Question about 2003 Yamaha YZ 250

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I have a 1994 yz250, it is stock other than a aftermarket silencer. the guy i bought it from had the carb jetted for racing fuel. it still has the stock pipe. what are the stock jets suppose to be and what octane fuel is recommended?

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  • JR in SC May 11, 2010

    Is there a problem with how the bike is running?

    I think the silencer is the biggest reason for the rejet so you should be OK running 93 octane.

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The stock main jet is #350. As to fuel, it is best to run premium gas.

Posted on Dec 12, 2009

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What should the jetting be for a 1994 yamaha yz 250 at 5000' elevation


Hi, Anonymous for more information about your question and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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Yamaha YZ250 Owner Service Manual
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Apr 19, 2014 | 2008 Yamaha yZ250

Tip

Get rid of the stock CDI use the 04 or 05 cdi


Want to really wake up the motor and feel some awsome power ? Get rid of the stock pipe and silencer V-Force reeds up one tooth on the rear sprocket . And toss the CDI Box replace it with an 04 or 05 CDI box then you'll have pleanty of over rev with out the motor poping or going flat up top the FMF Rev pipe with the short silencer is the way to go keep an eye on your jetting till you get it right use race gas Torco 2 gall race gas to 3 gall pump gas Ultra if you have the money have the carb riffled boared and head redone then look out all 250f's the kx 125 will kick ****..............

on Dec 31, 2008 | 2003 kawasaki KX 125

1 Answer

Yz250 jet needle how to remove


Hi, Anonymous sorry you can't find the first and best tool you ever bought for your Yamaha despair not for a mere $10 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please visit the websites below. Good luck and have a nice day.
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KTM Keihin Carb How To Jets Needle Clip Floats PART 1
YAMAHA YZ250 LC Owner Service Manual
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http://mybikemanuals.com/yamaha/yamaha-yz-owners-manuals

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Jun 06, 2012 | 1992 Yamaha FZR 600

1 Answer

What is the stock carb settings for a bone stock 1994 YZ250 ??


Hi, Clay_poque for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/gregg_c0ec1df182c7330e

Mar 28, 2011 | 2003 Yamaha YZ 250

1 Answer

Kmx 125 fully ported modified for MX racing consumes too much gas,what will i do to restore it back to normal consumption,want to use it daily...thanks a lot...


Install a new cylinder and re-jet the carb back to stock. If the ported cylinder has been bored you will need new piston and rings also. I would re-jet the carb first and see if that change will suffice in the fuel economy area. Changing out the cylinder etc., is costly. Check the front and rear sprockets. If they are not the stock sprockets, ( 14 tooth and 48 tooth ), replace with stock. Please rate my answer.

Aug 27, 2010 | 2000 kawasaki KMX 125

1 Answer

What should the stock carb jets be for a 94 yz250 with the stock pipe and aftermarket silencer


Stock Jetting for a 1994YZ250 is:

350 main
45 pilot
J8-6EJ33-61 needle

Adjust your jetting down one size for each 1000' of elevation above sea level. Needle clip position on the needle fine tunes the pilot circuit.

Scott

Dec 12, 2009 | 2003 Yamaha YZ 250

1 Answer

Re jet carbs? any help? i was driving for a couple days just fine then all of a sudden when ever i twisted the throttle the bike would bog down i would let off and it would idle rough then die i was able...


if you rejet the carbs. i would maybe take a plug reading. it sounds as if you might have gone too rich and the plugs began to foul. but a good plug reading will tell alot. if they appear to have a good tan color i would take a look and make sure no hoses are being pinched causeing a fuel starve problem.
fyi. if you just put on an aftermarket exhaust. sometimes you wont need to jump up in jetting that much. stay around the stock jetting and maybe shim the slide needle up a hair with a tiny washer. that usually puts you close. unless an elaborate aircleaner system and very high flow exhaust.

Mar 24, 2009 | 1994 Honda CBR 600 F(2)R

1 Answer

Cabrurettor


1. Install a larger main jet to your standard fxr150 cabrurettor. We suggest fitting a 117.5 main jet, also remove the airbox and replace with an appropriate pod type airfilter. you will notice a gain in power and also a cool induction noise! 2. Fit a new aftermarket carb like a Keihin PE28 this is a chrome round slide carb which has the advantage over the stock carb that while still being 28mm there is no butterfly and shaft obstructing the airflow. 3. Another easy option is a GN250 carb, it’s a CV type of about 33mm, you can fit this with stock GN jetting and the engine will run GREAT and give quite a noticeable gain in power all over the rev range. 4. Try a flatslide carb from a DR200 if you can find one that is! I have one fitted to my race bike (see projects section) and i'm now looking for the best jetting options, but for now with the jetting i have made it looks to be a very promising carb for the fxr150, check back soon! 5. Honda XL250 carb, this so far has worked by far the best with my race engine and also very good with the std engine, but i did have to make a new throttle cable. For my standard road engine i used a 140mains jet, for my race engine with cams i had to drop the size and use a 130 main jet.

Nov 10, 2008 | 2001 Suzuki FXR 150

2 Answers

Having motorbike trouble


have a VR 2000 Supermot and when I bought it the guy had taken off the air filter and box and put a racing exhaust on it. I dont know what other modifications he could have done. Anyway we put the original exhaust back on and just fitted an airbox with K&N air filter and it starts and ticks over fine and runs fine up to about 3 thousand revs and then it kangaroos (stop and start) and it stalled at one point. I checked and there is fuel in the tank. The fuel feed must be ok coz it ticks over and revs fine when stationary. I have a theory that the guy who modified it has put big jets on the carbs to give better air/fuel mixture. Would this explain whats happening? How can I fix it? Thanks for your time. i've been repairing dirtbikes and fourhwheelers since i was 12 with my dad, it sounds like a problem with the jets in the carburetor possibly one clogged with even the smallest piece of dirt will cause this, also how old is the bike, this sounds alot like a problem i had with an old dirtbike, sitting stationary the bike would run like new, yet get on it and put the engine under a load it would start sputterin and runnin like complete garbage, the bike was an 87 bw200 and after messin with the carb i ended up buyin a new one cause it was internally clogged but if its a newer bike i'd definently check the jets, and if you cant figure it out, then a local bike shop could probably diagnose the problem, if you have friends with bikes get suggestions from them on a good local place,,,

Nov 10, 2008 | 2000 Alfer VR 2000 Supermoto

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