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1998 RMX 250 info needed asap

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Hey fellas just trying to jet my brothers bike and i want to know a baseline of what is stock and compare to what is in now

basically id like to know what the stock specs of the following

pilot jet

main jet

needle position

float height

He has the lid off the air airbox and standard exhaust system afaik

what he has now is 172 main, 60 pilot unsure on float height and needle position but he needs to change the plug every ride in order to start it. Also what mixture is good 30:1 or 40:1? he has been running 30:1 but bike shop said run 40:1

ideas? recommendations?

Thanks in advance would like to get the stuff tomorrow while im at work

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Also to add it "may" have the pwk carb

im having trouble trying to find a picture of both stock and the pwk

from what it looks like the pwk is the one i have but if its similar lookin to stock one im not sure

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Autos280.jpg

Here are the PJ left and the PWK on the right

The stock jetting on the stock PJ is

MJ 165

PJ 60

3rd clip

16mm +-1mm float height

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Mass i thought stock Main Jet for the USA was a #170 mate?

Australia stock PJ38 main jet is the #175.

tek the best modification is a PWK carby.

But in the short term, set the float height correctly (16mm) and maybe grab some smaller pilot jets.

Also what spark plug is he running?

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Autos280.jpg

Here are the PJ left and the PWK on the right

The stock jetting on the stock PJ is

MJ 165

PJ 60

3rd clip

16mm +-1mm float height

Hey Massrider, Where did you pick up that sweet PWK? That thing is awesome. Who ever you got it from must be one cool dude.

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he is running the b8es or something like that

so go to maybe a 55 pilot jet?

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A #60 pilot is pretty big. I'd go through the jetting guide (in the FAQ section on the front page of this forum) and decide if you need to go smaller. I run a #40 in my RMX and it does really well.

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Hey Massrider, Where did you pick up that sweet PWK? That thing is awesome. Who ever you got it from must be one cool dude.

:)

I hear he is :banghead:

tek_01, how is the compression? does it start easy?

I ran the exact jetting he has in my PJ last year..it was rich but I never fouled a plug.

where is the air screw set?

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Tek i've just fitted a #48 pilot jet in my PWK35 on a '98 RMX and i live in Perth, Western Australia.

Seems to go alright but i am still in need of tuning.

Have you read the "2 stroke jetting thread" at the top of the Yamaha 2t forum?

mass: maybe the '98 one had a different spec. I was sure i'd seen it somewhere as a #170 coz i wondered why Australia would get a #175.

By the way Tek-01 as you're in Australia your specs will be different (i didn't notice u were in Aust before)

Main: #175

Pilot: #60

Needle: 3rd clip (centre) and it's an R1472 (i'm pretty sure coz i just took it out the other day).

I also have the service manual.

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Wow alot of replies

First off, im pretty sure its a 98... although it could be a 99 but i will have to get this confrimed by the vin number and ringing up the dealer yeh?

I went to the dealer today and he said my bike came with a 165 main and 60 pilot as standard. I told him it was a 98 rmx so thats what he must of looked up

I Have the 165 main on order to be picked up tomorrow

Starting is fine if it is with a new plug BUT after he rides it for a day.. the next time he goes to start it up it may take over 50 kicks and thats IF it even starts... change the plug and starts within 5 kicks.

I will take the plug out and look at it today when i go over there.

I have read the jetting faq and it looks like ill be doing a bit of work today on it ie: setting the float height and fuel mix screw which btw has a broken o-ring on it (picked up a new screw+ spring, washer and o-ring today)

Will also be repacking the muffler. The top end was done probably 6 months ago and he rides maybe 1 time every fortnight so i think it should still be good

Also another problem that i havent understood yet is this.. When he starts his bike and it is idling it isnt a smooth idle it sort of revving on its own like someone is twisting the throttle evey half a second ever so slightly. Any ideas?

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By the way Tek-01 as you're in Australia your specs will be different (i didn't notice u were in Aust before)

Main: #175

Pilot: #60

Needle: 3rd clip (centre) and it's an R1472 (i'm pretty sure coz i just took it out the other day).

I also have the service manual.

Reply With Quote

What year model service manual is it? dealer quoted me $200 to buy one today... how expensive is that!

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You can get a late 90,s rm 250 carb on ebay cheap easier to jet.

Check plug cap is screwed onto the plug wire nice and tight also make sure the wire is screwed into the coil tight. I cut about a 1/4 inch off the end of the wire and rescrew it in. My rmx was running like crap oil coming out of the exhaust. After making sure the wire was nice and tight, bike ran great.

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Thanks will check that tonight

Also on the ringing/surging sort of idle

doing some research and it sounds like i have an air leak or possible stator side crank seal is bad.

I pulled the reed cage out and it looked ok but im not sure what im supposed to be looking at. Is there some for of gasket/seal under the reed flaps where they seat on the cage? It looks like there is some sort of sticky seal there.. does that sound right? reeds look pretty new and they are i think a fibreglass type

on the crankcase seal,... how would that affect the idle? i dont fully understand

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Ok got the bike back together for a quick test to see if it starts

started ok not enough to tell if anything has changed or not

here are some pics of the spark plug after 2 rides

It is a br9es (right heat range?)

awfully black and oily

mini-DSCF0345.jpg

mini-DSCF0346.jpg

mini-DSCF0347.jpg

comments appreciated

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OOoo that is black!

To check for air leaks around the intake. Use a can of Throttle Body cleaner and spray it around the carby while it's idling. If it has an air leak it will suck some in and affect the idle.

The reeds should have a paper seal between the engine block and the reeds, then the black rubber intake boot bolts on (with the 6 x 8mm head bolts). Check for any cracks in that rubber intake boot. I just had a busted one on mine.

Checked the gearbox oil?, is it full?, is it still clear or has it gone black?

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On my 1998 RMX it also had 175 main 60 pilot (1471N needle, 2nd clip), main was fine but pilot way too rich, did exactly the same when starting. I dropped it down to 52 and could (should) have gone down to 50 or 48.

As they say though, each bike is different, so do the checks on your pilot circuit explained here.

http://www.thumpertalk.com/forum/showthread.php?t=327405

Or pull the PJ and get a PWK, I got sick of reading everyone telling me to do it but since I have, I cant believe I bothered messing around with the PJ, POS.

It's idle is never easy to set and once you do get it to idle, it will 'run on' when shutting the throttle when warm, it constantly needs fiddling with..

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That plug is way rich. I'd start with the pilot circuit after eliminating any air leaks.

For a manual, check this out: http://www.repairmanual.com/motorcycles/1998/62/0/6092/1143

The U.S. model is a little different than yours (lights, etc.), but this should provide you with most of the information you need.

Shouldnt he run a Br8es

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