20 Most Recent 2004 Yamaha YZ 125 - Page 7 Questions & Answers

Better re-check the timing, if it's off you may have bent a valve.

ck batt voltge and ck regulator/rectifier (charg signal)

Your spark should be a fat blue spark. Do a compression check, as it should get at least 100 psi or more, and do it with the throttle wide open. Make sure the air filter is clean!

i can't seem to figure out why my 2004 blaster 200 won't idle properly. i cleaned the carb and replaced the spark plug. it revs fine but when it goes down to idle it just dies. any help?

hi mate on the carb there are 2 screw one for mixture and one for idle you need to unscrew the mixture screw 1/2 of turns and see if this improves

it could be stator coils or regulator. there are guys that can rewind the stator and test. regulator cant fix have to replace, if this blows it will get very hot and even melt the wires

this will depend on what gas oil mixture you have

check this topic out.

http://www.dirtrider.net/forums3/showthread.php?threadid=117838

http://forums.dirtrider.com/70/7640379/yamaha-dirt-bikes/yz125-carb-settings/index.html

regards,

voodoo

I have the exact same problem with my yz125, just figured out that the entire case has to split in order to get a hold of the impeller wheel's backside nutjob - really bummed because id like to try and fix only the outside seal....

you might have to split the case to get to the back side of the impeller.

try a cooler range plug with the same jets and see w

The impeller screws onto the impeller shaft. Go to the site below and you can see a parts diagram. You will select the brand, year, model, etc... It has the part numbers and prices.
http://www.babbittsonline.com/pages/parts/viewbybrand/1/Yamaha.aspx

There are actually two seals. Are you sure the leak is a bad seal and not the water pump gasket or a cracked/broken housing cover?

Please post a top rating for this solution. Thanks! :)

i assume the MX is a 2 stroke engine ! Those can be tough at the best of times but let's get it going 1st...This is a tiny lite bike sooo,turn igntion on, shift into 2nd gear and push that little devil until she pops sputters and starts. Now only use premium gas, clean spark plug regularly and use a premium oil, don't overmix....run that baby out in the field for an hour to clean her out...good Luck to you friend...Tim

Are you bleeding it by gravity (flowing down from resevior thru caliper) or forcing the fluid up thru the caliper to the resevior. The latter will get more air out in less time. Simple cheap pump kits are available at you auto dealer and u can use it on your other vehicles.

Check your 2 stroke oil reservoir, got a feeling it's bone dry. If so your cylinder is scored and will need some machining, new piston and rings....Good luck to you friend...Tim

hi lilsilence, thank you for using fixya. below is a line from dirtrider.com, answered the same question for a 2003 which is the intro for speed sensitive suspension.

Several ways to go here. Remove half of the fluid in each fork and addback a 10wt. This will approximate a 7.5wt. Going to a 10wt. willreduce bottoming but will give you some harshness. Depending on yourweight and riding style it is difficult to give you proper advice, justgeneralities.
I use ATF fluid. I'm valved for wood and light MX, stock springs, and Iweigh 155 lbs. ATF is cheap and is something simular to 7.5wt. I'm noexpert and my explanation might not hold water but it works for me.

Mobil1 Synthetic ATF is a very popular fluid that will probably be the weight you want.

Seems to me that I can make much more difference in the action bychanging the fluid levels. If you mix up riding between track andtrail, you may want to consider sub-tanks.

Draw out half of the fluid with a piece of tubing attached to a saryngeand put back an equal amount of 10wt. Adjust the level from there tosuit your comfort.
Sub-tanks give a greater amount of adjustability and plushness. Pricey but do the trick when properly set up.

http://www.dirtrider.net/forums3/showthread.php?t=159185

I have use close to the same method on my rm250 and have worked for me, i sure hope it will help you out in another way.

if you have other question, please let us know.

regards,

voodoo

You have a bent shift fork. The repair means taking the engine out of the frame then removing the top end, removing the flywheel and electrics, removing the clutch , shift mechanism and kick starter and a few other parts. THEN you are ready to split the gearbox to remove the crankshaft and then the bent shift fork. Next you get to put it all back together. This is a pretty big job for the home mechanic.

You will need an impact driver, flywheel puller, case splitter and torque wrench plus the normal screwdriver, pliers, etc.. Alternate to the special tools is taking it to the dealer and say "Fix it".
I normally tell people to take it to the shop just so they don't get into such an involved project.

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if you use an impact and an air compressor it will spin the nut right off without having to hold the basket

Pull off the cylinder head. Look in the bore. Can you see seize marks on the cylinder? Nine chances out of ten you are going to have to remove the cylinder anyway, so go ahead and do it now. Did the piston seize up? Remove the left side cover. Rotate the flywheel. Crankshaft free to move now?

If not, drain the oil and look at it. Any metal shavings, cork or bits of ground metal in it? Remove the left side cover. Look at the kick start gear. Is it "locked up" in the clutch hub? Remove the clutch hub. Will the crankshaft turn freely now? Put the bike on blocks and turn the rear wheel. Will it turn? While the wheel is turning, can you shift into neutral? When in neutral, can you hold the clutch shaft still while the wheel turns? Any funny noises while the wheel turns?

The piston may have seized the engine. The kick start mechanism or a bent shift fork may have locked up the engine. Gremlins may have done it. Something did, so let's find out what.

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you will need to change the lower rocker link on the mono shock mount on the swing arm. they can lower the bike 1.5" There are aftermarket sources for this application & they have your bike in their stock. check out web site WWW.mountainmotorsports.biz

Its easy to test. take your plug out and ground it then crank your motor and check for spark. If no spark then its your ignition. probably a bad capacitor. If its your fuel system, drain it then, clean it then refuel.