HELP! Problems with my EXC

[mitch.ww]

Been having trouble with my EXC450 for far too long now, I just want it to bloody run :mad:

Basically there were a few problems with the carb such as water in the bowl etc which has all been fixed now - took carb out and cleaned and dried everything out completely!

Then discovered that there's a crank case pressure release type airline that runs from the crankcase and plumbs into the carb. Some idiot put too much oil in and caused the line to blow oil into the carb which meant it wouldnt idle properly. Ive since readjusted the oil level and now the line doesnt blow oil BUT the bike still wont run with the line plumbed into the carb.. Starts first time exactly as it should if I leave the pipe off though..

All help/ideas/suggestions are greatly appreciated!!

[Ocean1]

How much air can you feel puffing out of the breather tube when you take it off the carb? Is it clear or is there vapour/smoke?

[mitch.ww]

It is a fair bit of air being pushed out, I just assumed it was getting forced out by all the moving parts and it's a hell of a lot clearer than it was before but there is still some smoke coming out sometimes

[Ocean1]

See if you can find another EXC to compare. If your's is noticably more then chances are you've got worn or broken rings.

The racing dudes tend to dump the breather hose into a puke can 'cause the oil vapour can cause some minor problems. There shouldn't be the problems you're noticing though, unless there's serious combustion gasses getting into the sump.

Is the bike blowing a bit of smoke, either on the gas or off it?

[krad_nz]

Is it possible that the idle is now set incorrectly since you've sussed out the breather hose problem?

[mitch.ww]

See if you can find another EXC to compare. If your's is noticably more then chances are you've got worn or broken rings.

The racing dudes tend to dump the breather hose into a puke can 'cause the oil vapour can cause some minor problems. There shouldn't be the problems you're noticing though, unless there's serious combustion gasses getting into the sump.

Is the bike blowing a bit of smoke, either on the gas or off it?

I might try find one to compare that on then, i'd be surprised if it was the rings though cos it just decided it wouldnt start one day after it had been running mint.

What do they do at the carb end when they run the breather into an overflow??

And na not blowing any smoke at all, never has.



Is it possible that the idle is now set incorrectly since you've sussed out the breather hose problem?

I also thought that but when ive managed to get the bike going I can keep revving it to stop it dying whilst i chuck the breather back on and then fiddle with the idle adjustment but with the breather on it will only stay alive if the idle is really high. I hope that made sense

[barty5]

sounds like its staving for air or something given it runs with the breather removed ie more air can get it ( you have checked the air filter and box for blockages? ) or yeah it could be low on compression would pay to check it if you can. a hard to start motor will sometime run but only if you keep the revs up once at idle with low comp it can stall. the higher revs keep it rolling over if you get the idea.

[Ocean1]

What do they do at the carb end when they run the breather into an overflow??

Just plug it, but You'd just be hiding a problem. Better track down the real problem, start with that compression test eh?

[mitch.ww]

sounds like its staving for air or something given it runs with the breather removed ie more air can get it ( you have checked the air filter and box for blockages? ) or yeah it could be low on compression would pay to check it if you can. a hard to start motor will sometime run but only if you keep the revs up once at idle with low comp it can stall. the higher revs keep it rolling over if you get the idea.

I wouldnt say its hard to start because the other day with the breather off i got it to start first kick (the batteries flat) like it should but then struggled to keep it running, could it still be compression? I just find it odd that it would lose compression all of a sudden. It was starting, running, idling sweet the last time I rode it, clean it and put it away for a few weeks then have spent the last 4 weeks trying to get it going again :mad:




Just plug it, but You'd just be hiding a problem. Better track down the real problem, start with that compression test eh?

I tried plugging it and it didnt like running like that either? but yeah I do wanna find the actual problem, will try get a compression test done ASAP

[barty5]

I wouldnt say its hard to start because the other day with the breather off i got it to start first kick (the batteries flat) like it should but then struggled to keep it running, could it still be compression? I just find it odd that it would lose compression all of a sudden. It was starting, running, idling sweet the last time I rode it, clean it and put it away for a few weeks then have spent the last 4 weeks trying to get it going again :mad:

I tried plugging it and it didnt like running like that either? but yeah I do wanna find the actual problem, will try get a compression test done ASAP


If blocking causes it to run bad again then there has to be a restriction in the air in take of some sort it cant be getting all the air it wants.
But yes id get a comp test done just to be sure rules it out.