Need help jetting

[rayman375]

In need of some help jetting my 250R. I live in vegas and the elevation can range from 2000-2500 ft above sea level, I have a stock cylinder, stock reed cage, fmf pipe, 38mm pj carb, and an open air filter box with uni filter, I just did a compression test and it showed 210psi so I will be running race gas mixed 32:1. I don't know what size jets are currently in the carb but I can check if need be. It will start and idle fine, but if you stab the throttle it bogs out, if you ease the throttle up it's fine. Any help is appreciated.

Thanks,
Ray

[265 sleeper]

Pull the carb off check your jet sizes and look to see what color your plug is always a good indicator on what to go with your jetting

[hartwill]

Rayman, if your idle is good and your airscrew is 1-2 turns out, and it runs good at wot, you can try leaning out your needle 1 clip position, or richen it up one position. One clip change either way should make a pretty significant difference better or worse in throttle response, and adjust accordingly. This is a fast fix to stop bogging under fast acceleration. Usually people prefer to stay in the middle clip position, so you may want to see where you are. But again if your idle and wot are good this is a good way to fine tune.. Hope this helps..

[tex250r]

Man Hartwill nailed it. I just proved that on my 250r. In the middle clip she would start to bog, towards the bottom it would barely pull itself and load up and at the top she runs pretty well. (kinda proved I need a smaller main jet to stay with the clip in the center). I haven't figured out all my jet problems yet but one clip higher or lower sure makes a big difference in response.

[rayman375]

Thanks guys, I'll take it apart tomorrow and see what's in it for jets. I can't run it yet though because I've got the head off and waiting on new o-rings to re-install.

[hartwill]

Also make sure your running fresh gas. 110 tends to start losing its potency after a week or so... let us know how everything turns out..

[hartwill]

Originally posted by tex250r
Man Hartwill nailed it. I just proved that on my 250r. In the middle clip she would start to bog, towards the bottom it would barely pull itself and load up and at the top she runs pretty well. (kinda proved I need a smaller main jet to stay with the clip in the center). I haven't figured out all my jet problems yet but one clip higher or lower sure makes a big difference in response.
I have done quite a bit of research on jetting and from what I understand the pilot and main work together, so if your top end seems good and your idle is good as well but your bogging in the low end of your throttle you would Probly want to lean out your pilot and maybe richen up your main jet.. it works this way because there is a "bleed over" effect. For instance up here I am running a 48 pilot and 160 main with a CEL needle. At wot she runs great as well as at idle, but she was bogging about 1/4 throttle which told me it was a little fat there. so I moved my needle clip from middle position to one position higher to effectively lean it out because your needle controls most of your midrange, and that took care of my bog. In all reality I could have went down to a 45 pilot and up to a 162 or 165 main and left my needle in the middle position to get the same results. there's so many variables its impossible to explain(not that I know them all). you can also go with a different needle and see a huge difference as well. I have had best luck with the CEL needle. Sorry for the long post I just know how frustrating jetting can be, I've been there..

[tex250r]

I dont want to steal raymans thread. Can you read through the last few post i had on my 1988 Overhaul thread and post your opinion please. I understand its impossible to explain but you or anyone else helping me trouble shoot would be awesome. I did replace my needle when I got the carb kit a while back.

[socal]

Originally posted by hartwill
I have done quite a bit of research on jetting and from what I understand the pilot and main work together, so if your top end seems good and your idle is good as well but your bogging in the low end of your throttle you would Probly want to lean out your pilot and maybe richen up your main jet.. it works this way because there is a "bleed over" effect. For instance up here I am running a 48 pilot and 160 main with a CEL needle. At wot she runs great as well as at idle, but she was bogging about 1/4 throttle which told me it was a little fat there. so I moved my needle clip from middle position to one position higher to effectively lean it out because your needle controls most of your midrange, and that took care of my bog. In all reality I could have went down to a 45 pilot and up to a 162 or 165 main and left my needle in the middle position to get the same results. there's so many variables its impossible to explain(not that I know them all). you can also go with a different needle and see a huge difference as well. I have had best luck with the CEL needle. Sorry for the long post I just know how frustrating jetting can be, I've been there.. Great post!My needle is in middle position also and bogging at 1/4 throttle.I will try this next!

[trx750gsxr]

My 86 is good on the low to mid but wont rev out> get into the powerband and she falls on her face> not sure on the elevation here in emmett, MI but its really fustrating. Gonna pull the carb and soak it again in carb dip. Drain the tank and pull my petcock off and make sure thats cleaned out as well. The tempature last weekend we she ran well was around 75-80> yesterday it was like 95..................any help?

[fearlessfred]

Originally posted by 265 sleeper
Pull the carb off check your jet sizes and look to see what color your plug is always a good indicator on what to go with your jetting x2 i would like to add that you should get your main jet correct first by doing wide open runs ( after beakin if it is fresh) and then doing a plug reading, start by only running thru a couple of gears wide open pull in the clutch shut off the motor and then come to a stop and read plug. if it is not to lean keep adding gears at wot and read plug . the whole idea behind this is to not burn a hole in a piston if it happens to be to lean. once you have the main correct than go on with all the good info others have allready given you. if the motor is mechanicly sound and no ignition problems than the plug reading is the best way to figure your starting point of getting the main correct and once all the other fine tuning is done go back to the main with a wide open run and double check plug

[hartwill]

Originally posted by trx750gsxr
My 86 is good on the low to mid but wont rev out> get into the powerband and she falls on her face> not sure on the elevation here in emmett, MI but its really fustrating. Gonna pull the carb and soak it again in carb dip. Drain the tank and pull my petcock off and make sure thats cleaned out as well. The tempature last weekend we she ran well was around 75-80> yesterday it was like 95..................any help?
every quad I have seen from michigan is usually jetted WAY rich im not sure if this is an elevation thing or if people do this for the sand dunes up there. We have gotten them home and had to drop as much as from a 180 to a 162 just to get it to run correctly. I dont think there is that much of an elevation differene between ohio and michigan.

[trx750gsxr]

it was probally jetted for winter............

[265 sleeper]

Originally posted by fearlessfred
x2 i would like to add that you should get your main jet correct first by doing wide open runs ( after beakin if it is fresh) and then doing a plug reading, start by only running thru a couple of gears wide open pull in the clutch shut off the motor and then come to a stop and read plug. if it is not to lean keep adding gears at wot and read plug . the whole idea behind this is to not burn a hole in a piston if it happens to be to lean. once you have the main correct than go on with all the good info others have allready given you. if the motor is mechanicly sound and no ignition problems than the plug reading is the best way to figure your starting point of getting the main correct and once all the other fine tuning is done go back to the main with a wide open run and double check plug
You don't want to start off with wot plug chops in less your pilot jetting is correct . In order to get to wot you have to get through the pilot jet ,and needle position first . When they are good then work your way to the Main .

[fearlessfred]

Originally posted by 265 sleeper
You don't want to start off with wot plug chops in less your pilot jetting is correct . In order to get to wot you have to get through the pilot jet ,and needle position first . When they are good then work your way to the Main . were are you guys getting your information about the main and pilot having an effect on each other. every TWO STROKE chart i have ever seen ,shows the main having nothing to do with the pilot and the pilot having vary little to do with the main. all the charts i have seen,shows the pilot tapering off to nothing once your on the main. please show me what i have missed. i should say that i dont disagree with your way of doing it.,but my real point i was making was to use a plug reading to determine correct jetting,and i guess we agree on that