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snappy
13-12-09, 06:10 PM
Hey guys, well some of you know i just recently bought a real dirtbike, not those china bikes i had before.

Well anyways, ever since i bought it, it struggled to idle without me having to always rev it, I've only did 2 rides since i bought it 2 weeks ago, everytime my wheel locks up, it would stall like it wouldn't idle on with the clutch in, well today i went menai, same thing happened.

Got home today, adjusted the idle, it now idles okay in neutral, sometimes it would shut off, since getting that working okay, as soon as i change to 1st, it shuts off, this always happened when i had it, some friends told me the airfilters needs a clean, did that today, still same shit.

Also after 2 rides, ive been thru 3 plugs, and the engine seems to always flood.

Can someone tell me what could be the problem? and if anyone could rectify the problem for a fee?

-tom

mattymc
13-12-09, 06:32 PM
the Plugs make it sound like its running to rich. My kx125 doesn't idle but its never been a problem for me when i raced it. I'd worry more about fouling up all the plugs first

ReDeMpTiOn
13-12-09, 09:34 PM
What sorta oil are you running and how much u mixing with your fuel ?

Are u running the correct plug at the recommended gap ?

Last resort U could also try playing around with your jetting see if that helps..

benxxx
14-12-09, 12:47 AM
What type of oil are you running also ? makes a big difference

snappy
14-12-09, 01:33 AM
I'm using Motul 800, using about 32 : 1

Not sure about plug gaps, i just buy the ngk racing ones. there about 14bucks each.

brasher
14-12-09, 04:07 PM
rebuild it.

Dont ride at Menai, you are wrecking it for those of us with rego and licences.

nebuchernezzer
14-12-09, 04:23 PM
What sorta oil are you running and how much u mixing with your fuel ?

Are u running the correct plug at the recommended gap ?

Last resort U could also try playing around with your jetting see if that helps..

Kinda wrong way around, if your jetting is good you'll have a hard time fouling it up even running the oil rich or running crappy oil.

I run the generic NGK plugs, much cheaper (you'll go through alot of these till you get it to run right) BR8ES is the one I run (don't garentee that one will fit your Yammy but wouldn't be suprised if it does).

Not idling isn't really a big deal, the idle could just be set low, the clutch drags quite a bit when you have it in 1st compared to neutral. My bike stalls in 1st sometimes (not often).

If you don't know when the bike was last (or it was a while ago) rebuilt order a piston, ring, small end bearing and the base and head gaskets and pull the bugger down. If you are lucky the bore will still be fine and you can put all the new parts in and start fresh. Best to start playing with the tuning with the motor fresh than with it a bit worn.

There is a howto I have laying about somewhere on how to jet a 2 stroke, it's pretty universal.

snappy
14-12-09, 04:57 PM
rebuild it.

Dont ride at Menai, you are wrecking it for those of us with rego and licences.

Out of the 2 rides i've been there, i have only seen 1 out of 50 bikes there with rego.

snappy
14-12-09, 05:06 PM
Kinda wrong way around, if your jetting is good you'll have a hard time fouling it up even running the oil rich or running crappy oil.

I run the generic NGK plugs, much cheaper (you'll go through alot of these till you get it to run right) BR8ES is the one I run (don't garentee that one will fit your Yammy but wouldn't be suprised if it does).

Not idling isn't really a big deal, the idle could just be set low, the clutch drags quite a bit when you have it in 1st compared to neutral. My bike stalls in 1st sometimes (not often).

If you don't know when the bike was last (or it was a while ago) rebuilt order a piston, ring, small end bearing and the base and head gaskets and pull the bugger down. If you are lucky the bore will still be fine and you can put all the new parts in and start fresh. Best to start playing with the tuning with the motor fresh than with it a bit worn.

There is a howto I have laying about somewhere on how to jet a 2 stroke, it's pretty universal.

Previous owner told me he did a piston kit 4 weeks ago, could be bullshit, but the bike goes hard. And Jarich i was waiting for a response from you since you seem you like you know heaps about bikes. Was gonna pm you and ask but wondered what anyone else thought could be the problem.
Pretty keen on finding the howto to jet the bike or maybe you could help me ;)

brasher
14-12-09, 05:30 PM
Out of the 2 rides i've been there, i have only seen 1 out of 50 bikes there with rego.

Today when I drove home 1 in 100 did the speed limit.

