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05 brute force 750 hesitation and backfire

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  #1  
Old 11-06-2011 | 09:02 PM
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Default 05 brute force 750 hesitation and backfire

i just bought a used brute 750. idles fine but doesn't seem to have full power. has hesitation from a stop when you get on it hard and it backfires sometimes (just one or two big pops) when your going fast and then completely let off and slow down. from what i've read these should be able to do wheelies without problem. mine won't. replaced the plugs with no improvement. next? any idea where the mixture screws are on carbs and where to set? any help
 
  #2  
Old 11-07-2011 | 02:13 AM
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Was it sitting for any length of time? Could be plugged up carbs. The adj screws are hard to get to. You pretty much need a special tool to adjust them. Basically a 90 degree gear drive screw driver. K&L sells them. We have two of them. They could have dirt in them or water if the previous owner took them mudding or swimming. Also check yer airfilter. Is it a stock airfilter? If so I would put a K&N in it. I also have an 05 with some mods and I love it. I bought mine brand new and never had any probs. Keep the engine oil changed or you will be replacing cam chains lots. Also keep the front and rear diffs clean. These atvs are notorious for leaky diff seals. Mine seaps just a lil but I keep mine checked a lot. Yes they are wheelies machines. A stock one should pull a wheelie no prob. The real hot rods were the 06 and up 750's. 05 was the first yr and they had the timing retarded really bad. I advanced the timing and made a big diff. You might check your belt, could be slipping. Clutch kits make a HUGE diff with power. I recommend the Maroon primary and the almond secondary. Also, not to take you away from this awesome forum but since there isnt much atv traffic on here, you can go to mudinmyblood.com. That site is for all makes and models of atvs but probably 80% of the guys on there ride brutes that have huge lifts and tires. Im on there and I highly recommend them.
 
  #3  
Old 11-08-2011 | 09:55 PM
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hasnt been sitting a while. changed plugs and cleaned/oiled air filter. put some seafoam in it. no improvement after any of it. can you describe to me how to adjust the carb screws? do you have to pull the carbs and how do you get the plugs out of the screws? and where are they? i'm thinking about pulling the carbs and soaking in carb cleaner and cleaning really well and then checking and adjusting valve clearance. any other ideas?
 
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Old 11-09-2011 | 12:32 AM
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heard that adjusting the air pilot screws could help. where and what are those? and how do you adjust them
 
  #5  
Old 11-09-2011 | 02:10 AM
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If the plugs are still blocking the idle mixture screws you will have to pull the carbs to drill them out. If you soak the carbs make sure you take them COMPLETELY apart so no plastic is in them. Carb cleaner will mess up the plastic. Some of the early 05's some got away from the factory with the carb holder flanges on the heads had casting flaws that were very sharp and after you run the atv the pulsing action would slowly cut the rubber carb holder (aka carb boot between carb and head). The fix is inspect the holder for bad cuts and take a file and file down the mounting flange to get rid of the sharp edges. Yea I would def check the valves.
 
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Old 11-09-2011 | 08:49 PM
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ok i will check that first. whats the best way to drill the plugs out (never done it or exactly know what to look for) and do you have any diagram or pics of what i'm looking for? going to check valves same time as carb since i already have the plastics apart. also heard that the flame arrester could be blocked with carbon? any idea if the air pilot screwes could help if adjusted?
 
  #7  
Old 11-10-2011 | 01:52 AM
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I normally do not drill out the plugs per say, I prefer to use an ice pick or a scribe to puncture the sheet metal plug/cap, then with a prying action, pop the plug/cap out.
 
  #8  
Old 11-11-2011 | 02:05 PM
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any idea where to set them ?
 
  #9  
Old 11-12-2011 | 12:49 AM
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1.5 turns out would be a good start. I dont know the stock settings.
 
  #10  
Old 11-13-2011 | 12:08 AM
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Originally Posted by BleednGreen68
1.5 turns out would be a good start. I dont know the stock settings.

agreed on this generalized set up when the manual is not present.
 


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