, it stalls going down hills and basically has super-crappy throttle response if you are on and off the throttle a lot.

is wrong with this thing? What whould I adjust/replace/piss on?

Oh yeah, its an 06 Suzuki DRZ400SM. That would be helpful, wouldn't it?

[oreo_n2]

hows your plug look?

Did he richen it up?

Do you hve a vaccuum gauge?

Is the idle set low?

How does it pull under load?

Does it backfire on decel?

[SSearchVT]

Carbs are simple (especially when there is only one on the motor). First – take a look at the gas in the tank – take off the fuel line and drain some into a clear glass jar. Look for any water/crud/ etc. If the gas is crap – working on the carb will do nothing.

You can leave the top of the carb alone, unless you are going to change the needle around. If you take the bowl off the bottom of the carb (usually four Phillips head screws – replace with hex drive if you think you’re going to be in the often) the big black thing is the float. There’s a hinge pin on the end of it, and the metering valve (needle and seat) are attached to the flange. These control the level of fuel in the bowl. Look in the bottom of the float bowl for crud, water, varnish… The hinge pin slides out, and you can remove the float assembly with the needle attached - be careful - the needles like to jump to the ground and run for the corner - also carefully line everything back up on re-assembly.

If you want to remove any of the screws on the body count the number of turns to take it all the way in to snug (and write it down) before removing it.

You most likely have two circuits in the carb – pilot (idle/low speed) and main (high speed). Take these jets out and make sure they are clean – soak them in carb clean, and blow compressed air through them – Do Not use wire, drills, etc.. From the sounds of your problem the pilot jet has crud in it. You should be able to look through the main jet and see a nice round hole. The pilot jets usually have cross drills in them, so clean them the best you can (or buy a new one - they're cheap). Make sure to check any passages machined into the carb body itself also.

Work in a clean space, bright light, organized, and the right tools – don’t ham fist it… Good Luck…

[highsider]

Originally posted by oreo_n2
hows your plug look?

Did he richen it up?

Do you hve a vaccuum gauge?

Is the idle set low?

How does it pull under load?

Does it backfire on decel?

Havent looked at the plug, I will.

No, I dont have a vacuum gauge. Unless that is the thing that pushes the vacuum around my house and bitches because I never use the vacuum, in which case, yes I have one and will you please take her.

No, the idle seems fine.

Pulls well under load (or as well as that fucking load ever did pull, anyway).

Backfires like a mofo when off throttle, then stalls.

[ChR1s]

I'd guess that the idle circuit was clogged, and effectively bypasssed via jetting changes to compensate.

[SSearchVT]

Yup - backfiring is almost always the pilot circuit - should be an easy fix...

[636]

air/fuel mixture to rich?
does it pop or spit will deceleration?

[oreo_n2]

Originally posted by ChR1s
I'd guess that the idle circuit was clogged, and effectively bypasssed via jetting changes to compensate.

Sounds like the something might have been done masking something else.

I would say fully clean the carb, set it back to stock and start over. change one thing at a time and carefully note the effects of each change. Trying to straighten out and quarantine the issues when 17 changes have been made by more than one person can be more than moderately difficult.

[KB]

Dude sell that fuckin load and buy a Honda already.

But yeah dood clean that carb, drain gas, put in fresh, clean air filter, new plug, set carb back to stock, take out stage one.

Carbs are pretty tit once you understand them. check the interweb for some articles and it will be VERY clear.

KB

[rebelpacket]

+1 for putting it back to stock and adding to it until it messes up.

Also, dont buy a honda for supermoto, those things are a bee-yitch to work on, stupid expensive, and even more expensive to convert to supermoto. Plus, at the end of the day, you cant ride it on the road!

[KB]

Rebel whatchooo talkin bout?

Rebuild and adjust the valves once a year. Done deal.

As far as riding it on the road. All I gotta do is plug in my tail light put on the headlight and I'm off tearing it up.


