mr. shide
Expert
Looking for a little help, Any ideas what could be causing the throttle to brifly hesitate when hitting the throttle from idle? Its sitting in a warm shop, with the rear end off the ground. let it warm up for about a minute then when you hit the throttle it hesitates for about 1 second, maybe a bit less. then takes off. if the track is already rolling a bit then you gas it it is fine. or if you just hit the throttle moderately from idle it is also ok. I'm pretty sure it has about 2 month old gas in it. I purchased the sled a week ago and it hadnt been ridden much at all for about 2 months. any ideas on what the problem may be?
mbarryracing
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Could be stale gas, the warm shop air doesn't help.
Also do a search here for changing "CO settings"... When my Apex was still naturally asprirated I had bumped my CO's up to +5 each and that cured this stumble.
Also do a search here for changing "CO settings"... When my Apex was still naturally asprirated I had bumped my CO's up to +5 each and that cured this stumble.
mr. shide
Expert
ok will do. Thought it may have been the exhaust donuts, just disassembled and took a peak at them, they look like they are nearly new 2500 miles. what are "CO" settings?
thanks
thanks
mr. shide
Expert
i searched co settings and have found nothing, what do i need to check out?
shanksyamaha
TY 4 Stroke Guru
Its adjustable through your instrument pod. I can't remember the exact procedure but heres what ya do... go to ulmerracing.com. On the left side of the page, near the bottom, click on instructions. At the bottom of that page, click on "stealth air box" this will give you the procedure for changing these settings.
shanksyamaha
TY 4 Stroke Guru
Heres a copy and paste from that page so you don't even have to look for it. However the actual page on ulmers site has pics too so you know what wire to put the paper clip or wire ground to.
Stealth MOD Air Box
The Yamaha Genesis 150FI motor is the first fuel injected Yamaha snowmobile. With this technology is very little adjustability for air box modifications, etc. If you experience a hesitation in the low end RPM range with the MOD air box installed these are the steps you will want to take to richen the low speed fuel curve. Always make sure the snowmobile is fully warmed up before adjusting any settings. A cold engine will also result in a hesitation!
This will change your low speed fuel mixture much like the pilot circuit on a carbureted model. It does not effect on high speed fuel mixture. The engine will start and run normally in C0 mode so you can change settings with the engine running or on the trail. To return to the normal gauge functions simply turn the key or kill switch off and the gauge display will return normal functions.
1.
Apex C0 Fuel Adjust: - Install a wire (or paperclip) from ground to the pale green wire in the connector on the left of the delta box. This wire has no mating wire in the male connector and only needs to be grounded to the Delta Box.
2.
Enter Diagnostic mode: - With the key and kill switch off, press and hold both "Select and Reset" buttons then power up the gauge by turning both the key and kill switch on. - Wait 8 seconds and the gauge will go blank except for "DI" in the display. - Press "Select" to toggle between "DI" and "C0", Select "C0". - Press and hold both "Select and Reset" 3 seconds - Gauge will display "C:01", (this is where you select which cylinder you want to adjust) - Press and hold "Select and Reset" 3 seconds and 0 should appear in the odometer section - Press "Select" to increase the number (richer), "Reset" to decrease the number (leaner) - Example: (10 would be richer) (-10 would be leaner) - Press both "Select and reset" to chose C:02 and adjust the same as above (must do this for each cylinder)
You will want to go RICHER (positive numbers). Generally up 10 will be enough to get past any hesitation or stumble you may run into.
Ulmer Racing – 43230 290th St – Menno SD 57045
Phone: 605-387-2833 Fax: 605-387-2883 Email: Srxspec@Gwtc.net
Stealth MOD Air Box
The Yamaha Genesis 150FI motor is the first fuel injected Yamaha snowmobile. With this technology is very little adjustability for air box modifications, etc. If you experience a hesitation in the low end RPM range with the MOD air box installed these are the steps you will want to take to richen the low speed fuel curve. Always make sure the snowmobile is fully warmed up before adjusting any settings. A cold engine will also result in a hesitation!
This will change your low speed fuel mixture much like the pilot circuit on a carbureted model. It does not effect on high speed fuel mixture. The engine will start and run normally in C0 mode so you can change settings with the engine running or on the trail. To return to the normal gauge functions simply turn the key or kill switch off and the gauge display will return normal functions.
1.
Apex C0 Fuel Adjust: - Install a wire (or paperclip) from ground to the pale green wire in the connector on the left of the delta box. This wire has no mating wire in the male connector and only needs to be grounded to the Delta Box.
2.
Enter Diagnostic mode: - With the key and kill switch off, press and hold both "Select and Reset" buttons then power up the gauge by turning both the key and kill switch on. - Wait 8 seconds and the gauge will go blank except for "DI" in the display. - Press "Select" to toggle between "DI" and "C0", Select "C0". - Press and hold both "Select and Reset" 3 seconds - Gauge will display "C:01", (this is where you select which cylinder you want to adjust) - Press and hold "Select and Reset" 3 seconds and 0 should appear in the odometer section - Press "Select" to increase the number (richer), "Reset" to decrease the number (leaner) - Example: (10 would be richer) (-10 would be leaner) - Press both "Select and reset" to chose C:02 and adjust the same as above (must do this for each cylinder)
You will want to go RICHER (positive numbers). Generally up 10 will be enough to get past any hesitation or stumble you may run into.
Ulmer Racing – 43230 290th St – Menno SD 57045
Phone: 605-387-2833 Fax: 605-387-2883 Email: Srxspec@Gwtc.net
mr. shide
Expert
OK, sounds easy enough! I'll check out the ulmers website also for the pics. I'm gonna make sure the engine is fully warmed up before doing any adjustments. Maybe it wasnt warmed up enough. it was in a 55 degree shop, idled for about 30-45 seconds. it was still idleing at 2000rpm though, so maybe it was not completely warmed up?
mr. shide
Expert
i think the problem was that the engine was not completely warmed up. didnt do it today when i let it warm up real good. thanks for all the info though.
shanksyamaha
TY 4 Stroke Guru
Oh ya, they need to warm up for several minutes. The engine won't respond well until the coolant and oil are good and warm...
Bigvander
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Apex hesitation
I'm having the same issues. I just had the donuts and y-pipes replaced and I also replaced the plugs. I installed the CR10EK as those were the plugs that were installed when I bought the sled (previous owner did the minor airbox mod according to Ulmer's recommendation - just a bigger opening). After it warms up a bit I hit the gas and it hesitates, and sometimes backfires through the intake. I'm hoping that it's only because it has been sitting since March but at the end of the season last year it was incredibly responsive. I'm hoping the dealer didn't mess up the exhaust when they put it back together. Maybe after a good ride it will be good to go again? Does the cooler plug have anything to do with this?
Thanks.
I'm having the same issues. I just had the donuts and y-pipes replaced and I also replaced the plugs. I installed the CR10EK as those were the plugs that were installed when I bought the sled (previous owner did the minor airbox mod according to Ulmer's recommendation - just a bigger opening). After it warms up a bit I hit the gas and it hesitates, and sometimes backfires through the intake. I'm hoping that it's only because it has been sitting since March but at the end of the season last year it was incredibly responsive. I'm hoping the dealer didn't mess up the exhaust when they put it back together. Maybe after a good ride it will be good to go again? Does the cooler plug have anything to do with this?
Thanks.
