Page 1 of 2
help, i've got fuel/carb issues
Posted: Tue Mar 30, 2004 10:06 am
by coaltraintripn
On a recent weekend ride to the desert my buddy and I both expereinced some carb
or fuel issues with the KLR's at highway speeds around 60mph. I'm looking for help in
isolating the problem as we're leaving for Baja in 10-days!
At around 60mph and above, we both noticed our bikes power was pulsing - it felt
exactly like the pulsing you might have right before you run out of gas. At higher
speeds the pulsing was extremely noticable, if not downright violent. The bikes would
go through spells of operating normally for 10-15 miles, then start the pulsing again,
then return to normal, or near normal. Pulsing spats would last from 10-30 mile
stretches. Below 50mph or so, the effect was not noticeable at all.
I suspect the problem could be related to jetting, however neither previous owners
mentioned anything to me, or my friend, about either bike being rejetted for alititude
(a definite selling point around here). We live at 8,000ft. The bikes run fine here (but
it's rare to ride above 60mph here either). The pulsing kicked in after we dropped
2,000 feet or so. Additionally, there was no pulsing when the morning temperatures
were cold. The problem only surfaced after the day warmed up...
Any help would be greatly appreciated. The last thing I want to be doing is figuring
this out in Mexico!
Gracias!
-Mike
help, i've got fuel/carb issues
Posted: Tue Mar 30, 2004 12:10 pm
by Jim Ousley
--- In
DSN_klr650@yahoogroups.com, "coaltraintripn"
wrote:
> On a recent weekend ride to the desert my buddy and I both
expereinced some carb
> or fuel issues with the KLR's at highway speeds around 60mph.
If you have added a fuel filter take it off.
The filter can cause a kind of vapor lock.
The fuel gets hot and causes a vapor bubble to
form in the filter, restricting fuel flow.
Also , the vacuum line from the carb to the
vacuum port on the petcock can become very soft as the temp rises.
This will cause the vacuum line to collapse and restrict
vacuum from completely opening the petcock.
Replace it with a piece of stiff vacuum line from a auto parts store.
Jim
Lexington, Ky
help, i've got fuel/carb issues
Posted: Tue Mar 30, 2004 12:21 pm
by rsanders30117
I had a similar pulsation in my A14 KLR650 until I installed a
DynoJet stage 1 kit & moved the needle up one notch from the center
start point. The pulsation is "lean surging" & at 60 m/h the mixture
is primarily regulated by needle position. The factory needle is non-
adjustable but I think some minor adjustment is available by shimming
it. By design, the OEM cab doesn't permit much adjustment. This is
why I installed the DynoJet kit, so I could tweak the mixture for
better operation.
Assuming you don't have an air leak some where, tinkering with
carburetor will be required to correct your problem.
--- In
DSN_klr650@yahoogroups.com, "coaltraintripn"
wrote:
> On a recent weekend ride to the desert my buddy and I both
expereinced some carb
> or fuel issues with the KLR's at highway speeds around 60mph. I'm
looking for help in
> isolating the problem as we're leaving for Baja in 10-days!
>
> At around 60mph and above, we both noticed our bikes power was
pulsing - it felt
> exactly like the pulsing you might have right before you run out of
gas. At higher
> speeds the pulsing was extremely noticable, if not downright
violent. The bikes would
> go through spells of operating normally for 10-15 miles, then start
the pulsing again,
> then return to normal, or near normal. Pulsing spats would last
from 10-30 mile
> stretches. Below 50mph or so, the effect was not noticeable at all.
>
> I suspect the problem could be related to jetting, however neither
previous owners
> mentioned anything to me, or my friend, about either bike being
rejetted for alititude
> (a definite selling point around here). We live at 8,000ft. The
bikes run fine here (but
> it's rare to ride above 60mph here either). The pulsing kicked in
after we dropped
> 2,000 feet or so. Additionally, there was no pulsing when the
morning temperatures
> were cold. The problem only surfaced after the day warmed up...