Are you going to bite the bullet and hit the race series next season??? Start saving.

KB

[highsider]

I'm going to edjumacate myself on the witch-craftery of carbs, and just clean the piss out of it, and maybe dial the mixture back a bit.

Then it probably wont run at all.

[SSearchVT]

Simple cheap and dirty clean job

- take the carb off the bike.
- Take the float bowl off
- take the float assembly out.

- PUT ON SAFETY GLASSES AND NITRILE GLOVES!!!!

- Use a can of spray carb clean with the tube and spray carb clean into all the little holes you can see.
- Blow compressed air through the same holes
- Keep spraying and checking until carb clean and air comes out of holes somewhere else in the carb
- Put it back together
- Use a few can of carb clean in the gas...

[beet]

Ok my boy I gots 2 bring Mom to Canada . How far from 91 are ya ? You need a good set of flat drivers . For removing jets on that 400 clean burn I would bet are small .. Carefully, remove & clean um take small wire & clean , or replace the buggers . I bet your stealer just carb douchs, & been leaving the jets in .
Ive been in the back room of most of dealers around here .
& I would not let them next my bikes .

[beet]

Originally posted by beet
Ok my boy I gots 2 bring Mom to Canada . How far from 91 are ya ? You need a good set of flat drivers . For removing jets on that 400 clean burn I would bet are small .. Carefully, remove & clean um take small wire & clean , or replace the buggers . I bet your stealer just carb douchs, & been leaving the jets in .
Ive been in the back room of most of dealers around here .
& I would not let them next my bikes .

PS Rap the driver with the end of a other driver 1 or 2 times (Don't slam it) . How hard is it to get @ the bowl drain that bitch .
When you put it away ..

[Josephd14]

God love ya Beet, but i can't understand a word you just said ..(typed)..

[beet]

Originally posted by josephd14
God love ya Beet, but i can't understand a word you just said ..(typed)..

Je devrais peut-être de lui a dit en français pour vous Joe .

[beet]

13281-05A00 is this part removed from your carb?

[selltekk]

If you remove and clean your carbs, do you have to re synch them? Is it necessary, or not?

[TheIglu]

Not on a single. On a multi, pretty much unless everything is put back exactly. Even then, I still would. Sound insurance against a rough running bike.

Chris, does that carb have an air cutoff diaphram? Sounds to me like how the Kay El Arrrr was running before I fixed a small vac leak and replaced a torn/dry/sticky air cutoff diaphram.

[Tabby]

Don't be afraid to take out the pilot jet. It is pretty much the smallest orifice in the carb, and usually the first one to clog. Look at it with an eye loupe or magnifying glass. You can clean it with a strand or 2 of copper speaker wire, that won't damage the brass. Also, since you are in there, you can check to see if your carb has a small snap-on screen on the back side of your fuel needle valve seat. I'm talking about the seat for the needle, that the float operates. On my RS38 Mikunis these little screens got fuzzed up with dried fuel and I just took them out.

[schleppy]

Completely off-topic here, I'm still laughing about the smashed assholes comment. I have never heard that saying before, and now I love it

[TheIglu]

I wouldn't go telling too many people you like Chris' smashed asshole.

To reiterate what others are saying, it sound like too much air/not enough fuel at times.

I'd check the air cutoff diaphram (it's easy to do with it on the bike, two screws on the side of the carb) and then dive into the pilot jet system.

Or....

Come racing and I'll fix it for you

[Paul_E_D]

Carbs are very easy to work on, but take time and experience to actually set-up well. I'm sure there's plenty of reading on-line about the process. It's almost never jus a matter of changing one jet or something like that. It's a sytem, and the whole system needs to be looked at one step at a time. It's a worthwhile process to learn. You can achieve very sweet results on most any bike.

[highsider]

Holy crap, this thread is old.

I still have yet to pull the carb apart. Beating the everloving snot out of the bike at VIR cured a couple of little issues, including the carb.