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Discussion Starter · #1 ·
How wide does a stock 300ex sit in the front? I dont know if my quad has stock 400ex a-arms. I wish there was a sticky with the common specs for our machines. I seen one on another site but it didnt have what I needed. I imagine if all the good info was put together alot questions wouldnt be asked. I did a search for what I wanted and read through 30 mins of threads until I gave up and posted this question.

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18,211 Posts
overall width is 43.5 inches that's for a 250X but they are the same frames,A-arms ect ect as the 300EX

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18,211 Posts
That is what was in my manual for the 250X but I can assure you they are the same. Most people do not run stock width anyway it's more stable with it wider.

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23,587 Posts
I would say the 43.5 inches is the width at the rear, since 43.5 inches is the overall width.

· Premium Member
18,211 Posts
I would say the 43.5 inches is the width at the rear, since 43.5 inches is the overall width.
I think you may be correct on that sir... I can't measure mine since I have it widened. lol

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7,526 Posts
I wish there was a sticky with the common specs for our machines..
Here is a little info for you.
stock valve lash =.004
Stock jetting = 122 main , 120 main (high alttitude), 38 pilot, stock needle position - 3rd groove
Wheel offsets - front = 4/144 rear =4/110
Stock gearing = 13 / 38
stock spark plug # - DR8ES-L

stock carb 32mm keihin with accelerator pump.

Ignition: CD with electronic advance
(300ex CDI will not work on 250x)

Ground Clearance : 4.6 in. (stock)

Will 400ex a-arms work?
yes, you will need a-arms, tie rods, and 400ex length shocks (16.25), and a shock relocator bracket, 400ex spindles are not neccessary but are an improvement with this set-up,and yes stock brakelines will stretch far enough.

will a 400ex steering stem work?
yes, stops on bottom need cut off beacuse there 180* off, and the little washer about 3/4 will need removed, it is roughly 1'' longer

will a 400ex carb work?
yes, i recomend it for engines that have atleast the basic mods, such as pipe. filter, ect.. stock boots will stretch, all you need to do is rejet, and i recomend a 42 pilot jet

Hardweld rockers are only necessary for a hard weld cam -
EX. web cams. billet cams such as hot cams do not require hard weld rockers, they will actually cause damage to your cam

What is max. compression piston on 93 octane. - 11:1
any thing over is pushing and detonation could result.

engine idle speed = 1,400 +/- 100 rpm
stock pilot screw setting = 2 1/4 out from closed

engine compression with stock piston - 171 - 200 PSI

engine oil capacity -
oil change only - 1.6 quarts
oil and filter change - 1.7 quarts
totally engine dissambly - 2.11 quarts

*if you run a oil cooler about 2 quarts even on basic oil and filter change*

Front: Independent double-wishbone with dual hydraulic shocks, 5-position spring-preload adjustability; 7.1 in. travel
Rear: Swingarm with single shock, 5-position spring-preload adjustability; 7.9 in. travel

Fuel Capacity- 2.2 gallons, with a .5-gallon reserve

chain free play - 1 3/4 in. at most

heres a gearing calculator to show how variables such as rev-limit, tire size and gearing affect speed .Gearing calculator

here is the link from the tech section on how to rig your reverse set-up, used when you use a aftermarket clutch lever & perch or if you are just tired of hurting yourself when you try to engage revers Reverse bypass

quad clicks when start botton is engaged -
its can usually be narrowed down to 2 things, assuming your battery has a proper charge, and it putting out correct voltage at (100% it should be reading about 13 volts)
now, its either your solenoid, or contact brushes in your starter

Common Rear end Swaps:
A 01 raptor rear shock will work but they are famous for blowing bladders on the 300ex. newer raptor shocks can be made to work. but because these shocks have a piggyback resivior the left tube that goes to the airbox will need to be cut out and the hole in the airbox will need to be sealed up.

a 450R swingarm will also work, how ever this set-up requires tabs to be welded or bolted to the frame to accept the linkage. You WILL have to use a 250R rear shock, linkage is up to you, the 250r or the 450r linkage will work, carrier and axle, and rear brakeline will also be needed. the swingarm is around 3 inches longer
the 350x rear end will also work
same as 250r
more info will be added by me constantly,, don't be shy feel free to add anything you think would be useful

alot of times it is your carb vent tube. the one that hangs down behind the motor. the problem is this tube gets submerged, you can either trim the tube shorter, or put a T splittler on it and add a different length hose. other possibilites are an exposed wire.
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