Rotax500

88 vert, street ported, 20k miles. Trying to figure out my high idle problem. Starts up, revs quick to 2500 then wants to die unless I keep my foot in the throttle. Warms up in about 5 minutes, but keeps idling around 1700 rpm. I'm going to adjust the TPS. The Thermowax is still connected, but I'm having a tough time seeing the "CAM" that everyone is talking about. A few posts said how they can reach around the TB and lift the throttle off the cam, I want to try this to see if it's my problem but don't really see where its at. I'm assuming though, if I have a cold start problem, AND a high idle once warm that the thermowax is not the problem, but I'd like to make sure. Can someone post a pic of the thermowax and cam and how the works, I don't want to remove the entire TB if i can just reach around and lift it off. THANKS.

RotaMan99

You can remove the dashpot which makes it easy to see and get to the thermowax. I had a pic, maybe I can dig it up.

Now im having a hard time understanding whats going on here.

Engine revs up to 2500 but wants to die while reving up to 2500 rpm?

So far it does not sound like the thermowax. I have way to much experience with the thermowax on my car and the thermowax will not allow the engine to die as long as the piston is contracted into the housing when cold to allow the primary throttle plate to open to some degree. When the engine is warmed up, the thermowax piston will extend out to allow the primary plate to close off a little bit to allow the engine to idle down. The thermowax will forever hold the primary plate open a little bit even when warm.

Rotax500

Thanks.

It's like this: No gas, turn key, car starts, jumps to 2500 for a second and then starts to die off unless I hold the gas in, it does this for about 5 minutes, until the temp guage comes up, then holds steady idle at 1700 rpms.

NZConvertible

There are pics and info covering the thermowax in the Factory Service Manual. If you don't have the FSM, click here and download it in PDF format for free. The thermowax and TB are covered in the Fuel Systems chapter.

Rotax500

yes, i have the fsm, but the pics are very hard to see. I was looking for a digital pic so I could see exactly where the "cam" arm is and how it moves off the thermowax. thanks.

NZConvertible

The pictures on page 4A-56 (2nd from bottom) and 4A-57 (2nd from top) are pretty clear and look just like the real thing. The 2nd pic even has little arrows showing what happens as the coolant heats up. The cam is the bit in the middle with the alignment marks on it. The bottom link is what turns the throttle.

HAILERS

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NZConvertible

That's for a Turbo so it's upside-down. Don't confuse the poor boy.