carb problems, hoping dax carb would solve it, not really

[fischer550]

So as I live in denver tuning the carb is turning out to be a pain. For the NT carb, I had the c-clip at the leanest notch and a size 64 jet size in (I am not talking about drill bit size people, I prefer to just order jets that already have the numbers on them it saves me time). It would 4 stroke heavily at 0-half throttle, but with nice top end. Decided to buy dax RT carb. Installed it today with the stock jet (75 I believe), ran horrid 4-stroking through all rpm's. So I put in the size 64 jet in thinking it would be much better. To my surprise, I barely felt a difference Put a size 60 jet in, and turned the idle screw way up, and 4 stroking improved somewhat on the bottom end, but the top end although it does not bog or anything does not feel as strong as it did with the NT, and I have not checked the plug color for this jet yet but am worried the plug will not dark enough. Any advice from high elevation people?

 

[greaser_monkey_87]

Is this on the motor you are breaking in? Carb tuning should really be done after break-in is complete. I know you think it won't hurt anything, but messing with the tuning affects the mixture, which isn't really good for an engine that's breaking in, also the carb may not be tuned properly anymore once break-in is completed due to a leaner mix ratio. And the only accurate way to know if your carb is tuned right is to read the plug. Without a plug reading, you're relying only on your own senses, which many a backyard mechanic have been betrayed by.

 

[Davezilla]

Are you talking like Denver high or are you up higher?
The RT carb is usually on the rich side from the get go but where you're at it'll be even richer.. I'm thinking you went too lean with teh #60 jet and that's why it's boggy on top.

You'll need to get yourself a few cheap spark plugs... I like the Autolite #275's for these engines, they ARE better than the stock plugs that came with the kit, but way cheaper than wasting an NGK iridium plug on while tuning the engine, The Autolite 275's are about $2 each at most auto parts stores and come in packs of 4.

Take it for a spin and get the engine warmed up, then pull off the road and swap out your plug for a new one. Once you got a new plug in the engine, take it for a spin and do a plug chop (Run it at WOT for a few seconds, then kill the engine and coast to a stop with the clutch pulled in) to see where you're at.

You'll want to see a nice dark tan color on the insulator, if it's white you're too lean, and if it's dark brown to black it's rich, and if you're not sure, take a picture of the plug after you do the plug chop and post it so we can see it and give you the right advise.

 

[mapbike]

Just wanted to say here that we have other members here that live in Colorado and other high elevation areas that have had no probl ms getting their carbs tuned right.

The method 2door myself and other recommended which is to solder and drill the jet is the easiest, simplest and quickest way actually to get it right on these engines in my opinion.

I'm with Dave here on the probability that a 60 is to small and that is why you are having issue with power loss.

What exhaust are you running on this engine?

If its a stock pipe that has the catalytic mess in it and the tiny exit pipe like all of them I've seen do that is another power robbing part that prevents the engine from breathing like it needs to to run right, you're already in a thin air situation there so having an exhaust that will allow the engine to breathe better will help with the 4 stroking issue even if you get the jet close to where it needs to be, a restrictive exhaust is a power and over all performance killer on these little engines.

Best wishes

Map

 

[2door]

Fischer,
Several times we've told you that trying to get good performance from a new engine with less that 200 miles on it is futile. Stop worrying about the "four stroking" and ride the bike. Burn at least a couple of gallons of fuel, hopefully you're not using a 16:1 mix, and then we'll be able to offer some advice.

New engines that aren't broken in will NEVER perform to their full potential.
Stop changing parts and settings. Ride the bike.

Tom

 

[mapbike]

Fischer,
Several times we've told you that trying to get good performance from a new engine with less that 200 miles on it is futile. Stop worrying about the "four stroking" and ride the bike. Burn at least a couple of gallons of fuel, hopefully you're not using a 16:1 mix, and then we'll be able to offer some advice.

New engines that aren't broken in will NEVER perform to their full potential.
Stop changing parts and settings. Ride the bike.

