flat acceleration
Forum rules
Please can you post items for sale or wanted in the correct For Sale section. Items / bikes for sale here will be removed without warning. Reasons for this are in the FAQ. Thanks
Please can you post items for sale or wanted in the correct For Sale section. Items / bikes for sale here will be removed without warning. Reasons for this are in the FAQ. Thanks
-
glimmer
- Settled in member
- Posts: 14
- Joined: Wed Jun 04, 2014 12:35 pm
flat acceleration
initially my bike was bogging on take off, but once moving it would accelerate hard right through the entire range.
So i stripped the carbs and discovered 2 of the 4 o-rings were missing from the pilot air jets.
all the o-rings have now been replaced, pilot air jets returned to 1.5 turns out , carbs balanced and a new air filter fitted. the old one had been modified to let more air through.
my bike now idles and takes off beautifully but at about an eighth of a twist on the throttle through to about three quaters of a twist the acceleration is flat.
any suggestions?
So i stripped the carbs and discovered 2 of the 4 o-rings were missing from the pilot air jets.
all the o-rings have now been replaced, pilot air jets returned to 1.5 turns out , carbs balanced and a new air filter fitted. the old one had been modified to let more air through.
my bike now idles and takes off beautifully but at about an eighth of a twist on the throttle through to about three quaters of a twist the acceleration is flat.
any suggestions?
-
SevenThreeSeven
- Settled in member
- Posts: 176
- Joined: Wed Feb 26, 2014 4:45 am
Re: flat acceleration
Factory Pro has this to say about your carbs... http://www.factorypro.com/tech/tech_tun ... gines.html
-
Marsbar
- Settled in member
- Posts: 225
- Joined: Thu Sep 08, 2011 5:27 pm
Re: flat acceleration
Hmm,i am having same problem that when i go to set off its poo, have to slip the clutch. will have to check my O rings on the pilot. I have my pilots set to 2 turns out, and it starts and idles perfectly.
-
glimmer
- Settled in member
- Posts: 14
- Joined: Wed Jun 04, 2014 12:35 pm
Re: flat acceleration
hey thanks for that 737, ill drop the needle one shim and see how it goes. hopefully tomorrow.
-
glimmer
- Settled in member
- Posts: 14
- Joined: Wed Jun 04, 2014 12:35 pm
Re: flat acceleration
Before i messed wit the needle washers i checked the third plug to see if it was white ( running lean) it wasn't. it was in fact quite sooty.
Armed only with my stupidity i proceeded to drop the washers on the first three needles down one notch. on the fourth i discovered i'd put the spacer and the spring stop washer on the needle the wrong way round. as a result the fourth needle wasn't doing its job.....
So, needle washers put back to factory , the bike runs at 85% of what it did previously. its still a little flat, comparatively ,but ride able. the flatness seems to come on at about the half way point now.
More reading and a fine day to have a proper ride are now required.
Armed only with my stupidity i proceeded to drop the washers on the first three needles down one notch. on the fourth i discovered i'd put the spacer and the spring stop washer on the needle the wrong way round. as a result the fourth needle wasn't doing its job.....
So, needle washers put back to factory , the bike runs at 85% of what it did previously. its still a little flat, comparatively ,but ride able. the flatness seems to come on at about the half way point now.
More reading and a fine day to have a proper ride are now required.
-
glimmer
- Settled in member
- Posts: 14
- Joined: Wed Jun 04, 2014 12:35 pm
Re: flat acceleration
before messing with the carbs i was blissfully ignorant of all those little noises the bike made.
a friend told me that, when riding if you apply the choke, a bike that is set up right wouldn't be affected.
a rich bike would go flat and a lean bike would rev slightly. when i tried this my bike went slightly flat. which confirmed my thought that i was running slightly rich.
So i dropped the needles one notch to lean it out.
the bike now pulls hard right through the range. the exhaust note is higher and when i applied the choke the revs went up slightly.
So it is now running slightly lean but works great.
Q) is slightly lean going to create damaging heat?
A bike that was too lean wouldn't pull hard through the rev range....me thinks
Q2) is there an adjustment that is finer than moving the needle washers?
a friend told me that, when riding if you apply the choke, a bike that is set up right wouldn't be affected.
a rich bike would go flat and a lean bike would rev slightly. when i tried this my bike went slightly flat. which confirmed my thought that i was running slightly rich.
So i dropped the needles one notch to lean it out.
the bike now pulls hard right through the range. the exhaust note is higher and when i applied the choke the revs went up slightly.
So it is now running slightly lean but works great.
Q) is slightly lean going to create damaging heat?
A bike that was too lean wouldn't pull hard through the rev range....me thinks
Q2) is there an adjustment that is finer than moving the needle washers?
-
SevenThreeSeven
- Settled in member
- Posts: 176
- Joined: Wed Feb 26, 2014 4:45 am
Re: flat acceleration
I think you're correct. If it will pull smartly to the redline in 3rd, 4th and 5th you're probably good (6th is hard to judge because you're running into so much wind resistance by the time you get near the redline).Q) is slightly lean going to create damaging heat? A bike that was too lean wouldn't pull hard through the rev range....me thinks.
The bad lean scenario, the one that burns holes in pistons, is when the bike goes lean at sustained high-RPM during high-demand (meaning wide open throttle which brings in a lot of air). In this situation you've got a lot of heat (because lean air/fuel mixtures burn hotter and more slowly than rich air/fuel mixtures) and a lot of oxygen left over after the fuel has been consumed. In this near-plasma state the leftover oxygen decides that if it can't oxidize a hydrocarbon it might as well oxidize aluminum.