CKRC Forums

One other unusual thing happened this last weekend that I forgot to mention, the tip of the exhaust pipe that is welded in broke and shot out of the exhaust pipe. It looks like they are welded in pretty well so I am not sure what happened except that it had a lot of laps. I didn't see any cracks but I wasn't looking for any either. When that happens I learned that if you have to go to tech after the race and a part that has a technical specification fiche gets broken, cracks, or is changed for any reason, you will get a DSQ and have to start at the back along with a points penalty

Hi David,

I can't remember if you said so before, but do you use a foam air filter inside the airbox? If not, this addition will save a ton of wear on the internals of your motors.

John K

John, do you use your filter dry, un-oiled, and just let fuel mist coming from the carb do the oiling for you?

Dry isn't good enough to stop the really small particulate getting through. I have an air filter oil spray that I spray on the exterior of the filter. It only needs a very light coating so that the airflow is not restricted.

John K

Hi John,

I did add a foam air filter a couple of months ago and spray it with oil but the engine builder told me to take it out during races so my new motor that seized never had it but it only had about 2 hours on it. I did pour about 2 oz of oil in the airbox to catch some sand and dust and cleaned it each day to get rid of anything that accumulated (it is actually quite a bit). Another thing that I learned at this race was to check your reeds daily when it matters. During tech on the second day, they checked reeds and carburetor profile of 5 karts and in the masters VLR 3 of us had broken reeds. It seems like loosing a 5cm chunk off of an outside corner is the most common failure. I have also had mine fray on the edge. I could be wrong, but I think it is harder to start when the reeds have a problem so maybe also check if you notice it takes a bit to start. Now I will be checking reeds daily along with cleaning and greasing the clutch and checking the chain stretch.

Yeah, I've heard similar things about the reed petals, so I'll definitely be checking them often, although I don't have a spare set on hand as of yet.

A question to the more experienced guys, do you, and if so for how long, re-use the intake gaskets. I picked up a fresh set to begin the season, but they seem to be of high quality, rubber-ish material. I'm thinking they could be re-used for quite a while.

Hi David,

I would recommend always running with the air filter inside. I can't believe that the motor builder told you not to run it but I do believe it was to promote more wear and ultimately more work for him.
With an air filter the motor will stay strong longer and you won't kill reeds from debris. Believe it or not the little plastic debris covers that go over the reed box holes cause more restriction than an internal air filter because they cause the flow of air to deflect over the airbox intake holes.

John K

We aren't allowed to cut out those screens, are we?

Those black screens are useless except to keep out rubber and you do not have to run them.

Hi John,

I was told that the plastic airbox screens shouldn't be used because they restrict airflow. One person who told me that is a tech that works for ROK USA and he said it would make enough difference to need to change jetting. I haven't seen anyone in any class using them here.

I have heard the same thing about air filters from a few people here, including the engine builder. From what I have seen here locally, and from what people tell me here, they generally don't run air filters even though there is a fine sand that gets blown onto the track fairly frequently. However, fuel filters are pretty common. The builder told me to take out the air filter when I rented a motor from him so in that case it was his motor. He said I should only run an air filter in practice. It would be interesting to see if it has an impact on a dyno, which I would hope is the basis for his recommendation, but I didn't think to ask. I will ask him when I pick up my motor next week and if he says he just hasn't tested with a filter I will ask him if he can do a test.

I could see if the difference is very tiny, going without an air filter during qualifying and then putting in an air filter for everything else since hundredths or even a 10th of a second doesn't seem to really matter much in a race. I have seen in the rules for some tracks/classes that they require an air filter, which seems like a good idea to just eliminate the concern and keep everyone even if there is any advantage.

Thanks!

--David