I am thinking I may ditch the stock filter and put on a Uni on my little guys stock Viper 90.
It runs a Mikuni 18mm carb with an 85 main jet.
Anyone have any idea what main jet I should run with a Uni?????

 

I would make sure the needle is adjustable before you try. Then I'd guess 95-105.

 

My guess 149 mainjet. My recommendation - dont do it stock carbs are a pain to jet with podfilters, as they need good airflow to suck up fuel thru mainjet. Usually doesnt run right for long. Sorry just my $.02

 

I have another one that I run a Uni, 54mm cyl, and a Hetrick pipe. I run a 125 main jet and it's been trouble free for a year.
Maybe the Mikuni 18's are not as big a pain as the 16's???

 

There could be variables, but a stock motor shouldn't require much of a jet change if any.
Let the plug color guide you (as allways).[img]i/expressions/face-icon-small-wink.gif[/img]

 

Fastestdad is right about people having trouble with some of the stockers but I would think the 18mm would be easier. Also, you can buy a universal vent filter if interested. I think you could go with a small one and be just fine but I haven't tested this theory. Smaller surface area, less air gets in......is my "theory" anyway. Right or wrong. [img]i/expressions/face-icon-small-wink.gif[/img]

 

Don't know what jet size you would need but just thought I'd add that the needle is adjustable on our 04 viper.

 

Do you think changing the filter to a Uni would even do enough to notice? I have been kicking around doing that also.
Wasn't looking to put a pipe on it at this time.

 

It's not so much the quest for power on this particular unit. If you have ever looked inside the stock filter on an e-Ton Viper, then you know it leaves much to be desired in terms of good filtering. I think the Uni will protect me a bit more, and ad a side effect I MAY get a bit more power. But the power is not the issue here, it's the filtering.

 

I just pust a UNI filter on my son's Viper 70 and I had to use a 100 jet and adjust the mixture screw.