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Old 3 Weeks Ago
450EXCR 450EXCR is offline
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08 450 oil breather +fine tuning

Hi all,

I recently purchased an 08 450 EXCR and had a couple of questions. Firstly, I noticed after any ride it would leave oil on the floor under the bike. I noticed it was losing fluid out the countershaft sprocket seal, so replaced that. But it was still happening, and then i noticed it was coming out of a case breather behind the starter motor. Im guessing the bike had a smog setup at some point and it now just has a hose to nowhere that was leaking oil. I replaced it with a longer one running up higher and see that after i finish a ride the hose is holding a decent amount of fluid in it, as high as the top of the starter. I wouldnt think that much oil should be getting into the tube if its just a breather? As this bike has two oil circuits, can anyone tell me if this would be engine or g/box fluid? Ive checked the level on both, and neither are over full? engine oil is just at the top of the sight glass cold, and g/box oil just starts to dribble out the bolt hole level, like it says in the manual.

Also the bike seems to backfire alot on decel/rolloff throttle etc. It has a full akra pipe, so i pulled the carb to clean the jets and see what it had in it. Had a blocked idle air and pilot jet, but even after cleaning them, its still doing it. It has a 42 pilot jet, 180 main, and 85 idle jet.clip is on 4 out of 7. does this jetting seem ok for full pipe/desmog bike? do i just need to play with mixture screw?

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Old 2 Weeks Ago
450EXCR 450EXCR is offline
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is there a more active dirt bike forum i should be posting this on?
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Old 2 Weeks Ago
380EXCQLD 380EXCQLD is offline
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Old 2 Weeks Ago
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Quote:
Originally Posted by 450EXCR View Post
is there a more active dirt bike forum i should be posting this on?

KTMTalk
For problems with these bikes there is a wealth of knowledge there.
These bikes were notorious for having problems with the seal between the crank and the gearbox. You may have a problem with the gearbox being pressurised and forcing gearbox oil out through the breather.
Popping on throttle shut off is often caused by an air leak in the exhaust. Make sure it is well sealed before you play with the idle mixture.
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Old 2 Weeks Ago
450EXCR 450EXCR is offline
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yeah ive just been reading up on the oil migration issue. This isnt my first 08-11 450, and ive had mates with them too and ive never heard of or seen it before. ill check out the exhaust for leaks, cheers.
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Old 2 Weeks Ago
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RMJay84 RMJay84 is offline
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I generally loop any breather hoses up under the tank with a little inline filter and back down to where all the carb hoses hang. It gives you a bit more hose length for expansion etc, and seems to keep water out

I haven't heard of gearbox oil migrating to engine, usually it's the other way around with these bikes (engine oil migrating to gearbox)

Other 4strokes I've known, oil coming out of breather could be worn rings if the levels are correct.

I'm no jetting expert but could try a 40 pilot and/or 182-185 main jet. I had a berg 550 with an akro slip on that would burble and carry on during decel, I had to go down on the pilot and up on the main.
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Old 2 Weeks Ago
450EXCR 450EXCR is offline
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yeah no problem routing them, just havent seen volume of oil pushing up a breather that far. Set the oil level on the sight glass 3/4 up. Go for a ride and its settled above full on the glass. So it would seem that i do have g/box oil > engine oil? Ill try chasing the exhaust leak route 1st, then ill look into those jets, cheers.
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Old 5 Days Ago
450EXCR 450EXCR is offline
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just a quick update:

Ive fixed the oil migration issue i believe. Turns out it was the kickstart idler gear. The inner brass bushing had spun, and therefor blocked the gearbox vent. Im guessing this was causing the gearbox to force oil/pressure elsewhere and into the engine circuit in this case. The user "alongat" in the below thumpertalk thread is a life saver. Detailed explanation on all the common 08 faults, and how to fix each one. I only did the free fixes like the idler gear and tighten the E-start gear as all the parts for the upgrades arent in the country and dealers said ETA was weeks away due to COVID-19.

https://thumpertalk.com/forums/topic...into-gear-box/
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