Maintenance Questions


(Liam Sergeant) #1

Hey Guys,

I’m after some opinions on when you do your maintenance items. I’ve just had my second session last weekend and first in the dry. The kart performed great and I learnt a lot more about It and it’s performance. I have been accumulating spares as I see them come up on sale etc. When do you guys change the following items and what else should I look to do very soon, and what in the future?

Brake pads - Arrow X1, do I wear them down to the backplate?
Brake Fluid - yearly?
Brake Rotor - when it’s not straight?
Gear Oil - yearly?
Bearings - ever?
Coolant - yearly?
Spark Plug - only if fouled?

I run a pre-evo Rotax engine and so far I’ve changed the coolant because it had a glycol based coolant previously. I have purchased a spark plug, gear oil, coolant hoses, brake pads, brake fluid, a throttle cable and brake safety cable. Plus I’ve changed out a bunch of the old nyloc nuts and replaced some bolts. I’ve also replaced the fuel lines and fuel filter, and I replaced my air filter but haven’t re-oiled it yet.

I bought some as useful spares and some to do so I have a clean slate.


(Dom Callan) #2

Brakes go a while but I like to bleed them every few outings. Brake pads last longer. You can see when they are visibly getting done.


(Tony Zambos) #3

Most of your routine sounds good.

  • Brake pads, I’d replace them around when they’re 3/4 worn.

  • Brake fluid, either at the end or being of your season.

  • A dead blow hammer while on the kart can take out little tweaks out of the rotor, otherwise replace.

  • Won’t hurt the change the gear oil. Depending on your engine, 50 or 100 ml.

  • Clean the power valve, every weekend.

  • Replace the exhaust packing, every second or third weekend should be often enough.

  • Carb, disassemble and clean after every race weekend. A sonic clean is great if you have one. Do not spray brake cleaner on the needle valve.

  • Axle beatings, without a chain on, spin the axle. If there is any roughness, squeaking or grinding, replace them. It will usually be the right one but replace them both.

  • If your engine is stored anywhere where it could freeze, get every ounce of water out of it. Fill with antifreeze. Refill with water before racing again.

  • Plugs, we would run three different plugs during the season because of changes in temperature. Think they were a W27, W29, W31. The W29 got the most use. I’d retire them all at the end of the year.

  • Check the shoe thickness on the clutch and wear on the drum gear.

  • Be pro-active on anything you think might end your day at the track.

  • Check your chain for wear.


(Liam Sergeant) #4

Thanks guys, that’s awesome information.


(Liam Sergeant) #5

Has anyone changed the brake fluid on their Arrow kart (or any kart with a similar system, i.e. no fitting for brake bleeder in master cylinder)?

I was planning on flushing it by pushing it through, in one bleed nipple and out the other. Does anyone have any tips? Is it possible to over fill the system?


(Liam Sergeant) #6


(Marin Vujcich) #7

The dent brake system is IMO one the best there is. Super maintenance free with no special bleeding quirks.
Just bleed like a car.
Open lid, crack one nipple at a time on caliper, attached bleeding tube, pump away. Once happy you have flushed old fluid through, hold down brake pedal and tighten nipple. Repeat other side.
All done. You wont need to touch again until next service.


(Jason Allan) #8

Bleed or flush by filling up reservoir in you first picture,
crack the top nipple in the bottom picture. should be one each side of caliper.
pump the pedal and fluid will come out.

Very important to close the nipple before the end of the brake stroke (ie while its under pressure) otherwise air will get into the caliper when pedal is released.
Also keep an eye on how full the reservoir is, because if the fluid drops too low you will also let air in the system.
Arrow brakes are very easy to bleed, once you have got the cordiatntion of pedal and bleed screw correct.


(Liam Sergeant) #9

Thanks Marin and Jason.

Do you think it’s worth trying my idea of leaving the system closed and letting the fluid flow through from one nipple to the other? Or should I drain it and refill it with the cover off the master cylinder?

Is it possible to over fill the system?


(Jason Allan) #10

I think would be easier to do it as described.
Don’t drain it, lower the level of the reservoir with out emptying it, by pumping the pedal. Then refill.
You cant over fill the system


(Liam Sergeant) #11

Awesome, thanks heaps. I’ll do it as suggested.


(Marin Vujcich) #12

As Jason said, easy peasy…:wink:


(Liam Sergeant) #13

Can anyone explain to me how the Power Valve really works?

Does it matter that mine sits ‘in’ as it’s neutral position?

What affect does the change in length of blade/valve have? Mine’s (Rotax Max) ~72.5mm is that an issue? Is it good for performance? Or bad?
I found a recommendation of 73.5-74.5mm, but I can’t work out how you would lengthen it without leaving the blade rattling loose on the thread.


(Curtis J Cooksey) #14

Liam, you should be able to get 1mm more without the blade rattling loose. The power valve helps your engine run better at low RPM and at high RPM by changing your exhaust port. It is a variable exhaust, similar to changing the cam timing on a 4 stroke engine.


(Liam Sergeant) #15

Thanks very much Curtis.

I’ll give it a tiny bit more and try get that 73.5mm mark.

Would you think I’ll be losing low down power with such a short measurement?


(Curtis J Cooksey) #16

No, the most important thing is to get that thing to open at about 7500 RPM’s.