Brute running bad?

[Mudforce]

Well as some of you know is was out yesterday with Just T and had to end the day early. The bike has a very strange problem. It starts like normal idles great, dead stop to wide open like a champ, when cruising at 35km it will only heat up to 180 when I stop it goes up to 220 like normal. If I bring it up to anything above 35 it starts to fart and sputter real bad to the point were it starts to loose power. So last weakened I went and put about 2gal of gas from my jerry can that had been in my shed for a few weeks, so if it was bad gas would it not clear up after a few miles? I am pretty stumped on the this one and not quite sure were to go. Do I need to pull carbs and clean them? And why would it only run at 180 on a warm day when it normally goes to 220 before the themostate opens. And when we started to ride it would go through the normal heat cycles and then stop and stay at 180 when driving and the go up once I stop. I need some help!

[Mudforce]

Oh ya and it only does it under load, standing still if you rev it up it is no problem and the throttle is nice and crisp. Could it be a coil?

[JB]

Could be many things....coil, carbs, sensor, carb boots......have to start the elimination process i guess....lol Hopefully the brute guys can chime in on this one though.

have u checked the carbs lately, like all the jets and what not? Sounds like when u pin it, it's fine, but that's cause your main jet is open at full throttle. If you say your just cruising and it's sputtering, it wouldn't hurt to check your other jets....could be one plugged for the mid range?? Could be something totally different, but never hurts to check i guess...lol. If not carbs, could almost be something electrical.....try to eliminate the little things first. Free play adjustment on the throttle cable??? lol i don't know....just giving some ideas..haha

[Mudforce]

Ya I will have to tear into it and see what I can find. I was just reading on another forum that it might be a vacum issue too. I guess I got some work to do if I want to ride next weakened.

[Fat Cat]

check your air filter mine was plugged did the same thing you describe. It was my prefilter. I cleaned it all the power came back. also don't over oil it.

[tyndall]

Most likely stuff first. Clean the carbs. Pull the bowls off, remove all the jets, blow through every port with carb cleaner. Pay extra attention to the little ports in the air intake side. Check the vent lines all the way up to the pod. Polish up the choke plungers too. Make sure the carb boots are not cracked and are sealing good.

If no change, swap out your dynatek, check fuel pump flow, test coils.

[Mudforce]

Update, I cleaned the filter it was dirty, reoiled lightly but enough. While I was waiting for the filter to dry I did a quick visual and found the rear spark plug was loose, so I put it together and no change at all. So now I am going to take the carbs off and clean them and hope for the best. So weird, starts great idles great, great acceleration till I hold it at any speed then it stumples and sputters.

[Wolf]

I'll throw my .02 cents in there too (remember, you get what you pay for... LOL)

While you're checking the carbs, also look at the exhaust for any obstructions and also check your fuel filter as it could be clogged, especially if you suspect some bad gas.

[Mudforce]

I don't think I have a fuel filter, I guess checked my repair manual and it doesn't show in any.

[four_420_twenty]

youd think it would have a inline fuel filter.

[tyndall]

Originally Posted by four_420_twenty

youd think it would have a inline fuel filter.

Nope. Maybe in the tank. And getting at that makes pulling the carbs seem easy.

[Jaxx]

just my opinion here, but if your bike is snorkeled, maybe, just maybe your carb veny line to the pod is slightly kinked. I had that similar issue last week, and it was my carb vent line, or just a coincidence that we pulled it straightened it then it worked just fine.

[Mudforce]

More stuff to check, tomorrow night is going to be busy!! Thanx guys!

[motorboat]

Clean Your Spark Arrestor.

[3Wheeler]

Originally Posted by Mudforce

More stuff to check, tomorrow night is going to be busy!! Thanx guys!

You have a carbureted model, check the foam seal between the air box lid and the air box. If it's deteriorated then change it! Common problem as they are a sealed pressure system. (finicky but awesome)

[Mudforce]

I have done away with the foam crap and made my own out of silicone, it is sealed real good. Not a problem there.

[Mudforce]

Originally Posted by motorboat

Clean Your Spark Arrestor.

Checked that and it had a little bit of packing in it but nothing severe.

[Mudforce]

Update. I got it running a lot better. I am going out Saturday and will see how it does. It turns out the guys on MIMB do a spark plug wire mod, they twist off the plug end of the wire and put on a automotive style end, and add the screw on end to the spark plug and giver. The stock wires have a resistor in the end and this mod takes that out which increases the spark. So I got it running better as well as better throttle response to boot.

[Mudforce]

Oh ya and it cost me $5.00.

[JB]

did u see this done?? I need to do this to my grizz.....cause i'm just not used to just having the threads on the end of the plug. I want to do it, but never knew how to get the plug wire end off without screwing things up. What's this MIMB?? I'm having a brainfart...lol. Glad u may have fixed it....and good info...i'm gonna mod mine up too.