Author Topic: ST appears to lean out of 4000rpm  (Read 1576 times)

Offline HunterTodd

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ST appears to lean out of 4000rpm
« on: September 25, 2019, 04:20:17 PM »
Hi All
have been grappling with an issue for over twelve months and was hoping to benefit from the collective wisdom.
Issue is bike will rev ok to about  3800revs but push it harder and it progressively develops a vibration which is bad enough to trip both knock sensors. Sounds to me like it is starving for fuel. Pretty sure the cause is not misc. Mechanical.
Have had bike apart multiple times.
Checked following
All injectors
Leak tested all vacuum hoses using propane enrichment
Balanced starter valves
Checked entire fuel delivery system and vacumn system and all is squeaky clean
Replaced fuel filter and inlet strainer
Check map air inlet and throttle position sensors.
Checked fuel pump pressure.
Everything checked to date is in spec.
Had it suggested to me that even though fuel pressure is ok fuel flow could be the issue.
Now the question.
Does anyone happen to have a spare fuel pump i could borrow to rule that out? I dont feel like buying a new one just to rule something out.
Problem is that bad i had to buy a CB 1100 to stop my bottom lip from quivering.
Any suggestions appreciated.
Cheers
Todd

 

Offline HunterTodd

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Re: ST appears to lean out of 4000rpm
« Reply #1 on: September 25, 2019, 04:24:05 PM »
Further to earlier post.
Have had bike on computer at two honda dealers no issue with cpu.
I would be happy to have a mechanic look at it but have yet to find one i am confident can fix it.
I can throw parts and hours at it just as easily as they can.
 

Online Brock

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Re: ST appears to lean out of 4000rpm
« Reply #2 on: September 25, 2019, 05:16:25 PM »
Are you using a K&N Air flilter, if so is there a finer outer filter in use. This has been found to be the problem a few times, as the airflow is too restricted.
Brock
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Offline winston66

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Re: ST appears to lean out of 4000rpm
« Reply #3 on: September 25, 2019, 05:49:57 PM »
Have you looked at the various electrical components , Ie, spark plugs, leads, coils, etc, You neglected to say. I suggest that rough running might be caused by  some of the ignition components breaking down at the higher rev range , is there any noticeable difference in power output as you change through the gears. More info on the symptoms might be helpful in bringing out suggestions of areas, things , too check.
Cheers,
Winston66
winston66 Northampton
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Current Rides,
1996 Yamaha XVZ 1300 Royal Star,
2003 ST 1300 A (red)
Mazda Miata MX5 Turboed 14 sec.
2006 ST 1300 ABS Ex Police (white)
Honda CT 110 Postie, (Being rebuilt)
 

Online STeveo

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Re: ST appears to lean out of 4000rpm
« Reply #4 on: September 25, 2019, 05:51:48 PM »
Are you using a K&N Air flilter, if so is there a finer outer filter in use. This has been found to be the problem a few times, as the airflow is too restricted.
My first thought too. Also check the mufflers are not blocked up.
 

Offline alans1100

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Re: ST appears to lean out of 4000rpm
« Reply #5 on: September 25, 2019, 05:55:05 PM »
Are you using a K&N Air flilter, if so is there a finer outer filter in use. This has been found to be the problem a few times, as the airflow is too restricted.
I suppose that could be an issue but just for purely interest sake the air filter in my 1100A has been in the bike untouched for almost 100,000 km which replaced the original one at 120,000 km; unless it was replaced on age instead of km.

Not sure about the one in our Territory but I haven't even looked at it since we got the the car in Oct 2010

As for our 1300A I have no clue as to when it went in but there doesn't seem to be any lack of performance up to 5,000 rpm which the engine might get to once or twice in a blue moon. Must check to see what's in it.
1999 :bl11  2004 :13Candy

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Online PC

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Re: ST appears to lean out of 4000rpm
« Reply #6 on: September 25, 2019, 08:34:16 PM »
Can't help with fuel pump
I would try a ecu reset  I have recently done mine and got rid of an annoying throttle snap when accelerating out of a corner / intersection ect