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post #1 of 6 (permalink) Old 02-08-2011, 08:01 PM Thread Starter
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carb spring mod

on my 09 350 grizzly how can i do a carb spring mod ? how many coils do i cut off and will this help my low end?
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post #2 of 6 (permalink) Old 02-08-2011, 08:04 PM
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If I recall correctly you cut off 3 coils. All you do is pull the top of the carb off...cut the spring. Put it back together. It doesnt affect power at all. All it does is make the throttle feel "lighter" and it will make it feel like it has more "bang" when you hit the throttle because the slide in the carb will engage faster.



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2004 Grizzly 660 - Maxxis big horns and a few other things

2006 Kawasaki Brute Force 1000M
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post #3 of 6 (permalink) Old 02-08-2011, 08:16 PM
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Credit for this info goes to wayupnorth, I just was able to find and edit the post.

This is the slide and spring for the 660. These mods work on carbed Yamahas as well as other make bikes. Dynojet picked up on the spring mod and started suppling a weaker, lighter spring in their kits that gave the same effect as clipping coils of a stock spring. The effects of the mods were better throttle response when you mash the throttle and better acceleration. You don't gain power, just apply it differently than stock. I did the spring mod first and noticed a seat of the pants difference. Later the slide mod and noticed no difference. Maybe just me, other reported feeling a difference. Who knows. Not me.





Take the top cover off the carb. The spring is slid onto a metal sleave attached to the cover. Remove spring and cut at least 4 coils off not more than 5 IMO. IMPORTANT: Place the end of the spring that you cut back onto the sleave in the metal cover and not down into the plastic slide where the sharp end of the coil can damage the plastic slide. Done.
If you want to do the slide mod just pull it out after the top cover is removed. All these slides look different on different model and make bikes so the hole or holes to drill are different. Some you drill one hole and some two. On this 660 there are 2 holes below the needle and they get drilled out to improve the slide speed and throttle response. Maybe
They are 3/32" holes. You drill them out to no larger than 1/8" holes.
That's all I got on these mods.

2002 Camo Grizzly 660
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2002 Blue Wolverine 350
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post #4 of 6 (permalink) Old 02-09-2011, 11:24 AM
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Thats a 660 spring in the pic, you can cut 4-5 coils on it. The 350 and 450 have a different spring that you should cut no more than 3 coils off of.

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post #5 of 6 (permalink) Old 02-09-2011, 11:37 AM
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Also when you put the cover back on i would suggest putting a thin layer of grease around the diaphragm.



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2004 Grizzly 660 - Maxxis big horns and a few other things

2006 Kawasaki Brute Force 1000M
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post #6 of 6 (permalink) Old 03-27-2011, 07:10 PM
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Today I was just tuning my carb and I toke a few pics comparing the stock 660 spring to the dynojet spring. I found the dynojet spring was 5 coils shorter the my stock spring.
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File Type: jpg 111_0001.jpg (71.4 KB, 18 views)
File Type: jpg 111_0003.jpg (61.3 KB, 13 views)

02 Grizzly 660 Green warn winch, 26" 589s and 29.5" Outlaws
Uni, Hmf utility slip on, dyno jet kit.
Machined clutch sheave, 14 gram greaseless weights, and 2mm shim.
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