Phase two: Exhaust and Carbs

[Trondyne]

It'll be awhile before I get around to doing the carbs and exhaust, but I figure I'll post this now since I just learned what I have...

I was going through the giant binder that came with my, now two month old 1993, Max... I discovered this jet kit was installed some time ago along with the dreaded Cobra 4 into 4 slip ons...

https://thumpertalk.com/shop/Cobra-Carburetor-Jet-Kit-92-2168-p4125515.html

So this is what she's running now... I don't know much about this kit but I suspect this kit combined with the Cobra exhaust isn't helping performance... anyone know anything about these?

But I would like to replace the Cobra exhaust down the road (6 months) and service the carbs...

I like the idea of putting back the stock exhaust, I really like the look of the stock system and I'd like to put back a center stand...

The goal is to keep the cost down while bumping performance up a bit.... I am not looking for a loud setup, quiet is good...and torque is good...

Given that, what might you suggest as the best options for jets and exhaust ...?

 

[Conman]

If you want stock pipes I'd recommend not spending any money on the intake and reverting to factory specs as cheaply as possible. Yamaha did what they could to squeeze out the most power given the db restriction, and the stock setup is pretty well optimized. To get noticeably more power or torque than the stock setup, the headers should be swapped since they're the biggest restricting factor, but swapping headers means getting louder and spending money, especially since new headers will work best with a new jet kit (stage 7 and Morleys muscle kits are the best). Slip on mufflers will save weight vs the stock ones, but won't gain much (if any) power.

Nice stock pipes can be had for less than $100 (shipping is expensive though), and centerstands are very cheap. I'd recommend going to 100% factory since you won't find a quiet or cheap performance system (used perf exhausts are +$500 and perf jet kits are +$200). Some perf exhausts are ear splittingly loud and all are much louder than stock.

You're right about the cobras. Ditch them and you ought to just about break even or even be able to trade straight up for what you're looking for, while gaining about 10% power.

 

[sdt354]

Looks like stage 1 needles. Not my favorite. Marks 4-2 exhaust and a Morley jet kit or stage 7 are good choices and you'll feel the difference. If it runs ok now, I'd leave it as is until your ready to dig into your pockets.

 

[Fire-medic]

"Just say, 'no' to the Cobras," you're giving up probably close to 20 RWHP. Stock expectation (OEM carbs & exhausts) is ~110 RWHP, some are a bit more, some a bit less. A full performance exhaust & a good jet kit is +10 to 15 RWHP, tuned so you have good throttle response. I like the VBoost, not necessary to remove it like the Dynojet Stage 7 kit recommends. The Cobras really affect the mid-range power, which is where you ride most of the time. I would describe the powerband w/the Cobras as, "soggy," and not near as-much at the top 1/3 of the powerband.

I'd just contact Sean Morley of the banner ad, 'Morley's Muscle,' email him rather than PM, [email protected] and follow his advice on his jet kit and exhaust recommendations.

To my ear, the Kerker 4/1 sounds the best, especially at idle, everyone says, "man, what's that got in it? Sounds like a cammed small-block Chevy!" But Mark of Mark's Exhaust has several packages of exhausts to try/buy. They make power above stock [if you go for the complete 4 header and exhaust can(s)], look good, and I'm pretty-sure you can use the centerstand, though I'm not sure with his 4/1 if you need to re-fit it for use, but it won't be able to retract, so you have to just slip-in the bolts for using it, and remove them, and the centerstand, for daily riding. The UFO 4/1 is like that, too, install the centerstand for service, but you have to remove it to ride. I think the Mark's 4/2 does retain the fully-functional OEM centerstand. The founder of UFO is deceased, but his co-worker is still producing exhausts and other parts.

I think someone posted that Mark may not be making the 4/1 anymore, just the 4/2, contact him to get the latest production options, or Sean Morley may know.