Tom

Completely agree Tom,

It doesn't matter what you do to one of these engines until they have some decent run time on them to settle them in and loosened up a bit they will act weird and 4 stroke at times and not have nearly the power that they will end up having once the engine is broken in good, it's just the nature of these little engines.

fischer550, if the engine will run and pull you down the road just do as Tom suggested and ride it for a few days and run three or four tanks of gas through it, but since you have put such a small main jet in that RT carb I would suggest watching the plug color closely because if you have gone to small on that jet you will be running that engine way to hot and could kill it, my suggestion would be that if you have a jet that may be just one or two sizes less than the stock just go ahead and put that back in the carb and then just run it like has been suggested, and as Tom mentioned I also hope you aren't running 16:1 mix which is way to much oil and can cause you all kinds of problems.

Map

 

[2door]

Wait a minute. Is this the same engine as mentioned in this thread? > http://motorbicycling.com/showthread.php?t=55667

If so, adding hot rod, go fast parts to a new engine that you have little experience with isn't the best choice. You really need to spend some time with a stock engine, learn about it and get familar with what it takes to make it run right, then, start buying those aftermarket things.

Tom

 

[fischer550]

Yes it is the same engine as the one in that thread. The problem people is that, during break in I am told to take it easy in the 1/4 to half throttle range with occasional bursts of throttle. However, in that throttle range it four strokes so bad it would be a real pain in the ass to ride it for 200 miles like that, but if you insist. The pipe I have on it now is the torquer 2 exhaust pipe from arrow, and I am running a 27:1 mix but I will switch to 100:1 opti-2 as soon as it comes in the mail.

 

[mapbike]

Wait a minute. Is this the same engine as mentioned in this thread? > http://motorbicycling.com/showthread.php?t=55667

If so, adding hot rod, go fast parts to a new engine that you have little experience with isn't the best choice. You really need to spend some time with a stock engine, learn about it and get familar with what it takes to make it run right, then, start buying those aftermarket things.

Tom

Ditto........110%

Map

 

[fischer550]

Put the size 64 jet back in, 4 stroking through all rpm's plug is black

 

[mapbike]

Yep thats rich, its yout call fischer550, either run it for a couple tanks like we have suggested or do as we also suggested and get some wire gauge bits, some small dia solder and small torch and start jetting down until it runs like you want it to, honestly short of coming to Denver and fixing it for you Im not sure if there is anymore advice anyone could give to tell you from our several years of experience whT you should do, if you choose not to follow the advice that is fine but the continued repeated questions on the same isue over and over makes me wonder if you are paying attention to what we have been telling you, im not trying to be rude here in any way but you have been told whT you should do multiple times and yet for whTever reason you keep changing this or that instead of following our advice, what is it we can do to help you understand we have given you the answers to your issue several times already...

I wish you the best and hope you get it sorted out asap.

Map

 

[Davezilla]

Yep thats rich, its yout call fischer550, either run it for a couple tanks like we have suggested or do as we also suggested and get some wire gauge bits, some small dia solder and small torch and start jetting down until it runs like you want it to, honestly short of coming to Denver and fixing it for you Im not sure if there is anymore advice anyone could give to tell you from our several years of experience whT you should do, if you choose not to follow the advice that is fine but the continued repeated questions on the same isue over and over makes me wonder if you are paying attention to what we have been telling you, im not trying to be rude here in any way but you have been told whT you should do multiple times and yet for whTever reason you keep changing this or that instead of following our advice, what is it we can do to help you understand we have given you the answers to your issue several times already...

I wish you the best and hope you get it sorted out asap.

Map

I fully agree... All we can do is give you advise and help as much as we can from the keyboard, what you do with that advise is up to you and if you're doing something different, we can't help...

