I need the help of a yammy yoda

[theultrarider]

so now, in regards to the 03 viper mtn, my buddy changes jets when he goes out west. sounds like he just picked up another whole set of carbs so he is going to set up one for here and one for the bighorns.

so should he take the specs for here and for the horns and go up one size on the pilot jets for both?

You are kidding right? I would rather change jets than the whole carbs! Butter yet, if he has the money to buy another set of carbs, just buy a holzman AATAC for it and be done. Yes, they really do work, especially on the yamis. Most everyone in our parts had them on the 700 tripples since we live done by sea, ride from 0 and go up to about 6000' and back down again. Same goes for temps. -40 to 60 above and no changing of jets. They are great.

Yes on the starting. Any sled with mikuni carbs, If you hold the throttle open while trying to start them, you have essentially just shut the choke off. Do not touch the throotle while the choke is on when pulling the rope.

 

[catmechanic]

You are kidding right? I would rather change jets than the whole carbs! Butter yet, if he has the money to buy another set of carbs, just buy a holzman AATAC for it and be done. Yes, they really do work, especially on the yamis. Most everyone in our parts had them on the 700 tripples since we live done by sea, ride from 0 and go up to about 6000' and back down again. Same goes for temps. -40 to 60 above and no changing of jets. They are great.

Yes on the starting. Any sled with mikuni carbs, If you hold the throttle open while trying to start them, you have essentially just shut the choke off. Do not touch the throotle while the choke is on when pulling the rope.

he found a used set off another 03 viper mtn for 50 bucks. otherwise the AATAC was the next idea. but, doesn't that only adjust the main jet? the specs for his viper mtn say that he has to change the main jet, pilot jet, and e-clip setting on the needle for a rise in elevation.

as far as the throttle is concerned, when you try to start the sled and it fires, and then you burp the throttle to keep it running, are you also shutting the choke off? or does this only apply before the engine fires?

 

[theultrarider]

Once the engines fires off, the choke certainly still has an effect while your hand the throttle open. However think about it. If you hold it wide open with the sled running, it will still run and move. Quite well actually at wide open throttle. However, take an engine that is warm, at an idle, and hit the choke. It will die almost instantly. It has it's most effect (the choke) with no throttle being applied. The choke on the mikunis dont have a butterlfy valve like the old school sled carbs or those on a holley or edelbrock. Instead, you open up a fuel passage to allow it to draw more fuel. In order for this to happen You are relying on the vaccum throw the carb to pull the fuel up through that passage way. The throttle slide alters the air/fuel flow and vaccum in the carb. With the slide in the down postion (idle) it forces the majority of the flow to come from the choke circut. With the slide open, the path of least resistance is right down the main throat of the carb and it will not draw fuel up out of the choke circut. Hope this makes sense to you.

 

[M.M. 700]

otherwise the AATAC was the next idea. but, doesn't that only adjust the main jet? the specs for his viper mtn say that he has to change the main jet, pilot jet, and e-clip setting on the needle for a rise in elevation.

Nope changes everything. If it just changed the main jet, it wouldn't do ya anygood....

Jet to your lowest temp and elevation, and forget about it.

Automatic Temperature and Altitude Carburetor Compensator


http://www.holtzmaneng.com/

 

[Trashy]

I wouldn't care if the second set of carbs was free... just not worth it from a hassle point of view.
Buy the ATACC and be a happy dude! But that still doesn't necesarily fix your starting issue. PM me if you need jetting info, I have a couple Yammy service manuals and can scan them and email it to ya if you need 'em.

 

[catmechanic]

Once the engines fires off, the choke certainly still has an effect while your hand the throttle open. However think about it. If you hold it wide open with the sled running, it will still run and move. Quite well actually at wide open throttle. However, take an engine that is warm, at an idle, and hit the choke. It will die almost instantly. It has it's most effect (the choke) with no throttle being applied. The choke on the mikunis dont have a butterlfy valve like the old school sled carbs or those on a holley or edelbrock. Instead, you open up a fuel passage to allow it to draw more fuel. In order for this to happen You are relying on the vaccum throw the carb to pull the fuel up through that passage way. The throttle slide alters the air/fuel flow and vaccum in the carb. With the slide in the down postion (idle) it forces the majority of the flow to come from the choke circut. With the slide open, the path of least resistance is right down the main throat of the carb and it will not draw fuel up out of the choke circut. Hope this makes sense to you.

that does make sense now. i guess i never understood the way that mikuni chokes worked. i have taken them out a thousand times but never actually knew the mechanics of it. i always thought when you pulled the choke lever, you were closing off the air flow like you do on a holley, not opening a fuel passage. you see, you learn something new every day. thanks man.

