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Old 06-03-2009, 04:22 PM   #1
Ralphlupe
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Default Rejetting

I have a 2008 yamaha v-star custom, does my carbs need rejetted
after putting on straight pipes, Or will it still perform ok?
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Old 06-03-2009, 04:24 PM   #2
longride
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It needs rejetting, and it will sound like shyt. Keep the stock pipes and do every one within earshot a big favor.
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Old 06-03-2009, 04:27 PM   #3
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Don't listen to him!

Just do it, get a Hypercharger and don't worry about that "blue" effect on your pipes. It's nothing. Some Simichrome will take care of all that..............
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Old 06-03-2009, 04:31 PM   #4
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Default Rejetting

I forgot to mension this is a 2008 650 v-star custom.
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Old 06-04-2009, 05:29 AM   #5
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Quote:
Originally Posted by Ralphlupe View Post
I forgot to mension this is a 2008 650 v-star custom.
Dont care too much for the hyper charger gimick but yes you'll have to install a jetkit.Do the pipes have baffles?
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Old 06-04-2009, 06:56 AM   #6
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It will perform like shyt. I should know having fallen for the "less back pressure = more power" bs myself too many times.

Most recently I bought a used stock ZRX1100 with a Yoshi race slipon and stock jetting. After a couple of month of popping and backfiring I put on the stock muffler and experienced a measurable freeway roll-on acceleration increase and better throttle response. So I rode it around that way and ordered a jet kit from Holeshot just for fun. With proper jetting the loud pipe ran well without popping but the roll-on acceleration and response weren't much better than stock. The bike is back to stock now because of the local high fines for noise violations and the fatigue of listening to the stupid race pipe.

Do not run open pipes on a V-twin. They are proven to reduce low and midrange performance while giving a small gain at the top end. Even rejetting won't solve that characteristic. You are also into an area where a lot of pipe makers make a lot of false claims and some of the rejetting kits simply don't work. Unless you want to spend a lot of time, and I mean a LOT of time, screwing around with pilot jets, main jets, needles and screws I'd suggest you leave it stock. Aftermarket people lie too often and anyhow the idea that some guy in a garage with a G.E.D. and a hacksaw is going to out-engineer Yamaha's professionals is kind of silly.

The cam timing on an engine like the 650 is so mild that you aren't going to get much increase even if you do find the perfect intake/exhaust combination. There are two methods of determining this. One is to get time on a dyno as you rejet. The other is to get a friend and a stopwatch and test the bikes 1/4 mile times as you rejet. Check the 40-60 and 60-80mph roll-on times also.

Or you can do what most cruiser riders do. Simply put on straight pipes and tell everyone how much better your bikes runs without testing anything. This ensures that you never learn how much slower the bike is after you hack up the system.
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Last edited by seruzawa : 06-04-2009 at 07:01 AM.
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Old 06-04-2009, 07:40 AM   #7
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Everything Seruzawa said and more. leave it stock, save your money for tires and oil changes which is about the only thing you'll need to do on that bike in stock form to keep it running for many thousand miles.

aftermarket pipes are the biggest scam going, about all they do is rob horsepower and piss off your neighbors.
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Old 06-04-2009, 07:50 AM   #8
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Quote:
Originally Posted by seruzawa View Post
Do not run open pipes on a V-twin. They are proven to reduce low and midrange performance while giving a small gain at the top end.
But they sound manly and brave. Chicks dig loud pipes, they'll sleep with you if your bike has them. And when you snap the throttle shut at speed, it makes that bitochin BLAAAP BLAP BLAP BLAP BUDDA BUDDA BLAP sound. What good is a motorcycle if it doesn't do that?
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Old 06-04-2009, 11:40 AM   #9
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Default Get some glasspacks!

Cherry Bombs work excellent on Viragos, and when you chop the throttle it will sound just like a phifty one Cheby. Also get some pink and purple tuck-and-roll, some fuzzy dice, and you're cool SA.
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Old 06-05-2009, 11:33 AM   #10
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I dont think most people with vtwins are looking for power, just sound most times. And yes that you can achieve with simple slipons. I believe the best gain you get isnt outright hp its things like off idle response. Crisper pull throughout the entire rpm range when installing these products. Seruzawa have you ever used a the dynojet jetkits, at the same time dynoing after every application was installed?
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