[nomad]

New to this form and got some great help on a problem with my Dads Shadow. I'm just wondering what Honda riders thought about adding a K&N air filter to a stock bike? Do you need to rejet or not? Please help with a father and son disagreement.

 

[CPTRICK3]

I'm looking forward to what the guys that know the answer have to say. In my opinion, it may depend on how old the bike is. Newer bikes tend to run lean from the factory, adding a free flow air filter to that may make the bike run hot and could cause top end damage.

 

[Kechke]

I don't know, who say rejet is needed, but he's right. If you modify something on the intake or the extake system, you must accomodate the carburetor settings to the changes. The reason is simple. If you add an air filter with higher transmissivity, the vacuum will be weak in the carburetor, so, with the more air becomes the engine less fuel. :arrow: the carburetor must be adjusted, in the most fall it must be rejtted. If you modify the exhaust system, the gas-exchange process modified too (caused by valve overlap) :arrow: rejet is needed.
It is true for all the petrol-work engines, except the fuel injection systems.

Hope it was helpful

 

[nomad]

Thanks, my Dad said that a Honda mechanic told him that anyone that adds a K&n Filter to a stock bike allways has to return to get rejetting done.

 

[JPDiesel]

Ditto

I did the air filter change first and noticed a problem. Then I just went ahead and put the pipes on. I had a buddy jet and sync the carbs. Made a huge diffrence on my bike.

JP

Good luck.

 

[Cbjr]

Normally you don't have to rejet, even the dynojet kit don't say to rejet for just a KN upgrade.

But some bikes are so lean from the factory it could go either way.

 

[mike1]

I have a K&N air filter on my 97 Shadow Spirit.
With the K&N, plus Samson pipes or Cobra slash cut slip ons, I never could get it to run right despite various rejetting combinations.
Finally, last week, I gave up and replaced the stock pipes and stock jetting, but added one shim under the needles (a guess).
It runs as well as it ever did when it was factory stock.
I think the K&N filter makes no difference on my bike. I will check plugs in a few hundred miles.
The bike feels OK. Therefore, I won't mess with it.
(I bought the K&N air filter for cost reasons. It has already paid for itself.)
Good luck