Throttle body cleaning

Well,, I am up to my elbows in it now. While doing my first valve clearance inspection,,, I have been coming across a number of other issues that need attention. One is,,, now that the throttle bodies are exposed,, they look like a good cleaning is in order. There is a black coating on the inside edge of the butterflies which I would not want to touch. Is there a spray only solution that would be best for this ?? I tried a search,,, but did not come up with anything. Maybe I shouldn't improve things too much,,, because of the seized idle adjustment cable. It is currently stuck in a good position,, idling nicely at about 1150rpm.
thx,,, Cat'

Spray a good shot of nothing in there.

Seriously, the black stuff is there on purpose and should not be cleaned. More details in this thread.

--Mark

Yes,,, I hear you, Mark. I assumed the black coating was to improve the sealing along the inside inflow edge of the butterfly. It is 95% intact and I would not want to degrade it further. It is the rest of each bore that looks like a good cleaning is needed. But the bike is running good,, so best leave well enough alone. It's not like I don't have a dozen other issues to resolve. thx,, Cat'

Blrfl said:

Spray a good shot of nothing in there.

Seriously, the black stuff is there on purpose and should not be cleaned. More details in this thread.

--Mark

Click to expand...

Are you running a K&N air filter?

Blrfl said:

Spray a good shot of nothing in there.

Click to expand...

Make sure you use a good quality synthetic nothing, like Mobil 0. It will do nothing better and the non-effects will last longer so you won't have to do it as often.

Whew! You just avoided the major tenet of motorcycle repair....if it ain't broke, work on it until it is...........broke.............ff

The previous owner used a K&N,, but changed back to oem style before I purchased it. I know this because he included the K&N along with a bunch of spares when I purchase the bike. I plan to keep using oem type filters. Cat'

hoowasat said:

Are you running a K&N air filter?

Click to expand...

There is a possibility that if you see black "gunk," it may have resulted from whatever liquid is used to "charge" K&N filters. Several owners, myself included, experienced runability issues when running K&N filters. My engine would simply stop sometimes when I came to halt. When I switched back to a paper filter, my ST1300 ran fine again, and that issue has not repeated.

From my experience with other engines,, I am no longer a big fan of oiled foam filters,,, at least on bikes. Possibly some of the dirty throttle bodies is due to that,, however it looks much like any automotive unit that needs a cleaning. The difference is that I have not encountered the black sealing compound before. So I will leave it alone,,, as I have seen worse in cars and trucks before.

But tonight's valve inspection went very well,, with only one intake valve out of spec at .008 . Many thanks to the author/s of the Valve Spec Worksheet,, as it made the job much easier. And a bonus was that the seized idle screw cable, which I had saturated with Release-all, is now functioning. Once I get some replacement hardware, I should be able to start putting things back together again. Yippee !! Cat'

hoowasat said:

There is a possibility that if you see black "gunk," it may have resulted from whatever liquid is used to "charge" K&N filters. Several owners, myself included, experienced runability issues when running K&N filters. My engine would simply stop sometimes when I came to halt. When I switched back to a paper filter, my ST1300 ran fine again, and that issue has not repeated.

Click to expand...

Another ST-O user reported finding the inside surfaces of vacuum lines becoming deteriorated with black gunk (softening hose material perhaps). I believe he found the same thing on multiple ST's and the common denominator among them was K&N air filters.