750 brute dont run

jackson · April 4th, 2010, 12:54 PM

I have a 06 750 brute, It has the almond spring in the seconday and the morron spring in the primary. Im running 26 inch ITP 589s on maxis wheels. I lined up with an 07 650 brute and I got him off the line by 1 length but he ran right around me. For some reason my 750 doesnt run as strong as it should. Im gonna put a cdi box on it but I would think the 750 should run harder than a 650. Ive noticed the other brutes seem to have more power than mine. Does anyone know what the problem might be with my 750. It has just been rebuilt, and 200 miles on the engine.

NMKAWIERIDER · April 4th, 2010, 01:11 PM

Quote:

Originally Posted by jackson

I have a 06 750 brute, It has the almond spring in the seconday and the morron spring in the primary. Im running 26 inch ITP 589s on maxis wheels. I lined up with an 07 650 brute and I got him off the line by 1 length but he ran right around me. For some reason my 750 doesnt run as strong as it should. Im gonna put a cdi box on it but I would think the 750 should run harder than a 650. Ive noticed the other brutes seem to have more power than mine. Does anyone know what the problem might be with my 750. It has just been rebuilt, and 200 miles on the engine.

And what does the 650 have that yours does not...CDI, Pipe, carb kits, performance air filter,cams...ect.

The 650 has been known to work-over the 750 as it does wrap-up faster. It has almost the same HPs but a little less tork, so it will give the 750 a run for its money. It's not unheard of for them to win in a fair race. But with a few simple changes, it will be your taillight he sees.

jackson · April 4th, 2010, 01:30 PM

The 650 is stock. But I go rideing alot and it just looks like the other brutes have more power. When they get in the gas the rear end drops and the front comes up. I think with diff. tires and the cdi box mine will wake up quite a bit. I hope.lol

NMKAWIERIDER · April 4th, 2010, 02:40 PM

Quote:

Originally Posted by jackson

The 650 is stock. But I go rideing alot and it just looks like the other brutes have more power. When they get in the gas the rear end drops and the front comes up. I think with diff. tires and the cdi box mine will wake up quite a bit. I hope.lol

Oh it will, and these Brutes are pretty fusy about things being right like valves, jetting air intake, timing and so on. Anything off just a little will make a big difference. One thing that I noticed on the spring charts was that the almond is much like my Dalton except its stronger toward the low end but after about mid-way on the throttle, it will allow the clutch to shift-out faster then my Dalton which is stronger on the upper half because of my need to hold in the tork and power band at a higher RPM for my hill climbs. Yours may be great out of the hole with the Almond but it may be shifting out past say...25..fast enough that it falls below the best power band until it gets close to say...50-55 or so. Just thinking out loud.

jackson · April 4th, 2010, 02:57 PM

The guy that does my work is good but I dont know how he is at tuneing. Im gonna put the cdi box, a slip on hmf exhaust, and dial a jet on and see where that gets me. I have noticed that my brute has alot more engine noise than others mabee that has something to do with it. It may be the timeing chain, not sure but ill get it checked out thanks.

jackson · April 4th, 2010, 03:20 PM

Hey whats the deal with the twin air filters? If I decide to go that way will I have to change my air box? Also I put a k&n on it and had to take it off. The machine just dednt run right.

NMKAWIERIDER · April 4th, 2010, 04:13 PM

Quote:

Originally Posted by jackson

Hey whats the deal with the twin air filters? If I decide to go that way will I have to change my air box? Also I put a k&n on it and had to take it off. The machine just dednt run right.

No airibox change..not even with the powerflow. I have the OEM replacement TwinAir. Works well. So, what was the deal with the K&N? They do flow better but filter less. Made it run too lean maybe? Maybe you do have a jet problem...too small. That little extra from the K&N shouldn't have made that much difference unless you are already borderline on jets. I still have my K&N and it does run better with it, but I need it to run a long time so its out.

VTprairie · April 4th, 2010, 05:33 PM

pull the almond it slows your top speed by at least 10 mph and you dont need it for 26 tires the stock is more then enough. Put a CDI in as well but a stock bike with stock tires will get you everytime It takes alot more juice for aftermarket tires esp top speed thats just the way it is. Pull that spring and get a CDI and you will gain alot back

jackson · April 4th, 2010, 08:57 PM

What exactly do the springs do. I think the primary affects the bottom end and the secondary the top is that right? All I told the dealership was that I wanted more power on the low end. My top speed is 60mph what should it be.

NMKAWIERIDER · April 4th, 2010, 10:12 PM

Quote:

Originally Posted by jackson

What exactly do the springs do. I think the primary affects the bottom end and the secondary the top is that right? All I told the dealership was that I wanted more power on the low end. My top speed is 60mph what should it be.

The primary spring sets the stall and the initial Pace of shift out. Its the centrifugal force generated by the flyweights that bare against the spring and allows the shive to come together at a regulated pace. As this shive squeezes down on the belt, the wedge effect bares pressure on the belt which is transferred along with the tork of the engine to the secondary clutch. That clutch also has a shive that a spring is baring on but trying to keep it closed instead of open like the primary. So, as pressure builds, it overtakes the pressure on the secondary and it opens and the belt starts it run down to the center where the primary is on its way up from the center. This is what we call shift-out. When its fully over or shifted, you are in the highest range. If the secondary spring is too heavy or strong or has an extra loop like the RED one does, then it can't shift-out completely like it did stock and you loose top end. If its too light, then it will shift-over too easy and not give enough pressure on the belt to stop it from slipping so you will burn a belt and shift into high too early. Not good either.

Tuning a clutch is about the most important things you can do for yourself and your machine. There are many many combinations of springs from several dealers like EPI and Dalton along with many different flyweights. There is also a clutch body modification itself. You will hear about the VFJ stage 1,2 or3 mods. These are high performance mods. VT is probably right in that you are close to stock on wheels and tires, and the ratio the stock secondary gives might make it better for racing then the Almond spring which is what one would use with heavier tires and did a lot of low end work.

I hope this helps. 60mph is a little slower then most. 68 is more average. Mine now is back to 65 sense I removed the red spring and wend down to 26" tires.