Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums - Reply to Topic
Engine / Exhaust / Cooling
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  Topic Review (Newest First)
05-13-2011 03:41 PM
Dianna
Quote:
Originally Posted by flitecontrol View Post
laorentu10, a spammer, has been reported.
Along with laorentu1, 2,3,4,5,6,7,8,and 9
This guy is persistent so.. I just customized his profile a bit
05-13-2011 10:10 AM
flitecontrol laorentu10, a spammer, has been reported.
05-13-2011 08:00 AM
n2omike
Quote:
Originally Posted by CuriousGeorge View Post
Highly unlikely that you'll need to rejet BECAUSE of a lack of back pressure. The air/fuel ratio remains virtually unchanged due to any increase/decrease in scavenging due only to minor exhaust changes such as baffles except at the very top end of the rpm scale. If you run the bike at over 7500 rpms for an hour or so it's gonna get hot and eventually burn the exhaust valves. However, the VN750 does benefit power-wise from CORRECT tuning, which involves more than just seat-of-the-pants feel or generalized guessing by reading spark plug colors. An exhaust gas analyzer is needed at the very least, and a dyno always proves fact from fiction. That being said, the Keihin CVK seems a little lean from the factory as a compromise to CAFE standards and a bump up in jets is commonplace. But you're not going to do the bike any harm by just running stock jets without exhaust baffles. Now for all the kids that like loud toys and remove the tuned chamber (goat's belly), removing that item saves a few pounds and immediately loses 4-5 Hp and an equal amount of midrange torque. But you seem to be going in the correct direction, so Kudos to you.
This is completely wrong. Backpressure isn't needed. Freeing up the exhaust simply leans out the mixture on the carbs... and they are already on the lean side from the factory. That's the only reason straight pipes/deleting the 'goats belly' will lose power if swapped with no jet changes. The FIRST thing most people do with dirt bikes (easier to work on) is to free up the exhaust and jet up the carb. Nice seat of the pants difference in power. People also do it with street bikes when switching to free flowing exhausts, as it puts the bike in an extremely lean condition.

An engine is an air pump. It doesn't need backpressure. I've been doing this stuff for a very long time.
05-13-2011 04:35 AM
laorentou10 Pay no attention, I'm just a stupid spammer that shows up every day with a different ID and from a fake IP
05-10-2011 02:34 AM
RakerBill I ran a set of Dynas hooked to the goats belly, and I really liked the sound, and they didn't affect my low end torque or power at all. I think I might have had a slight increase as it would idle better and wind up quicker than with stock mufflers. The sound was great, had a nice low rumble and sounded awesome at hiway speeds.
05-09-2011 05:34 PM
The Admiral
Dyna's

Curious what do you think about a set of Dyna's connected to the goats belly? Has anyone tried this? I want to keep my low end torque but with a bit more rumble. Not V&H screaming rumble just a bit more but I am reluctant to drill my stock baffles because you can't go back.
05-07-2011 05:30 PM
CuriousGeorge Highly unlikely that you'll need to rejet BECAUSE of a lack of back pressure. The air/fuel ratio remains virtually unchanged due to any increase/decrease in scavenging due only to minor exhaust changes such as baffles except at the very top end of the rpm scale. If you run the bike at over 7500 rpms for an hour or so it's gonna get hot and eventually burn the exhaust valves. However, the VN750 does benefit power-wise from CORRECT tuning, which involves more than just seat-of-the-pants feel or generalized guessing by reading spark plug colors. An exhaust gas analyzer is needed at the very least, and a dyno always proves fact from fiction. That being said, the Keihin CVK seems a little lean from the factory as a compromise to CAFE standards and a bump up in jets is commonplace. But you're not going to do the bike any harm by just running stock jets without exhaust baffles. Now for all the kids that like loud toys and remove the tuned chamber (goat's belly), removing that item saves a few pounds and immediately loses 4-5 Hp and an equal amount of midrange torque. But you seem to be going in the correct direction, so Kudos to you.
05-07-2011 05:11 PM
vulcanpower Bump ... I know I'm double posting, but does anyone know if I will need to resize my jets due to the loss of back pressure running the pipes without any baffles?
05-04-2011 05:24 PM
vulcanpower That helps a lot, however, I would assume the choice I make will affect the back pressure a huge amount and would like to get as close to the OEM as possible ... I have one of the originals but if I'm going to buy a new one I might as well replace them both. Would anyone be interested in fabricating this for me? I'm looking to purchase asap ...

Edit: WOAH. On second look, my pipes are pretty much cleared. There's nothing inside of them, and the one baffle that I have looks nothing like what I've been seeing on these forums. I'll post pictures, but what is this doing to my engine? Do I have to rejet? Any suggestions?
05-04-2011 03:36 PM
JM2001 See if this helps. They list several as fitting the V 750. I don't know what size we need.
http://www.jpcycles.com/2001-kawasak...affles&Ntk=All
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