hi I have a gasgas 125 2011 with standard carb, it seems to run ok, but can't seem to get it to 'tick over'

i'm going to strip the carb down and thoroughly clean it,

but can anyone tell me how many turns of the (idle/mixture/air screw) out it has

any other advice appreciated

thanks

hi mick,

yes give carby good clean out, shove some thin thin fuse wire down any passageways to clear any blocked debris

sometimes you get a bit of hard gritty stuff jammed in.

as a general rule airscrew in 1.5 turns out.

can you adjust by the tickover thumbscrew on side?

get engine hot then alter airscrew when running, so tickover speeds up to a regular beat.

presume its on standard jetting etc? no air leaks anywhere?

jubilee clips tight?

float height correct?

needle valve sealing ok?

see you soon

ian

always check the banjo filter is clear and the floats are set at 18.5

thanks guys for your help, have stripped and cleaned it, going to put it back together then fingers crossed it's sorted

The RPM at idle screws always do the same thing...

BUT! Delorto is opposite & different than the Kehins on idle mixture screws, AND function they do, and starting point. Seems to me 3 turns or 3 & 1/2 turns out on Delorto? Least it was on my last 300. 1.5 turns is starting point for Kehins.

Course I'll post it backwards, due to brain fade...

Ok, on Keihin it is an AIR management screw. But on Dellorto I think it is a FUEL management screw. So for tuning, what this means is "closing" or tightening (righty tighty) the screw affects/cuts down on the aforementioned AIR or FUEL allowed at idle. So if bike is lean (bog on quick blip) you close a Kehin, or open a Delorto. usually.

All the above is "IF" my memory is correct.

Edited June 12, 201313 yr by sting32

Hi Sting32, I have Jotagas 250 with Delorto and I closed idle mixture screw a bit to get a higher idling speed. But now motor runs too lean. I didn't tuch air screw. Should I open mixture screw back, but how I get higher idling speed than? (sorry for bad English..)

Hi Sting32, I have Jotagas 250 with Delorto and I closed idle mixture screw a bit to get a higher idling speed. But now motor runs too lean. I didn't tuch air screw. Should I open mixture screw back, but how I get higher idling speed than? (sorry for bad English..)

samo,

You probably have the standard PHBL Dellorto on your bike. If you stand on the side of the bike and look at the carb, you'll see two screws, the one in the center of the carb body is the idle speed (it raises and lowers the slide slightly) and the one to the left (towards the manifold, not the airbox) of that screw is the fuel mixture screw (it fine tunes the low-speed mixture).

The idle speed screw adjusts the idle speed by raising or lowering the slide a slight amount.

The fuel mixture screw makes slight adjustments to the low-speed air/fuel ratio and in combination with the pilot jet, affects throttle response up to about 1/8th throttle opening. Contrary to what a lot of riders will tell you, there is no "standard" setting as that fuel screw adjusts the carbs ability to maintain the necessary mixture according the that particular engine's need and the outside weather conditions that affect the air/fuel ratio (temp, barometric pressure, humidity etc.). If there was a "standard" setting that worked for all engines, there would be no need for it to be adjustable so it would just be sealed off.

The quick way to adjust the fuel screw is: engine warm, "blip" (quickly open and close throttle) the engine and adjust the fuel screw in or out in 1/4 turn increments until you get the best throttle response. The setting you end up with will be different for conditions, such as, the setting for a cold, dry Winter day will probably be different than for a hot, humid Summer day. The technique for setting an air screw is essentially the same.

Jon

Thanks Jon. I didn't know that Dellorto has no air screw. The small one is mixture screw and that explain everything. If I turn it out Motor gets more fuel, not air..

I cleaned carb yesterday and turned small screw 3,5 turns out and it runs perfectly.

Samo

a friend with a jotagas 300 2013 in the manual it says turning the small screw out makes it leaner and in richer?!! yet on my gasser out is richer and leaner is further in?!