Right now the best thing you can do is ride it and break in the engine before you start adding a bunch of performance parts to it. Probably your best bet would be to return it to stock and ride it stock until you feel the engine free up and become faster and stronger, THEN and only then, you can start upgrading, doing one mod at a time, test ride it to see how it performs, if it's better, keep the mod, but if not, at least now you know what went wrong. IF you just throw a bunch of parts on it and something goes wrong, good luck finding out what went wrong and it's a LOT more difficult to figure out the problems. When you do one upgrade at a time After it's borken in it's real easy to fine tune it for the upgrade, then when you add another upgrade, same thing, it's easy to fine tune again, but not so easy when you try to do everything, especially to a brand new engine that's not ready to run like that.

It's also a LOT easier for us to help you when you keep track of the mods and do them one at a time as well.

 

[fischer550]

How am I supposed to make it stock? Take off my cylinder, my head? Is there even a point in doing that? Isn't the whole purpose of breaking in a motor for the piston to bore into the cylinder?

 

[mapbike]

Just run it fischer550 and if its to rich, what does common sense tell you that is causing that based on what you have been reading on here?

We're really trying to help you here buddy but there is no magic answer we can give you that is gonna be the cure to your issue, there is basically one primary object that determines whether your engine is gonna run rich or lean and that is the main jet in the carburetor, think about what you have already dicovered yourself...?

You reduced the main jet size and said it got a little better but is still running rich, 4 stroking and the plug is running black.

The questions you keep asking honestly reminds me of something simular to " I dont understand what is happening? I have cut this board three times and it's still too short..." what should I do?

Think about it, if reducing the jet size as you did improved the rich run condition, but yet it was still running way rich, does it not make perfectly logical sense that what you need to do is reduce jet size a little more?

If you dont understand how simple and obvious the solution is here I'm afraid you will have nothing but solid heck continually with your bike, you need frankly to quit over thinking things, quit the 101 questions on a subject that has been thoroughly addressed by several people here and just roll your on sleeves up and start doing what you have been told to do to get the engine jetting closer to where it needs to be, Im telling you this now not to be rude or harsh in any way but because obviouly you have no intention to just get on that bike and put some gutless 4 stroking miles on it to loosen things up and get the rings seating in, so if you have to jack with things like you have been you may as well jack with the right stuff and just reduce the jet size until the 4 stroking is at a minimal amount and then ride it like you plan to ride it.

People here are really sincerely trying to help you fischer550 but it is becoming harder and harder to reply to your questions when it seems your not getting it... Im looking forward to seeing you post that you have it running real nice and that you're enjoying it, but that ain't gonna happen until you do what needs to be done to accomplish that.

Best wishes

Map

 

[fischer550]

Think I am just gonna bring it to a moped repair place around here to see what they have to say and if they can tune it right, cause I'm obviously doing it wrong.

 

[Davezilla]

I'm with Map on this and I'm here to help, but yet I can't help because you're either not continuing on far enough with your tuning to effectively get it running the way it needs to be or just simply overthinking it all.

Taking it to a shop may get it running about the same way it did before you made a lot of changes to the exhaust and carb, but it's still going to 4 stroke and have a dull top end until it's run in, or if they don't catch that it's not broken in yet, they may just lean it way out and give it back to you, or just refuse to work on it since it's not a brand that they're familiar with...

I can't even take my Harley to a Harley shop without them trying to sell me a few grand worth of stock parts before they're even willing to try to work on it so I got records of everything that I got done to it and notes on ALL my settings, jet sizes, timing advance settings... everything, because the only person that can work on that bike is me. I see it all the time where the shops turn people away because they got an aftermarket carb or fuel map, aftermarket cams, ported heads, or even aftermarket pipes as well as convince people that there's no way their bike will ever run right because of all the aftermarket stuff they got installed, but the real truth is that they either don't know what it takes to make a performance bike run right and dependably, or they just don't want to bother with it since it'll take extra time to get it right.

