HPD, CPI, FMF, and DG all make in frame pipes for Polaris Scramblers. My questions are: Can any of these pipes be used without porting and extensive race mods? Has anyone used any of these pipes? And, what other mods were used in conjunction with the pipe?


I am building my quad in stages and I plan on starting with bolt on mods first (pipe, Wiesco piston, jet kit, air filter, air box mod, and a clutch kit). I prefer an in-frame pipe, but don't want to have to port the motor yet.

If I need more power I will continue mods with porting, billet head, V-Force reed, and 39mm PWK carb (I already have the carb). I want to continue to use pump gas, and I am concerned about fuel consumption with these mods.

I've already begun my suspension and steering mods, and am ready to order a "stage one" engine kit. Just need to find an in-frame pipe to use.
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Ajo771 - you can get substantial additional power from the addition of the pipe alone; it allows the complete fuel/air delivery system to function more freely - so, IMHO the first mod should be the pipe and a UNI filter or K&N (both excellent - the K&N requires you to be a little more diligent with maintenance). You will definitely need to change your carb jetting with the addition of the pipe / filter. Your system will be breathing better while getting the stock amount of gas if you don't change to a larger main jet. This creates the risk of running too lean which will hole your stock piston sooner or later. Learn how to take a plug color reading to help you get the jetting down.

These mods will not 'require' clutching but you will have enough power to gain arm-stretching punch from even mild clutch mods (weights and springs) - engine mods beyond piping will definitely require clutch mods to reap the benefits.

You will probably find most people in this forum tend to stick with aftermarket companies that cater to the ATV / snowmobile group and shy away from FMF and DG preferring HPD, Aaen, HSP, Dyno Port, EPI and all the goodness that Rick at Ritter Cycles can provide.

Good luck!