>
> Any help would be greatly appreciated. The last thing I want to be
doing is figuring
> this out in Mexico!
>
> Gracias!
>
> -Mike
help, i've got fuel/carb issues
Posted: Tue Mar 30, 2004 12:22 pm
by rsanders30117
I had a similar pulsation in my A14 KLR650 until I installed a
DynoJet stage 1 kit & moved the needle up one notch from the center
start point. The pulsation is "lean surging" & at 60 m/h the mixture
is primarily regulated by needle position. The factory needle is non-
adjustable but I think some minor adjustment is available by shimming
it. By design, the OEM cab doesn't permit much adjustment. This is
why I installed the DynoJet kit, so I could tweak the mixture for
better operation.
Assuming you don't have an air leak some where, tinkering with
carburetor will be required to correct your problem.
--- In
DSN_klr650@yahoogroups.com, "coaltraintripn"
wrote:
> On a recent weekend ride to the desert my buddy and I both
expereinced some carb
> or fuel issues with the KLR's at highway speeds around 60mph. I'm
looking for help in
> isolating the problem as we're leaving for Baja in 10-days!
>
> At around 60mph and above, we both noticed our bikes power was
pulsing - it felt
> exactly like the pulsing you might have right before you run out of
gas. At higher
> speeds the pulsing was extremely noticable, if not downright
violent. The bikes would
> go through spells of operating normally for 10-15 miles, then start
the pulsing again,
> then return to normal, or near normal. Pulsing spats would last
from 10-30 mile
> stretches. Below 50mph or so, the effect was not noticeable at all.
>
> I suspect the problem could be related to jetting, however neither
previous owners
> mentioned anything to me, or my friend, about either bike being
rejetted for alititude
> (a definite selling point around here). We live at 8,000ft. The
bikes run fine here (but
> it's rare to ride above 60mph here either). The pulsing kicked in
after we dropped
> 2,000 feet or so. Additionally, there was no pulsing when the
morning temperatures
> were cold. The problem only surfaced after the day warmed up...
>
> Any help would be greatly appreciated. The last thing I want to be
doing is figuring
> this out in Mexico!
>
> Gracias!
>
> -Mike
help, i've got fuel/carb issues
Posted: Tue Mar 30, 2004 12:53 pm
by Tengai Mark Van Horn
At 6:08 PM +0000 3/30/04, Jim Ousley wrote:
>--- In
DSN_klr650@yahoogroups.com, "coaltraintripn"
> wrote:
>> On a recent weekend ride to the desert my buddy and I both
>expereinced some carb
>> or fuel issues with the KLR's at highway speeds around 60mph.
>
>If you have added a fuel filter take it off.
>The filter can cause a kind of vapor lock.
>The fuel gets hot and causes a vapor bubble to
>form in the filter, restricting fuel flow.
>
>Also , the vacuum line from the carb to the
>vacuum port on the petcock can become very soft as the temp rises.
>This will cause the vacuum line to collapse and restrict
>vacuum from completely opening the petcock.
>Replace it with a piece of stiff vacuum line from a auto parts store.
>
>
Could also be a fuel petcock vacuum leak.
You can either:
-rebuild it (not my choice)
-pull the spring out of it (did it on my Tengai on my way home from
Florida, fine ever since)
-get a vacuum bypass kit from
www.bigcee.com (the better choice, got
one for my '89 KLR)
Mark
http://www.reelrider.com
help, i've got fuel/carb issues
Posted: Tue Mar 30, 2004 1:53 pm
by Don Kime
At 03:56 PM 3/30/2004 +0000, coaltraintripn wrote:
>At around 60mph and above, we both noticed our bikes power was pulsing -
>it felt
>exactly like the pulsing you might have right before you run out of gas.
