I have a question on this topic.... is the reason that tuning to the temperature (aside from the NOS issue) is so important in this situation due to running a higher compression piston? I read Hightowers post and it makes a lot of sense. I have not upgraded my piston (stock) and I have been able to ride in weather anywhere from the high 90's to the low 40's with the only noticable difference being slightly snappier throttle response when it is colder, but nothing dramatic. Does running with the higher compression make that much of a difference. Should I also be concerned about changing my tuning between seasons on my stock piston? Am I doing damage to my bike? I would also like to advise some of my riding crew on this subject so for example I think the YFZ has a stock compression somewhere around 11:1... would it be more sensitive to weather changes? I notice that they get some pops out the exhaust when it gets colder and they often complain that their fuel screw is off. I know for a fact that none of my riding crew ever changes jetting between seasons... but most are running stock pistons. I really don't think that anyones performance is suffering significantly but maybe it is.... I don't know. Now none of us are racers by any means... we stop at the hill and maybe stay for 15 minutes taking a couple runs, but most of our time is spent in the dunes. Performance is important but not as much so as the guys who race the hill exclusively. That being said, should we be tuning to the weather every trip? I'm not as interested in getting that last hp out of her as I am in making sure that I do not damage my bike. Thanks.

 

I can tell you the power difference it makes is night and day. Last ride, we were at Christmas Valley, and the weather changes were just like what Viper had. During the day it was dry and close to around 75. At night, it would still be dry, and drop to around the upper 30s. Massive changes. During the day, Crash would run rich and my jetting would be close, not perfect. And my much more modified ride would blow him away. At night, his would come on perfect and I would go lean. He was just killing me in the drags. I am talking 5 or 6 lengths. Ouch. After I figured out how lean I must have been, I backed it off in the evenings when it would get cold. I am only running an 11-1 piston, so I may have lucked out. But the effects were there. We are talking an 8-10 bike lenght change in overall performance between the two....

 

Keep one thing in mind. Lower compressions and lower powered motors are not effected nearly as much as the opposite. My motor should be around 70+ on all motor. So when I add that 30 shot, things need to be pretty darn close. The further we move our power up, and the more nitrous you add as well, the smaller the margine of saftey.
I dont think there is much chance of doing the this kind of damage on all motor, usless you are super high comp, and low octane.

 

Thats along the lines of what I was looking for. So do you think its a combination of the high hp and the high compression or is the fine tuning more a factor of the high compression alone? What is it about each that requires the fine tuning?

 

The higher the compression you are running the more the danger exists. However it will be there for any level, just not as likely. But if you are already running boarder line for your Octane requirments, and running on the edge of lean for your set up, and the weather takes a major change, you could be in trouble. If you are running close to the edge for this current alt and temp (basically air pressure), and the air pressure changes dramatically, even on all motor could be a risk....

 

I am too tired to read the whole thread again. Just get her running Napoleon so we can go riding this weekend!!!!

 

[quote]
Originally posted by: 650VIPER
My motor should be around 70+ on all motor. q]

Do you take it off of any sweet jumps?

By the way, Is that lbs or HP? no way is it HP hehehehehehehehe


Just have your new Icon's suck start the quad. It will run like it never ran before.


Another thing, I was just wondering.....Do you do that dance at the top of the hill after you win a race? You know, the one you helped Pedro win with.

 

"Hey you need to get your things out of my locker, I cant fit my numchucks in there anymore." "GOSH.....IDIOT"


And Hey, why do you stay home and eat all the chips?

 

Fatlholly no matter what compression or bike, tuning and power is effected by weather - temp and humidity, as well as altitude - and like Jed says the higher compressions may be more effected than the lower ones but none the less there is gain to be had by tuning correctly for the climate regardless of motor mods. But also to answer your question, as far as motor on gas is concerned, nitrous set aside and out of the picture, you will do no damage being lean due to climate shift. being a couple jets off, even a few jets off, is not going to hurt a 4-stroke motor that is running the correct fuel in the first place, you will only be missing some power that you could otherwise get back if tuned properly. but like Dragon says, if you are the threshold of too low octane, and also lean, well maybe there could be some bad news arise from that. but this is not something you would be worried with on a stock piston where pump gas is fine and dandy to run.

I add to this that being a couple jets rich does not cost you as much power as being a couple jets lean, but it does throw more soot in your exhaust ports and pipe to build up over time. if a guy wasn't gonna bother changing his jetting for the seasons, I'd rather be right on in the summer and lean in the winter to avoid sooting, and also since its colder in the winter this helps offset the slightly higher combustion temp associated with being lean. Not to mention most guys don't rde as hard in the winter anyway, and are less likely to notice the power loss since they are not hammer down as much as in the summer, its that nasty wind chill factor at play you know...




Jed and Marky, thanks for the info and conversation, I do believe I understand the theories of what happened now, and also have a better understanding of how the Boss system works apposed to the others.
None of it has made me scared of Nos in my motor, but rather will aid in making me more confident in setting it up and running it, should I ever choose to go down the road in the future.

 

Mine has blown smoke for a month or so way before the bottle was added so that is not my problem it has ring problems but because they where gapped wrong!!
Brindley's broke the rod and nothing to do with detenation, because piston had no sign of it and was getting great burn by the look of the plug.
I believe derby's detonated on the two inner cylinders because he thought there was more heat in there then on the outer two..