Need to jet?

[assassinx1]

Hey everyone I've had a vmax for about a year now. I love this bike. Dreamed about one for years, I found a 1986 with custom pin striping in PA with only 3000 miles on it. Anyway I put cobra 4 into 2 exhaust on it and I want to debaffle the cobras. The carbs are stock and the intake box is stock. Do I need to jet the carbs?

 

[KJShover]

Hey everyone I've had a vmax for about a year now. I love this bike. Dreamed about one for years, I found a 1986 with custom pin striping in PA with only 3000 miles on it. Anyway I put cobra 4 into 2 exhaust on it and I want to debaffle the cobras. The carbs are stock and the intake box is stock. Do I need to jet the carbs?

Your going to loose some HP with the Cobras, If you drop your main to 147.5 (Mikuni size) you'll get a little of it back. But other than a little turn of the A/F screws you really don't have to do anything with slip-on mufflers.

 

[naughtyG]

Like KJ said, with any slip-ons you're not going to need any jetting.

 

[maleko89]

With Cobras I'd do 145's.

 

[assassinx1]

What I meant was the cobras that are on there Im going to gut them. So there wont be any baffles. Do I need to jet at that point? Basicly its going to be four empty mufflers.


Not doing anything with air box its staying stock stock carbs too.

 

[bazwell]

You will only need to worry about jetting if you reduce the restriction in the exhaust system.
The restriction is not the mufflers, it's the pipes!
Removing the baffles makes no difference to performance.

 

[assassinx1]

Thanks for replies, theoretically if you removed the muffler and kept the header pipes. Running open header you still wouldn't have to re jet unless you inrease intake size/flow or header diameter/flow?

 

[assassinx1]

no?

 

[one2dmax]

Correct. The biggest restriction is the primary pipes. BUT, the secondary effect is the loss in the scavenging. Do a search on that effect which should give you a few good articles on it.

 

[RaWarrior]

With my Holeshot cans I changed from the stock 150's to 147.5's at the suggestion of Sean. The top end seems to be a tad "crisper", the throttle response may be a touch snappier. No drastic change but enough I'm pretty sure it wasn't "placebo effect". No worries about nuking the motor leaning it a touch, I've held mine WFO at 8500+RPM for minutes at a time (top speed on highways). Motor never skipped a beat, hell the water temp barely ticked 10 degrees up past normal.

If you just want more noise, punch out the stock mufflers. It won't be a very good noise....punched out stock mufflers have a distinctive "muddy" quality to the sound...indistinct, not a crisp, clear note that aftermarket baffles usually give.

Straight pipes will make the bike run like doggy doo. Straight pipes on virtually anything will do this. It's still common on harley's and cruisers in general since people who ride those typically don't really care about power anyway (and the erroneous mindset that louder=faster more than makes up for the reality that the bike is actually slower).