Tuning This Monster 250r

**kbyeeeeee** · 05-21-2005, 06:44 PM

1984 ATC250r k&n filter, no airbox lid, wiesco top end .80 out
I checked the jets and it has main 130 and 50 slow
I have the outside air screw at 1.5 turns out the float is at 21mm
honda oil 32:1 I will be getting my rings on monday and will start it as soon as it is possible. Just wanted to know if this is ok and how should i go about tunning??
thanks

**kbyeeeeee** · 05-21-2005, 11:06 PM

Any help out there????

**jmack3986** · 05-21-2005, 11:15 PM

make sure that you have evrything jetted properly or you rill fry the motor. jet you jetting because of the bore i would suggest one up from stock on pilot and 4-5full 5 step sizes on the jet

**Meat-BoX** · 05-22-2005, 01:54 AM

Dont Know Jetting But I do know that no AirBox Lid is kinda sketchy. Why dont you just Vent the Lid and maybe attach some screen to the inside of it. You'll still be suckin in alot of good air but the chance of something Jammin up are allmost impossible. I know alot of people go without a lid and use the outwears and all that, but after dumping a ton of money into your ride it would suck to have a pebble or something Bring you down. Just my 2 Cents.

**hrc85250r** · 05-22-2005, 01:55 AM

check the idle screw, you dont want it revving to the moon....

**MTS** · 05-22-2005, 01:59 AM

do a search on the fourms under jetting, there are ZILLIONS of threds on it, only true way to properly jet a bike is plug chops....search!

**kbyeeeeee** · 05-22-2005, 11:37 AM

I have put the lid back on and put 8 5/8 holes in the top. Dose any body else agree with the 4-5 up jet on the main and 1 up on the pilot?? main gets richer or leaner??

**RideRed250R** · 05-22-2005, 06:31 PM

i say dont screw with it till you get the motor together and do a plug chop. they jet stock jettin rich so that, were ever a stock bike goes it should be ok. they cant afford to have different jets in different bikes at every other dealer.. i had mine bored out to 80 on a 83R it was stage 3 ported and milled head... i had the carb "jetted" by a professional and i keep foulling plugs and runnin rich, so i went back to a stock jetting and it ran fine and would rip.... when i sold it, it had the same compression as it did when i did the top end close to 8 monthes earlier.
adam

**kbyeeeeee** · 05-22-2005, 08:19 PM

Ok I wanted to keep the jets stock untill after breakin can i do a plug chop during break in. I did put holes in the airbox & I put the needle clip on 3rd from top stock setting it was all the way up which makes it leaner.

**MO350X** · 05-23-2005, 07:57 AM

Have you checked out FMF's site for their jetting recommendations?
For a Fatty/their silencer/no air box lid, they recommend NO jetting change for an '86 ATC250R.
The only change being on the pilot screw-almost 1 turn LESS out!
I called and they said that was fine.
Whew!
Problem is, their site only goes back to 1985.
Here's their jetting page:
http://www.fmfracing.com/jetting_center.aspx

Have you thought about a carb. change?
Trike Dude just went to the '86 R carb on his air-fooler and it runs like a raped ape now. EASY swap and it ran GREAT with the stock '86 jetting.
Amazing.

Best of luck on the new motor, it'll be sweet I'm sure.

**sandpuppi101** · 05-23-2005, 12:02 PM

I agree with ride red,get it all together to stock specs,then keep checking the plug to see what you got.Going with a K&N is a great idea but with or with out the lid or putting holes in it is a ? you have to ask yourself !What kind of riding are you gonna do,trails/mud/race etc. I took my airbox off completly and put on a K&N but I only ride in drags.It all depends on Application!! Sounds like she is gonna be nice for you.

**kbyeeeeee** · 05-23-2005, 12:09 PM

Ok I got my rings and repacked a scilencer that i had in a parts box. I also picked up a 52 pilot, and a couple of richer main jets 134 and 132. keep the stock in or to be safe richen up the jets.

**kbyeeeeee** · 05-23-2005, 12:11 PM

I only ride in dry sand or grass trails. no wet riding

**jmack3986** · 05-23-2005, 12:34 PM

Look go ahead and put 5 sizes up on main. then do a plug check during break in it would not be a good thing to be running lean during break in trust me a work on bikes all the time. Make sure to go up it wont hurt your motor as bad as it would being lean. start rich and and go from there i am guessingwith the bore you have i would say 2 5 steps from stock on main i had to go up one and a half on my mainm on my 200x i am at a 118 now so i would try that and i am .40 out

**kbyeeeeee** · 05-23-2005, 08:50 PM

Well the quy at the dyno shop started me at 150 and I broke it in at that. Runs great on the low and mid. The top is way to rich however and tommorow i will be putting in a 145 and running a plug chop. I will also pick up a 140 and a 135. just in case its still to rich.

Thread: Tuning This Monster 250r

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Tuning This Monster 250r

hmm

What FMF recommends.....

Jet your motor a little before break in if you have a Bore