07 Apex GT... Does anyone know what this problem is?

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I recently did 1500 miles of riding in northern Canada up near St. Zenon. I'm consistently having a problem with low to mid throttle from 4k to 7k rpm. I hear a little bit of an uneven gurgle sound that seems to go away at full throttle. My close friend who always goes with me on trips also has an 07 apex gt. When I ride his sled - I hear a distinct harmonious sound like his sled is perfectly in tune. I sometimes hear this sound from my sled after I get to the bottom of a mountain and begin to hit the throttle. I've also raced my buddy and he seems to have a slightly quicker response out of the hole but at full throttle we stay pretty much even. Our sleds are set up virtually the same including skis and but his fuel economy is better than mine. Has anyone ever experienced this issue on the apex or might anyone know what this is?

For those who might suggest exhaust donuts I submit that I've had this problem since it was brand new.

 

[Len Todd]

Apparently, you are getting no Error Codes displayed. Is this correct? This makes finding problems a bit more difficult.

How many miles are on the sled? Any other abnormal indications?

Are you using 87 Octane Fuel. This is what you want to use. If you go up in octane rating, they run typically run worse.

Have you checked the coils to ensure they are not arcing to the valve cover? Remove the rubber grommet on coil and reinstall coil w/o grommet. Then look for "lightshow" down in coil hole, with darkened room. Maybe they need cleaning.

I am wondering if you have to sync the two throttle bodies. It looks like there is a connection on each one to do this. But, in the Tech Manual, there is no mention of syncing them. When we sync the carbed RX-1s, this makes them run smooth, eliminates some vibration and they sound synchronized.

Spark Plugs gapped correctly?

Has anyone been friggin' around with the Fuel Mapping? You can make some limited adjustments. A search on the site will turn up the Procedure for this. Maybe your friend did some adjustments to his?

Something as simple a track tension, different wearbars, windshield height, ski pressure, rider weight, etc. can adversely affect mileage. I would not worry about finding a cause for the mileage delta.

 

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Apparently, you are getting no Error Codes displayed. Is this correct? This makes finding problems a bit more difficult.

How many miles are on the sled? Any other abnormal indications?

Are you using 87 Octane Fuel. This is what you want to use. If you go up in octane rating, they run typically run worse.

Have you checked the coils to ensure they are not arcing to the valve cover? Remove the rubber grommet on coil and reinstall coil w/o grommet. Then look for "lightshow" down in coil hole, with darkened room. Maybe they need cleaning.

I am wondering if you have to sync the two throttle bodies. It looks like there is a connection on each one to do this. But, in the Tech Manual, there is no mention of syncing them. When we sync the carbed RX-1s, this makes them run smooth, eliminates some vibration and they sound synchronized.

Spark Plugs gapped correctly?

Has anyone been friggin' around with the Fuel Mapping? You can make some limited adjustments. A search on the site will turn up the Procedure for this. Maybe your friend did some adjustments to his?

Something as simple a track tension, different wearbars, windshield height, ski pressure, rider weight, etc. can adversely affect mileage. I would not worry about finding a cause for the mileage delta.

1. No error code

2. There's 2k miles on sled but sled has done this since new.
3. I replaced plugs and checked everything at break-in oil change.

4. I bought sled brand new no one has messed with mapping.

5. The gurgle is slight and faint but it's deninately there!

6. Throttle not as crisp as my buddy's sled out of hole.

 

[Len Todd]

Thanks for the info. There is nothing there that changes my above suggestions.

 

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Went through everything except Throttle sync. There is a spot in service manual for throttle sync but I don't have tool to do it.

 

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bought a vaccum guage to check throttle sync only to find out that there must be some valve overlap because the needle was jumping back and forth frantically. I suspect that the one the dealers use must have some kind of a check valve with it that holds it.

Does anyone have any ideas?

 

[Len Todd]

The correct tool is a 4 tube Manometer with Mercury in it. But, in some states, that is hard to get cause they don't allow the sale of Mercury. This type tool allows you to hook up all 4 carbs/throttle bodies at once and visually see them all at one time to balance them. Even with this tool you see the pulses a bit, but the affect on the gage is minimal.

That being said, with enough frogging around, you might be able to get close enough with a single vacuum gage. To dampen the gage, you may have to install a plug in the tube with a very tiny hole through it between the gage and the carb. However, even with this, I am not sure if you can get the gage dampened enough to be steady because the vacuum source is pulsing. That is one of the reasons why we use mercury in the manometers. The pulse has less effect on the heavy liquid.

Did the gage come with a dampening insert for the tube? Sometimes they do. I even got some with the Manometer.

Be careful when you have the gage installed. if you blip the throttles, you could whack the gage permanently. Once you bend the gage's internals, the gage is junk.

 

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I have a good buddy who owns an auto shop and he also stated to me that I needed a manometer. Thank you for ur input. I have the utmost admiration and respect for people who share their KTE (Knowledge, Time, Experience).

 

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I took it out this morning and now realize that all of the different problems I was experiencing with my sled was related to spark loss.

It's like buying a new sled all over again! Yamaha should take better car of its spark.

 

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So what did you do to fix the problem? Change plugs or was it an issue with the coils?

 

[Len Todd]

Glad you got it. You must have been watching the other "Coil Post." Eh?

 

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So what did you do to fix the problem? Change plugs or was it an issue with the coils?

You can read detailed explanation in my other post ( backfiring with cr10ek )

 

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Glad you got it. You must have been watching the other "Coil Post." Eh?

Funny... two totally different symptoms caused by the same problem.