Trust me, when you get done for no licence, no rego, riding in a prohibited area and crash out there all alone you won't think you are such a tough ****.

snappy
14-12-09, 06:13 PM
Today when I drove home 1 in 100 did the speed limit.

Trust me, when you get done for no licence, no rego, riding in a prohibited area and crash out there all alone you won't think you are such a tough ****.

I dont think im a tough ****, just trying to get into the sport, fair enough i'm not doing it the right way, i understand that, but like i said in my other thread, this bikes for practice, will be getting a registered bike soon, I've got my lic, just not a proper bike yet.

nebuchernezzer
14-12-09, 08:18 PM
Well it's not like i have years of experience it's just that i've recently rebuilt and jetted my bike.
First thing i'd do is check the settings on the carby, it'll probably be a keihin slide carb which makes things easy.
Check the pilot and main jet sizes and the needle setting (the needle can be set at different heights to lean/richen the mixture).
Set it all back to stock (should be able to find the settings online) and use that as your starting point.

Anyways this is the guide I've used to help me somewhat

A correctly jetted carb makes a tremendous difference in the torque, midrange pull, top-end pull, and over-rev of your engine. If you have never jetted your bike correctly, you will almost certainly gain some performance at some point in the bike's powerband.

A cleanly jetted pilot circuit can be the difference between having to clutch the bike out of a turn or not. The needle can make all the difference in the world for the power of the machine in most situations, as it controls the throttle range that most riders spend most of their time using.

A correctly sized main jet could mean the difference between being able to rev out high enough to not have to shift one more time at the end of the straight, or the power falling flat on top and requiring you to make that extra shift.

Are you fouling plugs? Many people will tell you all sorts of band-aid fixes, from running less oil, to running a hotter plug. Both are incorrect fixes for plug fouling. It's all in the jetting.

The only way to know what jetting changes you will need is by trial-and-error. No one can give you jetting specs, because every bike is different, every rider has a different style, and jetting is totally weather dependent. Unless the person telling you what jets to use is riding an identical bike, on the exact same track, at the same time, his recommendations are meaningless.

Jetting is fairly simple, and is a useful skill to learn if you ride a two-stroke and want it to perform at it's best.

It's very important that you start with the pilot circuit. The reason is simple. The pilot circuit affects the entire throttle range. When you are at full throttle, the main jet is the primary fuel metering device, but the pilot is still delivering fuel as well, adding to the total amount of fuel that your engine is receiving.

Before you start to rejet your bike, you need a clean air filter, a fresh plug (actually you need several plugs to do plug-chop tests for the main jet), and fresh fuel.

One important detail: Make sure the engine is in good mechanical condition. If your engine has a worn top-end, fix it first. Trying to jet a worn out engine is a waste of time. The same goes for reeds that don't seal properly, and a silencer that needs re-packing. Worn reeds will mimic rich jetting, and worn rings will mimic lean jetting.

Before you start the jet testing, Install a fresh plug. Set the float level to the proper specs, an incorrect float height will affect your jetting all across the throttle range.

Warm the bike completely, and shut it off.

As already stated, start with the pilot circuit. Turn the air screw all the way in, then turn it out 1.5 turns to start. Start the engine, and turn the idle screw in until you get a slightly fast idle, or hold the throttle just barely cracked, to keep the engine idleing. Turn the airscrew slowly in, and then out, until you find the point where the idle is fastest. Stop there. Do not open the screw any farther, or your throttle response will be flat and mushy, and the bike may even bog. This is only the starting point, we will still have to tune the air screw for the best response.

Now is the time to determine if you have the correct pilot installed in your carb. The air screw position determines this for you, making it very simple. If your air screw is less than 1 turn from closed, you need a larger pilot jet. If it is more than 2.5 turns from closed, you need a smaller pilot jet.

Once you have determined (and installed it if it's neccessary to change it) the correct pilot jet size, and tuned the air screw for the fastest idle, it's time to tune the air screw for the best throttle response. Again, make sure the bike is at full operating temperature. Set the idle back down (the bike should still idle, despite what you read in the Moto Tabloids), and ride the bike, using closed-to-1/4 throttle transitions. Turn the air screw slightly in either direction until you find the point that gives you the best response when cracking the throttle open. Most bikes are sensitive to changes as small as 1/8 of a turn.

The air screw is not a set-it-and-leave-it adjustment. You have to constantly re-adjust the air screw to compensate for changing outdoor temps and humidity. An air screw setting that is perfect in the cool morning air will likely be too rich in the heat of the mid-day.

