Gen 2 C28 stva repair keihin 35D1004

[Dafeimao85]

Hi All,

Here is the self evaluate method to troubleshoot your C28, C29. Do note my method is for Keihin 35D1004 model stva. Do check if your stva is this model

If the sympton fits, it may solve ur C28, and C29 with few bucks.

First identify it's a solenoid motor issue or the gear valve issue.

If the secondary Butterfly valve in the video act the same as your bike (full open when power on, open and close non stop few times and end up full open) after engine started. You are 99% chance having a faulty gear!

Next you have to bite the bullet and remove the stva from the throttle body. The user manual says "Never remove the stva" and that's the bull poop!

Note: Hold the butterfly valve in close position with your finger before remove the stva. The stps will run away if you just pull out like that. It may take someone inexperience some time and a multimeter to calibrate it.

Then check your stva whether did the gear wedge into a hour glass shape.

Image for faulty stva gear

Image for correct stva gear

 

[sixpack577]

Great info for an uncommon problem.
Someone will definately be glad for this during their troubleshooting.
It was good to be able to see the video of the secondary plates moving irradically.
And that the stva motor will reset normally and does not need Suzuki SDS to reprogram it.

 

[Dafeimao85]

If yours wedge into the hour glass

Do a 3D reprint at your local store. Attached is the 3D print file for your to download and print


STVA Gear using material PETG 100% fill and fine mark up.

If you need help. I can help you do a 3D print and send to you.

Next open up your STVA and replace the gear with the gear facing bottom.

Reinstate with the hand closing the butterfly valve.

Note: during the whole operation, you do not need to take out the STPS! In the event of a C28 and C29 after gear replacement. Your stps most likely have run away. You need to recalibrate.

 

[Dafeimao85]

And for a rare combo case for my busa. My stps is abit "jam". I end up still getting c28 and and same behavior as the beginning after replacing the gear.

I finally solve it by WD40 onto the stps blue moving part

Lube the blue part.

May I wish you will never use my information for your bike

 

[Dafeimao85]

Great info for an uncommon problem.
Someone will definately be glad for this during their troubleshooting.
It was good to be able to see the video of the secondary plates moving irradically.
And that the stva motor will reset normally and does not need Suzuki SDS to reprogram it.

Precisely,

The source of my 2nd half headache. Unfortunately everything keep adding on. Luckily I manage to untie my problem 1 by 1 slowly.