Originally Posted by
richard baker
Gents
i hoping you can help as i need some advice,
go 7 port uk import ( think gen4 )
hn 2047 pipe
os p3 plug
optifuel 30%
HN silver alloy shoes with 2 x1.1 and 1 1.0 spings 13t bell.
All in XT8
I can get this engine to fly but seems to be suffering the usual too rich LSN as it takes time to drop down back to idle then wont idle very long.
Did 3 os plugs yesterday 1 where the wire had melted to side of coil apature in glow plug, rest showd white colour coil.
Also after jumps or bad landings takes time to pick fuel up gain stuttering until this has cleared.
ive recently changed my line routing so the fuel pick up runs back round filter neck and in from top rather than above exhaust could this be cause.
if i tune to get LSN to where is recommended around the 2 turns in mark i get bog out of slow corners like the clutch killing engine ?
Im running on astrotruf too so v high grip.
Help
Spud
Sounds like you are too lean on top. That's why you are cooking plugs and getting the bog out of corners. Probably too rich on bottom as well.
Did you read my post on page 453 ? This should set you on the right track.
Also here is a cut and paste from the other GO forum that I posted recently. It will help explain what is happening with your motor I hope.
"The GO's are a little different because the long tapered LSN never actually comes out of the spray bar, so in effect it tunes the motor right through the entire range as opposed to the normal situation where the LSN does up to say 1/2 throttle then the HSN from 1/2 to full throttle.
With the long LSN GO's you just need to make sure the HSN is rich enough (.5 turn in) to supply a big enough volume of fuel to push the fuel past the taper tip of the LSN at wide open throttle. This is were most people go wrong when trying to tune the long needle GO's like a standard short needle carb.
I have always used the analogy of a garden hose to clarify how the needles work. Your HSN is the tap, and your LSN is the variable nozzle on the end of the hose. You use the nozzle (LSN) to regulate the flow of water out of the hose depending on what you are doing. But in order to get the right amount of water out of the nozzle, the tap (HSN) must be turned on enough first.
If you have the tap turned nearly off you might get a reasonable gentle spray pattern, but when you turn the nozzle to jet to reach something further away, all you get is a trickle out of the end (lean bog).
A standard carb is no different, just that the nozzle (shorter LSN) is more, shall we say efficient, so it doesn't need the tap (HSN) turned on quite so far to get a good flow on the jet setting.
GO use this long needle method to give a smooth power band and better economy, which works very well, as long as you are rich enough on the HSN."
Set the HSN to 1/4 turn in from flush and the LSN at 1.5 in from flush to start with. Set the idle gap to what looks like .7 - 1mm and then tune in LSN as described in article on page 453 and go from there.
I am assuming you have a long LSN carb as nearly all Gen 4's came out with them.
Hope this helps.