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Discussion Starter #1
I just picked up a 08 brute 650 sra with 575 miles on it. It sat for a year in a garage and was not winterized. I put a new battery in it and it will start with the "choke", idles high for 20 seconds, then wants to die. This seems normal but with the choke off it doesn't want to idle without dieing. The idle speed adjuster is turned ALL the way up just to get it to idle.

Took it riding this weekend and it stinks like fuel, like it's running really rich? It stumbles off idle but seems to run good after that. I put a whole bottle of techron in the tank and rode it for 2 hours. No change. Not really looking forward to tearing apart the carb, is this my next step or is there an adjustment I'm not aware of?
 

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It sounds like a dirty carb. The bottom part gets dirty first, either the idle (pilot or starting) jet, main jet or the float valve. I clean the float valve seat with aluminum polish on a Q-tip (just spin the Q-tip a few times), and wipe off the black rubber point of the float valve with a cloth. Make sure the spring in the float valve is working.

These 2 videos might help:



You could also add a lot of StarTron cleaner to the fuel, ride it for awhile, and then tap on the side of the carb with a rubber mallet- you might get lucky and not have to take the carb apart for cleaning.

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Discussion Starter #3
What confuses me though, is why does it smell so strongly of exhaust/gas? We were riding for several hours today, with several bouts of full throttle acceleration and plenty of hard running climbing steep rocky trails. If it were running lean, causing the poor idling issue, would it still smell so strongly? It back fires through the carbs, not really through the exhaust so all signs point to lean condition. I guess I could pull the plugs, they are most likely originals with 575 miles on them.

I will say this though, it starts right up with the choke when its cold. How could I tell if the choke slider(s) were stuck? Can I just pop off the air cleaner, start the bike and look down into the carb? I didn't see anything moving when I pulled the choke in and out when I did that but the bike wasn't running at the time....
 

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Sometimes the main carb passages clog so it runs on the choke passages all the time, or the float valve sticks slightly open, so it runs way too rich once it gets warm.
 

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Discussion Starter #5
That makes sense. Guess I need to pay up to get it done or tear into it myself. I must admit I've never done carb work before but have done just about every other type of work short of rebuilding engines on cars. Is there a nice write up start to finish with pictures? I have a garage to work in with a heater and don't need the bike till next weekend.

Am I doing any damage to it if I run it on another ride like it is?
 

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Running rich might eventually foul a spark plug. Long term running too rich can cause extra fuel to make exhaust valves dirtier, it can clean oil off piston rings, and fuel can get in the engine oil, but the engine will run cooler on a hot day. I would just do short rides until getting it fixed. If the spark plug does not foul right away and no fuel is dripping from the carb, you just can smell fuel and it will not idle when warm, it is probably not extremely rich.

These 2 videos below might help - I do not know of a video or series of photos made for your ATV carb, but it is similar to the carb used for a lot of other engines:
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Discussion Starter #7
I tried to take the carbs out today, that was a miserable fail. I could not for the life of me get to the clamp screw for the front carb. Because of this I could not flip the carbs upside down in the bike. I was able to remove the rear carb bowl, and it was spotless inside. I puled the main jet and it was clean, no varnish anywhere, looked brand new. I couldn't get the pilot jet out because of the angle to get a screwdriver on it, but I shot carb cleaner down through it from the top of the carb and the was no blockage. I could not get the front bowl off though, but based on the condition of the rear I have little reason to think it would be any different.

I pulled the rear spark plug while I had the plastics off, and it looked nice and clean, just a touch of black on the tip. The front plug, on the other hand, was all oily. My new theory is that one of my choke plungers is stuck, causing only the front cylinder to run rich. I put it all back together and it fired right up and will idle with no choke after 30 seconds or so. The idle speed adjuster still has to be turned all the way up to maintain the idle but it does seem to be running nicer off idle.

I'm gonna call a local ATV shop (not dealer) and see what they want to tear the carbs/choke off and try and correct it. I will install a new plug up front though just to be sure. What is everyone paying independent shops to do their carbs, assuming no rebuild is necessary, just a cleaning.
 
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