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Location: Brisbane
Registered: October 2002
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18RG/solex/ingnition tuning issues
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Thu, 01 April 2004 10:37
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i have had a flat spot in my corona for a while now, i couldnt work out what it was
story:
when u take off it'll flatspot at about 1500rpm to 2500rpm, if u keep the revs up and ride the clutch it'll still flatspot even at 3000rpm
when u r cruising and go to overtake ect it'll flatspot,
when i go to race someone i have to rev the tits off it and feather it at the same time to try and eliminate the flatspot, only minimises it tho.
last night when i was bleeding my cooling system, i brought the revs up to 1500-1700rpm, itd sit there fine and then the revs would drop {down to 800} and it'd run like shit, then if i blipped the throttle itd come back up and it'd be fine,
the car has always run rough when at idle, i thought hat thats how it was, but after last night seeing how smooth it could run when u blipped the throttle, i started thinking.....maybe its a carb problem, when at 800-1000rpmidle i could always pull no 1 or 2 lead off and it'd run the same {similar} but if nor 3 or 4 came off it'd run like a bag of shit and i'd have 3 secs to put hte lead on or it'd die.
today i gassed it and when i hit 6000rpm it just went to shit, it had the same feeling all thru the rev range that it does when it flatspots, so i pulled over and a lead had come off the dizzy , so i am now thnking its maybe either a lack of fuel to those front 2 cylinders OR or maybe a spark problem
when i put the engine in we rebuilt the engine, but didnt have the valves done, i had the carbs fully rebuilt {$500 } but am still running the std points dizzy, i was told the dizzy was fucked but i pulled it apart and the mechanical advance weights were slightly seized, i fixed that, but the vac advance was rooted so i unplugged it.
and it has always run like this, at idle playing with the mixture screws does nothing
which way do u turn to richen/lean the mixture
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Location: Brisbane
Registered: February 2003
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Re: 18RG/solex/ingnition tuning issues
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Thu, 01 April 2004 11:22

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i'd attack the timing problem first - then onto idle mixture and eventually carbi jets.
can you at least move to electronic spark of some sort to so you points last longer or get trashed?
could you adapt the reluctor/ignitor from a smegma (seeing as you work wof them?) or a newer 18RG? i think there were some recent threads about what electronic points fit inside the RG dizzi?
even if you remove the vacuum advance, you'll need the mechanical advance working, unless you get a computer of some sorts to do spark advance for you?
from memory, you changed your leads recently - so have a closer look at the dizzi cap also. constantly removing them leads to do dun stuff like painting the rocker cover and/or change air filters may have stretched the connections for pots 1 & 2.
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Location: Brisbane
Registered: October 2002
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Re: 18RG/solex/ingnition tuning issues
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Thu, 01 April 2004 11:34

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new leads, new plugs, new cap, new rotor, dont have to touch them for filters tho.
i have fixed the mechanical weights, so its curve is ok
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Registered: May 2002
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Re: 18RG/solex/ingnition tuning issues
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Thu, 01 April 2004 12:34

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sounds to me like your carbys arnt properly synchronised.
if your carbies arnt properly balaced your engine will never perform to its potential.
perhaps try adjusting the balance screw .Do it it in *very* small increments.
youll need a vacum gauge to get it exact, but you can do it reasonably well by ear.
I had this exact problem with my 2tg (only really ran on 2 cylinders at idle, i adjusted the balance and she was sweet.)
cheers
tom
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Location: Rocklea qld
Registered: February 2003
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Re: 18RG/solex/ingnition tuning issues
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Fri, 02 April 2004 09:58

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Have they ever been tuned. I tuned my old ones and never had a problem. I can get my timing light and then we can make sure everything is fine. Turn all 4 screws in all the way and then out about 2 turns each. Then after that start balancing them. They way yours idles are you sure its doesnt have some aggressive cams or anything.
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Location: brisbane
Registered: March 2003
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Re: 18RG/solex/ingnition tuning issues
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Fri, 02 April 2004 10:32

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sounds like your carbies are up to shit... clean them out and check yout jet size
it sounds like it might be leaning out it is ither that or your dizzy is stuffed if leads and plugs are new
check movement of the shaft int he dizzy.. if that has a fair bit of sideways movement its time for a new dizzy
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Location: Brisbane
Registered: October 2002
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Re: 18RG/solex/ingnition tuning issues
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Fri, 02 April 2004 23:38

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i had them rebuilt and tuned, all the jetting is the same,
i tried to re-sync them but all that did was bring the idle up, i'll have to get a vac guage and try it
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Location: brisbane
Registered: March 2003
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Re: 18RG/solex/ingnition tuning issues
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Sat, 03 April 2004 04:45

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what size main jets did they put in the carbies?
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Location: Adelaide
Registered: June 2003
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Re: 18RG/solex/ingnition tuning issues
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Sat, 03 April 2004 05:47

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Buy or borrow a vacuum gauge and go balance the carbies.
The vacuum at 1000RPM idle (factory idle) should be 330mm/hg. for the left carbie and also for the right carbie.
This would be the place I would start.
What is your ignition timing set to?
Start the tuning procedure with your idle mixture screws out 1.5 turns(from the manual) to 2 turns (from experience).
Once it is running, then do the balance. Now lower the idle speed until it is only just running almost smoothly. Now adjust the idle mixtures individually (if you drop the revs to tune the car, it is easier to tune it by ear, as changes are more noticable). Start with 1/4 turns of idle screw, then when you find the best range, make smaller movements.
Repeat for other screws.
Now check balance again after raising idle speed back to 1000RPM.
They seem a bitch to tune, but after you do it ten or so times you'll get used to it and you can do it really quickly.
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Location: Brisbane
Registered: October 2002
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Re: 18RG/solex/ingnition tuning issues
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Sat, 03 April 2004 07:06

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jet sizes are
main air bleed 140
starter jet 50
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Location: brisbane
Registered: March 2003
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Re: 18RG/solex/ingnition tuning issues
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Sun, 04 April 2004 03:33

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main is 140?
is it really rough or just slightly?
i got 140 in mine and it was onle really slight
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Location: Madrid - Spain
Registered: August 2002
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Re: 18RG/solex/ingnition tuning issues
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Mon, 05 April 2004 03:21
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Check your venturi tubes, they tend to work loose in solex's and give the symptoms like you are getting. Stick your fingers down the throats and make sure nothing is loose.
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