Throttle Body Vacuum Leak, New Bearings

Bought a leak tester recently. The DIY version I had been using is jank, this is plug and play – works really well. 

As an initial test I check the Sportster intake, surprisingly found a leak (aside from the intake hole 😉 ). The throttle body bearings are leaking:

After some searching, this thread on SpecE30 had the part numbers needed to replace them:

http://spece30.com/t/throttle-body-vacuum-leaks/7489/6

Manufacturer: INA
Part number: HK0812-2RS

I ordered from Bearing King, search: HK0812-2RS-FPM-DK-B-L271

 

I also purchased a bearing puller kit with a slide hammer off eBay, but this was a waste of money as it didn’t touch the bearing regardless of how much I tightened it up.

Get some good quality diamond grinder bits for your Dremel/rotary tool – they will get destroyed though bearing races are very tough.

Getting the throttle blade out was a challenge as the screws are very well secured. Next take off the throttle position sensor – make a note of its position to help get it back in the right place. There is a spring clip under the position sensor that keeps the main shaft located in the housing. Unbolt the main lever, with the spring clip off and the main level unbolted both will slide up and out. Watch out the spring are under tension.

Now spend the next hours grinding the bearing housings while swearing profusely and questioning the meaning of life (or maybe you have a bearing puller that’s not compete ****).

Use a vice to push in the replacement bearings. A 10mm socket is needed on the underside as there is a lip you need to push past.

Reassemble, ensure there is enough tension on the springs, the one around the throttle blade shaft needs a good amount. You can test once assembled, the throttle should snap back without hesitation. Careful not to loose the spring clip they like to hide when launching off your tools (guess how I know). Be sure to use high strength thread lock on throttle blade and give the end of the screw a bash to reduce the chance of them back off and being eaten by the engine.

When putting the TPS back on grab a multi-meter and ensure the idle switch opens the moment you move the throttle blade, also check to ensure the wide open switch engages as you get towards 2/3s or more throttle.

The final result is a much smoother idle, and way better low RPM drive ability. Despite being a pain to do, it’s worth it.

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