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post #1 of 22 (permalink) Old 05-30-2012, 08:53 PM Thread Starter
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best performance essentials

OK.. Here's the deal.. before I get all of the talk of leaving your bike stock, thats not what I did so if thats your explanation, dont bother.

I bought my '01 vn750 back in march. I have been adding to it ever since, as you can tell by my signature. My biggest issue now is a drop in top end performance. When I first purchased the bike, I had been over 95mph several times and it felt like there was much more there to run. I wanted to add the V&H Cruzers and I love the sound but noticed the drop in torque and top end. I have now added some torque cones at the manifold and that has brought back some of the off the line accel and little to the top. It will now go 95, but it sure doesnt get there as fast and you need to keep the rpms up there as well.
Its not that I want to go that fast all the time, I am just wondering about the power drop and what causes it. Could I have a problem somewhere else?
So... if I am going with the V&H pipes, what else can I do to improve performance? I know other have siad you don't need to re-jet, but V&H says yo do. What about better air filters for intake.?? I have added the Iridium plugs, so that part is already taken care of. Can any other electrical issues cause a power drop??
I would just like to know what are the best things that need to be done for best performance

Pittsburgh Dave
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post #2 of 22 (permalink) Old 05-30-2012, 09:13 PM
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Ear shave, and rejet!

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

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post #3 of 22 (permalink) Old 05-30-2012, 09:20 PM Thread Starter
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ok.. ear shave wont happen.. I have the Highway Hawk Airboxes and I like that look.

So to re-jet.. which ones should I get and how hard is the procedure

Pittsburgh Dave
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post #4 of 22 (permalink) Old 05-30-2012, 09:21 PM
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I'm going to bother. You answered your own question. The bike ran better stock. You should re-jet with V+H Cruisers, they recommend one size up. If you put a 4 inch mini baffle at the end of the exhaust pipe before the muffler ( extending into the muffler) you will increase your back pressure and improve low and middle range torque. I'm not familiar with the torque cones. You may be running lean on the top end.

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post #5 of 22 (permalink) Old 05-30-2012, 09:46 PM Thread Starter
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the torque cone is a drop-in up at the top with man made by la choppers to increase back pressure. What are the rejet numbers

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post #6 of 22 (permalink) Old 05-30-2012, 10:34 PM
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since you are kinda going all out, i would suggest putting it on the dyno. a good tuner can dial in your jetting and such just right.

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post #7 of 22 (permalink) Old 05-31-2012, 03:55 PM
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Quote:
Originally Posted by pittdave View Post
the torque cone is a drop-in up at the top with man made by la choppers to increase back pressure. What are the rejet numbers
Increasing backpressure reduces overscavenging at low RPMs, where some of the fresh air/fuel mixture goes through the exhaust valve at overlap. This increases power/torque a little at low RPM, but at high RPM power/torque are affected a lot more-- you can easily lose 10%! Some manufacturers are putting in exhaust throttles, but they are only actuated AT valve overlap (and I presume only at lower RPMs.)

Rejetting won't fix your reduced volumetric efficiency at high RPM, and you may actually need to jet leaner! Check your spark plug condition to see if they indicate where you are.

Last edited by Kelly2001; 05-31-2012 at 05:17 PM. Reason: Typo
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post #8 of 22 (permalink) Old 05-31-2012, 06:03 PM
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post #9 of 22 (permalink) Old 05-31-2012, 06:29 PM
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Quote:
Originally Posted by thtanner View Post
Ear shave, and rejet!
This is the only way to make any noticeable increase in power.... Anything else is pointless. You can rejet, but without more air all you're gong to do is run richer and burn more fuel.
V+H wants you to rejet because you can open the throttle to redline and see a power increase on a dyno. At just off throttle to midrange your going to see a slight loss.

If you insist on keeping your airboxes, your never going to make any more power than a stock bike.... Unless you know how to reshape your cams and alter your timing....(but again it will only run well at a narrow rpm band)

You did not say what your plugs looked like, why do you believe rejetting will fix your issue?

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post #10 of 22 (permalink) Old 05-31-2012, 07:47 PM Thread Starter
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i looked at one of my plugs today and all seemed normal.. just a basic tan. I am only going by what others have said with the Cruzers in that rejetting has helped. I am also going with the regap on the pickup coils as others have said it helps a little as well. I guess by looking at other posts since I am still topping out at about 100mph, I can't complain too much.. After all, I am 270lb on the bike, so thats some extra load for it anyway.
I am going with the stock replacement KN filters

Pittsburgh Dave
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2003 VN1600.. new ride
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