Wed, 29 Apr 1998 16:24:03 +0200
- Message No. 2753
From: Sture Qvarfordt
Subject: More tuning of an AT07
I did some modifications a year ago and a run in a DynoJet testbench.
Modifications was done to the air filter housing a la Raymond F(but I had 6x20mm),
a modified original air filter with washable foam filter on original housing (get rid
of the paper and net, a slip-on "clear tube" exhaust (type Arrow etc.), main jets
of 130/132, needle lifted 0.30 extra, increased hole in vacuum slide to same size
as the bigger one.
The carachteristics I got was in short:
Torque close to 63 Nm from 3500 to 5000 and 61.3 at 3000 and 61.0 at 6000
(very flat curve!).
This means a quite flat power curve with 51.4 at 6000 and 51.7 at 8000 with a
maximum 54.1 at 6750
I have not made a new test bench run since, but I have done some modifications
now and then.
- I increased air inlet to 8x20 because we thought the drop of torque at high revs
could be lack of air and I increased pilot jet? to 42. This resulted a to rich mixture
at low revs and lean on high.
- Back to 40 on pilot jet and up to 140/140 on main jets, via some intermediate
steps (I'm quite fast on mountind/demonting carbs by now). I lifted the needle
to +0.50 mm. This has been the best feeling so far. More power on high revs but
maybe a bit lean on medium revs 4500-5000 (but it's just a feeling).
- I'm now on setting where I increased needle lift to 1.1 mm but thats to rich
from 3-4000 and possibly onwards to 6000.
I will go back to 40, 140/140 and possibly +0.6-0.7 mm and have a run on the
test bench. I think the test guys has got a lambda sond by then, which will
improve the rich/lean guessing.
Be back whith a torque/power curve by then.
BTW - I think you understand by now that I'm going for much torque on low revs.
I think it's nice on gravel roads.
/Sture Qvarfordt,
Stockholm,
Sweden

dipper@normans.isd.uni-stuttgart.de