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03-03-2008, 11:13 PM
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#1
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Junior Member
Join Date: Feb 2008
Mileage: o
Primary Sled: Yamaha VK540
Where I sled: Alberta
Posts: 12
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VK540, Starts and runs, but won't idle??
Have had this problem since I bought this sled recently. Compression was 100 a side hot. New Fuel Pump, good fuel, runs strong when on high idle. To keep it running need to keep throttle cracked a bit. Won't idle down and keep running. Changed to a 140 jet, ran alcohol through the carb and blew it out with compressed air. Changed the bowl gasket. Why won't this thing idle? Any ideas on what to check?
Drewski
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03-05-2008, 03:15 PM
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#2
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Junior Member
Join Date: Mar 2008
Location: Soo Ontario
Primary Sled: 07 Venture GT
Posts: 8
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I have alot of family members that have Vk 540's they have had ones from the 80,s, 90's and newer , I am yet to see one idle...Some of them will idle a bit, but not very well........
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03-05-2008, 11:27 PM
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#3
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Junior Member
Join Date: Feb 2008
Mileage: o
Primary Sled: Yamaha VK540
Where I sled: Alberta
Posts: 12
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I suspect the problem is the T.O.R.S.
I looked in the shop manual and the VKs have a Throttle Override System. Basically, it stops a run away engine if your throttle jams. Problem is there is a switch on the throttle and on the carb. If you have a defective throttle switch, you have to crack it a bit to de activate the throttle kill, so it will idle and start. The funny thing is when the engine dies, it is DEAD, not sputtering to death, which suggests no spark, which is consistent with the TORS being faulty at the throttle.
I will report what I find out.
Drewski
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03-06-2008, 10:10 AM
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#4
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Junior Member
Join Date: Mar 2008
Location: Soo Ontario
Primary Sled: 07 Venture GT
Posts: 8
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All my Yamaha's and the people I know have disconnected the TORS because of all the issues ( problems ), I know it's not the best thing to do, but you keep on having problems with the tors it's a pain..The TORS has to be set up right in order for it to work properly , you have to have the right amount of adjustment on the throttle cable.......
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03-07-2008, 11:36 PM
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#5
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Junior Member
Join Date: Feb 2008
Mileage: o
Primary Sled: Yamaha VK540
Where I sled: Alberta
Posts: 12
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Bad Crank Seals = poor idling
Brought the sled to Alberta Cycle in Edmonton. Not the TORS System, Not the Carb, but poor vacuum at low speed as a result of bad bottom end seals on the Crank resulting in lost vacum for the fuel pump unless you keep the choke on. Damn expensive to fix, but the sled then will idle I am told.
HAS ANYONE ELSE EVER EXPERIENCED BAD IDLING FROM LEAKING CRANK SEALS????
Drewki
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03-09-2008, 02:40 PM
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#6
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Junior Member
Join Date: Mar 2008
Location: Soo Ontario
Primary Sled: 07 Venture GT
Posts: 8
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Let me know how it idles after the fix , I have my doubts....Good Luck.....Usually leaking crank seals will make it very hard to start, and it will idle rough...
__________________
AKA sledman92
07 Venture GT The Suburban of Snowmobiles
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03-11-2008, 04:40 PM
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#7
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Senior Member
Join Date: Mar 2008
Location: Alaska - 63North, 162West
Mileage: More than the knees can take!
Primary Sled: Arctic Cat T570
Where I sled: Bering Sea coast
Posts: 471
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It's been years since I've run Yamahas, yet the two-stroke transfer port design is common. Seals around the crank were my first thought also. You need good pressure in order to flush the fuel upward into the cylinders. If the seals leak, that can cause the problem of poor idling.
__________________
Formerly known as 63November, and before that as Golsovia.
Riding since 1983.
-Scorpion Whip
-Ski-Doo Skandic
-Yamaha Enticer LTs
-Polaris Trails
Current:
-97/98 Polaris Trail RMK hybrid with over 40,000 combined miles
-99 Arctic Cat 550 Panther 14,000+ miles
-01 Polaris SuperSport 5 rebuilds
-340 eBay Edge from AK, and 10+ other states
-'11 AC T570 brand new...1700 miles
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03-11-2008, 07:21 PM
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#8
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Premium Member
Join Date: Feb 2007
Location: wisconsin Beaver dam
Mileage: 1500++
Primary Sled: 1998 Summit 670 600zl cat
Where I sled: WIS Beaver Dam Or a snow coverd lake
Posts: 1,394
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Had to replace seals on a 1988 srv did the same thing as yours.
__________________
670 SKIdoo  
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03-20-2008, 08:37 PM
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#9
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Junior Member
Join Date: Feb 2008
Mileage: o
Primary Sled: Yamaha VK540
Where I sled: Alberta
Posts: 12
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Mystery Solved!!!!
Alberta Cycle in Edmonton had a problem getting the parts, and agreed to put the sled back together for me and get it running. One of their mechanics had a look at it, and decided the seals were not THAT BAD. He took the carb off, drilled a hole in the WELSH PLUG ?????? blew back on the three jets, pushed out DEBRIS that was plugging off the venturi, soldered the welsh plug (apparently not replaceable) and starting, idling, acceleration all seem to be solved.
I still intend to tear down this perfectly good engine this summer to replace the seals, re ring the pistons, etc, as I just can't resist! That and hot compression is only 100 a side.
Drewski
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01-24-2009, 06:04 PM
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#10
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Junior Member
Join Date: Jan 2009
Posts: 1
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Hi guys, I bring this thread up because I have some similar problems with my VK540 2002.
At idle, it run only on the MAG cylinder, the sparkplug on the PTO side is always wet. As soon as I give it a little throttle both cylinder run fine and the motor run very well.
I've changed everything: sparkplugs, the whole generator assembly, the ignition coil, everything!!! I took all the parts on my father's good running VK, and this thing still running on 1 cylinder at idle.
Also, I switch the reed valves assembly from the PTO side to the MAG side, and the PTO cylinder still not running.
It look like it getting too much gaz at idle.
The crank seals look fine.
Any idea?
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