4 stroke carb fule adjustments1

Posts: 185

idled at 1800 rpm,turned fule screw in all the way(no bogging) turned it way out same thing.Theres a 40 pilot jet in it,so with no bogging eather way does that for sure mean i need a larger pilot jet.Its that 30mm mrp for the gtr .

Posts: 1907

if you reduce your idle, you will find the A/F adjustment will have a "sweet spot" where it idles better than other positions. Once you have the A/F adjusted, return the idle to normal.

Posts: 200

Hi Gocartus,

First of all warm up your engine for a good 10 minutes.
Then set your idle slighty higher than normal (500-1000 rpm)
This will make finding that sweet spot phruby means a bit easier.
Turn the airscrew all the way in (be carefull do not tighten!!)
Then keep turning out at 1/4 turn increments till revs increase to highest level. To far and the revs will drop again.
Let the engine adjust to new level for about 10 sec each time.

If you need 0-1 turns to reach that sweet spot,
you need a bigger slow jet, if it takes more than 2
you need a smaller slow jet.

If the revs won't come down immediately when closing the throttle, and engine keeps revving high until you give some throttle again, you definably need a bigger slow jet.

With the proper jet in you can adjust the airscrew for throttle response.
Crack it open quickly, there shouldn't be any bog or hesitation and the revs should go down almost as fast as they go up. (this can also be done as a quick test beforehand).

All of this will set you up for closed to 1/4 throttle.
Next up is the 1/4 to 3/4 which is mostly affected by the needle.
Only above 3/4 the main jet kicks in. (a plug chop is the best way to set this one)

On most carbs one system affects the other,
but I don't want to over complicate this write up.

Jackster

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Posts: 185

Jackster,when you say air screw do you mean the fule adjust knob.How can i tell if i overtightened it.Ill try this in am.Figure out that 300 motor ad the part list and your other mods now jacksters mod dvd is worth 75.00-100.00 bucks !!!!

Posts: 200

Airscrew is mostly located on the side of carb.
I think for yours it's on the left side (little 4mm screw)
Not that adjuster under your fuel bowl, that's the substitute for your main jet.

Jackster

Posts: 269

Quote:

jacksters mod dvd is worth 75.00-100.00 bucks !!!!

I dont no bout $100, but may be a must have at $25.99 (+ tax + ship'n/handlin + more tax), cant even imagine Jacksters local tax stucture -- would I also be paying an import tax ? tarriff fee ?? LOL Very Happy

Posts: 185

Info could be a down load from source,no shipping-local tax -import tax.I my self have spent well over 100.00 in gas, time, wrong parts,shipping,phone calls.Then comes Jackster who did the leg work and research and was willing to share info and with a few post awnsers questions even the importers dont know which means the dealers selling prouduct wont know.If any one could provide me with the proper parts # and where to buy the parts to make the gtr 250 a 300 id gladly pay for that info.I called carters the day i bought my cart,sitting in the dealers lot moments before the transaction.I asked is this the most current cart,any thing new comeing out,the awnser was current cart and nothing new comeing out.So i lay out my cash and low and behold a week later there is a 300 comeing i would of waited for it to come out.Id pay 300.00 to get this info as i cant go buy a new 300 or swap motor.So to me this info would be priceless.

Posts: 200

Thank you guys.... Embarassed

much appreciated.

Jury is still out on that 300 upgrade (lets call it that for now).
But we're getting there. slowly...

At this time it's not even sure when (or if) the 300 will be available in Europe. Something about legalities... Sounds like BS to me.
Surplus stock will have to be sold first I suspect.
So the effort is worth it for me...

But at this rate the 400 will be on sale before we do find out Wink

(No need for research on that one, different engine entirely)

Jackster.