DRZ 400s hesitating when snapping throttle

[mattydrz]

The only mod on the bike is a billet end cap on the exhaust which just makes the bike sound a little louder. Apparently doesn't require any jetting to the carb? Bike hasn't hesitated until today right after I fueled up with highest octane gas which is all I put in it. Have had the exhaust cap for about 3 weeks and just started hesitating today. It happens when I'm in mid range rpms and then crack the throttle to bring the front tire up or just speed up, then it hesitates, then kicks in and goes. Please help me figure out what it could be.

[westerncan]

Fuel delivery to slow, could be running lean . Have re-jetted yet? you will have better throttle response if you do.

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[mattydrz]

I was told you don't have to jet if you don't have a pipe? Is that not correct? This problem just showed up today though. It's an 02 and I've owned it for a month only and it's not done this until now. Could it be the end cap causing it to run lean?

[vanram]

You pretty well have to re-jet if you want to be real fussy with the way it runs. Could have a gummed up carb which might not be totally plugged, just a slight restriction. Rejet anyway for ultimate performance. After you do you will wonder why you didn't do it sooner. vanram

[Glack Rabbit]

Stop putting high octane gas in the damned beasty. You only need 87.

I'm too lazy to post a link, but you're wasting money and the bike will run worse if anything.

Then, put the original endcap on and see what happens.

[Balkos]

Stop putting high octane gas in the damned beasty. You only need 87.

I'm too lazy to post a link, but you're wasting money and the bike will run worse if anything.

Then, put the original endcap on and see what happens.

I agree. Try going back to regular gas. Your compresion is not high enough to completly burn all that high octane fuel.

[WOLFDOG]

If its just started doing it, I would sugest its likely to be a bit of sediment that may have built up in the fine holes of the emulsion tube ( Needle jet ) if you are competent with working on your bike, give the carb a good stip and clean befor you go and buy something that you may not need

[Jim Hale]

What model/year is it... or alternately what carb is it? The circuit you're describing involves climbing the needle. The stock needles don't have the washer adjustment so not much you can do there. I would agree you should consider getting a dj or jd kit and doing the 3x3 mod, particularly if it's the Mikuni 36 carb (stock S/SM and (and E this year)). Cheap mod, you'll get some nice gains and you can clean the carb while you're in there.

[mattydrz]

thanks everyone. I'm not confident enough to do that carb work myself. It's a 2002. I was always told to run the highest octane. Thanks for letting me know it's not necessary. I really like the look of the billet end cap, but if it's the problem then it's gotta go until I can buy the yosh. So forgive my ignorance but what exactly is a 3 x 3 mod kit?

[vanram]

Stop putting high octane gas in the damned beasty. You only need 87.

I'm too lazy to post a link, but you're wasting money and the bike will run worse if anything.

Then, put the original endcap on and see what happens.

Side by side racing and top end drags with two DRZ's tells me that premium fuel makes a difference in output. The gocart racers run premium in their low compression lawnmower engines for an advantage on the track. My particular bike likes the premium and seems smoother with it in there. Post a link, I would love the info!! For me the results speak for themselves. vanram Do a search for 3x3!!

[LAZYRIDER]

The 3x3 Mod Is Just Cutting A Bigger Hole In The Top Of Your Airbox For Better Airflow-it Doesnt Have To Be Exactly 3x3--you Should Buy A Jetting Kit.the Carburetor Is Very Hard To Get Off So You Want To Rejet It Once And Be Done With It.i Also Have The 2002 Model.i Put A Dyno Jet Kit In My 400 Following Their Recommendations And It Runs Much Better.also Run Only 87 Octane. Use The Money You Save To Keep Good Tires On Your Bike

[kman780]

I have been running 93 in my DRZ from the day I brought it home, actually the dealer put it in since they sell mostly sport bikes. I have never had an issue with it. I think it makes sense to run 93 since if your bike sits and the gas starts to break down the lower octane will still be close to 87.

I bet your jets are dirty, if you are going to get it rejetted make sure you tell them what you want. Jetting the stock DRZ carb is probably the easiest carb I have ever worked on. If I were you I would get the jet kit, do the 3x3 and then give it a shot. Worse case scenario is that you don't get it right and you just take it in. Do some searching or check the sticky at the stop of the page I thought there was a step by step with pics here somewhere.

[npm]

thanks everyone. I'm not confident enough to do that carb work myself. It's a 2002. I was always told to run the highest octane. Thanks for letting me know it's not necessary. I really like the look of the billet end cap, but if it's the problem then it's gotta go until I can buy the yosh. So forgive my ignorance but what exactly is a 3 x 3 mod kit?

https://www.thumpertalk.com/forum/showthread.php?t=378193

Start here on the 3x3

[Balkos]

Side by side racing and top end drags with two DRZ's tells me that premium fuel makes a difference in output. The gocart racers run premium in their low compression lawnmower engines for an advantage on the track. My particular bike likes the premium and seems smoother with it in there. Post a link, I would love the info!! For me the results speak for themselves. vanram Do a search for 3x3!!

Premium gas does not produce more energy than regular or mid-grade fuel.

If your running a stock S or SM and your engine does not knock on 87 than you should run that. Your engine simply doesn't have the compression to burn all of that high octane fuel. If you like fouled plugs and carbon keep putting that 93 in.

There are better expanation than this but i amlazy and don't feel like looking.

http://www.mydailydriver.com/mdd_content.cfm?ID=27

[madrivermaz]

there's nothing like a little (about a tblspn) of STP Gas Treatment to get the ol' beast running smooth again. Try mixing it in your tank. Its a miracle drug for bikes!

Once it gets into the carb, run full throttle for a bit a few times and it'll clean everything out and you will be amazed!

[mattydrz]

Good ol Sticky Toilet Paper will do it hey? Ok great I'll give it a try and we'll see. Thanks for all your comments everyone.

[vanram]

Premium gas does not produce more energy than regular or mid-grade fuel.

If your running a stock S or SM and your engine does not knock on 87 than you should run that. Your engine simply doesn't have the compression to burn all of that high octane fuel. If you like fouled plugs and carbon keep putting that 93 in.

There are better expanation than this but i amlazy and don't feel like looking.

http://www.mydailydriver.com/mdd_content.cfm?ID=27

I don't think I said that premium gas has more energy, I think I said it made a difference in side by side drag races with two similar DRZs. Octane rating is the ability for a fuel to resist detonation. If the fuel starts to burn at a fraction of a second before the optimum, power WILL be lost. You cannot hear all detonation in an engine, therefore run a fuel that makes the bike perform the best. When you are able to do side by side comparisons with bikes you are familiar with and the high octane makes a difference, I will continue to run it. Check the gocart guys, they have factory sealed low compression lawnmower engines and they run a particular brand of premium fuel for the most performance, if you deviate, you lose the advantage? A freind runs the carts and they all use the same fuel. If the fuel is being spit out of the motor not being burned, lean it out:excuseme: An 11:1 motor will use premium without a problem, I don't think I have ever heard of leaning out an engine because of premium fuel being used from a gas pump. As for the link I read it and well, I agree that if your particular engine runs better on regular, use the cheaper stuff, mine doesn't. Fouled plugs from premium.?? vanram

[harjp1959]

I'm not confident enough to do that carb work myself.

If you can use a screwdriver, you can remove and take apart, and reassemble your carb.

[421Slicer]

My SM did the same thing... I pulled the snorkle out and it fixed it! It's an air delivery problem. Gets starved at mid rpm when you crack it open.

[DRz40s]

sounds like high octaine burp! STOP buying high$ fuel and it will probly not happen anymore