Honda Dirt Bikes Forum

well the way its acting is like its not getting enough gas at top end and bogging dowm and sputtering  
everything looks better 35 ft off the ground...Generation DMF

When a topend wears, it mimics a lean condition.  What you 'feel' as lean, is more than likely the result of a trashed topend. Sputtering (sounds like misfiring) is typical of an overly rich condition. Not running well on the topend can be a lean main or a worn topend.  Considering that it's well-known in the industry that these bikes came with overly rich main jets stock, I have to believe your problem is caused by a worn topend.

ANy attempt at jetting a bike with a worn topend is pointless.  You need to make sure the topend is fresh, the carb is clean, the spark plug is fresh (and correct heat range) and the air filter is properly serviced and installed before tackling the jetting.

I cannot tell you why other boards are saying what they are about jetting this bike.  What I CAN tell you is that with a fresh topend and the other above-mentioned items, the spec I provided will get your bike pretty close as far as jetting is concerned.  
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ok nevermind the last one, i see what you mean skip when the longer it runs the richer it gets, so i need to go to a 45 pilot, what about the main or is that the main?, and the needle, move it down to a 2?, got it,  
everything looks better 35 ft off the ground...Generation DMF

so how much aould a top end cost?  
everything looks better 35 ft off the ground...Generation DMF

Your spark plug should indicate a lean condition if it's not getting enough gas.

The best advice I can give you is follow Skips directions.

I have an 04cr125 jetted rich from the factory, I have leaned the pilot,needle and main and the bike runs like a scalded dog. It ran like a slow POS w/ factory jetting.

Skip, when did the price of jets go up? I was paying 2$ and change, but the last one I bought was 5$.  
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Nobody's gonna hurt anybody. We're gonna be like little Fonzies here. And what's Fonzie like? Come on what's Fonzie like?

when i went to 36:1 spark plug looked alot better, just a slight brown with a flat black on the threads and bottom part  
everything looks better 35 ft off the ground...Generation DMF

I dunno Chud - seems like Keihin raised the price on jets this past season.. last year I was paying $2-3 as well!

Muddycreek - if you do the work yourself, the parts to do the topend will cost around $150 or less. I can tell by the tone of your posts that money is tight, but you HAVE to service the topend before you cause even more damage.  Now here's the good part - it costs nothing to take the topend apart and check everything out.  You only need to replace the parts that are worn.  If by some miracle nothing is worn, then checking it out will have cost you nothing at all, except for time.

As for the 36:1 vs 32:1.  We're talking about a .37% difference in AFR.  It's not enough to make any difference in this case.  Your spark plug color sound right, but I can promise you that 36:1 vs 32:1 isn't the cause of any changes you are seeing in your plug.  
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ok, i went and attempted to take of the top end, had to unhook all the coolant lines and theres one aggervating nut that i cant get any wrech to and im afraid that im gonna have to take the gas tank off to get to it, any suggestions?  
everything looks better 35 ft off the ground...Generation DMF

I've never done a topend where I DIDN'T have to take the tank off

I'd say take the tank off - it's no big deal, and it will make the job so much easier!  
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ok, it looked fine, the walls werent scratches and the head was good, but the top of the cylinder was a little rough, so?  
everything looks better 35 ft off the ground...Generation DMF

Uh... not so fast, friend!

You can't assess the condition of a topend by looking at it.

The cylinder has to come off.  You need to inspect the cylinder and make sure none of the Nikasil plating has flaked off.  Also, check for any grooves or damage.  You should still see crosshatch marks in the cylinder from the honing process. If you don't then the cylinder plating is worn.
Next, you need to take the ring(s) off the piston and put them into the cylinder - 1 inch from where the head bolts on.  Now measure the gap in the ring to determine if the ring is worn or not.
Now you need to measure the piston with a caliper and see if it's within spec.  Measure it in several places and write the dimensions down. You really need to consult a Service Manual to determine what the service limits for the piston and ring end-gap are.

Finally, take a look at the tp of the piston.  It should be almost entirely black with some shiny spots at the edges.  If it's pitted, this is an indication that the engine is pre-igniting.  If it's shiny with no black deposits, then the mixture it too rich.  If it's solid black, then the mixture is too lean.  
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damn! i knew it was to easy to be true!

so back out i go!  
everything looks better 35 ft off the ground...Generation DMF

Also, Please look at todays posts and you will find a Sticky post about rebuilding the topend of a YZ250.  It's not the same bike as yours but it's a great explanation on how to check and rebuild a topend. I'd suggest you give it a read..  
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ok, ill check that out, but i cant get the cylinder off!!!, it wont come off, ive beatit, pried on it cnad beat it some more and nothing  
everything looks better 35 ft off the ground...Generation DMF

DO NOT EVER PRY A CYLINDER!!!!!  EVER!!!

Read the article - Dave gives some great tips on removing a stubborn cylinder... and pray you didn't damage it trying to pry it off.

This is a precision piece of equipment, built primarly out of soft aluminum.  There is not a singe part in it that should be pried or beaten on..  
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