>At higher
>speeds the pulsing was extremely noticable, if not downright violent. The
>bikes would
>go through spells of operating normally for 10-15 miles, then start the
>pulsing again,
>then return to normal, or near normal. Pulsing spats would last from 10-30
>mile
>stretches. Below 50mph or so, the effect was not noticeable at all.
I recently experienced the same thing on a trip to Florida and again after
I got home (to Ohio). There was no altitude involved at all with mine. It
just acted like fuel starvation. I'm fortunate to have a parts bike, and
changing carbs completely solved it. I haven't taken the time to diagnose
the carb, but I'm guessing that fuel just couldn't flow into the bowl fast
enough to meet the need - perhaps related to float level. At this point,
I'm just guessing. When I have time, I'm going to go completely through
the carb and adjust the float levels. Some day I'll get gutsy enough to
put it back in. Another lister emailed me of an identical
problem. Something w/ the carb and the KLR must be right at the edge(?).
Good luck &
Ride safe,
Don Kime - VFR750F, GL1500SE, GL1100, KLR 650
OH - M/C Safety Instructor/RiderCoach dkime@...
http://forums.delphiforums.com/MCTourer/
help, i've got fuel/carb issues
Posted: Tue Mar 30, 2004 2:09 pm
by Devon
I had problems like this, and also problems with the bike running onto
reserve really early (but the fuel level in the tank was higher than the
reserve tap).
Switching to the Mikuni carb completely solved this, but I've gone back
to the Keihin because it's a better street carb.
I think the vacuum tap on the Keihin is pretty marginal at certain
throttle openings overcoming the spring in the fuel tap. Either a weaker
spring in the fuel tap, or perhaps just cutting out a coil or two might
help.
Devon
>At 03:56 PM 3/30/2004 +0000, coaltraintripn wrote:
>
>
>>At around 60mph and above, we both noticed our bikes power was pulsing -
>>it felt
>>exactly like the pulsing you might have right before you run out of gas.
>>At higher
>>
>
>
help, i've got fuel/carb issues
Posted: Tue Mar 30, 2004 3:13 pm
by Paul
I've noticed the exact same thing on mine. A slight surge on the highway ~60-70 mph in 5th gear, reminiscent of that "need to switch to reserve" sputter.
Mine's an A10 with 4,800 miles on it, in my possession for all of four days and 200 miles, btw. That equals a bike that has spent a good bit of time sitting around and perhaps slightly gummy carbs. Maybe I'll run a tankful with Techron additive through it and see if that helps, although I've not noticed any problems with driveability elsewhere. And it idles just fine; in my experience that's there dirty carbs are most noticeable when the idle jet get plugged. Oops, I almost wrote "idle jets." It's hard for me to refer to engine parts in the singular. This is my first thumper.
BTW: any tips on using the Yahoo archives? When I search, I only get hits from a very narrow range of messages, only one hundred or so. No doubt these topics have been flogged to death, but I can't seem to dredge 'em up from the archives. Frustrating, but perhaps it's pilot error. Any help appreciated.
Paul in DC
96 KLR - 95 VFR
-----Original Message-----
From: rsanders30117
I had a similar pulsation in my A14 KLR650 until I installed a
DynoJet stage 1 kit & moved the needle up one notch from the center
start point. The pulsation is "lean surging" & at 60 m/h the mixture
is primarily regulated by needle position. The factory needle is non-
adjustable but I think some minor adjustment is available by shimming
it. By design, the OEM cab doesn't permit much adjustment. This is
why I installed the DynoJet kit, so I could tweak the mixture for
better operation.
Assuming you don't have an air leak some where, tinkering with
carburetor will be required to correct your problem.
.....
help, i've got fuel/carb issues
Posted: Tue Mar 30, 2004 3:37 pm
by rsanders30117
At a steady 60 m/h, you're just sipping fuel. Maximum fuel flow
occurs at full throttle, not cruising along. So keep this in mind
when working through this problem.
