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Discussion Starter #1
I am not sure if the YFZ has a rev limiter or not.. I bring this topic up because I was in Lucerne Valley, Ca. today and drag raced a cr250 on the dry lake and my bike felt like as if I was hitting the rev limiter while I was in 5th gear, pinned. This is my first ride since I installed the full HMF exhaust and 180 main and 48 pilot jets. I did another test run and it felt as if I was hitting a rev limiter in all gears while pinned. I did not make any adjustments to the needle because I didn't want to take the carb off during my rejetting, nor did I make any air screw adjustments. As far as who won the race, he did because my bike either hit the rev limiter and started sputtering or something else is wrong. Any help would be appreciated.

Thanks,
Frank :re
 

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The YFZ does in fact have a rev limiter in it. If i'm not mistaken the rev limit is 10,500RPM. (please correct me if i'm wrong). Mine hits it all the time, but there is NO sputtering whatsoever. It just winds out and won't go any faster. There are a few aftermarket rev limiters out already.

Vortex CDI $500 over at duncan racing allows a bit of adjustment of the mapping and pops open some more whoop ass at 1000 extra rpms.

or you can buy the one i did from team alba for 199 and still get 1000 rpms, but not adjustable as the vortex.
 

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Discussion Starter #3
OK, so I am not hitting the rev limiter? So there must be something wrong with the jetting maybe. Any suggestions....

Frank
 

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:ihit


Actually,..I think I did,..in Dumont,...dusting my buddies... :rock
 

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The Rev-limiter on the YFZ kicks in at 10,750 RPMS.

Which is really pleanty but a little more is always good. I am not too sure about all the other boxes out there, I know that most of them just raise the rev by a set number.

I am testing the DynaTek box right now and I can set my limit where ever I want it to be at, and I can change the entire timing curve. advance, retard etc. It also has programmable settings like a two-step for take off in a drag race, and a window switch for nitrous etc.
 

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Discussion Starter #7
So you guys think I was hitting my rev limiter, or ya think something is wrong in my jetting??

Frank
 

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I dunno I was not there. :)


But its possible that you were hitting it. I can hit mine pretty easy.
 

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Originally posted by nextasex@Dec 22 2003, 09:00 PM
Pahrump, I was kinda concerned because a 1991 CR250 is faster than my yfz.. :(

Frank
Speed or should I say top speed depends upon gearing.

I have not come across many things that are faster than mine. I can now have a rev limit of 11200 and can hit it easy with the 15T on :O
 

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you may be a little rich on that main jet. try dropping down one size at a time. but also richen up your mid-range (needle) because with a pipe you are bound to be very lean.
 

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I agree with the quadfather in that sputtering is definitely a symptom of running rich and 180 is bigger than 99% of the mains I've seen posted. Most run 165 to 170 but that usually includes a bigger pilot jet (45). I'm not sure why you chose 180 but I'd drop to a 175... then a 170, 168 to a 165 till you find the right one. Be sure to read the pinned jetting info on this forum its very informative.
 

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Discussion Starter #13
Originally posted by SoonerYFZ@Dec 23 2003, 12:44 PM
I agree with the quadfather in that sputtering is definitely a symptom of running rich and 180 is bigger than 99% of the mains I've seen posted. Most run 165 to 170 but that usually includes a bigger pilot jet (45). I'm not sure why you chose 180 but I'd drop to a 175... then a 170, 168 to a 165 till you find the right one. Be sure to read the pinned jetting info on this forum its very informative.
I chose 180 because that's what HMF recommended with the exhaust system I purchased. I will be trying the bike out in Glamis for New Year's, so after that I will be able to tell how it's really performing.

Frank
 

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Originally posted by 2000racing@Dec 23 2003, 10:19 PM
Where did you get that Dynatek cdi at Pahrump,and if you dont mind me asking, how much?
I am testing it for the Company they will be avaliable to the public in late Feb/March, I think.

And I think that they are gonna be around $400 bucks.

Seems to me so far that its well worth it.
 
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