Trottle body STPS motor

[Idh]

Good morning all. 
I had a topic open on vacuum hoses, but my issue appears to be totally different, so opened another topic.

The secondary valves on the throttle body are not moving when the ignition is switched on.

I have the airfilter out and can move the valves manually and this clearly the shaft that operates the STPS.


Has anyone had this and fixed it? I can't see a replacement motor online anywhere.

I am thinking of getting a full used throttle body.

[Eric GSX1400K3]

Have a search on here, you should be able to pull the stva apart to see whats wrong, alternatively check the TB once you've removed them from the bike. If you have access to another set of tb's, verify of course that the stva works, you will need a 5V supply, I think 12v will be too much.

[grog]

Pretty sure it was Snapey repaired his, re glue magnets from vague memory. Worth searching before rushing in IMO

[Hooli]

This isn't the best pic as I can't find the ones I took of the STVA in bits, but the big square lump made of thin layers in the centre of the TBs is the STVA. You get to it by taking the TBs apart, there's two long bolts that hold them together end to end with, I think, 10mm heads on the RH side of the bike. Then there's four little nuts from the LH side that hold the plastic cover on the side of the STVA. Once you lift that off you'll see the magnets in there, if they are loose then glue them back (epoxy works) where the marks are from them being glued previously.

[Eric GSX1400K3]

Exactly, as Dr. Hooli says.

[Idh]

Thanks all, brilliant help as always.

Having a weekend off, so will look again next week.

Ian

[Idh]

Well, throttle bodies out and long bolts removed.

Unfortunately I don't have JIS screwdriver head to take the fuel rail off to allow me to separate the bodies.  On order for tomorrow.

However, I have found an issue.

There is a spring missing. Can't describe it, but the picture shows it. This missing is stopping the right hand secondaries moving the same as the left two. So definitely needs anew one. Don't suppose anyone would know where I could source such a beast?

[Idh]

0

[Hooli]

Ahh those springs, they often pop out as you're twisting the TBs put when the long bolts are out.

You can probably get real ones from Webike Japan, but I've often found random springs that look about right and used them. One thing I'd say, is don't use ones that are too soft as the throttle vacuum can overcome the spring and give alsorts of odd issues.
I can't suggest where to find them locally though as I nicked the last ones I needed from some 125cc carbs in the corner of the garage.

[Eric GSX1400K3]

If you can get a complete set of TB relatively easily, you could cannibalise one to make a complete full set.

[Barbastro K6]

Do not leave out AliExpress. An example:

https://es.aliexpress.com/item/1005008369380644.html?pvid=37e5f6ba-83bd-48ac-9db1-ed6453d6fe99&_t=gps-id%3ApcDetailBottomMoreOtherSeller%2Cscm-url%3A1007.14452.396806.0%2Cpvid%3A37e5f6ba-83bd-48ac-9db1-ed6453d6fe99%2Ctpp_buckets%3A668%232846%238108%231977&pdp_ext_f=%7B%22order%22%3A%22726%22%2C%22spu_best_type%22%3A%22price%22%2C%22eval%22%3A%221%22%2C%22sceneId%22%3A%2230050%22%2C%22fromPage%22%3A%22recommend%22%7D&pdp_npi=6%40dis!EUR!2.43!2.42!!!18.92!18.81!%40210388c917779591547783402ee22d!12000044772289354!rec!ES!135463698!X!1!0!n_tag%3A-29919%3Bd%3A26674c2d%3Bm03_new_user%3A-29895&utparam-url=scene%3ApcDetailBottomMoreOtherSeller%7Cquery_from%3A%7Cx_object_id%3A1005008369380644%7C_p_origin_prod%3A&search_p4p_id=202605042232348122981266911596170176_1

[grog]

So those springs just sit there, nothing holding top end in just spring tension?What adjustments is the screw for? Never messed with TB on mine, never needed to. Just wondering.

[Eric GSX1400K3]

So those springs just sit there, nothing holding top end in just spring tension?What adjustments is the screw for? Never messed with TB on mine, never needed to. Just wondering.

no, there is a screw in the bottom bit, same as the top, but looks like that screw is also missing, that holds it in place. The spring force should hold the screw in. Suspect they may have some loctite on them to ensure.  I have adjusted mine, as I found that the voltage reading on the STPS when opening #1-#2 by hand was different when doing the same with #3 and #4, which meant that 1-2 and 3-4 were not opening together.  Fine adjustment is possible to ensure that they do, and allows accurate TPS and STPS setting.

[grog]

Thanks Eric 👍Looks like correct parts needed then. Parts diagram says discontinued, that's if I'm seeing correct bits, lots of little bits in TB diagram.Hard on old eyes to see

[Hooli]

So those springs just sit there, nothing holding top end in just spring tension?What adjustments is the screw for? Never messed with TB on mine, never needed to. Just wondering.

As Eric said, you can balance the secondary throttles just like the primaries.

When I've had TBs off I see if they look equal & if not adjust them slightly. I tend to push them nearly shut at the STVA & use a drill bit to slide in past them to check all the gaps are the same without moving anything.