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No Bottom End


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I just purchased a 97 yamaha banshee that is bored .40 over has T5's and K&N's

in first and second i have no bottom end but it hits third and then screams like no other. does anyone have any suggestions as to how i can take care of that bottom end lag. i just purchased reed spacers to see if that will help and i'm also changing my front sprocket to 13 any suggestions would be great.

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Start with the simple stuff. JETTING

 

Remember jetting is not rpm or what gear your in... it's throttle position. When you say bottom end.... how does it run. Sputter, bogging, ???

Yep, tell us what your jetting is currently, and where it feels dull, or does it actually bog or anything, and if so, how far in is the throttle?

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yeah it bogs and sputters. the primary is i belive stock 25 and the main is 290

i was going to put 30 primary's in to see what that does. any reccomendations?

Yep, go with the 30 and see how it runs. Your probably lean with the 25. Where is the needle position currently? Probably going to want it in the 4th clip from the top/blunt end.

 

Try it out and get back.

 

Later.

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If your running K&N clamp on pod filters 290 is way too lean on the mains.

 

I think It should be more like pilots - 27.5 or 30's adjust air screws and/or pilots untill it runs good between 1 and 2.5 turns out on the sir screws, needle 4th clip from the blunt end, and 340 mains if your at sea level and 60 - 80 degrees.

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I don't think its pilots or needles....Sounds to me that its the mains...The details you gave us don't tell us squat...What kind of mods do you have? Pipes? Air box mods? Lid on? Filter? Any other mods to the quad? Reeds? DETAILS!!!! Does it sputter or just hesitate? At wide open throttle (wot) or just off idle? We need to know this. W/o it, we can't help you... :cry:

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Yes it hesitates and sputter's a little at wide open throttle. i'm not sure what the needle is at it does need to be adjusted. i think that i'm running rich when i pull my plugs the tips are wet. i'm in utah at an altitude of 4400 feet.

 

IT HAS K&N'S, MILLED HEADS, TOOMEY T5'S, AND IT'S BORED .40 OVER.

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sounds like your too rich on top and too lean on the bottom....Run it wide open in 6th gear for 5-10 seconds, shut it down, coast to a stop, pull the plugs..If they are black, then drop the mains 2 sizes and retest....ONce you get the mains dialed in then raise the needles one slot and go from there. Let me know if that helped...and symptoms of it..

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yeah it has great compression, lindsey machine in salt lake did the work and everything checks out great. i will definitely try running it in sixth and see what that does. my reed spacers will be here tomorrow and i will be putting boyesen power reeds in so i will keep you all posted. any other suggestions would be greatly appreciated.

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Yes it hesitates and sputter's a little at wide open throttle. i'm not sure what the needle is at it does need to be adjusted. i think that i'm running rich when i pull my plugs the tips are wet.  i'm in utah at an altitude of 4400 feet. 

 

IT HAS K&N'S, MILLED HEADS, TOOMEY T5'S, AND IT'S BORED .40 OVER.

Saying it has K&N's doesn't help much. It makes a huge difference on how your air box it set up. So, do you have a K&N inside the stock air box, and is the airbox lid on or off. Or is the stock airbox completely removed and you have 2 individual K&N "pod" style filters (one on each carb) clamped directly to the back of each carb? If you have the individual pod filters then 290 is way to lean. I run 290's with a foam filter and the stock air box lid off, 0- 450 elev.

 

At 4400' you should drop about 2 main sizes from sea level reccomendations, so roughly:

 

With pods at 4400' I'd think you should still be at 320 mains at the smallest.

 

With K&N lid off at least 300

 

Lid on 280

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After an afternoon of jetting, my shee, with very similar mods as yours, seems to really like 280 mains with a 30 pilot, needle clip in the second notch from the blunt end. I was experiencing the same kind of bog and sputter you are, and the pilot made the difference. You'll definitely wanna go up from stock!! Hope this is a good starting point for you!!! Oh yeah, gearing is not gonna help your problem out, by changing to a 13 it'll just sputter for less time, and give you less top end...won't fix the hesitation though. I run a 15 tooth front and love it!!

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