Snowmobile World banner

1 - 11 of 11 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
I'm looking at putting a set of K&N filters & snowchargers on my Formula Z 670. I put a cold air intake with a K&N filter on my Durango and I love the added performance and throaty sound :sly: , now I'm thinking of doing the same thing to my sled.

I've seen a couple post that talked about changing the jets when doing this. Is this necessary?
 

·
Registered
Joined
·
120 Posts
Best thing to do is to contact K&N and ask them what to do. I bought an air filter from them for my CR500 and I called them to find out what carb adjustments to make. After the adjustments the bike ran tops!

The funny thing is that the performance shop that I bought it from had no idea what adjustments to make.
 

·
Registered
Joined
·
3,910 Posts
Your supposed to have to jet up when you add a k&n. More air means more fuel.

However stock jetting is rich, you might get away with it. However you will have to check to make sure by reading the plugs. Plus if you ride in real cold weather you will no longer have that margen of safety.
 

·
Registered
Joined
·
1,106 Posts
Leave the air box on the sled, unless you have a full race engine. But if you need to have the filter's, start with the jetting ten points higher then with the factory air box. If you have a 300 main now start with a 400 main, then tune from there.
 

·
Registered
Joined
·
624 Posts
;) Wouldn't leaving the OEM Airbox in place defeat the purpose of the K&M filters? I got one on my truck, and I gained MPG, and Grunt by REMOVING my OEM airbox and filter. Relacing it with the K&M filter and intake runner.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #7
I have VM 40mm carbs 670. Doesn't that have 500 for main jets already (& 35 for the pilot jets)? I thought that was pretty big already.

Thanks for all the info & keep it coming! This site is great!
 

·
Registered
Joined
·
400 Posts
When I had my 670, it had 330'ish jets in it - I don't remember
exactly. I put filters on it and twin pipes and had to jet
up to 450's.

My experience was that if you don't port the engine, the
filters OR pipes do not give you any performance increase.
Again, this was just my experience with a certain manufacturer
of pipes.

The filters alone sounded like it made more power, but the
sled was slower. I don't remember the jetting with just the
filters, but it was more.

Good luck.
 
1 - 11 of 11 Posts
Top