# brute force 840



## Isenburg765 (Feb 28, 2014)

Ok so having some problems with my brute. New to this so cut me a little slack here. I recentely bought a 2005 brute force with the 840 big bore kit. After riding it for a while i had a problem with it blowing oil out the side breather. was told it was rings or gaskets so i went threw and replaced both. in the process i jammed the timing chain in the rear so tore the side cover off and realized why my electric starter wasnt working right... my fly wheel was missing about half the teeth. so after pulling off the one way clutch and changing the fly wheel and the chain coming loose i replaced all the gaskets and got it all put together. When i timed it i timed it according to the manual and adjusted the valves according to the manual and well now its running worse than ever, there is a loud tapping sound cant pin point it. My questions for you professionals are:
1) is there different specs to time it with it being the bigger bore
2) what about specs for the valves
3) any suggestions as to what i might be missing
ANY AND ALL TIPS AND ADVICE IS WELCOMED, been working on this turd off and on for about 5 months now and i just wanna ride! :banghead::yell:
Thanks in advance!!!


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## btap (Mar 23, 2014)

I know the feeling! Have you tried reading on the BBK website the kit came from?


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## Waddaman (Oct 3, 2010)

Timing is the same.

Valve lash is dependent on which builders cam you are using really. .007 In and .009 Ex should be a good start on the safer side.

I would assume your timing is off some way or another.. its hard to tell with a vague description. Where is the noise coming from? video? what are the possible things or issues you may know of?


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## Sallzy (Nov 25, 2012)

Hopefully you went with a 2012 or newer starter gear. It's 40% thicker than the older starter gears. When you changed gaskets did you remove the cams. They are specific to the cylinders. A front one and a rear one and they can get mixed up. As far as timing, go to YouTube and search brute force timing and you find a couple very good vids on how to time these motors. One is a factory vid which shows you how to set up the cams, intermediate shaft and all the chains, the other is from a guy who walks you through how to set your valve lash. I'd start with that first.


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## Isenburg765 (Feb 28, 2014)

I appreciate the input guys, as far as the cams go I went off what the manual said about one of them having a small groove in it and thats how to differ the front from the back. When i bought the quad it already had the kit on it(was a little skeptical at first but once i tore it down all the gaskets and rings lined up perfectly) I'm about 99% sure its the timing but havent had a chance to tear it back down and try it again, would the timing effect compression? I feel like when trying to start it (starter or pull) it always hits like a real hard stroke(pretty much impossible to pull past at first but after a couple tries goes past it). as far as the starter gear goes i just went back with the 05 :/ while i was into the side case i ended up having to replace the seals for the water pump too but that was because i torqued the rotor down too tight and busted that ceramic one so i just replaced em all. I should know more as to exactly where the noise is coming from either tonight or tomorrow will try and post a video of it for better reference. The only other issue i can possibly think of is possibly stretched the chain when i got it jammed but everything seemed pretty tight when i assembled it. I appreciate the help!! and like i said ill try and get a video up soon!


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## Isenburg765 (Feb 28, 2014)

also another stupid question if i just replaced all the gaskets.... when i tear it back down am i gonna have to replace em again?


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## Sallzy (Nov 25, 2012)

Depends. I've heard some people say they reuse gaskets as long as they still look good. My feeling is it's cheap insurance to replace them and you don't second guess gaskets being a problem if it runs like crap or leaks when you get it back together. When you pull it back down, double check all the timing marks. I'm guessing your off by a tooth somewhere.


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## Waddaman (Oct 3, 2010)

gaskets depend on how they look when you take it apart.. most likely they will be alright, I would replace head gaskets though if you take the heads off.


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## Isenburg765 (Feb 28, 2014)

Trying to upload a video of trying to start it to give you a better idea but won't let me off my phone now so I'll have to try the pc at home


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## Isenburg765 (Feb 28, 2014)

well it wont let me upload video from my pc either :aargh4: like i said before and like you guys said im pretty sure timing is off just a nut hair so im gonna tear her down and try again let you know if that helps


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## Isenburg765 (Feb 28, 2014)

Sorry for the long delay here just got a day off but checked my timing marks on the cams and everything lines up perfect so I'm gonna pull the side case off to see if maybe it jumped teeth there but before I tore it down the first time I could only turn the side crank bolt one way without taking the flywheel and everything off well now I noticed I can turn it both ways. Does everyone's turn both ways or is this a sign of something being broke inside? Thanks in advance

---------- Post added at 04:21 PM ---------- Previous post was at 04:16 PM ----------

Also figured out why I can't upload video gotta transfer it to a jpeg file to upload it will have the video of it running on here tonight


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## Sallzy (Nov 25, 2012)

I guess I don't understand what your asking when you say "turn the side crank bolt one way"?


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## Isenburg765 (Feb 28, 2014)

Sorry not 100% sure what it's actually called it's the bolt and clutch under the pull start. What you turn to turn the engine over. I did a little research and it's supposed to be a one way clutch.


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## Isenburg765 (Feb 28, 2014)

20140405 212954 - YouTube

sound quality isnt the greatest but theres a video finally of it running. thought it was the timing and like i said when i tore the top end off the timing was right on the money.... as always any advise is appreciated!

p.s. still couldnt quite pinpoint the sound either just coming from the engine lol


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## Sallzy (Nov 25, 2012)

Sounds like two different noises. Loose valves and clutch shoe noise or piston slap. Did the motor make these noises before you pulled it apart and changed the rings? Did you mic the cylinders and pistons before putting it back together. What was your ring end gap when you put it back together? Other than the noise, Does the motor run ok?


