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Honda ST1300 Section => Ask A Tech about your Honda ST1300 => Topic started by: Squeakers (formally SlowRider) on January 21, 2018, 10:01:05 PM

Title: Another Start Valve Sync thread (But it's different)
Post by: Squeakers (formally SlowRider) on January 21, 2018, 10:01:05 PM
Over the last few weeks my ST1300  ('08)  :slvr13 was finding it hard to wake up, both morning and evening.  The bike would start,  but idle was very rough or it would stall. Once it warmed up a little idle was 1000 rpm +100.  Good as gold once the gates opened.

I read everything I could find on the internet and the service manual. It all pointed to syncing the starter valves.

I don't own a manometer and I can't justify the price of buying one.  I do however have 10 metres of clear tube, blue food colouring and water.

The manual says valve 1 (the non adjustable one) has a vacuum of 20 mm hg.  Back of the envelope calculations I need ~300 mm H2O have the same reading. I used a 2 metre stick a meter rule and set up a simple vacuum gauge. This isn't the first time I've made one of these. It was the full length of the stick.

I found the five way valve and followed multiple sets of instructions on recording the vacuum.

But this is where my problems started. To "calibrate" my gauge I connected it to valve 1 with the bike running at 1000 rpm. I maxed the gauge and needed to disconnect before sucking the water into the valve. Valve 3 (the one next to valve 1) was the same. It's very quick, I ran out of tube before it looked like slowing down.  Putting my finger over the tube it sucks my skin in and leaves a red mark. My calculations put this suction at ~150mmhg+.

Does anyone have an idea on what could be wrong? Is this normal even though it doesnt agree with the calculations? I think my gauge setup is true, but I can't explain the crazy high readings.

Thank you in advance,
Bernard.
Title: Re: Another Start Valve Sync thread (But it's different)
Post by: Jdbiker on January 21, 2018, 10:39:49 PM
Over the last few weeks my ST1300  ('08)  :slvr13 was finding it hard to wake up, both morning and evening.  The bike would start,  but idle was very rough or it would stall. Once it warmed up a little idle was 1000 rpm +100.  Good as gold once the gates opened.

I read everything I could find on the internet and the service manual. It all pointed to syncing the starter valves.

I don't own a manometer and I can't justify the price of buying one.  I do however have 10 metres of clear tube, blue food colouring and water.

The manual says valve 1 (the non adjustable one) has a vacuum of 20 mm hg.  Back of the envelope calculations I need ~300 mm H2O have the same reading. I used a 2 metre stick a meter rule and set up a simple vacuum gauge. This isn't the first time I've made one of these. It was the full length of the stick.

I found the five way valve and followed multiple sets of instructions on recording the vacuum.

But this is where my problems started. To "calibrate" my gauge I connected it to valve 1 with the bike running at 1000 rpm. I maxed the gauge and needed to disconnect before sucking the water into the valve. Valve 3 (the one next to valve 1) was the same. It's very quick, I ran out of tube before it looked like slowing down.  Putting my finger over the tube it sucks my skin in and leaves a red mark. My calculations put this suction at ~150mmhg+.

Does anyone have an idea on what could be wrong? Is this normal even though it doesnt agree with the calculations? I think my gauge setup is true, but I can't explain the crazy high readings.

Thank you in advance,
Bernard.

Hi SlowRider, I had a similar problem with mine...rough idle,stalling. Turned out to be partially blocked 5 way connector, all good after a clean. Mine’s a 2008 model too.
Title: Re: Another Start Valve Sync thread (But it's different)
Post by: Squeakers (formally SlowRider) on January 22, 2018, 06:33:02 AM
Thanks for the quick reply Jdbiker. I did check the five way valve when it was off, It is clear.

The funny thing is, after having no luck with syncing the valves I put the bike together as is. So I still have the high vacuum. I needed to reset the FI error code. I read a post about disconnecting the battery to reset the ECU. After about 10 minutes or so I reconnected the battery and sure enough the error code is clear.

ALSO, the idle is smooth, the bike is more responsive and my fuel economy has improved (14 km/L to 16.2 km/L).

I think by resetting the ECU I did something. I put this down to an accidental fix.  I still have in the back of my mind that there is something funny going on with the starter valve vacuum readings.