drz 400 3/4 throttle miss

[Randyvb]

Hello everyone, I am having a slight miss, skip at high rpm at about 3/4 throttle. On the highway at about 120 130 kms is where i am seeing it the worst like it is lean. My setup is

Jd kit 160 main, stock pilot with extended fuel screw, needle at 4th from the top

uni filter

Rmz 450 muffler 'free flow'' stock head pipe

3x3 mod

stock carb

It works perfect other then at high rpm 1/2 to 3/4 throttle so I am not sure where i should be riching it up at.

[QuaXum]

what do u mean by miss? may i know? does the engine shut off or something?

[Craigo]

How long has it been doing it?....

A high rpm missfire.... ever changed your spark plug?..could have a main jet blockage..

[Randyvb]

It has been since i did the jetting, I think I have to go richer on my pilot but I am not sure, There is no way i should have to go any richer on my main, a 160 is quite big as is but when Put the muffler on I had to go from the 155 to the 160 because it was lean so i guess i will have to do the same with the pilot. I just hate taking the carb off because it is such a pain in the ass haha. By the way I am at sealevel.

[bink98xcab]

Pilot won't effect rpms in that range, what elevation are you, sounds like a main blockage or main jet issue

[One Less Harley]

Been having the same issue w/ mine 434 BB, not sure of the needle though. 160 mj, 22.5 and 2.5 jets, needle at 4th from top, slight miss or sputter at 65-70, changed to a calif carb (same jetting)with a Dyno jet kit, needle second from top, and there was a huge difference in throttle response, no miss either. In the process of putting ht original carb back on w/ the Dyna Jet needle and see what happens.

Not saying that's your problem, and I'm still tinkering w/ mine.

BTW-3x3, and stock exhaust. no noticeable difference when removing air filter side cover.

also you can rotate the carb, buy pulling the throttle cable and twisting the carb to get to the float bowl and swap out the jets, be careful not to drop any thing. Too bad I havent been able to change the needle clip position that easily!!

[Randyvb]

Thanks, I might try messing with the needle clip a bit and see what happens, I know for sure the jet is not plugged. At wot it works perfect its just at that constant rpm about 60 70 mph that you get the serge, miss, even a reel light backfire

[Craigo]

Thanks, I might try messing with the needle clip a bit and see what happens, I know for sure the jet is not plugged. At wot it works perfect its just at that constant rpm about 60 70 mph that you get the serge, miss, even a reel light backfire

It would be helpful if you could list all the symptoms in your OP...

So now its' surging as well..This would normally indicate your are running lean..

So you are on Blue needle clip 4 from top?... is your 3x3 mod exactly 3"x3".?

[Randyvb]

It would be helpful if you could list all the symptoms in your OP...

So now its' surging as well..This would normally indicate your are running lean..

So you are on Blue needle clip 4 from top?... is your 3x3 mod exactly 3"x3".?

Yep blue needle 4 from the top, checked and the hole is exactly 3x3, I am 99% sure it is lean i was just not sure whether to up a jet size or fuss with the needle.

Thanks

[One Less Harley]

Not saying this will work for you, but the needle position was the issue for my DRZ. Jets-160, 22.5 and 2.5, Dyna Jet needle clip 2nd from top, working flawlessly up to 90 mph, no surging at all.

First time since having the bike and 434 BB kit that the carb hasn't surged, the only change was the needle position. changed from 4th from top to 2nd. Elevation 500 feet.

Before the surging wouldn't happen immediately usually took around 30 seconds at 65-70 for it to start, almost felt like a little bucking. Concerned me that it would just quit. Which at times at the end of summer last year. I switched to the FCR and all problems disappeared. Just not happy with the MPG w/ the FCR, 42 just plain sucks especially when it's only a 434 cc bike. The power just is not worth it. We'll see what the stock carb does.

[Craigo]

If you raise the needle to clip 3 or 2 it will be leaner...

Try partly taping your 3x3 , a little at at time, to see if it runs better...If it is no better ,lean running is not the issue..

[One Less Harley]

When surging I pulled the air filter cover off, leaning the mixture and if anything it made the surging worse...maybe, that small of a difference. This indicating the need for a richer mixture...correct??

So such a marginal difference w/ the cover off, but still lowering the needle, leaning the mixture made all the difference in the world. Now remember the removal of the air box cover if anything made the bike surge more, but lowering the needle two spots leaning the mixture improved performance. With opening the airbox results one wouldn't expect the needle change to leaner to effect the bike the way it did, for good!!

My results though.

[Randyvb]

Not saying this will work for you, but the needle position was the issue for my DRZ. Jets-160, 22.5 and 2.5, Dyna Jet needle clip 2nd from top, working flawlessly up to 90 mph, no surging at all.

First time since having the bike and 434 BB kit that the carb hasn't surged, the only change was the needle position. changed from 4th from top to 2nd. Elevation 500 feet.

Before the surging wouldn't happen immediately usually took around 30 seconds at 65-70 for it to start, almost felt like a little bucking. Concerned me that it would just quit. Which at times at the end of summer last year. I switched to the FCR and all problems disappeared. Just not happy with the MPG w/ the FCR, 42 just plain sucks especially when it's only a 434 cc bike. The power just is not worth it. We'll see what the stock carb does.

Thanks very much, i will giveer a try today and see what happens.