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Does my motor sound normal ? 2006 YZ450F

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Sounds just like a YZ450F.  You will find that some of the noise will disappear if you pull in the clutch lever.  That's because when you release the clutch (by pulling the lever) it releases the transmission main shaft and stops rattling the gears around.  It's always difficult to really gauge from a recording like that, but it does sound normal.

The welded crack bears watching, however, not only for external leaks or re-cracking, but you'll want to keep an eye on both your coolant and your oil for signs of coolant loss and of coolant contamination in the oil.  Neither one is healthy in the least on these engines.

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4 hours ago, grayracer513 said:

Sounds just like a YZ450F.  You will find that some of the noise will disappear if you pull in the clutch lever.   That's because when you release the clutch (by pulling the lever) it releases the transmission main shaft and stops rattling the gears around.  It's always difficult to really gauge from a recording like that, but it does sound normal.

The welded crack bears watching, however, not only for external leaks or re-cracking, but you'll want to keep an eye on both your coolant and your oil for signs of coolant loss and of coolant contamination in the oil.  Neither one is healthy in the least on these engines.

Thanks .When I pull the clutch in it sounds the same .  thats a good point about watching the inside of the welded Head  . I just brought home fresh oil , oil filter and will give it an oil change tomorrow . 
 What I'm looking for are any large metal shavings a bike this shouldn't have ,Brass shavings and as you said any signs of coolant mixing with oil .since doing the oil change I'm going to check the valve clearance too . Found out that the previous owner recently had the Cam chain replaced from a local shop I know . also found out he swapped out the frame of the bike and that has me thinking of going over the whole bike just to make sure everything is torqued to spec and such .
 

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22 minutes ago, TN Dirt Rider said:

Holy crap.......dude I hope you got a smoking deal on that thing.

Wish I could say yes but not so much . Paid 2,000 for it .

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I found some cams and got the bike back together this evening . went to kick it over, got some serious backfire and when I got it running it didnt sound so well . idle wasn't steady and I noticed when I pull the hot start lever while running it did not increase the idle speed . had a bit of a surge happening aswell . all this was not a problem before I replaced the cams .
 Going to re check the timing and valve clearence tomorrow to see if I slipped some how some where  . Are there any other idea's to look for ? 

Edited by xxcody2gunsxx

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The weld was there probably becuase he spun a cam gear on the cam shaft.  It happens. That is the only reason for that little weld that I know of...

The inside of the motor looks spotless, so it couldn't have been a neglected bike...

 

Yes, it sounds like your cam timing is off.

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Alright so after taking a morning ride with another bike then taking my wife out for a mother's day lunch I  was able to give some attention to the YZ450F .
 Pulled the valve cover and timing was spot on .Checked the valves and found one exhaust valve is out of spec . So I have a valve shim kit coming some time this week .

 


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 I checked the gap on the plug and it was right at .30 

I Was looking over everything I touched and found something . I guess when I cleaned the bike before the valve check /cam replacement I managed to turn the air/fuel screw almost fully closed position .
 After resetting it and putting the bike back together it fired right up .

Now just waiting for the valve shim kit to come in .I'll probably go through the carb while waiting and grease all the linkages ,bearings etc .. 

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With regards to the comment about the hot start not affecting the idle, it's very easy with things being as tight as they are to get the cable housing pulled up out of its socket, holding the HS plunger open, or to break the plastic nut that holds it in place.  Check the free play. The hot start needs it like everything else.

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3 hours ago, grayracer513 said:

With regards to the comment about the hot start not affecting the idle, it's very easy with things being as tight as they are to get the cable housing pulled up out of its socket, holding the HS plunger open, or to break the plastic nut that holds it in place.  Check the free play. The hot start needs it like everything else.

I noticed that as well . Turns out that the Plastic threads that connect the hotstart to the FCR Carb has been stripped over time So I ordered a billet aluminum replacement . Thanks for your help 

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Most parts I ordered arrived today . Valves are now all in spec ,new valve cover gasket ,Header gasket ,intake boot ,Carb is cleaned ,linkage greased ,Fresh oil ,New air filter and more to come . 
 I noticed when cleaning the carb the AP adjuster was screwed in quite a bit . I back it out so there was zero  freeplay but not any further . I took the bike a few rounds in the backyard and noticed when I cut the throttle fast to brake quickly or turn ,it "would" or"almost"  stall . any idea's ? Its been awhile since I fiddled with Carbs .
It idles great . Response in acceleration is great . Bike sounds much better as well . IT just that sudden cut of of the throttle that it wants to stall in motion .

Edited by xxcody2gunsxx

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My bike was doing this when I got it.  Found the accelerator pump diaphragm was disintegrating.  Picked up a new K&L diaphragm and been running like a champ since.  In fact, I've only stalled it twice since, both times my fault.

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2 hours ago, High On Octane said:

My bike was doing this when I got it.  Found the accelerator pump diaphragm was disintegrating.  Picked up a new K&L diaphragm and been running like a champ since.  In fact, I've only stalled it twice since, both times my fault.

LOL . Thanks for the advice . I'll get a new diaphram asap . 

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The AP timing screw you fiddled with should be set so that as you open the slide quickly, the squirt "just misses" hitting the slide as it opens.  Too much too soon can cause a stumble almost as bad as too little too late.

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