Pro_Marinero
Newbie
- Joined
- Dec 8, 2024
- Messages
- 3
- Age
- 49
- Location
- Washington
- Country
- USA
- Snowmobile
- 2012 Yamaha VK Pro RS
Tried this 2012 VK Pro out finally. It was in excellent shape with very low miles but had sat for 6 or 7 years under a cover before I bought it last March. The carbs needed cleaning and it had a stuck piston ring. I soaked all cylinders in Marvel Mystery Oil and compression jumped to 180 across the board. I pulled the carbs and gave them a good cleaning, but I didn’t pull the diaphragms and needles. I removed the bowls, enrichener needles and all jets. I replaced the float needles with new. All pilot jets were plugged but I was able to clean them with air and carb cleaner (I didn’t ream them out). I also rebuilt both fuel pumps.
The sled runs great except for idling. It immediately fires up on the choke and will fluctuate between 2500-3000 until the temp light goes off if I leave the choke on full. Once the light goes off it idles around 3000 with full choke. I can take the choke off all the way and it will idle down. Once I ride and warm it up, the idle will go up to almost 3000 when I stop. I can adjust idle down to 1400, but when I stop again the idle will be up again. It seems like a vacuum leak, but I can’t find one anywhere. I’m going to pull the carbs again, clean them more thoroughly, and also sync them when I put them back on. However, is there some kind of cold feature on these carbs I’m unaware of? Like a thermowax air valve or the like? I’m guessing the fluctuating idle is a function of the ECU changing timing but it sounds like I might still have something plugged somewhere. I also might just get new pilots as these 45’s are so tiny it’s hard to tell if they’re totally clean. Thanks.
The sled runs great except for idling. It immediately fires up on the choke and will fluctuate between 2500-3000 until the temp light goes off if I leave the choke on full. Once the light goes off it idles around 3000 with full choke. I can take the choke off all the way and it will idle down. Once I ride and warm it up, the idle will go up to almost 3000 when I stop. I can adjust idle down to 1400, but when I stop again the idle will be up again. It seems like a vacuum leak, but I can’t find one anywhere. I’m going to pull the carbs again, clean them more thoroughly, and also sync them when I put them back on. However, is there some kind of cold feature on these carbs I’m unaware of? Like a thermowax air valve or the like? I’m guessing the fluctuating idle is a function of the ECU changing timing but it sounds like I might still have something plugged somewhere. I also might just get new pilots as these 45’s are so tiny it’s hard to tell if they’re totally clean. Thanks.
74Nitro
VIP Member
- Joined
- Feb 18, 2013
- Messages
- 5,353
- Age
- 52
- Location
- Dublin Ontario
- Country
- Canada
- Snowmobile
- 2019 Sidewinder LTX
You're about to do what I was going to suggest anyway.
Sync carbs and new pilots.
Wouldn't hurt to do a leakdown test or compression test on the cylinders also.
There is a timing change for cold starts, but it reverts to the run map when the temp light goes off.
Sync carbs and new pilots.
Wouldn't hurt to do a leakdown test or compression test on the cylinders also.
There is a timing change for cold starts, but it reverts to the run map when the temp light goes off.
I have a 09 vector and it acts very similar to yours. When it was new I could start it fully choked for a short bit and then it would idle perfectly with choke off now it wants to die until it is fully warmed up. And when it is warm up it wants to do the high idle to for probably a good few minutes before it comes to an idle.
