rejetting 250R carb question?

[garrettagr]

I have a qestion that is probably really east for many of you but i am new to the 250R realm of quads. I have a 86 250R with a 36mm esr carb, fmf glod series fatty and power core silencer. Also have a K&N filter is an aluminum airbox. My quad has almost no bottom end at all and then his the band hard but way up high in the revs. Could this be remedied with jetting or maybe a cool head with a higher compression dome. What are you running with jetting if you have a similar set up. Any help would be appreciated.

[wilkin250r]

The power hit generally has very little to do with jetting, unless the jetting is WAY off and you have no power at all.

But if you are hitting the powerband, it's a pretty sure bet the jetting is at least close, and your problem is somewhere else.

Now, the 2-stroke won't have a whole lot of power in the low end anyways. For example, you'll never be able to pop a wheelie without revving the snot out of it and being in the meat of the powerband. But when the power does hit, the rear wheels should break traction on gravel and throw a roost, that's just the way the 2-stroke power works. It's like a light-switch, one second you've got no power, and the next second you're struggling to hold on.

From your description, it's very difficult to tell whether you have a problem or not. The power shouldn't be hitting WAY up high, that wouldn't be normal. But if you are used to 4-stroke, you might describe it that way, even though it's perfectly normal.

My best advice would be to try to find somebody with a 250r that you KNOW is normal, and compare.

[garrettagr]

yeah i will try that.It dosent run bad at at all but i just had that question. The second part would be if i do change the head to a cool head which i am going to do, and up the compression a little bit, would i have to rejet? Also i am going to be running race gas, like 105 to 110 leaded so would i need to rejet if i do that. thanks

[garrettagr]

also, does anyone have any ideas on water temp gauge for my 250R. I like ESR but they would be up under the fenders a little bit. Would like to have something a little more remote if possible. thanks

[Kirt13]

It's also possible that your jetting is too rich. This would cause it to be a little slugish on the bottom end. Is your exhaust smokin' a pretty good amount?

[garrettagr]

only at startup. But after it gets warmed up it dosent smoke much at all. It does put out a little poof when i hammer down on the throttle though. I am running the oil at 25:1. maybe that is a little rich. I think im going to try 32:1 when i mix gas again.

[Kirt13]

If your not smokin' much with 25:1 you are definately not too rich. What size are your rear tires and what size sprockets are you running? I'm just trying the most simple things first.

[garrettagr]

thanks for all the help. i really apprecate it. The rear tires are 20 inches. they are the same as on a 400ex. The sprocket size is stock on both front and rear. Maybe the person who posted first is right. i have only ridden four strokes and am not used to a two stroke. any more info would be appreciated. Anyone have info on a temp gauge.

[Kirt13]

Not to disagree with the first responder, but my 2 stroke has absolutely no bog on the bottom and I can take off on wheelis in any gear. I'm not sure of your problem though. I'm not really an engine expert.
I got my temp guage from eBay. What type of guage do you want? You want something that does or does not stay under the plastics?

[garrettagr]

i think that i got the temp gauge figured out. Thanks for the help. I also belive that i figured out my problem as well. My fuel/oil mix has to be a little off being at 25:1. Everyone i talk to says that it is pretty rich and suggest more like 32:1. I will try that and see what happens. Thought of this due to the huge amount of smoke during startup and it does smoke more than it should when running at operating temp. Let me know what you think.

[garrettagr]

also. Got a duncan racing cool head without the head stay yesterday. It has a 20cc dome in it. Wondering if that was a stock size dome or if for compression wise i will be ok. I plan on running race gas. thanks. ps.what is the stock dome cc size?

[draggin-accord]

i'm gonna bring this back to life because the 1st poster is in a similar situation as me. i'm new to 2 strokes & i'm trying to learn the whole jetting thing. i've be doing my research & have a diagram when i go to pull my carb apart to check the jets. i bought the bike w/ fmf fatty & silencer, k&n - no lid (which i switched to an uni), esr ignition, & a keihin carb (think a pj). i'm using the be9XXX plug & am bored 20 over & run 32:1 castor 927 on 93-94 pumpgas. plugs are usually dark colored. i put 13/39 gears in also. at start up i have some smoke, i dont think its excessive. at wide open in the sand quarry is fine, very little or no smoke. i do notice that in tight woods riding it seems to load up a bit. is that normal? any recomendations / words of wisdom?

i will be checking jet size hopefully tonite.

where can i mic the carb to tell what size it is?

[draggin-accord]

a little help please

[draggin-accord]

carb: keihin pjh26a

main: 168
slow: 58
idle adjust: approx 4.5 turns
needle: r1368n, 3rd slot outta 5

why do these jets seem to be waaay to big?

[C-LEIGH RACING]

You can go down a size or two on the slow jet to clear it up some in the woods.
If you can get a good clean idle with the idle screw turned out 2 1/2 turns it should be about right. Do some testing though with the slow jet, dont just put a smaller one in & leave it.
Temps outside can play a big part as well, cold = lean,,hot = rich I know it sounds crazy but thats how it is.
Neil