04 yz250 plug problems now?

sodflyer · Sep 27, 2004

04 yz250 plug problems now? .....No more :)

Went riding this weekend on my 04 yz250 but this time I was fouling plugs EVERY time I shut of the bike.... it would not start for anything unless I installed a new plug. Now the only thing that was modded on the bike was the V-force 3 reeds... but I had been riding it a few times before with no problems.... can't figure this thing out as to why it was loading up so bad.... here is the list so if you have any ideas please clue me in.

new plug's BR8ES and EG
New fuel ( 2-3 hrs old)
Yamalube R2 @ 32:1
3 ride old V-force 3 reeds
carb was re-jetted but otherwise did not foul plugs that often.
plugs are black and wet sortof before hand and after the reeds..

Never could jet the bike for the "tan" color plugs.... don't know kow you guys do it but I have had it re-jetted a few times to where it's cutting out but still having black plugs...went back to the stock jets and it runs great....when it's running. Thanks for any help! Jeff.

oldguy · Sep 27, 2004

were you running at the same altitude or temp as when it was running properly before. If you gained alot of altitude or the temp went up you could be running rich.
Also check to make sure that the carb bowl is clean and the float is working.

sodflyer · Sep 27, 2004

Forgot to say I did remove the carb, every thing looks fine there. I also removed the reeds and there are no cracks or seperation from the frame... it all looks good. Jeff.

sodflyer · Sep 27, 2004

Float is working fine...the temps were close to the same as normal and as far as altitude it was next to nothing... I live here in Colorado Jeff.

sodflyer · Sep 27, 2004

What I have in there now is...

pilot jet 58
main jet 178s

spare jets

pilot
50
52
48
45

main

180
172
168
165

any ideas on what to use here? Thanks Jeff.

sodflyer · Sep 27, 2004

Just changed the jets to a 172 main and a 52 pilot ( did not see it ) plus adjusted the float to 0.27... I know I had it there before or at .26 but I just checked it again and it was at .13 or something close to that.... don't think this would cause the fouling at cutoff do you? Thanks Jeff.

sodflyer · Oct 9, 2004

Well......Last weekend was the test. The bike ran awesome! it just ripped up the turns and flew down the long track... showing 74 mph on my trail tech comp....:) Checked the plug yesterday and it was a nice "dry" dark brown color :) no more black goo all over the plug. I know I am close on the jetting now but I will try a few more rides just to see if this was a fluke before I change jetting again. Anyway thanks for all of yall's help in this and other posts! So if you live here in colorado, run pump gas, and yamalube at 32:1 with a 04 YZ250 then this set up will get you close. Jeff.

jsmoto · Oct 12, 2004

2003 YZ250 plug fouling

I'm still dealing with start-up fouling problems with my 2003 YZ250, and it hasn't gotten any better with the colder temps lately. The colder temps should have leaned it out and cleaned things up if the jetting was too rich. It's my understanding the 2003-2005 engines are all about the same. Only mods are a slighty leaner pilot and addittion of VForce reeds. Lots of exhaust spooge out the power valve vent, and from the pipe-to-silencer boot, all over the swingarm. My suspicion is that there is a load of oil residing in power valve chamber which loads up the plug at start-up ??. But is it the jetting that's making it run too cool and allow the oil to puddle ?. Once past start-up, the bike otherwise runs great. Could trans oil be leaking into crankcase ? - how would you check for that ?. Any thoughts ?.

sodflyer · Oct 12, 2004

What jets do you have in there now? Where is youre float set at? Jeff.

va_yzrider · Oct 13, 2004

sodflyer, your solution was adjusting the float height, right?

Jarda · Oct 15, 2004

When I'm looking to the OSM std. pilot jet is 50! It's mean that your mixture is rich. And pilot jet and screw are maintaining 0 to 1/4 throttle open. Maybe this was a problem too. Jarda

sodflyer said:
What I have in there now is...

pilot jet 58
main jet 178s

spare jets

pilot
50
52
48
45

main

180
172
168
165

any ideas on what to use here? Thanks Jeff.

sodflyer · Oct 15, 2004

Yes it is still a bit rich but I have not burned through a plug in four rides now. I am going to lean it out another size down before the weekend and do a good run and check with a new plug. I think it was a combo of the jets and the float adjustment, Before I adjusted the float (again) the last time I changed the jets the bike would not crank over at all... I changed the gas line to clear and to my suprise it was not getting any fuel to the bowl other than just a trickle.......I do remember that I had a few hard wrecks so that must have been the cause of the float not letting gas through. I tore it apart again and readjusted the float again ( did anyone tell you just how hard it is to get the carb out of this bike?) to the height listed and now I am real close to getting this thing spot on.... but now it's getting colder out.....go figure :) Jeff.

sodflyer · Oct 15, 2004

Mine came stock with the 58 pilot jet in the carb, What do most come with in this bike? Plus I live at 5000 + feet.... so that makes it fun... Jeff.

