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I keep seeing conflicting opinions on 1) whether I need to do this at all, and 2), whether it is something that is feasible for a normal, non-techie person like myself to take on. ( I do my own oil changes, fluid changes in transaxles, brake jobs, etc. but not carburators). Bought my Griz new in 2006 and it has about 1280 miles on it. Has always run great and still does. Pure stock except for replacement tires. I recently moved from New York Sate (elevation 900 feet) to Colorado and now ride at about 8500 feet. Both my Grizzly and my 2006 Kawasaki Prairie 360 seem to start and run just fine at this altitude. The only differences I notice is that the exhaust "smells" a little richer, and the top end is not quite what it was at sea level. The local dealer told me I probably could just adjust the screw on the carb and that would make it better, but he does not work on Yamahas and said the carb is so hard to get to it may not be worth the trouble. Am I risking doing damage to my Griz by riding it like it is? Someone else told me the only bad thing I'm doing is burning more fuel than necessary because the engine is running rich. So what's the real deal on this issue? I could probably take it to a Yamaha dealer which would be a few hours away, but I'll attempt it myself if you guys say it's possible for a DIY project. Thanks in advance.
 

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Welcome from Colorado.
I wouldn't re-jet my carb again, it was a waste of time. You need more air, not less gas. Go ahead and try it if you think your guy knows more, you can always put everything back like I did :)
To understand, remove your air box lid and take'r' for a good, long day ride to see. I drilled holes in the lid for more volume, the reducing gas idea is wrong around here.
 

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Thanks for the input Ridgeway. I'd really prefer to just leave it alone since as I said, it runs fine. I'm just concerned that I may doing some damage although what that might be I have no idea. My fan does seem to run a little bit more than it used to, not continuously, and not sure if that means the engine is running hotter than it did at sea level or not.
 

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I live at 7000 ft. and can ride to 14,100 ft without a problem, or causing damage. I rode stock for a few years and did the air box lid mod for better than stock performance, not to prevent damage.
The plug will run very dark, I change mine once a year before a no start situation happens.
C.V.T. mods will make'r' run right (better), are easy to do and not to expensive. Do the air box if you want, after you run without it to feel the difference.
As for the fan, everything is on an incline around here with less air going through the radiator, mine got hot a few times so I added tubing in the radiator hoses as additional heat shrink, running hot has not happened again.
 

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Sea level air has about 20% oxygen. 8000ft air has about 15%. A 25% reduction, thats huge.

So, your definitely over-jetted, and like ridgeway has said your plug will be really dark because your running super rich.

The only potential damage you need worry about would be from too much gas in the oil, and unless you do LOTS of idling it's not a concern you should have.

Your fan running more, I would guess, is all in your head, as a motor that runs rich will run cooler than a truly lean one, or even one with an optimal a/f ratio.

Its common practice to re-jet when going up in elevation to retain as much performance as possible.. as a rich motor will be a little sluggish.

Its absolutely essential to watch your jetting when doing DOWN in elevation (substantially).. because a lean motor will burn itself up.
 

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Depends if you want to get some performance back on it. Is it worth the hassle of getting to the carb, was to me. I re-jetted to I think to a #140 main jet and it runs real well at altitude. I've been as low as Moab Utah and didn't have to re-jet (wouldn't want to have gone lower). I was constantly getting 20+ mpg. I too live in Colorado and am familiar with the real high country. Not to get into a pissing contest with Ridgway, as he has his own ideas, I'll just mention when back in the day of carbs everyone that ran Pikes Peak always and I do mean always changed jetting. They didn't even have airboxes just from the carb bell to a filter.
Will it hurt your motor, no as your just going to be running rich (bring spare spark plugs). Is it worth the hassle, that's your decision to make.
 
