Author Topic: Another Start Valve Sync thread (But it's different)  (Read 321 times)

Offline Squeakers (formally SlowRider)

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Another Start Valve Sync thread (But it's different)
« on: January 21, 2018, 11:01:05 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.
 

Offline Jdbiker

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Re: Another Start Valve Sync thread (But it's different)
« Reply #1 on: January 21, 2018, 11:39:49 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.
Jdbiker.
2008 red ST1300A
1980 Yamaha XS 1100
1974. Yamaha TX 500
1984   Kawasaki GT 750
Honda XL 250
Suzuki TS 100
2000 Honda ST1100P
 

Offline Squeakers (formally SlowRider)

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Re: Another Start Valve Sync thread (But it's different)
« Reply #2 on: January 22, 2018, 07:33:02 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.
 
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