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Carb problems, Idling fast

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2000 DRZ400 3X3 mod, stock carb, jetted? It used to run well, seemed like it was jetted properly. Lately is has started idling very fast once it gets hot and seems to be getting worse. Usually I can put it in gear and put a load on the engine to slow it down and it will stay idling slow, but seems to be getting worse. It idles the correct speed when is is cold and if I turn the idle down further it stalls. Maybe it has a vacuum leak or something, but I should pull it off and see what the jetting is set at anyway. Hopefully I will see the problem along the way. I was considering getting an aftermarket jet kit to have on hand in case I needed it. Just in case something is missing or I need to change jetting. That way I wouldn't have to pull it twice, and it wouldn't be down waiting for parts. But that may be a waste of money. What do you think? What kit should I get?

What problems should I be looking for when I take this off. Should I do any testing before I pull the carb? :applause: Ken

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Try a larger pilot jet if everything checks out.

I would check for a vacum leak. Make sure the two bolts in the side of the intake on the barrel are tight. Make sure the clamps on the manifole are tight. Check the vacum hose to the petock for leaks or splitting. Check the fuel screw. I would check all this before a kit is put in as you want it running good before you add the variables of the jet kit.

You say it has a 3X3 but no idea if a jet kit or jetting was done? James Dean is the consensus for a jet kit.

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This is going to sound pretty noobish, but where exactly is the fuel screw? Does any one have a picture of where it is? Thanks, Ken

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Try a larger pilot jet if everything checks out.

I would check for a vacum leak. Make sure the two bolts in the side of the intake on the barrel are tight. Make sure the clamps on the manifole are tight. Check the vacum hose to the petock for leaks or splitting. Check the fuel screw. I would check all this before a kit is put in as you want it running good before you add the variables of the jet kit.

You say it has a 3X3 but no idea if a jet kit or jetting was done? James Dean is the consensus for a jet kit.

I have never had the carb off, never a reason to. It had the 3x3 when I got it and always ran great. I had an intake valve issue, but Eddie hooked me up with some new valves. I have only owned the bike for 1500 miles. This idling problem started a couple hundred miles before the head was done and I have only put a couple hundred on it since. I thought maybe it was the cables, so I lubed them up. The throttle doesn't snap closed when you let it go like I think it should, but I have heard most don't. Thanks for your reply, I am just looking for more info before I tear into it. Ken

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What happened to the valve? The throttle should snap closed. Any that do not have a problem. You should remove the throttle cables and manually rotate the throttle wheel on the carb. Comfirm it is smooth and 'snaps closed'.

This added bit about the throttle not willinglv closing changes the diagnosis greatly.

If it does snap closed, while the cables are disconnected from the carb, turn the throttle on the bars. Is it smooth? Do the cable ends move smoothly in proportion the the throttle movement?

If both these tests are ok, then it must of been the way the cables were attached to the carb.

If the carb seems ok, you will want to inspect the cables for kinks or poor routing. A kinked cable should be replaced.

If the cables are fine and it is the carb, you or a competent mechanic will have to delve into it to discern the issue.

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Eddie said dust was the probable cause. The previous owner must have not used a quality air cleaner or didn't have a good seal on it. One of the intakes was moving up into the seat.

It had a unifilter on it when I got it, but I didn't see any grease on the rim when I cleaned it the first time. It had "0" clearance on the intake when I bought it, I shimmed it and not much more than a thousand miles later it was back to "0".

The same dust that was eating the valve had to go through the carb, could it have worn something inside the carb? On second thought this problem just started and I have always had a good seal on the aircleaner since I have owned it.

The throttle grip seemed smooth with the cables unhooked at the top, but I have never had them unhooked at the carb before. I will unhook the cables at the carb tomorrow and see how that goes. Thanks, Ken

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Thanks for the help, this is a great site, it appears to have been as simple as a bad spot in one of the throttle cables. It wasnt getting hot that was causing it, it was moving the handle bars side to side enough times it would get to a certain spot and stick. I would think the cables would last longer than 6000 miles. What does everyone use for replacement cables, OEM or are there aftermarket ones that are good? Thanks again, Ken

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OEM unless there is a reason for afermarket/custom cables. They can last 20 years/100,000 miles. if cared for. A bad spot happens for a reason. Solve the reason.

Glad you figured out the issue. :applause:

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Did a long test drive today, still have the same problem. The only difference is that now the throttle snaps closed when I let it go. I am guessing a lean condition. I am going to pull the carb and see if something is partially blocking a jet or something. It is getting hotter than normal and idling high when hot. I rode pretty high elevation today probably 2500' to 5000', but it did the same thing a couple of weeks ago and that ride varied from 217 feet below sea level to 4300' Ken

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If then throttle is closing as it should, you are correct, lean jetting. This can be cause by a clogged or partially clogged pilot jet, incorrect jetting (go up a size of pilot) or a vacum leak.

The hot temp engine and idle issue make me bend towards a pilot jet change up.

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I had the same issue, turns out the idle was set too high, it just wasn't noticeable until the engine got warm. Try turning the idle down (it actually sound too low when it's right).

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