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In theory your fan will run more at altitude, because your rad has less air molecules to help dissipate heat with. If your engine is getting less air (because of altitude) your cooling system should also be less effective
 

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Depends if you want to get some performance back on it. Is it worth the hassle of getting to the carb, was to me. I re-jetted to I think to a #140 main jet and it runs real well at altitude. I've been as low as Moab Utah and didn't have to re-jet (wouldn't want to have gone lower). I was constantly getting 20+ mpg. I too live in Colorado and am familiar with the real high country. Not to get into a pissing contest with Ridgway, as he has his own ideas, I'll just mention when back in the day of carbs everyone that ran Pikes Peak always and I do mean always changed jetting. They didn't even have airboxes just from the carb bell to a filter.
Will it hurt your motor, no as your just going to be running rich (bring spare spark plugs). Is it worth the hassle, that's your decision to make.
No piss contest here :)
wgc and I have ridden together a few times and never had a problem. This thread got going about jetting/re-jetting and I said it didn't work for me. I dropped down one level in jetting (don't remember the number) and she wouldn't pull a sick whore of a pot, so I put her back to stock and opened the air box lid for more air. I threw the damn jets in the burn barrel to make damn sure someone I know didn't make the same mistake.
I ride from 3000 ft. around Moab to 14,000+ ft above Telluride with this set-up. So the plug runs darker than at sea level, one plug a year isn't a big deal to me.
 
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Like someone else stated, not to start a pissing match lol, but to the best of my knowledge its strictly the oxygen part of our air that gets the fuel mixture to explode. If a certain altitude has X amount of oxygen in its air, then that's all the motor can take in with each "breath" regardless of how free flowing/large the intake path is, and will only burn as much fuel as its percentage of oxygen will allow.

You opened up the intake, reducing restriction, making it easier for the quad to breathe.. but it still can't optimally burn a sea level jetting amount of fuel with 25% less oxygen than sea level.
 

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I wonder if your jets were set to your altitude before you bought your machine? That would somewhat explain why jetting down in your case hurt performance.
 

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Like someone else stated, not to start a pissing match lol, but to the best of my knowledge its strictly the oxygen part of our air that gets the fuel mixture to explode. If a certain altitude has X amount of oxygen in its air, then that's all the motor can take in with each "breath" regardless of how free flowing/large the intake path is, and will only burn as much fuel as its percentage of oxygen will allow.

You opened up the intake, reducing restriction, making it easier for the quad to breathe.. but it still can't optimally burn a sea level jetting amount of fuel with 25% less oxygen than sea level.
Not really, try breathing through a drink straw, then a garden hose. As for a/f mixture and not burning all the gas up here v down there, that one I go with.
I think the available jet's can't/don't meter fine enough to remove the slight amount of un-burned gas exhausted. For me here, stock works best.
So you know, the parts changers at the local dealership changed the jets on ALL carbed bikes sold at that store, and charged a lot of $$$ to the buyer, additional dealer profit. No bike left that store without this work being done.
I could have drank the local cool-aid but I bought my 660 300 miles away, got it right out of the crate unmolested and in fact, put two 660's on the debit card that day and brought one back for my hunting buddy.
We got them back here and started riding with locals the next day, the others on machines bought locally, and we all noticed a difference in the bikes.
Eventually some locally sold bikes got sold off because they ran like shit, and some others I helped change the jets back to stock. One locally sold machine, used by a local ranch, got resold because of how it ran, sold to another member here because I told the member/buyer I could fix it, of how I re-jetted my bike not knowing what the performance difference would be, then changed it back.
I never said the a/f mix was perfect. To get that I can do a little engine work and bore the carb throat. I can have this thing running perfect for about 6 grand, running at 10,000 ft like a stock bike does at sea level, but as I paid only 5800 out the door for the bike, I'm not doubling the expense for a 30% gain in performance.
This thing can get 34 m.p.g. depending on the c.v.t. ratio I install for the day ride, this has been proven while riding with other members visiting this area. I did 136 miles one day (Aug 13, 2014) needing one tank of gas, and only used the reserve part of that tank for the last 1/4 mile on that day. The day before (Aug 12, 2014) another member and I did 455 miles on one calendar day, and had to carry all the gas we needed from camp for the day. We rode from 5:30 a.m. until 10:30 p.m. and the other griz (a 700) was getting 20 m.p.g. I had to get the m.p.g. up on both bikes because there is only so much gas you can store on a griz and still ride it. The 700 was also running c.v.t. mods.
This carbed bike hauls ass....all the following picture were above 13,000 ft. Some might take these as showing off, but I ride these places constantly and was just up to the Humboldt Mine yesterday with two others tagging along. (I am going to add a link, read all but notice the 3rd paragraph says the mine is not reachable by jeep, but can be walked) The first picture is looking up the trail (I'm holding the camera level to the earth), the next picture is looking back down;
https://flic.kr/p/fy8fb9 https://flic.kr/p/fxSUq8 This one is down 52% on oxygen, with the suspension sacked out in loose rock and a stock carb;
https://flic.kr/p/fwWEYM Perfect burn on the plug, not...but its performance is damn acceptable.
This link is written by another talking about one small area of my local mountains. In the 1990 a friend of mine owned the Ruby Trust, and yes I have held bleeding silver....its so cool. I had the key to take guests in when the snow was out, and its the same mine where the bull dozer jumped off the mountain the day Policy Peddler was out for a visit.
I don't care what others do with their rides, this all started with questions from conflicting reports so I chimed in with what I like best. The pictures are to let others see what the conditions are here and what you can get your wawa into :)
OK the views are nice too, but the pictures and video let you see and hear how a 660 can run, and all mods currently installed are listed in my signature.
This first part of this video was riding the Humboldt Mine walking trail with a member, his son and their friend. Some years this trail is not open, closed all summer with snow, and in some years open 2 to 4 weeks. The trail was closed a month before this video (Aug 11, 2014) when Hammer was out......enjoy;
Anyone can take their time and get to the carb, remove the bowl and change jets. Keep the stock jets just in case.......
 
