# 05 750 Brute, Motor Locked, looking for advice/guidence



## rushchaser (Oct 4, 2013)

Subject says it all,

I have a 2005 Brute Force 750. about 6 months ago my wife decided to crank it up and ride around the yard at probably 5 mph. after 3 laps she pulled it back into the garage and shut if off, immediatley as it shut off there was a ping and now the motor will not turn over, nor can you pull the rope adn get it to turn over. First thing I checked was the belt and that was not the problem. 

So I need to rebuild it, and instead of bringing it to the dealer I am going to attempt to rebuild it myself. I have stripped off all the plastics, air box and plan to remove the throttle bodies tonight, and drain the fluids (oil and anti-freeze). 

Which brings me to where I am going to need advice/assistance. I have downloaded the shop manual but I am not sure where to go from here. should I start by removing the heads and continue to reove parts until I think I see somehting that is not like the picture in the manual, then post a pic on here? Or sould I jsut completely remove the motor and then start removing parts or just leave it in the frame?

Thank you all in advance for any input/advice.

Rush


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## NMKawierider (Apr 11, 2009)

Before you get to pulling it down, you might check the oneway clutch on the starter drive. They are known to come apart at shutdown whey it kicks-back and sometimes they lock the crank up. If that's the problem, put all 2012 parts back in. Beefier.


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## chevzr2 (Nov 25, 2009)

bahh these motors are easy to do if you take your time and check it over twice, i had no experience with motors and built 3 already and they all run great, 2 750's, one with a blown crank and valves and one with valve drop, and the latest one was a 801cc big bore, a 650 bottom end with 840cc cylinders and put into a '10 750 fuel injected rolling chassi, now that was a project though getting it to run right with no base maps for the msd, but now its just a plain stupid powerhouse!


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## Sallzy (Nov 25, 2012)

Before I took the heads off or pulled the motor I'd drain the oil the coolant and pull the side cover off. Check the starter gear and timing chains. If you still can't turn the crank you could pull the valve covers to see if you've dropped a valve and if it's still locked up your gonna need to pull the motor and tear it down. I just got Done rebuilding my 2005 and even though it took me 8 months ( kid duty, hunny do list, insane work schedule etc...) it was a lot of fun to rebuild. The service manual and you tube make it pretty easy to do if your the least bit mechanically inclined. And the feeling knowing you put it together yourself and know how it was done is awesome. But then again, I like projects and this was a fun one. The best part is knowing I saved 800-1200 in labor by doing it myself.


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## rushchaser (Oct 4, 2013)

First off thank you all for the reply's!

Ok so I pulled the throttle body, and when I went to turn the crank as the manual describes it hit something and stopped before it got to the T mark, So I turned it the other way past the R and it hit something else which prevented me from turning it anymore. The Honey do list you spoke of prevented me from getting on here to ask what I should do next, but finally got to it this afternoon. Any ideas what this could be? I plan to drain the oil and antifreeze tonight.


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## Sallzy (Nov 25, 2012)

If your lucky you broke a timing chain and nothing else. Those are fairly cheap at 100.00 approx for all four ( two cam chains, intermediate chain and oil pump chain.) obviously the first thing you need to do is find out exactly what is stopping the crank from turning. Timing chain is the easiest and quickest to check. Bent or broken valves could also be the culprit. Other than that it's broken gears in the transmission or a piston in pieces. If a timing chain let loose and the motor was still spinning one of the pistons went up and hit the valves that were probably still open. You'll need to look at the chains first I'm thinking unless someone else has a better idea.


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## rushchaser (Oct 4, 2013)

ok so I got the valve covers off and its not the timing chains that you can see in the top.


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## Sallzy (Nov 25, 2012)

Sounds like you need to go deeper into the motor.


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## Nate_1503 (Jan 17, 2012)

Thinking starter gear...


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## rushchaser (Oct 4, 2013)

Ok so how do I get to the other chains or the starter gear? I am not sure what to remove next. This is my first time rebuilding a motor, so I am a bit lost and don't want to do more damage. Do I remove the large bolt that is in the center of the metal cup that would be behind the pull starter cover? I have downloaded the manual but it itsn't real clear. Is this where I am going to need a fly wheel puller and a clutch puller? Sorry for the ignorance but again this is my first time.


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## Saintsation (Mar 2, 2011)

Sounds like the piston is hitting the valves that's a common problem when the chains get worn out and jumped timing you probably have a couple bent valves. I would pull the left side cover off to check for broke timing chain or check to see if both of the tensioner a are all the way out when they are all the way out timing chains need to be replaced, just keep reading your manual and you
Will eventually find the problem!! Good luck !!


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## dman66 (Feb 20, 2011)

Go pull the timing chain tensioners from the engine block . Put the trans shifter in neutral and don't turn over the engine - pull the small cap off first,but be aware there is a little tension spring that can fly out and a pin that can fall out. Once they're pulled out,then undo the two bolts holding the tensioner to the block. Check and record where the inner ratchet mechanism ratcheted out towards the chains,then you can reset the mechanism to full retracted position to get an idea if your chains are stretched or not. DO NOT TURN OVER THE ENGINE AT ALL WHILE DOING THIS !!!!if the ratchet mechanism is all the way out - your chains are stretched, and you may have jumped timing. A fly wheel puller is used on the left side behind the pull start,and a clutch puller is used on the cvt on the right side.


