Today's Message Index:
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1. 05:24 AM - Re: Carb synch issues (Roger Lee)
2. 05:30 AM - Re: Carb synch issues (David Weaver)
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| Subject: | Re: Carb synch issues |
You should have no problems syncing at 3500 and then at idle. Some of you use a
very thick throttle cable (i'e. vernier type) and or have to tight a bend in
the cables. Many times it isn't the carb that won't sync, but the throttle cable
that causes you grief. This will usually let you set the high sync, but will
make the idle sync tougher to zero. The issue is that each time you pull the
throttle cable back and forth it never exactly goes back to the same idle point
on each carb which makes you think they aren't synced. I just did an RV12 and
that's what's wrong with that throttle cable system. The cables are thick and
there are bends which makes the cable bind just enough to drive you crazy on
a sync at idle. You may need to physically push the throttle arms back into
an idle position by hand to get them all the way down instead of allowing the
throttle in the cockpit do it.
If you have thin enough cables and no tight bends and the cables move freely then
syncing the idle shouldn't be an issue. Start with the mechanical sync to get
you close. Some carbs are a little more finicky too. Instead of moving one
side idle stop screw you may need to screw one out a little and one in a little.
You may not be able to just move one screw.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center - Heavy Maint. Rated
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
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Message 2
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| Subject: | Re: Carb synch issues |
The carb sync procedure from Rotax does not address those installations, li
ke yours and mine, where it is not possible to achieve even throttle cable
pull throughout the full range of travel.- Tether your airplane (I use he
avy rope attached to lower landing gear legs with wheel chalks) and sync yo
ur carbs in upper RPM range only.- Forget the low RPM range since the goa
l is to achieve smooth engine operation in RPM range where-the engine-i
s under load.- I frankly do not care what my Carb Tune tool is indicating
at engine idle (which is smooth with little prop loading).- I go for clo
se to 5,000 RPM to do my carb balancing and like very much the results I ge
t both at cruise in flight and at engine idle.- If it were up to me, I wo
uld change the published carb tune procedure as I have a header tank in my
XP and can not route the unequal length throttle cables to achieve even car
b throttle arm pull through out the-range of travel.
Dave Weaver N912GR
--- On Mon, 12/12/11, egp8111 <egp8111@aol.com> wrote:
From: egp8111 <egp8111@aol.com>
Subject: RotaxEngines-List: Carb synch issues
I can't get the carbs on my 912ul to synch at both idle and about 4000rpm.
- If I adjust it for one setting it runs rough at the other.- I'm using
the dual throttle cable from ACS .- Any suggestions ?
thanks,
EG
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