OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines G4/LM Carby - Idle Speed?

hi gents , any one have a tip on how to lower the idle speed on LM/G4's ? 2 yesterday that were way too high for my liking and ran out of washers to put in them .
anyone know of another way ? both had starter manifold and carb 'o' rings replaced . both had good bore n pistons not too much play in rings . ran ok right through the revs but couldnt seem to get them down low enough
not really had much of a problem with them before , its just 2 in one day ? odd hahaha
one was a vortex too but both doing same things .
one was a dead plug the other fuel leaks and pullcord repair .
thanks for any tip , got me stumped these 2 .

Dave

mate the only thing i can say is i had the same prob today so i pulled the whole thing apart and when i took the cable off the carby i found, when in the full throttle position, two small kinks, straightened them out and now i can run it at any revs. made me think of the others i have with that prob. hope it is useful,

thanks mate for the try but 2 in a few hours ? cables are fine no problems there

you can cut a few coils off the long spring, or try replacing it with a short front spring if that doesn't work,

tried that too , even took out the spring on the mustang (easier to get too) a little change but not enough , both are dry around bottom seals and not rumbling bearings so i'm not going there .. so far as i cant tell no air leaks , no cracked manifolds , nothing wrong really seems they just dont wanna play the game !!
one was a tradein so it might become parts yet hahaha . but thanks squizzy

no probs

Did you try adjusting the screw on the throttle control? That does help with idle speed.

thanks blumby , yup sure did i tried almost everything i could think of , might change the diaphragm in the vortex its a brown one ? never seen one before and a little stiff and looks like maybe it wasnt seated right too , dust everywhere . i did move the screw on the mustang .. made a touch better but no cigar still .

i'll change that one from a good runner n see what it does then tomorrow , gotta be something i missed . thanks mate

, Dave

Ok bringing back up an old topic but my question today is does anybody know what the actual difference is between the LM and G4 carbs. The only things I have noticed is the G4 has a black poppet which is different to the white one in the LM, (why?) and the cap has the adjuster screw fitted.I guess Victa dropped that to cut costs and it probably didn't work any way, at least I can't see how it would. I'm going to modify the cam as per all the LM's I have done so far(fantastic mod on these carbs and they work brilliantly) but I was just curious if anybody knew the actual differences. I'm tempted to try a white poppet in this one to see what happens. Anybody tried this?

G'day Norm

The Service Manual has a good discussion of the differences.
It's Part Two in the following link:-

https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/67386/BULLETIN_-_G4_Carburettor_-_Ma.html

Hope this helps.
------------------------
Jack

can i get some details on that mod please NormK

Hi Alan, it is very simple but a bit difficult to explain in words. I cut the 3 lobes off the cam with a hacksaw from where the lifter hits the high point before it starts to drop in the stop position to the low part of the full run "V". File it up and make it smooth so all 3 are a gradual rise and fall for the lifter to work. This takes about 5 mins. I then fit 3 very thin washers under the cam (pain because they need a 7mm hole in them, I file them out to fit), this lifts the cam about 1mm, I haven't really measured it, but it seems to work. This lifts the cam so that when you bring the throttle control back to the start position it actually shuts the poppet completely so the motor will stop. Then I have the modified cap with an adjuster screw in it and when it is screwed in it starts to open the poppet and this is how you set the idle.This way you can have the motor idle perfectly and then you have full rev control through to max which is controlled by the fixed length of the throttle cable. Then you have the fun bit refitting the kill switch setup. Sounds complicated but is very simple. I did put a pic of the modified cam on here somewhere, I'll see if I can find it

Hi Alan, this is when we were working it out, you will see the first cam I modified, but I had taken a bit much off the high point, I still fitted it in a carby and it is working fine. Don't worry about the first 2 pages, the relevant info is on page 3


https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/77320/2.html

The cam on the left is one I just modified. You can see the new ramp on the rear of the one on the left compared to the rear ramp on the factory one

This is hurting my head now, I have been able to master the LM carbs to get them to do exactly as I want them to do, nice low idle speed and full throttle control through the rev range but using exactly the same components in a G4 carb body I am unable to achieve a low idle speed. I have rev control, no problems, switch off ok but the idle speed is too high and there seems to be nothing I can do to lower it. As I said it is now hurting my head, I hate being beaten with this sort of thing. I probably have half a dozen G4 carbs here so I might be on the look out for some LM's if I can't solve this mystery