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Discussion Starter · #1 ·
Who here has done some of these mods? The search feature here sucks (I can say that since I wrote that pathetic piece of crap) so I didn't find anything on the topic. I promise to work on the search feature VERY soon!!!

Since my Grizz burns a lot of oil (roughly a quart every 15 hours), I'm giving serious thought to, at the very least, new rings. But I figure while it's apart, I might as well do a 686, and a cam. Then of course I might as well send the head off to Craycraft for some porting too. So one thing leads to another.

While I'd look forward to the power, I'm wondering what it'll do to the fuel economy. I don't wanna lose much, but some more low-end torque would be nice. The Grizz feels very undergeared in low range (meaning it needs more low range), at least compared to my SP800, so the extra torque would be really nice.

It's always done pretty good on gas. I'd say overall average is 15 mpg, with upper-teens fairly likely if there isn't too much slow-going low-range stuff... and even more than that if it's largely fire roads.

Cams... I see that both Hotcams and Webcams makes one for this. The specs show duration to be very similar between the two. The Hotcams cam appears to be the more radical of the two, with a bit more lift. I'm not really sure which way to go here.

It'll be neat to see if this thing ends up with more power than my SP800.

Any input is appreciated!

Rob
 

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Rob,,,if you put a 686 kit in,you MUST get a better con rod than the stock one

from what ive heard was the stock con rod lets go,and you will throw the piston,,,,the 686 kit is just too much for it

all of the Raptor riders found this out the hard way
 

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Don't worry about the con rod. There are very few people that change the con rod in the grizzly. I did the 686 kit with the mudbuster cam and what a differnce it made. By far the most HP gained over any other modification.
 

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Discussion Starter · #4 ·
Never heard about needing a rod until you went over 700cc.

A friend has a Raptor 686 done up by Craycraft using a Hotcams Stage 2 cam and the thing hauls holy ass, and has done so repeadly out at the dunes. Thing eats up his pristine Banshee.

Rob
 

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just giving input on what ive heard,,,good luck

ive seen atleast 4 threads on other forums reguarding con rod failure after 686 upgrade in the last six to 8 months,they were devestated because instead of replacing a simple con rod,they were now replacing a whole engine,,,do what you will with the info,just thought i'd pass it along
 

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Rob how many hours/miles on your griz. I have had honda products all my life and nrver had to add oil to them like I have this griz, I'm not use to that. I check the oil everytime before I ride it and it seems like every 150 miles or so I have to add oil to keep it topped off.Read several other post about this same thing, you would think that in a years time and 4300 miles the engine wouldn't be using oil. I had 7000 plus miles on my XR650L air cooled shonda dual sport and never added oil to that and it sure ran a lot hotter than this liquid cooled griz does, if anything the honda should have eaten the rings up long before this one.People here have as much as 8 to 10 thousand miles on theit air/oil cooled atv's and no oil consumption. Is this a griz trademark? Danny
 

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The 686 con rod thing were probably in Raptors which is recommended but not essential. This is becuase the raptor is always revving up and down and shocking the engine with a load each time you shift. This adds alot of strain to the con rod. The Grizzly however sees very little engine fluctation as the raptor because of the CVT. I take part in another forum with 100's of people running the 686 kit and never heard of any stock conecting rod failure. If you wish I could PM you the site and you can check it out yourself.
 

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My 04 started burning oil at about 1500 miles. It's now at 4500 and in the shop getting a 686, hot cams, and higher compression piston (not a lot higher, but some). This combination should give it better power throughout, but especially on the low end where it really needs it.

And it should stop the oil problem. I was adding at least a cup after every 80+ mile day and as much as a quart. Not sure why it varied so much. I had to check the oil just about every time I stopped and top it up. When it got to be too much of a pain the pajamas, and I had two weeks when I wouldn't be riding, I took it in.

Should get it back next week. Do a breakin ride Dec. 6 and then off to the Hatfield McCoy system in W.V. for 4 days the next weekend. I'll post how it does for performance and mileage. The mileage baseline is between 15 and 20 for "normal" riding. Whatever "normal" means! LOL!
 

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I have a 2005 grizzly 660 fried the rings at 1500 miles i have a good friend that is a yamaha mechanic and this is what i did: bored it out .100 high (now a 700) compression athena piston ceramic coated 12.5:1 compression ratio stock 9.5:1. extreme duty rod If u set the stock and aftermarket rod together its like night and day highly recommend after seeing the stock tinker toy. mudbuster hotcam hmf penland series exhaust big gun rev box clutch machining dyno jet kit k&n filter 26" mudlite xtr's and oh my god waxes a sportsman 800 about a bike length behind a outty 800 he has me by about 2mph his does 74 mine 72 more low end than u know what to do with u actually have to be careful no joking
 

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oh yeah the motor work was $1,850 done by the yamaha dealer with motor pulled by me and taken in.
 

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welcome madgrizz. the rules to this forum are we need pics,alot of pics!!
 

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were all these mods due to failure or just cause you wanted more power? Im curious because i have noticed that my bike uses about half a quart every 150 miles or so, does this mean i need to rebuild it? and man does it overheat.

brian
 

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well the motor did blow the rings were flush with the piston. me and the mechanic and yamaha (which i know very well)thought it might be because i was running aftermarket oil filters on it. what caused it to blow was a lack of oil to the piston and he had told me that the 660 motor runs a high oil pressure around 70 psi and that maybe the oil filter restricted the flow of oil or he said it wasnt changed enough but i changed about 5 times in that 1500 miles using amsoil but i do ride in alot of mud and dusty conditions so i was told to change it after every long ride that im pretty hard on it. which my motto is gas is on the right. how many miles do you have on your grizz? as for over heating does your temp lite come on? have u tried cleaning your radiator?
 

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my grizzly was takin oil, so i have it oversized one size larger.then i asked the dealer about a hotcam.they told me a cam out of a raptor would probably make it run just as good as a hotcam.i had it installed and seems to have made a big difference.more mid to top range.my speed increase as well.i can now race a 700 kvf kawasaki easliy,he also has a chip installed.my grizz also has a white bros e series exhaust, kn air filter,dynojet stage1.i was wanting more speed any suggestions?
 

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The hot cams stage one will make even more mid to top range power than the stock raptor one. If you want huge bottom end the mudbuster would work great. I would have went with the Hot cam just for cost savings. When I priced it out the Yamaha Raptor cam was $50.00 more than the Stage one and made less power.
 

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THANKS,for the responds.I want as much power as possible, without sacifcing speed.maybe ill try the hotcam instead.the tires i use are 25 inch mudzillas, would the EPI kit be best for me.my previous grizzly had 27 inch mud lites i had an EPI clutch kit installed,but found no speed increase at top end.great in bottom though.
 
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