1 Cold starting issue after TB change Fri Jan 25, 2019 1:03 pm
glennpm
Silver member
Hi,
I'm having cold starting trouble with temperature in the low 40sF or around 5C or so. My normal method of using the "choke" half or full open no longer works. The only way I can start it now is with no choke and holding the starter button in for 5 or 6 seconds or more. I usually just bump it once at the beginning to get fuel pressure up. I arrived at this with multiple other variations. Clutch lever pulled in to reduce drag. It will then start at low RPM, maybe 5 or 600 or so. I then can add the choke a little while holding the start button in to enrich, tweak the throttle slightly to raise the RPM and it will idle faster. Any attempt at this point to go full choke kills it.
A year ago I was unable to start my bike and went through the whole trouble shooting guide of Frog's and eventually changed the fuel pump. Problem was solved then and it ran and started well. I have put very few miles on the bike since then. This was my thread on that past problem, https://www.k100-forum.com/t13459-another-hard-starting-problem
I just completed switching out my K100 2-valve TBs to K1100. Once I get the bike started now, has noticeable more and smooth power.
Status now:
- K1100 from low mileage bike. All cleaned out with new needle valve O-rings. All blue paint was intact and looking through closed butterflys showed all closed with throttle off. Smooth operation of TBs through the stroke
- Fuel and air filters all good
- new fuel pump
- fresh rebuilt fuel injectors
- All new rubber boots and rear vent hose with the TB change. I did have a bad crack in one boot on cylinder #4 that I could never balance well
- vacuum hose to K100 fuel pressure regulator good
- I have manifolded all the vacuum lines together with two taps, one between 2 and 3 for my cruise control and then on the end at #1 for the K100 fuel pressure regulator
- synchronized the TBs three times, balancing was easy but did it to tweak the idle RPM up
- idle RPM once warmed up is about 900
- TPS (K100) is set so just clicks with throttle just starting to open. disconnecting it made no difference in starting.
- fresh 89 octane ethanol free gasoline
- battery new
- Once warmed up it starts immediately with a touch on the start button
I also checked the AFM setting this way and got the "ideal" situation per below:
Air-flow meter vane check.
To set it correctly - engine idling, press the starter button.
That causes a 10% enrichment of the mixture. Listen to
the RPM:
- if RPM increase and stay increased - the mixture is lean.
Adjust screw in.
- if RPM decrease and stay decreased - the mixture is rich.
Adjust screw out.
- Ideally - the RPM should increase about 100RPM, then
drop down to the same speed or lower as it started at
Looking for suggestions please.
Thanks,
Glenn
I'm having cold starting trouble with temperature in the low 40sF or around 5C or so. My normal method of using the "choke" half or full open no longer works. The only way I can start it now is with no choke and holding the starter button in for 5 or 6 seconds or more. I usually just bump it once at the beginning to get fuel pressure up. I arrived at this with multiple other variations. Clutch lever pulled in to reduce drag. It will then start at low RPM, maybe 5 or 600 or so. I then can add the choke a little while holding the start button in to enrich, tweak the throttle slightly to raise the RPM and it will idle faster. Any attempt at this point to go full choke kills it.
A year ago I was unable to start my bike and went through the whole trouble shooting guide of Frog's and eventually changed the fuel pump. Problem was solved then and it ran and started well. I have put very few miles on the bike since then. This was my thread on that past problem, https://www.k100-forum.com/t13459-another-hard-starting-problem
I just completed switching out my K100 2-valve TBs to K1100. Once I get the bike started now, has noticeable more and smooth power.
Status now:
- K1100 from low mileage bike. All cleaned out with new needle valve O-rings. All blue paint was intact and looking through closed butterflys showed all closed with throttle off. Smooth operation of TBs through the stroke
- Fuel and air filters all good
- new fuel pump
- fresh rebuilt fuel injectors
- All new rubber boots and rear vent hose with the TB change. I did have a bad crack in one boot on cylinder #4 that I could never balance well
- vacuum hose to K100 fuel pressure regulator good
- I have manifolded all the vacuum lines together with two taps, one between 2 and 3 for my cruise control and then on the end at #1 for the K100 fuel pressure regulator
- synchronized the TBs three times, balancing was easy but did it to tweak the idle RPM up
- idle RPM once warmed up is about 900
- TPS (K100) is set so just clicks with throttle just starting to open. disconnecting it made no difference in starting.
- fresh 89 octane ethanol free gasoline
- battery new
- Once warmed up it starts immediately with a touch on the start button
I also checked the AFM setting this way and got the "ideal" situation per below:
Air-flow meter vane check.
To set it correctly - engine idling, press the starter button.
That causes a 10% enrichment of the mixture. Listen to
the RPM:
- if RPM increase and stay increased - the mixture is lean.
Adjust screw in.
- if RPM decrease and stay decreased - the mixture is rich.
Adjust screw out.
- Ideally - the RPM should increase about 100RPM, then
drop down to the same speed or lower as it started at
Looking for suggestions please.
Thanks,
Glenn