I'm lost.

[2003TrX400eX]

So I'm rebuilding my 400 to a 440. Got it all finished last night, fired right up, but had a oil leak between the head and the valve cover. Sealed that back up, and now she won't fire. Didn't feel much compression, so I took the valve cover back off, and it feels like I have more compression with it off. I do have spark.

Any suggestions? Thanks.

[81dasher81]

check the timing and adjust your valves

[2003TrX400eX]

That's what I'm gonna start with.

Thanks.

[JOHNDOE83]

If you have a 440 your gonna need to up the jetting ALOT!!! or your never gonna see the true power potential and possibly ruin your motor. You will deffinetly have starting issues without a bigger pilot jet.

With a stock carb I used a 42pilot jet and a 210 main jet.

With a 450r carb I use a 50 pilot and a 220 main jet.

Plan on using atleast a 190 main jet and atleast a 42 pilot jet.

440 has the most potential out of any motor for a 400ex, good luck with your build I hope everything starts and rides fine soon.

[2003TrX400eX]

So do you think it's not starting because of jetting issues? I'm getting fuel and spark.

[JOHNDOE83]

Its hard to say, you said compression was low so I dunno it could be a number of things.

Sure it has fuel, but only enough for a stock 400ex motor.

Your pilot jet may have gotten cloged from sitting around and turning around and upside down after removal.

If it fires up when you physically pore gas in the carb then either your pilot is clogged or isnt giving enough fuel.

Turn the lil A/F screww out to 3.5 turns, if it starts turn it in to 3 turns before you ride.

you will deff need a bigger pilot in that case also. "you need one anyway"

[2003TrX400eX]

Well I got the compression back. I also cleaned both jets out. Did the timing three times today.

[JOHNDOE83]

does it start? :blah:

[2003TrX400eX]

Nope ):

[Chukkinsod]

I had a similar issuewhen I went witha WB 479 grind cam....I didnt think about hardened rockers and bent the heck out of my stock rockers. check them if you have it apart also REPLACE your cam chain tensioner if you have not already. A few $ now will save you in the long run. Also check your Cylinder to head gasket and make sure that you have a good seat and didnt pull your studs when torquing.

[JOHNDOE83]

well today my hybrid which will start on first kick everytime, suddenly wouldnt start and fouled the plug. The plug looked bad and it was the one thats been there since I owned it "2 years".

went and bought new plugs and the gaping on the old plug was bad and the porcelain was even no good. I havent started it yet after but it would fire when I cleaned the plug then die, so I suspect a bad plug in my case.

Maybe yours to?

A bad plug will still spark.

[2003TrX400eX]

That was my next question to you. Going to get a new one tomorrow. When I clean mine, it won't fire though.

[Thumpin440ex]

How fresh is the battery? If your sure it has compression, make sure the timing is correct if so, then check the jetting. Up to a 50-52 pilot jet. That should get your started.


John

[2003TrX400eX]

A 50-52 pilot with a stock carb?

[Thumpin440ex]

Im sorry i thought you had a 450 carb. You could put in a 40 pilot. Again check to be sure your battery is fully charged, not weak cranking. If all else is correct ( timing, jetting- fuel, spark) No reason it shouldn't fire.


John

[2003TrX400eX]

Well I'm cranking it right off the battery charger.

Thanks.