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## Isenburg765 (Feb 28, 2014)

Okay so didn't mic em but when I fit it all up I mean it fit like a glove the ring gap would be the rings I replaced the gap between the ends right? If so I'm pretty sure there wasn't much of a gap maybe just a very slight gap but I'm almost positive there wasn't one. Didn't sound like this before I tore into it and it runs like cap had to drive it around the corner and there is no power at all!! Honestly I'm almost to the point of dropping it off at the dealer and take the high bill


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## kygreen (Oct 15, 2011)

What about the chain tensioners ? Thats kind of sounds like a chain floppin around


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## Isenburg765 (Feb 28, 2014)

Both tensioners went together just fine if I remember right when I pulled the cam covers off there doesn't seem to be any slack at all in either one... didn't mess with the interior tensioner though


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## Isenburg765 (Feb 28, 2014)

been doing a little reading....... could it possibly be the main bearing? idk if the sound is right but the loss of power kinda goes with it? is there a way of knowing without taking the whole thing apart? if i do have to tear it down what should i look for?


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## Sallzy (Nov 25, 2012)

You should be able to take the spark plugs out, grap the clutch and rotate it back and forth. That's how I found out my front rod bearings were gone. You should be able to feel the looseness in it. When mine let go it blew the front piston skirt to pieces sending it through the motor.


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## ICRage42 (Nov 13, 2013)

:rockn:Thanks Sallzy that's a good bit of info there and pretty basic too.


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## Sallzy (Nov 25, 2012)

These things are notorious for losing crank bearings. You def want to check for play before you run it anymore or you'll do to yours what happened to mine. Do you know how much run time was on the 840cc build before you got it? I'm still thinking it's something to do with what you did when you rebuilt it. It ran good ( other than blowing oil) until you tore it down. Did you find out why it was blowing oil? How'd the old rings look?


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## Isenburg765 (Feb 28, 2014)

No idea how much time was on the build before i got it honestly i kinda screwed myself when i got it because i didnt ask all the needed questions but i finally got it tore down and got the generator cover off... so far everything has been perfect as far as specs goes except the half moon key that locks in the alternator rotor in place was laying inside the alternator rotor on the inside where the magnetized parts are. So far that has been the only thing that i have found to be out of place, i went ahead and ordered new chains just to be safe but so far everything has been to a T what the specs call for except for the key being out. My guess is that the key was disrupting the read from the magnetized rotor and the ignition coils and it was throwing the spark out of whack but idk cause well im not a mechanic but so far this has been the only thing that has been wrong. oh and also the rear set of rings were kinda seized in the piston head but the front was nice, didnt get her extremely hot to find out if i fixed the oil spraying out but every person i talked to said either piston rings or gaskets and i replaced both so im hoping it fixed it. Im slowly getting more educated on these things thanks to you guys and a lot of research and from what ive been reading if i plan to keep this beast long i might as well get used to working on em haha I appreciate your guys help. Let me know what your input is please!


edit*** also my "one way clutch" spins both ways but im thinking thats from the key being out


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## Sallzy (Nov 25, 2012)

That will def cause it not to start. Make sure to clean the crank bevel and inside bevel of the rotor with carb or brake cleaner before putting it back together. The woodruff key is only for locating the position of the rotor not to keep it from spinning on the crank. The pressure of the bevel is what keeps the rotor in place on the crank and if you don't have it clean and dry it'll shear the key and you'll be pulling it back apart for a no start issue. You may work on these beasts a lot but when they run good the power is unreal. Besides, look at all the cool stuff your learning. Good luck.


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## Brute 840 (Feb 9, 2012)

Sounds like piston slap and maybe rod bearing or bad one way gear just to hard to tell unless I have in front of me but I would check all rod bearings pistons for wear and jugs for wear and also pull the clutch and see how much play it has


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## Isenburg765 (Feb 28, 2014)

ok i have it tore down how can i inspect the one way clutch on the back side of the stator clutch? also if it is a bad one way clutch where can i get the 2012+ parts to put in there? thanks


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## Sallzy (Nov 25, 2012)

Just what the name says. The roller assembly should only spin one way. Grab the flywheel in one hand and try spinning the roller assembly both ways. It should spin freely one way and lock up the other way. Now I will tell you, I had my slip last winter and I thought I had lost a bunch of teeth on the flywheel but when I pulled it apart it was fine. I think what happened to mine was the 840cc and high compression pistons with the fact that it was **** cold caused mine to slip. I get most of my parts from Rocky Mountain atv. They can get oem parts fairly quickly.


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## Isenburg765 (Feb 28, 2014)

Ok fellas I got it all put back together went by the guide on timing and did everything to a T what the manual said.... put everything together went to fire her up.... nothing. Just cranks and cranks and cranks. Has new plugs and they are getting a spark. Tried putting fuel straight into the carbs and still nothing even gave it a little shot of starter fluid. Any suggestions would be greatly appreciated kinda scratching my head on this one


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## Isenburg765 (Feb 28, 2014)

Ok guys its that time again... finally got some time to get back into the garage to mess with the brute again. the last time i messed with it as you can see above i put everything back together and it wouldnt fire. I went through and tore the engine down again and everything is spot on! i mean the timing couldnt get any more perfect. so my question to you guys is what else should i look at while ive got the engine tore down? any suggestions as to what could be causing this? when i tried to fire it up before it cranked smoothly and everything so im not sure what the problem is...

also i even went as far as pulling all the guides out and making sure i installed them the way the manual says as well.


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