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## Nate_1503 (Jan 17, 2012)

Where u located?


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## rushchaser (Oct 4, 2013)

Sorry for the long delay work has had me on the road a bit, but I am located in Albany, GA. When I pulled the Cam Chain tensioners they were out most of the way, I removed them a long time ago, but the description of the piston hitting the valves sounds right.


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## rushchaser (Oct 4, 2013)

So you were correct it was actually a broken valve, I replaced all 4 valves in that head and put it all back together. Finally got it all closed up last night and tried to crank it. It did crank but was running rough and fuel was pouring out of the drain ports and even started backing up to the vac lines and came out of them. I shut it off and disconnected the battery pulled the throttle body and open up the bottoms and made sure that the floats weren't stuck. put it all back together and started trying to crank it again and still the same. Any ideas? Suggestions?


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## ICRage42 (Nov 13, 2013)

are you sure your choke isn't stuck on?

Did you check and recheck your valve clearances. Are you sure you were at the correct top dead center when doing valve clearances?

carbs clean? could of gunked up with sitting this long.


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## rushchaser (Oct 4, 2013)

Yes I pretty sure I was at correct TDC when I redid my valve clearances for the front and back. I watched several videos on Youtube as well as followed the maintence manual. What should I do to completely clean my carbs? Should I pull them and take them completely apart? I already pulled them and made sure that the float wasn't stuck and that the needle valve that the float should open and close functioned.


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## ICRage42 (Nov 13, 2013)

Im gonna go on a whim here then.

You never cleaned the jets out then? If not that prolly is your problem then. The bike sat for a while with some gas in it and it usually gums up restricting or blocking a jet. Sound like gas is just blocked and flowing out.


Even tho your sure it might be you adjusted valves wrong at tdc. Ive done it and it sounds like when I did mine wrong. Its easy to do the valves and pain in the *** to make sure you tdc just trusting the marks on the crank aren't enough. Id also make sure your piston is at tdc. Trust me rofl :34:


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## rushchaser (Oct 4, 2013)

To adjust my valves I followed a guy on youtube who explained that you cycle the crank counter clockwise watching the valves, once the intake opens then closes the exhaust opens and closes and as soon as it stops moving from closing you go 1/4 turn from there.

If this is incorrect please tell me a better way, maybe I should take out the spark plug and watch until the piston is all the way at the top (closest to the spark plug hole)?

I think it has more to do with the jets being gummed up. The motor ran there was just a steady stream of fuel pouring out the little tip that is sticking out the bottom (the carb drain spout) and then fuel start coming out of the vac hose spout at the top of the carbs. 

Is there something that I should soak the parts in, scrum them with a tooth brush and acetone, or do I just open up the carbs/jets and spray the hell out of them with carb cleaner? 

Thanks for the help, 

Rush


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## rushchaser (Oct 4, 2013)

ICRage42 you are awesome! Thank you very much!!!

OK so I put on my Big Girl panties and pulled the throttle body off, opened up the bottom and pulled out the jets, needle valves, float and its jet valve thing. Soaked in WD-40 and scrubbed with a tooth brush. The side that kept leaking was really gummed up with a resiny tar stuff. Also pulled the needle out of the side and the needle on that same gunky side had a bunch of the same gunk on it. Got it all cleaned up, put it back together, installed and it cranked up with no fuel coming out at all!

So NOW I think that maybe the valves aren't adjusted right. After running a minute or two it started sputtering intermittently and if I pushed the throttle or tried to push the choke in it would sputter and start to die. I hope this is as easy to fix as just adjusting the valves? For the record I think I adjusted the valves to .005 in. (intake) and .008 in. (exhaust) following the method I described in the above post.

Thanks for the continued help

Rush


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## ICRage42 (Nov 13, 2013)

yes you answered your own question. 

Literally take spark plug out and see when the piston is travelling up to the top at the tdc mark. You can set the adjusters 180 degrees out or one revolution past and it will show tdc but in reality your on the opposite stroke. Theres a tdc for exhaust and tdc for intake in reality. So if you followed the manual and youtube vids you adjusted not only the back but also adjusted the front as well the same way or vice versa. 

Quite easy to mess up and I myself as well did it. 

Start fresh and go through and check to see if piston is coming up on that stroke and you should be fine. 

Report back what ya find. But a random sputter sounds like perhaps you still have some gunk laying around somewhere being sucked in. Leaving a quad sitting for some time usually does it and hence why they put the drains on them so you can drain em out when ya park em. 

also when you do valves adjustment I usually adjust them and rotate engine a few times and find tdc and adjust again to check clearances. 

Hope this helps


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## Sallzy (Nov 25, 2012)

Since you said it started and ran I think your valves are good to go. Otherwise I'd think it wouldn't start at all or clack like a bastard. Your throttle body is still gummed up. This ethonol gas really plays hell with this stuff. You need to pull it back apart and blow carb cleaner through all the ports and openings. My 2 cents.


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