Now, it's time to work on the needle. Mark the throttle grip at 1/4 and 3/4 openings. Ride the bike between these two marks. If the bike bogs for a second before responding to throttle, lower the clip (raising the needle) a notch at a time until the engine picks up smoothly. If the bike sputters or sounds rough when giving it throttle, raise the clip (lowering the needle) until it runs cleanly. There isn't really any way to test the needle other than by feel, but it's usually quite obvious when it's right or wrong.

Last is the main jet. The main jet affects from 1/2 to full throttle. The easiest way to test it is to do a throttle-chop test. With the bike fully warmed up, find a long straight, and install a fresh plug. Start the engine, and do a full-throttle run down the straight, through all gears. As soon as the bike tops out, pull the clutch in, and kill the engine, coasting to a stop. Remove the plug, and look deep down inside the threads, at the base of the insulator. If it is white or gray, the main is too lean. If it is dark brown or black, the main is too rich. The correct color is a medium-dark mocha brown or tan.

Once you have a little bit of experience with jetting changes, and you start to learn the difference in feel between "rich" and "lean", you'll begine to learn, just from the sound of the exhaust and the feel of the power, not only if the bike is running rich or lean, but even which one of the carb circuits is the culprit.

The slide is also a tuning variable for jetting, but slides are very expensive, and few bikes need different slides, so we won't go into that here.

Keep in mind, even though this article is intended primarily for two-strokes, four-strokes also need proper jetting to perform right, although they are not quite as fussy as their oil-burning cousins. The only real difference in the two is with the pilot circuit.

Two-strokes have an air screw that you screw in to make the jetting richer, ansd screw out to make the jetting leaner. Four-strokes, on the other hand, have a fuel adjustment screw that you screw in to make the jetting leaner, and out to make it richer.

ReDeMpTiOn
14-12-09, 10:48 PM
rebuild it.

Dont ride at Menai, you are wrecking it for those of us with rego and licences.

Man fair go hes just out there having a bit of fun either way rego, licence means shit..

All it means is that u wont get hit with a big fine ull still get done for riding out at white rock, appin or wherever u choose unless its private property or a designated national park then u shouldnt be riding there in the first place regardless if ure bike is regod or u have a licence..



PS.. u shouldve bought a 4 stroke..

brasher
14-12-09, 10:49 PM
I dont think im a tough ****, just trying to get into the sport, fair enough i'm not doing it the right way, i understand that, but like i said in my other thread, this bikes for practice, will be getting a registered bike soon, I've got my lic, just not a proper bike yet.

I'll put it this way.

If you are learning to drift, it's quite irresponsible to do it on a public road. For both your safety and the safety of others.

In the same sense, Appin has a great Motocross facility, Pacific park has hectares of land to ride your unregistered bike in a safe environment to learn on. Mt Kembla also has a great track to ride. All within 50 odd km's the CBD.

brasher
14-12-09, 10:56 PM
Man fair go hes just out there having a bit of fun either way rego, licence means shit..

All it means is that u wont get hit with a big fine ull still get done for riding out at white rock, appin or wherever u choose unless its private property or a designated national park then u shouldnt be riding there in the first place regardless if ure bike is regod or u have a licence..



PS.. u shouldve bought a 4 stroke.. WR450F :twisted:

You are a fucking spud with no idea, Whiterock/Menai is now crown land. The rights changed over from the local Aboriginal Tribe 3 years ago. I have lived in Menai my whole life.

I also own a DRZ400 and a 09 Husqvuarna 450, The cops that ride menai ride with me and my father regularly, One is an ex NSW enduro champion, the other rode MX in the US and Europe. They could outride anyone bar Chad Reed and James Stewart let alone some junky scum from morebank on a fucked out chinese pitbike.

I'm trying to do this bloke a favour, because the cops can and will bend you over and make an example of you. I'm not trying to be a twisted jelous fuckwit that want's the place to himself either because we have trails that no one bar a few people know about. I steer as far away from that shithole whiterock as I can.

Next time you see a group on a Husky 450, CRF450x, EXCF530 and EXC300 say hi, we would more than gladly show you how well a copper can ride a bike :lol:

nebuchernezzer
15-12-09, 09:01 AM
Same, i heard the cops up this way (Newy area) have a few blokes who can ride really well out there now too. Ex racers and stuff. Heard it from a mate of a mate's mate but hey haha :P.