I doubt fuel starvation is the problem unless you're getting low on
gas and/or your tank is not being vented enough. Fuel to the carb is
a gravity flow system & as the fuel gets low in the tank, there's
less fuel pressure force the fuel through filters (if present).
--- In
DSN_klr650@yahoogroups.com, Don Kime wrote:
> At 03:56 PM 3/30/2004 +0000, coaltraintripn wrote:
> >At around 60mph and above, we both noticed our bikes power was
pulsing -
> >it felt
> >exactly like the pulsing you might have right before you run out
of gas.
> >At higher
> >speeds the pulsing was extremely noticable, if not downright
violent. The
> >bikes would
> >go through spells of operating normally for 10-15 miles, then
start the
> >pulsing again,
> >then return to normal, or near normal. Pulsing spats would last
from 10-30
> >mile
> >stretches. Below 50mph or so, the effect was not noticeable at all.
>
> I recently experienced the same thing on a trip to Florida and
again after
> I got home (to Ohio). There was no altitude involved at all with
mine. It
> just acted like fuel starvation. I'm fortunate to have a parts
bike, and
> changing carbs completely solved it. I haven't taken the time to
diagnose
> the carb, but I'm guessing that fuel just couldn't flow into the
bowl fast
> enough to meet the need - perhaps related to float level. At this
point,
> I'm just guessing. When I have time, I'm going to go completely
through
> the carb and adjust the float levels. Some day I'll get gutsy
enough to
> put it back in. Another lister emailed me of an identical
> problem. Something w/ the carb and the KLR must be right at the
edge(?).
>
> Good luck &
> Ride safe,
> Don Kime - VFR750F, GL1500SE, GL1100, KLR 650
> OH - M/C Safety Instructor/RiderCoach dkime@c...
>
http://forums.delphiforums.com/MCTourer/
help, i've got fuel/carb issues
Posted: Tue Mar 30, 2004 4:58 pm
by swampyankee45
the search function is slightly counter intuitive
you just have to click previous or next i forget which and yahoo
steps you down through the archive searching along the way. still
sucks but better than nothing
keep smiling !
Andy
--- In
DSN_klr650@yahoogroups.com, Paul wrote:
> I've noticed the exact same thing on mine. A slight surge on the
highway ~60-70 mph in 5th gear, reminiscent of that "need to switch
to reserve" sputter.
>
> Mine's an A10 with 4,800 miles on it, in my possession for all of
four days and 200 miles, btw. That equals a bike that has spent a
good bit of time sitting around and perhaps slightly gummy carbs.
Maybe I'll run a tankful with Techron additive through it and see if
that helps, although I've not noticed any problems with driveability
elsewhere. And it idles just fine; in my experience that's there
dirty carbs are most noticeable when the idle jet get plugged.
Oops, I almost wrote "idle jets." It's hard for me to refer to
engine parts in the singular. This is my first thumper.
>
> BTW: any tips on using the Yahoo archives? When I search, I only
get hits from a very narrow range of messages, only one hundred or
so. No doubt these topics have been flogged to death, but I can't
seem to dredge 'em up from the archives. Frustrating, but perhaps
it's pilot error. Any help appreciated.
>
> Paul in DC
> 96 KLR - 95 VFR
>
> -----Original Message-----
> From: rsanders30117
>
>
> I had a similar pulsation in my A14 KLR650 until I installed a
> DynoJet stage 1 kit & moved the needle up one notch from the
center
> start point. The pulsation is "lean surging" & at 60 m/h the
mixture
> is primarily regulated by needle position. The factory needle is
non-
> adjustable but I think some minor adjustment is available by
shimming
> it. By design, the OEM cab doesn't permit much adjustment. This
is
> why I installed the DynoJet kit, so I could tweak the mixture for
> better operation.
>
> Assuming you don't have an air leak some where, tinkering with
> carburetor will be required to correct your problem.
>
> .....