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If I had a AN400 I'd do some mods on the STVA. I'd try drilling holes in it. I'd try bending one edge out to leave an open gap. Just a little at a time till I went too far and then backup some. Holes can be soldered up.
 
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Discussion Starter #22
I dont know if the stva control unit starting up means that its working properly. I think its also calibrated at factory which means opening up is a problem when closed up. Notice a marker on the side of the unit? Maybe it needs a slight calibration for tweaking. I kept mine open after the c28 code.

Maybe try running it with the c28 code but the plate open (look into the barrel and adjust it because the throttle body is not level) and see how it runs and if it bogs down the same as now. If it does run well, then the stva unit ia mot doing its job as you rev it up. If it doesnt then something else is wrong.
Ckp stva dirt in gas tank. I have no idea. The scooter is very finicky and fragile

Btw @Uncle Fester. Healtech said they dont have an stva eliminator for the b400. I was looking to get one. They said they dont have one listed in compatible models
Not sure what plate u mean...the cover of the strva or the throttle plate? I have experimented with minute changes from centered on the green factory mark to other positions while the scoot is running and nothing seems to make it run better. I think I read that the setting position will show on the instrument speedo screen.
Can u help with resetting the odometer...the only reading I get now is trip mileage and I can’t reset that either. I expect delivery today of a replacement ECM...hope that solves most of my problems
Thanks wicker
 

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Discussion Starter #23
If I had a AN400 I'd do some mods on the STVA. I'd try drilling holes in it. I'd try bending one edge out to leave an open gap. Just a little at a time till I went too far and then backup some. Holes can be soldered up.
Please explain why drilling holes in the strva helps.
Thanks wick
 

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Discussion Starter #24
Should removing the strva from the scoot eliminate the coughing when advancing the throttle above 30mph 3000rpm. I understand the strva main purpose is to assist on starting.
Wick
 

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Inside the STVA is a secondary throttle valve that is mostly closed at low speed. It improves low end power. When you go higher in RPM's that STVA valve should go wide open.

My thoughts are based on old hotrod basics.

I think STVA is Secondary Throttle Valve
 

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I have nonidea how it will show up plon your screen to calibrate it

Yes mine also shows ttip npw and flashes back and forth beteen 2 modes abd you can do anything about it.

I wrote it to you above. So try this and see for yourself if its the stva ubit. Remove that unit from the side. Just let it hang off. Remove the rubber hose so ypu can see inside the throttle body
Once you remove the unit the throttle plat will speed 360 with no resistance so you need to keep it open but the end part of the metal where the stva doesnt mean the plate is conpletely open if you turned it parallel to the floor. The throttle body aits in a sliggt angle backwards.

Anyways. Keep the hose off, start it up, look into the body so ypu can see the throttle plate. Youll bel in an awkward position. Just turn steering habdle left a bit. While youre revving it, open the valve more and more. Keep the revs and the the throttle plate opening in sync gradually so you dont get too much/liytle air and it will seem weird. All in priportuon. You will see that it should rev above 3k and by 5k the plate should be horizontally open. Do this simple test and youll confirm to yourself that IT CAN run above 3k

I remember when my stva went wonky. I drove without the black plastoc body cover to access the TB. While i was driving. I didnt realize the throttle plate spins so freezly without the stva unit connected so when i turned it to the opened position it didnt stay open so i drove it bogged down, slipped my hand down the sidr and opened it and again it moved and it bogged down.i eventually used some epoxy on the while plastic (seems like an anti friction bearing) and glued it in the open position. But remember what i say. The Throttle body plat is not parallel straigh to the ground so if you adjust the side handle/bar/knob flat, and then look in the body, it is not horizontal. You have to adjust it by eye while looking in and mark it. Double check

Keeping it open made it very throaty/a bit noisier on start. Probably ruined mpg a bit and maybe mixture was great i dont know but it drove

I curse suzuki for their unit

Do that little test and see if it will rev past 3k
Dave might be thinking if its in the closed stage but the end lip of one side or holes are drilled, it will alow more air in for inital take off. And thats what i felt when it was open. Initial takeoff on it felt less "choked". Its sacrificing some mikeage but it is what it is

And again... I couldnt find away to adjust odometer/dash with the c28 code active

Let me know if you understood what i said
 

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Discussion Starter #27
If I had a AN400 I'd do some mods on the STVA. I'd try drilling holes in it. I'd try bending one edge out to leave an open gap. Just a little at a time till I went too far and then backup some. Holes can be soldered up.
After reading this several Times, i finally realized you were talking about modifying the butterfly/choke valve. It helps when offering suggestions to be as clear and correctly identifying what you are talking about. Please accept my comment as given in friendly tone.
Regards, Wayne Wicker San antonio 👆
 

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I understand. That is why I posted the second post. Sorry I did not say plate or butterfly. Added in my quotes below.

If I had a AN400 I'd do some mods on the STVA. I'd try drilling holes in the Butterfly Plate. I'd try bending one edge out to leave an open gap. Just a little at a time till I went too far and then backup some. Holes can be soldered up.
Inside the STVA is a secondary throttle Butterfly valve that is mostly closed at low speed. It improves low end power. When you go higher in RPM's that STVA valve should go wide open.

My thoughts are based on old hotrod basics.

I think STVA is Secondary Throttle Valve
 
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