mg_sxviper
Newbie
Had a little time today to pull the carbs off and inspect the jets and attached a pic. The main jets are 132.5 which would be correct for my altitude according to the service manual and they are in the correct spot. I counted when I removed the pilot screws originally and they were at 2. The cv springs are stock Yamaha. I have the c clip on the needle at 3 with washers as shown in 2nd pic. Airbox is stock. More testing tomorrow...
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mg_sxviper
Newbie
Today I did this...
Removed jets again, sprayed all orifices with carb cleaner and blew through with air gun.
Installed stock #135 main jet and set pilot screw to 1.75 out.
Pulled vacuum on fuel pump hoses and fuel flowed.
Started in the dark to see if coils were arcing and they were not.
None of this made any difference,
Here's a video of exactly what it's doing, check this out:
If any of you are carb experts or know of someone that would be willing to consult with me over zoom for pay let me know.
Removed jets again, sprayed all orifices with carb cleaner and blew through with air gun.
Installed stock #135 main jet and set pilot screw to 1.75 out.
Pulled vacuum on fuel pump hoses and fuel flowed.
Started in the dark to see if coils were arcing and they were not.
None of this made any difference,
Here's a video of exactly what it's doing, check this out:
If any of you are carb experts or know of someone that would be willing to consult with me over zoom for pay let me know.
Fast Lane
Expert
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- 2007 Yamaha Nytro ER
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- Winnipeg
As I mentioned earlier, have you tried to sync the carbs? I had an issue of a slight hesitation/stumble. I cleaned the carb, which were already clean so it made no difference. Turns out both my carbs were out of sync with the first carb. I adjusted and the sled has never ran so good. Ever. I think they have been out slightly since day 1.
mg_sxviper
Newbie
Yes I need to sync but considering I've never sync'd a multi carb setup, I don't have a tool yet. I've read instructions on the forums and could use some advice on what to buy. Do I need a motion pro or can I get a universal from amazon or ebay like this one: https://a.co/d/jgPdzmN?
sxr70001
Lifetime Member
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- Sidewinder LTX SE
SR Viper RTX SE
You could just do a drill bit sync to see if their close
mg_sxviper
Newbie
I did check with feeler gauges and they seem close. I also have an SX viper so I should get a real tool, just want to get the right one.
mg_sxviper
Newbie
New thought... TORS connectors are plugged together to bypass but what if one of the tors wires in the harness is broken somewhere.
Update... just measured the 2 wires and get 27k ohms so must not be that.
Update... just measured the 2 wires and get 27k ohms so must not be that.
Last edited:
- Joined
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- 2016 apex xtx
2011 apex xtx
2009 phaser rtx/x
1997 et410t/r
1988 vk 540
there is a tors switch in the throttle block as well. i have seen a few that failed there. just bypass the one in the block the same way and see if that cures it.
mg_sxviper
Newbie
Do you mean this one? It's the one I bypassed by connecting the harness leads to each other.
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mg_sxviper
Newbie
Further testing today but no solution yet...
1) Removed carb bank and applied shop vac to the inlet side and the piston needle diaphragms all raised so those are good.
2) Checked in tank filters and they are clean. Blew from tank outlet by mouth and easily bubbled in the tank.
3) Connected hoses to fuel pump outlets into measuring cup and started engine. It pumped 13 oz in 25 seconds so there's plenty of fuel.
I really think it's in the pilot circuit in the body of the carb I circled in the pic below. So even though the jet is clean and I blow air through I bet it's clogged in the body. I found an article on cleaning a mikuni pilot circuit which I might be able to translate to my carb. https://kzrider.com/forum/3-carburetor/489287-cleaning-mikuni-manual-slide-pilot-circuit. If anyone has an exact diagram or method for our carbs please send to me.
1) Removed carb bank and applied shop vac to the inlet side and the piston needle diaphragms all raised so those are good.
2) Checked in tank filters and they are clean. Blew from tank outlet by mouth and easily bubbled in the tank.
3) Connected hoses to fuel pump outlets into measuring cup and started engine. It pumped 13 oz in 25 seconds so there's plenty of fuel.
I really think it's in the pilot circuit in the body of the carb I circled in the pic below. So even though the jet is clean and I blow air through I bet it's clogged in the body. I found an article on cleaning a mikuni pilot circuit which I might be able to translate to my carb. https://kzrider.com/forum/3-carburetor/489287-cleaning-mikuni-manual-slide-pilot-circuit. If anyone has an exact diagram or method for our carbs please send to me.
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- 7,730
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- sudbury on
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- 2016 apex xtx
2011 apex xtx
2009 phaser rtx/x
1997 et410t/r
1988 vk 540
Snowhawk1
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- 07 Yamaha Attak GT
Hopefully this helps someone. I had the exact same issue as seen in video on the same year sled. I set the valves as they where tight, rebuilt the carbs with a full carb kit from Royal. Upon rebuilding the carb I confirmed the jets where marked the same as what I removed. Sync'd the carbs, long story short, base engine tested good, could not get any throttle, 3rd time pulling carbs I reinstalled factory jets and needles and problem went away. Again jets where all marked correctly, but sled would fall on its face with any throttle. Manufacture defect?
