Need help with exhaust and carbs

[cimberi]

i recently bought a 2004 Yamaha Vmax with what looks like the cobra exhaust kit. the bike seems to be running rich and everywhere i look and everything i read states that i should change out the carb kits. which kit do i get and how difficult is it to do yourself im not a mechanic by any means (but im better than a monkey with a wrench) if you know what i mean. any help please.

 

[sdt354]

1st make a positive ID on the exhaust system. If it's Cobra, I'd keep carbs stock
with 147 jets. Are there kits installed now? Carb work isn't hard if you can follow direction, have the tools needed, and are somewhat patient. A carb sync tool is going to be needed. The rest,common hand tools.

 

[cimberi]

they are the cobra exhaust, and like i said the original owner never did anything to the carbs. this is my first max but my father has had his since 02. he pulled the baffles out of his stock pipes and never did anything to the carbs and it runs fine. mine runs good just doesnt seem to be powerful on the low end side of the rpms. and the exhaust smells like its running a little rich.

 

[44boyd]

Cobras rob you of HP, probably need a sync and maybe adjust the a/f screws to see if it improves.

 

[Fire-medic]

Unless you love the looks, changing back to a stock exhaust should return your lost horsepower that is an unfortunate effect of the Cobras, because they have no scavenging.

Installed and tuned correctly, a full aftermarket exhaust and Stage 7 Dynojet or Sean's Morley Muscle kit should net you close to a 10% gain on top-end, and some more than stock below that.

 

[sdt354]

If you have to keep the cobra's I'd go with 147 jets. It'll run better, but like said above, not a great exhaust for HP.

 

[Biker Dash]

Actually, I found that dropping just one jet size on the main jets helps lean out the mixture in the upper RPMs. (I believe it was Sean who recommended the proper jet size)

Myself, I love the looks of the Cobra exhaust, a well as the sound. and the only time I see any time in the upper RPM range where the power loss is, I'm already doin shit that would land me in jail possibly if caught. (which is the BIG reason I do not miss the lost top end HP, in all honesty)

as far as running rich down low, I would guess that it is the A/F screws are in bad need of adjustment, as well as a carb syncing, as has been recommended. I run the Cobra exhaust, and I have full power down low, and on up to about 8 grand, which is where the power is lost.

 

[cimberi]

next question is i have a K&N Air filter in the cart ready to buy do i need to change anything up after installing

 

[Biker Dash]

The K&N really will not cause you to do any changes, from my experience. It DOES have the advantage of being washable, and if you take care of it, it will last forever.