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Discussion Starter · #1 ·
What is the redline for the YFZ, and does it have a rev limiter or do the valves just start floating? Anyone bumped it against the limiter or floated the valves? I need to know how far I can push mine, and i'd like to know what it redlines at. Thanks.
 

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10500 limit, and you should change gears well before you hit it.
 

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Originally posted by bildo696@Nov 24 2003, 10:12 PM
I need to know how far I can push mine, and i'd like to know what it redlines at.
I said it yesterday in a post and I'll say it again. Just cause it revs to 10k + doesn't mean diddly. Your best power comes from ~8k rpm. Look at a dyno graph and you'll see.

Note:

4-STROKES ARE NOT MEANT TO BE RIDDEN LIKE 2-STROKES.
 

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I suspect valve float isn't much of a problem. From what I've read on the Internet, Yamaha uses some pretty hi-tech springs on this engine. I've also noticed on the Hotcams site that you don't need to use different valve spring with their camshafts.

I suspect the 10.5K redline has more to do with the heavier engine components such as crankshaft and piston assembly. I've noticed the YZ450 has a RPM limiter of 11+K. I suspect the lighter components in the YZ version of the engine is what allows for the higher red line.
 

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My 450 still has around 35hp when I hit the rev limiter and is still pulling hard. It is strange going from a raptor to a YFZ. It pulls all the way till you hit the limiter. It takes some getting use to in order to shift before you hit the limiter.
 

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Jeddings,
That is not the rev limiter you are hitting, it is your bad jetting. Try going up on your main and I'll bet that changes things.
I had the same problem, it was pulling the front of the ground and popping its it head off at the same time.
Even my mechanic said it was the rev limiter, untill he had a ride of it. We changed the jetting and now I never hit it.

Good luck, Geoff.
 

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Had it jetted on a dyno while testing the fuel to air mixture. It is spot on. I have awsome power throughout the rpm range. I just havn't got use to it since the power on my raptor dropped off way before the rev limiter kicked in. This keeps pulling until it hits the rev limiter.
 

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Eddings,
Mate you must have a freak bike. :lol
Your dyno, and as selector said, should have shown you that peak hp should be around 8500, to keep going past that is a waste of time if you are trying to be fast.

Geoff.
 

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Discussion Starter · #10 ·
I was just making sure it has an electronic limiter? I never planned on hitting it on purpose, just making sure its there.
 

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I don't think you are listening. I never said the peak horsepower was near the top of the rpm range I merely stated it still pulls much harder and faster than my raptor at those rpm's which was hard for me to get used to. My peak is around 45hp at 8000 rpm., but it still has 42hp at 10000 rpm which is not a significant drop off in power. After 10000 it drops off quickly, but it pulls so hard so fast and revs so quickly that when I first rode it I hit the limiter quite often. If you don't understand now I give up. I have a freak bike. :eek
 

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Originally posted by eddings@Nov 25 2003, 12:15 PM
Had it jetted on a dyno while testing the fuel to air mixture. It is spot on. I have awsome power throughout the rpm range. I just havn't got use to it since the power on my raptor dropped off way before the rev limiter kicked in. This keeps pulling until it hits the rev limiter.
I would be curious to know where you ended up with jetting on yours after the dyno?
 

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195 main jet
 

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Maybe Dill you could inform us to a more accurate way to fine tune your bike.

Geoff.
 

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Originally posted by eddings@Nov 27 2003, 06:24 PM
195 main jet
thats just realy interesting.. a 195 main???

I'd like to contact this shop that did your dyno. Can you provide the name and number of the shop that did your dyno and the individual that did the tuning?
 

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Lonny @ Sand Traxx of Tulsa 918-4454153 he has done many and mine required the largest jet of all the ones he had done. He kept increasing the jet as long at it kept making more power and the fuel to air mixture stayed within 13.3-13.7 I believe were the numbers he liked. Since I was running the stock air filter at the time and had a [email protected] on the way he stoped with a 190 main and went up to a 195 to accomadate the [email protected] air filter so I wouldn't run lean when I put that on. I plan on going back when I do the cam mod.
 

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Originally posted by eddings@Nov 30 2003, 08:42 AM
Lonny @ Sand Traxx of Tulsa 918-4454153 he has done many and mine required the largest jet of all the ones he had done. He kept increasing the jet as long at it kept making more power and the fuel to air mixture stayed within 13.3-13.7 I believe were the numbers he liked. Since I was running the stock air filter at the time and had a [email protected] on the way he stoped with a 190 main and went up to a 195 to accomadate the [email protected] air filter so I wouldn't run lean when I put that on. I plan on going back when I do the cam mod.
wow!! what pilot jet, needle type and clip position did you end up with on your?


If I stick even a 175 main in mine with the GYT-R needle on the 4th clip.. it won't even run up the R's..way rich..
 
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