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Totally jealous of where you have to ride @Ridgway81432, Maine is nice.. but doesn't hold a candle to that.
 

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Totally jealous of where you have to ride @Ridgway81432, Maine is nice.. but doesn't hold a candle to that.
:)
120 miles from here everything is different, down around 3000 ft in the Utah desert. I have an 11,000 ft elevation range I run without changing the carb, the O.P. went from sea level to 8500 ft. and started this thread from elevation changes.....
In 2013 I met rio (lives in New Mexico) here in Colorado, rode the snow a couple days then we both headed to Moab, to meet 6 other members from Manitoba. We had snow melting off the machines on the desert rocks the first day there.....
One day;
https://flic.kr/p/fwGsV2 then the next;
https://flic.kr/p/fw1k4J The next year I met rio and wgc there for a few days;
https://flic.kr/p/mJ2eb9 and one day we found this;
https://flic.kr/p/mHZfr8 (it's highly recommended that short wheels based vehicles stay off this section of trail.)
This rock grabs tire rubber like sandpaper so a grizzly will climb differently out there, the problem is rolling over backwards and the long fall.
My go-pro failed earlier that morning, but rio got this video running that wall. In the picture, notice/see the oil running down the opposite face? You'll see it in rio's video;
Ya, all this riding can be had here in a day, but the lobster sucks here too :)

Hell's Revenge sampler mp41
 
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Like someone else stated, not to start a pissing match lol, but to the best of my knowledge its strictly the oxygen part of our air that gets the fuel mixture to explode. If a certain altitude has X amount of oxygen in its air, then that's all the motor can take in with each "breath" regardless of how free flowing/large the intake path is, and will only burn as much fuel as its percentage of oxygen will allow.

You opened up the intake, reducing restriction, making it easier for the quad to breathe.. but it still can't optimally burn a sea level jetting amount of fuel with 25% less oxygen than sea level.
The air is thinner and that is why there is less O2 but thinner and lighter air means less air per cubic foot, so leaning it out is the only way to get an air fuel mixture to optimal for good clean combustion.
 

