Winter Riding - 07 450f


14 replies to this topic
  • Todddob

Posted August 30, 2009 - 09:46 AM

#1

Hey, I ride an 07 yz450f. Everything in the carb is stock except for a 48 pilot jet. FMF Speed Ti Slip on. What would I have to change to ride in the winter? I'm thinking of doing some ice racing, I went out and watched and it looks wicked fast, 5th gear wide open straights. I would set it up for about -15C. Altitude 1600ft. I want to order the new jets so I will have them for winter, I know it's sad, the nights are already cooling off. Also, does anyone have a line on studded tires? Thanks.:ride:

  • Polar_Bus

Posted August 31, 2009 - 10:12 AM

#2

Hey, I ride an 07 yz450f. Everything in the carb is stock except for a 48 pilot jet. FMF Speed Ti Slip on. What would I have to change to ride in the winter? I'm thinking of doing some ice racing, I went out and watched and it looks wicked fast, 5th gear wide open straights. I would set it up for about -15C. Altitude 1600ft. I want to order the new jets so I will have them for winter, I know it's sad, the nights are already cooling off. Also, does anyone have a line on studded tires? Thanks.:ride:


I have had both my KX500, and my '07 YZ450F prepped for the ice. In hindsight, I prefer the mannerisms of my KX500 it seems to have better corner entry mannerisms than my YZ. Don't get me wrong I liked the YZF, as it had better acceleration, putting the power more efficiently into the ice, but my YZ was giving me some wicked rear wheel hop entering a corner. I fiddled with the suspension some, but never got it comfortable. For my 20F temps jetting, I went up 3 sizes on the main, and 1 size on the pilot from stock. The bike ran awesome with no lean poping I also used cardboard and blocked off 1 of the radiators to allow the engine to come up to adequate temps. Starting a stone cold 450 in real cold can be a prick, but some propane heat warming up the cyl a bit works awesome! Don't cheap out on the quantity of ice screws! I was using about 3-4 screws per knob near the middle, and 2 near the outer knobs. If you put too few screws in, it aggravates screw pull-outs. Run a thin, 10W-30 semi-syn oil as well. I dialed in lots of sag in the rear to help weight transfer. If you also plan on doing 90 mph speed runs, slide the forks flush to the top of the triple tree to minimise headshake on bumpy ice. Go out and rip it up! The ice is a BLAST on a big bore... Very few people get to experience a YZF 450 WFO, and on the ice, you will be flirting with a legitimate 90 mph !

Rich

  • grayracer513

Posted August 31, 2009 - 11:08 AM

#3

If you think your jetting is perfect at some temperature or other, figure 2% larger jet size for each 19 degrees F (10 degrees C) drop in temp as a starting point. Use that on both the main and pilot.

Don't figure on breaking 90 mph with stock gearing. Power drops off dramatically at about 10,300, which is around 86mph assuming 100% traction, which, even with spikes, is a myth.

I can't wait for winter, myself. Should be cool enough pretty soon to start doing some serious riding soon, and the racing season opens in another month. :ride:

  • Todddob

Posted August 31, 2009 - 02:34 PM

#4

can't wait for winter, myself. Should be cool enough pretty soon to start doing some serious riding soon, and the racing season opens in another month. :)


Thanks alot guys, really appreatiate it. I am a tad bit jealous that my dirt riding is coming to an end, but riding a snowmobile is pretty sweet too. It is "faster" in some ways and you can leave from one point and do 50 miles completely cross country, arrive in a small town and have supper and a beer :ride: , then head home, during the night, and get home when the wife is sleeping. BUT, it's the shit's at wheelies.Lol

  • Polar_Bus

Posted August 31, 2009 - 05:08 PM

#5

Sorry for some incorrect jetting specs, but I just found my winter setup notes. I was at work when I made my above reply, and could not remember exactly what my jetting was. When temps were in the teens, I was running a #178 main, #50 pilot, and 1 turn out on the screw.

when temps were in the 20's I swapped to a #172, and left everything else unchanged. Ideal ice is short lived, and I am no jetting expert, so I didn't spend a lot of time jetting, my bike did however run awesome so I must be close....

When I commented from "stock" I speak from MY "stock" jetting which is a #168 main and a #48 pilot, (not OEM stock jetting)

  • mikedabike

Posted August 31, 2009 - 06:20 PM

#6

I have had both my KX500, and my '07 YZ450F prepped for the ice. In hindsight, I prefer the mannerisms of my KX500 it seems to have better corner entry mannerisms than my YZ. Don't get me wrong I liked the YZF, as it had better acceleration, putting the power more efficiently into the ice, but my YZ was giving me some wicked rear wheel hop entering a corner. I fiddled with the suspension some, but never got it comfortable.
Rich


Ever think about a slipper clutch?

  • rufusz

Posted August 31, 2009 - 11:31 PM

#7

If you think your jetting is perfect at some temperature or other, figure 2% larger jet size for each 19 degrees F (10 degrees C) drop in temp as a starting point. Use that on both the main and pilot.

Don't figure on breaking 90 mph with stock gearing. Power drops off dramatically at about 10,300, which is around 86mph assuming 100% traction, which, even with spikes, is a myth.