Jarda · Oct 15, 2004

Manual says:
Main jet #178
Power jet #50
Air screw 1 turn out
Pilot jet #50
Needle N3EJ second groove (from needle top)
Those are for USA version, I have little bit richer in my european version (I live at Europe).
When air temp, humidity or altitude is higher, mixture is richer, then you should make setting leaner.
That's what I know:-)

sodflyer said:
Mine came stock with the 58 pilot jet in the carb, What do most come with in this bike? Plus I live at 5000 + feet.... so that makes it fun... Jeff.

sodflyer · Oct 18, 2004

I threw in a new plug before the ride yesterday and with out changing anything other than turning out the air screw to 2 1/2 turns out I pulled the plug after a good 3-4 hrs riding with lugging all the wat to high revs in 5th gear I am abit confused at what it looked like.... the tab was clean metal all the way to the threads and the insulator was a light tan color on 1/2 of it while the other 1/2 was a darker tan...... do you guys get the same on youre plugs? Can't tell you how much better this bike runs now :) and it's also a big plus not having to change a few plugs every time I went riding....Thanks! Jeff.

jsmoto · Oct 18, 2004

2003 YZ250 plug fouling

178 main, N3EJ-2 needle, 50 pilot is stock, and that's what came with my bike. Only jetting change I made is replacement of 50 pilot with 48 pilot. Otherwise, bike is stock, except for VForce reeds. Spooge and fouling problem was unaffected by reed change. Over last winter I checked the float height and it was fine, except I didn't use the procedure shown in the manual. The manual shows the carb completely upside down with full weight of floats up and down. Somebody at a shop told me the carb is instead held to the angle at which the seat just contacts, and that was consistent with other bikes I've had with Keihin carbs. I assume the 5.5-7.5 mm dimension in the manual was relevant to how I checked the float height.

500guy · Oct 18, 2004

Simple sounds too rich, especialy at your altitude. Search the old threads for plug reading. If you have not, repack you silencer and clean your air filter, that will make it run richer.

sodflyer · Oct 19, 2004

I will drop down the pilot size down one before the next ride, I don't want to mess this thing up either....... hopefully it won't be too much of a drop. I clean and oil my airfilter before every ride along with cleaning out the airbox as well. I just installed a new P.C. silencer before the last time out from the stock one....can't tell any difference though. I will try setting the float as you said jsmoto... when I set mine I had it completely upside down and not at an angle.... could help. Thanks! Jeff.

jsmoto · Oct 19, 2004

2003 YZ250 plug fouling

I'll likely the drop the pilot from 48 to 45 when I have it apart this winter, and that may be the only jetting change I make. Might drop the needle one step, but I'm thinking the bike just runs too good once you get past the occasional start-up fouling problem to risk messing with that. Silencer probably needs re-packing, but air filter is cleaned very regularly. Thanks for your help.

sodflyer · Oct 24, 2004

Something I have not worked out yet is I have a bit of a miss on the top end of the rpm range...I mainly notice it when I am in 5th gear wide open...it happens with a new plug or a old one that are gapped to speck...so it's not that...I am thinking the needlesetting might be a little lean now with the jetting change...or the main jet is too lean....plug still looks the same tan color..any ideas here?

Buckholz · Oct 24, 2004

Sodflyer had a pilot/slow jet in it about 4 sizes too big.

We run 45 or 48 slow jets here at 7,000-8,000' elevation.

Spine_Thrust · Dec 5, 2004

This problem is indicative of the float height out of spec. Every thread you read about this, there will be someone in the mix saying they changed the float height and viola! it's fixed. NO MORE FOULED PLUGS! HOOORAY!

(Float height fixed my plug issue too)

sodflyer · Mar 10, 2005

Well back to square one again....plugs were looking good during the summer but I am getting black plugs again...not as bad as the first round but I can tell this jetting will be a constant battle to keep it in the sweet spot....

04 yz250 plug problems now?

sodflyer

oldguy

Always Broken

sodflyer

sodflyer

sodflyer

sodflyer

sodflyer

jsmoto

sodflyer

va_yzrider

Jarda

sodflyer

sodflyer

Jarda

sodflyer

jsmoto

500guy

sodflyer

jsmoto

sodflyer

Buckholz

Spine_Thrust

sodflyer

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