Your best bet is to keep going with the jetting until your plug is at least brown and not black (and definitely not white or really light tan), then get that thing out there and ride it... it's not going to run perfectly no matter how much you mess with it until after it's broken in... and if you do get it spot on, it's going to be off within an hour or less as the engine breaks in and the rings start to seat and seal better so as long as it runs and it's not lean, just go ride it until you got about 10 hours of run time on your engine, you'll feel it getting better but not after the first few runs... Right now with a really new engine, it should run but it won't go fast, it will feel sluggish and may 4 stroke a lot, but we all have to get our engines passed that stage.

Also, when I was recommending returning it to stock during break in, I was talking about stuff like the carb and exhaust etc, not the parts that need to wear together...

Seriously, we're trying to help so you can enjoy your ride and have fun upgrading it after it's run in instead of wracking your brain why it isn't running right before it's run in because everytime you tune it it'll be off within a few miles etc...

 

[mapbike]

Probably taking the bike to a moped shop will get you ridicule and they will most likely tell you to junk it and buy a moped from them, Dave is giving you good advice along with good advice from others, je it down a little at a time until it will Cruise with just a light amount of 4 stroking and none when under a load going up a hill or under hard acceleration.

Honestly you're making this way harder than it needs to be, like Dave said you start off but dont go far enough to get it closer to where it needs to be, you have to follow through until......

Map

 

[fischer550]

Alright, I will switch back to the NT carb and just ride it for a good amount. I thought the main jet only controlled 3/4-full throttle, so how would down jetting have effect on the bottom end?

 

[mapbike]

Alright, I will switch back to the NT carb and just ride it for a good amount. I thought the main jet only controlled 3/4-full throttle, so how would down jetting have effect on the bottom end?

The main jet has effect on how the engine runs from idle all the way to wide open, but the metering needle does work to control/limit fuel flow at idle to lower part throttle rpms so that it doesnt run to rich in those lows rpms and then when fuel demand increases as the rpms increase the needle becomes less and less part of the whole process because it is moved at a greater distance from the main jet as the throttle is opened more and then the engine is running strictly off of the amount of fuel the main jet will allow the engine to pull from the carburetors fuel bowl, it all works together but ultimately the main jet size is important for how the engine will run all across the rpm range, but does become more critical as the metering needle moves father from it since the flow has to be regulated correctly for the engine to run like it should and the size of the orifice in the jet will determine how much fuel the engine is able to get mixed in with the amount of air it is able to draw through carburetors bore, the more air it pulls through the more fuel it needs to have a correct air/fuel mixture, .

Think of it like this, when you switch the choke lever in the up position it closes off the air flow to a big extent, so the engines vacuum is pulling the same but since it cant get much air all the vacuum is drawing harder on the main jet and pullint extra cuel and less air so that super richens the mix just to give the engine that extra big drink of fuel for initial start up and then the choke lever has to be moved back so the engine can breathe so it doesn't just flood out from all the fuel and so little air, so having a main jet that is to larger actually. Auses that engine to choke on more fuel than it can handle for the amount of air the it can draw in at any particular rmp, lean condition works right the opposite, and is a much worse condition because it doesn't allow the engine to get enough fuel mix for proper cooling or lubrication in the case of a 2 stroke engine.

Wise decision to switch back to the little NT carb for now and actually its just as good of a carb as the dellorto clone carb and easier to work with, I do like the NT speed carbs also, they do not add any performance gains over the standard NT carb but the fuel inlet is set up better so they will accept 1/4" fuel line but other than that wnd the extra fuel shut off valve they are the same carb.

Just jet the NT down a little and continue to work with it a little at a time until the 4 stroking isn't constant through low , medium and higher throttle positions and then put some miles on it and after about 150-200 miles you can do the final fine tuning and you will be good to go was proper maintenance and a consistent oil fuel mixture.

Map

 

[fischer550]

Alright will do, thanks guys. I should get my opti-2 in the mail soon, and I'm gonna switch to that when I get it, I will just ride it for now and see where it goes.