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I keep seeing conflicting opinions on 1) whether I need to do this at all, and 2), whether it is something that is feasible for a normal, non-techie person like myself to take on. ( I do my own oil changes, fluid changes in transaxles, brake jobs, etc. but not carburetors). Bought my Griz new in 2006 and it has about 1280 miles on it. Has always run great and still does. Pure stock except for replacement tires. I recently moved from New York Sate (elevation 900 feet) to Colorado and now ride at about 8500 feet. Both my Grizzly and my 2006 Kawasaki Prairie 360 seem to start and run just fine at this altitude. The only differences I notice is that the exhaust "smells" a little richer, and the top end is not quite what it was at sea level. The local dealer told me I probably could just adjust the screw on the carb and that would make it better, but he does not work on Yamahas and said the carb is so hard to get to it may not be worth the trouble. Am I risking doing damage to my Griz by riding it like it is? Someone else told me the only bad thing I'm doing is burning more fuel than necessary because the engine is running rich. So what's the real deal on this issue? I could probably take it to a Yamaha dealer which would be a few hours away, but I'll attempt it myself if you guys say it's possible for a DIY project. Thanks in advance.
__-

I put a Dial-A-Jet in my 2002 Grizzly 660 and it works AMAZING!!

Thunder Products Dial-A-Jet
Fits: YAMAHA GRIZZLY 660 4x4
 

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Discussion Starter #16
I keep seeing conflicting opinions on 1) whether I need to do this at all, and 2), whether it is something that is feasible for a normal, non-techie person like myself to take on. ( I do my own oil changes, fluid changes in transaxles, brake jobs, etc. but not carburators). Bought my Griz new in 2006 and it has about 1280 miles on it. Has always run great and still does. Pure stock except for replacement tires. I recently moved from New York Sate (elevation 900 feet) to Colorado and now ride at about 8500 feet. Both my Grizzly and my 2006 Kawasaki Prairie 360 seem to start and run just fine at this altitude. The only differences I notice is that the exhaust "smells" a little richer, and the top end is not quite what it was at sea level. The local dealer told me I probably could just adjust the screw on the carb and that would make it better, but he does not work on Yamahas and said the carb is so hard to get to it may not be worth the trouble. Am I risking doing damage to my Griz by riding it like it is? Someone else told me the only bad thing I'm doing is burning more fuel than necessary because the engine is running rich. So what's the real deal on this issue? I could probably take it to a Yamaha dealer which would be a few hours away, but I'll attempt it myself if you guys say it's possible for a DIY project. Thanks in advance.
Well, I read everyone's replies, thanks to all for your input and experience. At the end of the day, I guess I just have to repeat that what I see is a bunch of conflicting opinions. The good news is that there does seem to be consensus that I am not harming my Grizzly by leaving it stock and the worst case scenario is a slight loss of performance and a dark spark plug. Looking to buy a Wolverine as soon as they become available again and will keep the Griz as is owes me nothing and continues to be an amazing machine.
 

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My old 02 660 ran just fine at altitude but l live at 9,000. Wanted to comment on that oil leaked on the rocks...on two different occasions followed that cookie trail and found DRT vehicles and no one around.
 

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My old 02 660 ran just fine at altitude but l live at 9,000. Wanted to comment on that oil leaked on the rocks...on two different occasions followed that cookie trail and found DRT vehicles and no one around.
I guess the question would be whether you brought your 02 from sea level to 9000 feet or bought it from a dealer at altitude, in which case theoretically it would have been jetted for altitude when you bought it. Regarding oil on the rocks and finding DRT vehicles abandoned I have no idea what you're talking about; nothing like that mentioned in my post.
 

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All grizzlys come from the factory the same way (jetting), some dealers would re-jet.
Mine was bought in Denver, uncrated, put together and delivered the next day. That dealer does not re-jet unless the customer requests the work, and I didn't.
I linked a few pictures and video to show my bike working with the stock carb, at elevations 11,000 ft. apart, not to tell you what to do but to show you what can be done.
I mentioned the oil on the rock to point out the incline and what the bike needed to do. One hiccup or stumble and we could fall a long ways, and we were at 3000 ft. elevation. Then other pictures show the bike way above 13,000 ft. using the same carb set-up running well.
 

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Oh, OK I looked at the video and see what you mean now about the oil and stuff. I'll be leaving my Griz carb stock since it runs just fine here between 8000 and 10,500.
 
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