I can't wait for winter, myself. Should be cool enough pretty soon to start doing some serious riding soon, and the racing season opens in another month. :)


If I'm riding both summer (30 degrees C) and winter (-10..-20 degrees C) with the same jetting, then is it 100% that it's not jetted right for one or another (or maybe I'm in the middle) ? :ride:

Starting a stone cold 450 in real cold can be a prick, but some propane heat warming up the cyl a bit works awesome!


Never had problems with starting, prime it a few times, choke, kick it 2-3 times and voila!

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Polar_Bus

Posted September 01, 2009 - 02:40 AM

#8

Ever think about a slipper clutch?


Do you think a slipper would minimise the corner entry wheel hop?

From what I was observing, the harder I dragged the rear brake, the worse the wheel hop was. Using front brake only, was ok. I like dragging the rear brake entering corners kinda like "rear steering"

  • Polar_Bus

Posted September 01, 2009 - 02:42 AM

#9

Never had problems with starting, prime it a few times, choke, kick it 2-3 times and voila!


Then you have much more "leg" than me !

  • grayracer513

Posted September 01, 2009 - 11:09 AM

#10

If I'm riding both summer (30 degrees C) and winter (-10..-20 degrees C) with the same jetting, then is it 100% that it's not jetted right for one or another (or maybe I'm in the middle) ? :ride:

I'm guessing the middle. What you have there is a demonstration of how tolerant a 4 stroke is of imperfect jetting.

I run mine from the extremes of 80 feet below sea level at 50 degrees F to 4000 feet above at 95 degrees, and I could do it on the same jetting, although I like the way the bike runs better if I go from a 168 to a 165 in the warmer months.

Congratulations on spelling "voilà" correctly, BTW. You wouldn't believe how many times I've seen that one butchered.

  • YamaLink

Posted September 01, 2009 - 12:38 PM

#11

Snow and ice riding on mine was the introduction to ASV breakaway levers. Before that I would snap the cold metal off so much easier. I don't claim to be a metallurgist and the exponential increase in crashing was probably the main reason of snapped levers, but for my snowy riding it's the aforementioned levers, MSR brush guards to keep the digits warm, screws in the rubber and sometimes I gear it up a tooth in front.

  • rufusz

Posted September 02, 2009 - 01:18 AM

#12

I run mine from the extremes of 80 feet below sea level at 50 degrees F to 4000 feet above at 95 degrees, and I could do it on the same jetting, although I like the way the bike runs better if I go from a 168 to a 165 in the warmer months.



Do you actually "feel" the bike run better or just "hear it" run better. I hope you understand what I mean :ride: Does such a small change (from 168->165) have a noticeable (serious) effect on performance?? Guess I have to start jetting this bike. I suppose until now, with this "middle imperfect" jetting, power was always enough, and I didn't bother messing with the jetting...and also due to the fact that the only thing I can do is moving the clip up-down, since JD kit is not available (or very expensive) here...

Congratulations on spelling "voilà" correctly, BTW. You wouldn't believe how many times I've seen that one butchered.

thx :)

  • Polar_Bus

Posted September 02, 2009 - 02:50 AM

#13

I've been jetting 2 strokes for the past 25 years, and I jet a 2 stroke by "sound", "feel" and plug insulator color. Still i'm no expert, but I get good , safe results, and almost never foul plugs.

4 strokes however seem to be different. I can't tell you I feel much difference between say a main jet change 170 vs. a 172 or even a 175. However I can feel top end torque start to "flatten out" as jetting gets rich. 4 strokes don't seem to exibit much of a change in exhaust tone with respect to jetting changes like 2 strokes do.

The pilot jet is more critical IMO to overall starting, and "off corner" throttle response. But again, I don't notice a huge difference between a #48 and a #50 as far as drivability, just that when I do run a #50 pilot, I always need to use the hot start lever, and with the #50 pilot I get zero decell poping through the exhaust. I get nervous when I hear decell poping, as that's a tell tale sign your a little lean, but others comment if the YZF's pop, it's not an issue, and you in fact have a good mixture...

So my novice jetting recommendations: If you have flames shooting out the exhaust you're lean, if the engine won't pull past 6000 rpm's you're too rich :ride:

  • grayracer513

Posted September 02, 2009 - 06:48 AM

#14

Do you actually "feel" the bike run better or just "hear it" run better. I hope you understand what I mean :ride: Does such a small change (from 168->165) have a noticeable (serious) effect on performance??

It has an actual effect. If I run the 168 in the summer at the higher altitudes, it shows up as the power flattening out early, as Polar Bus mentioned. Even at low altitudes in the desert, the bike feels cleaner with the smaller jet in warm weather. In the cold, it feels crisper with a 168.

Read: http://www.thumperta...699#post2881699

  • SXP

Posted September 02, 2009 - 12:47 PM

#15

Congratulations on spelling "voilà" correctly, BTW. You wouldn't believe how many times I've seen that one butchered.


My favorite is "wallah". When I remarked about the incorrect spelling, the offender read me the riot act:smirk:





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