 

[catmechanic]

Nope changes everything. If it just changed the main jet, it wouldn't do ya anygood....

Jet to your lowest temp and elevation, and forget about it.

Automatic Temperature and Altitude Carburetor Compensator


http://www.holtzmaneng.com/

i have done some research on the atacc's. none of these sleds are mine. the 97 and 03 are my buddy's and the 99 is my cousins. i end up working on all of them. otherwise i think the compensator would have been my first purchase.

so, i need to find a main jet and pilot jet that are good for our elevation (1400 ft) and a low temp (lets say -20) and its good after that for a temp and altitude rise. but, what about the e-clip location on the needle? you still need to adjust that right?

 

[catmechanic]

I wouldn't care if the second set of carbs was free... just not worth it from a hassle point of view.
Buy the ATACC and be a happy dude! But that still doesn't necesarily fix your starting issue. PM me if you need jetting info, I have a couple Yammy service manuals and can scan them and email it to ya if you need 'em.

i might take you up on that jetting info. mainly for the 03 mtn viper. the 97 vmax more than likely will never go out west. the 99 mmax stays out west.

like i said, if these were my sleds, the compensator would be installed already. but my buddy that bought the carbs is bound and determined to save money, even if there is a hassle involved. don't get me wrong, im all about saving money, but i also like to save time and eliminate headaches.

 

[M.M. 700]

Stock Viper Jetting chart
http://www.zenitram-inc.com/Manuals/MtViperTU3.jpg



stock Mountain Max 700 jetting chart
http://www.zenitram-inc.com/Manuals/MM700TU2.jpg

 

[PowderMT]

I must be one lucky guy because yesterday I started my triple piped MM700 that had been sitting now for a couple of months and it started on the very first pull no problem. Man I love that sled.

 

[Trashy]

I must be one lucky guy because yesterday I started my triple piped MM700 that had been sitting now for a couple of months and it started on the very first pull no problem. Man I love that sled.

And thats why I wont sell mine. Makes a great spare!

 

[2005summit1000]

Jetting

where, other than the dealer do I purchase main and pilot jets? This is for a 98 700 MM I am riding 2800 feet or so to about 4000.
and about 20-40 degrees.

 

[stingray719]

Yamaha fuel system allows the fuel to drain back into the fuel tank. I always carry a can of starting fluid so as not to have to*pull on it forever. Note that the fuel pump is activated by engine pulses so at pulling the rope speed it is going to take a while to get the fuel up.

 

[SRXSRULE]

wow...9yr old thread brought back from the dead.

In case anyone reads this from the beginning and has hard starting issues after setting for a few days, there is a good chance you need to replace your fuel pump. The fuel pump has an internal check valve to prevent fuel draining back into the tank when sitting.

Also in a related topic, if you trailer your sled with a full tank of fuel there is a chance you can flood the engine, and I mean BIG time. Dont trailer long distances full, or install a fuel shut off valve. just an FYI. Eric

 

[Givemeaboost]

I've pinched off the vent hose and blew into the tank to push the fuel through to the carbs. I do believe the carbs dry up after sitting.


Ken..........

 

[stingray719]

wow...9yr old thread brought back from the dead.

In case anyone reads this from the beginning and has hard starting issues after setting for a few days, there is a good chance you need to replace your fuel pump. The fuel pump has an internal check valve to prevent fuel draining back into the tank when sitting.

Also in a related topic, if you trailer your sled with a full tank of fuel there is a chance you can flood the engine, and I mean BIG time. Dont trailer long distances full, or install a fuel shut off valve. just an FYI. Eric

Never stopped any of the dozen or so Yamaha I had that ALL drained back to the tank after a few days sitting.