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Discussion Starter · #1 ·
Recently started a tear down on the 06 750 brute, had the top end done by a “mechanic” whatever he did im pretty sure was done wrong. Tore it down to check the timing as the bike wont run over 1/4 throttle without popping in the carb. Upon removing rocker covers on both cylinders ive notice on the back of the cam there's massive gouges and wear marks on the head aswel as the rocker cover. Bad enough that theres a groove where the oil passage is. Really hope buddy didnt put it together like that but whats done is done, heads are trashed now, just trying to find out what could cause this, so i can check things out before installing new heads. Any help would be appreciated hope i was clear enough lol
 

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Discussion Starter · #2 ·
Also timing chains were all replaced not sure if tensioners or something could cause cam wear
 

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Hard to say what happened. He could've just dropped foreign material in there. Or he forgot to put the oil pipes in, or they were plugged up. In any case, yes, time for new heads.
 

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Discussion Starter · #4 ·
Think he used too much seelant on rocker covers, oil passage on the cam was clogged with silicone. Thanks for the reply.
 

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The top end gets it's oil through tubes through the cylinders from a galley port on the case. It must be sealed on both ends and as I recall they use O-rings. If he forgot one, the top end can starve for enough oil. The cam chain and tensioners get their oil from the return from the heads so if it's low...then the chains and tensioners will also be starved of oil and also show excessive wear. Just a theory at this point though. Something to check. These are the tubes circled in this pic:

 

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Discussion Starter · #6 ·
I checked out the tubes they were all clear. Still had o rings. Think the wear came from the big peices of black gasket maker stuck in the end of the cam Think it clogged the oil ports on the cam itself. Everything else looks normal.
 

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Discussion Starter · #7 ·
Still cant figure out why it wont run over 1/4 throttle checked the timing all seems good, retiming it anyways to remove the heads but i was really hoping the timing was causing my running issues, ive checked carb boots for cracks, cleaned the carb a half dozen times, changed plugs, chokes not stuck, tried the electric fuel pump mod, running out of things to check before i buy a cdi. Could an aftermaket exhaust cause this? The factory pipe cracked on the rear header so i replaced with a hmf only thing i could find i tried to rejet but seemed like bo matter what i put for jets it ran the same way.
 

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For the revving up, did you check to see if the slides move freely, check the slide diaphragms to make sure no holes in them - seated properly - and the little brass jet is installed in each diaphragm ? Do the slides move up when trying to rev it up ? Annnddd, did you check the carb float height setting for both carbs ?
 

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Discussion Starter · #9 ·
Not sure which little brass jet you refering too, im pretty sure the slides were moving never really revved it with the airbox off to look as i heard it wouldn't run right with it off. Ill have to take a look when my head gaskets get in and i put the engine back together. Not sure how to set the float levels im kinda new to carburetors, but ill do some reaserch n see what i can figure out, thanks willing to try anything at this point its been a year ive been trying to make this thing work about ready to give up on it.
 

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If you are new to carbs, there is a lot of information you need before you start tearing them apart and trying to rebuild them. These carbs have quite a few very small ports in them that need to be clear of any obstructions to make them work properly. The brass jet Dman is referring to is located in the tab on the diaphragm that locates in the hole on the carb body. When Dman was asking about your slides moving properly, he was referring to the action they make. you can stick your finger in the carb (bike not running) and push the slide back and it should slide freely and make a little vacuum like (don't know how to describe it!!) sound when you release it. When the bike is running, the slides should flutter back and forth as you rev the bike. If they don't, your diaphragm either has a hole in it, or they aren't seated properly. Also, the main jets are not the same. The front carb has a smaller jet than the rear, as the rear cylinder runs hotter than the front and they use fuel to cool the rear cylinder to compensate. Float height is critical for these carbs. They like it spot on to operate properly. Get yourself a service manual to get all the specifics as it would take forever to write the whole procedure down. Did you separate the carbs when you rebuilt them? If you did, you probably need to sync them.
 

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Discussion Starter · #11 ·
Nope didn't seperate just cleaned removed jets and cleaned ports with cleaner, has a152 jet in the front and 158 in the rear checked the float levels they were within the specs, slides move freely you can hear the vaccum when you realease them, cleaned out the diaphram jet. Geuss well see what happens when i get the motor back in the bike.
 
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