VK540 Sounds and issues

f4ttyg · Apr 11, 2013

Hi everyone,

I'll pretty new to owning a snowmobile. This VK540 is my first.

It's a 2010 Model and hasn't been used a lot.

My questions, if anyone can help.

- Some days I have a really hard time getting the thing to idle. I gather this is relatively normal, but it seems to run on one cylinder for a while before they will both kick in.. any thoughts on this? Oh, and when I say it seems to run on one cylinder, I'm gauging that purely by sound, I haven't done any tests and I'm not a mechanic, but I have a pretty good ear for something running properly and something not.

- When I finally get the thing idling properly, at idle there is a loud "knocking" sound. If I give it a bit of gas it goes away, no gas it comes back. There's another guy in town with a 2010 Vk who says he also has that sound, but i've never heard his machine to confirm it's the same thing.

- Fouled plugs. Again, I gather this is totally normal. Today I had to change them twice just to get it running properly. (We have pretty bad gas up here if that makes a difference)

- Whats the best way to get these beasts to warm up? I've been told by another owner that on the stand, start with choke full open, cut to half, let it start to die out then choke off and keep constant revs up to warm it as quickly as possible. He said that was the best way to stop the carby getting build up from the oil not burning while warming up. I don't particularly like revving cold engines, even if they ARE on a stand and there is no weight on the track. But I've bowed to his 20 year plus experience with machines so far, and it hasn't blown up on me yet.

Thanks for reading, thanks in advance for any help.

yamadad4 · Apr 11, 2013

you may consider cleaning that carb. not much to it, but it almost sounds like a restricted passage creating your "loading up" issues at idle. there may be other issues, but that a good place to start.

depending on your cold starting procedure, those fanners can be tempermental. your on the right track with the full choke fire down to half choke. from there theres a fine line timing wise
before you flip the lever to off. once you get to the off mode, i usually monitor the sled and keep the rpms just above idle, around 2000. this allows the engine to cycle and your not over revving a cold engine. seems like they take forever to warm up. common mistake is to let them sit at idle without feathering the throttle and they load up.

depending on how loud your knock is, it sounds like it could be the clutch weights. a few inspections can direct you to the problem. i usually refer to it as a rattle more than a knock. sounds like the same as once the centrifugal force takes over via higher rpms the noise goes away.

f4ttyg · Apr 11, 2013

Thanks for the reply.

I'll look into pulling that carby off and taking a look I guess, can't hurt to clean it out anyway. As for the starting, I usually open the hood and turn the idle throttle up a couple of turns until its warm then turn it back down, but lately it' still been dying doing that.

The knock really is a knock, sounds like someone hitting a coffee table, and its quite regular. It'll do one, then two or three in succession, then a break for a few seconds, then back to it again. If it's the clutch weights can you suggest what I should look for to figure that out?

yamadad4 · Apr 11, 2013

if you dont have the means to pull the clutch, start by simply removing the cover along with the spring and see what the weights and rollers are doing when not under tension. take it from there.

do you hear the knock when you pull the rope or engage the starter or is it only after the engine fires? possibly starter sticking? exhaust or intake leak even comes to mind. emulating knuckles on desk doesnt sound like clutch weights to me, but it can be difficult to relate "noises" via the keyboard.

video or audio, if possible, may narrow things down.

f4ttyg · Apr 13, 2013

Thanks for your help again, I'll try and have a look at it this weekend, and if possible will take a video as well.

VK540 Sounds and issues

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