just picked up a uni for a p90 and wondering if anyone has jetting info no pipe yet, no mods just want to start with the air filter

 

Depending upon your altittude, weather conditions, other mods, etc. jetting can be very funny at times. Sometimes after an "air filter only" upgrade you have to re-jet and other times you don't. With no pipe, reed or other air flow improvement changes, your factory jetting could be borderline. In other words, you may NOT have to change it. The best way to determine if re-jetting is required is to "Read your Spark Plug".

For pictures, surf:

http://www.motocross.com/motoprof/mo...lug2/plug2.htm
http://sportbikeguy.com/garage/floor/plugread.html

For detailed info on jetting, surf: http://www.motocross.com/motoprof/mo...1/carb101.html
* This is wrote for motocross bikes but the base foundation is the same for all 2-stroke engines.


Hope this helps...

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let me know what you find out...we just got our uni and will be doing tomorrow. so keep us posted.

 

If it runs out of fuel then the needle is not flowing enough fuel to the float bowl. The stock carb works like junk with a after market filter on it.

 

i put it on and it sounds much better louder and runs good off idle but just as soon as i crack the throttle open and get into the main jet it boggs really bad i might just wait and get the pipe and a 20mm carb i don't like the idea of drilling the main jet to a 149 like i have read other people are doing, maybe i'll go tp the dealer and see if they have jets if they have them in stock i might tinker with it other wise i'll wait

 

If you increase air flow than you will have to increase fuel flow

 

socalgrizz are you talking about drilling out the main jet on the stock carb to 149 or using a 149 on the 20mm carb. The Predator stock main jet is a 82.5 and going to 149 seems like a big jump after just adding a air filter. Keep us informed if you don't mind. I got my daughter a Predator about a month ago and am trying to gain as much knowledge as possible about these mini quads. Thanks for any help/advise

 

i'm just going by info that i'm gathering on various forums but it seems alot of people are drilling out the jet on the vm16 carb to a 149 i dont know if that's the drill bit size or the flow rate they do this when they install a filter with a pipe and they even have problems with the bowl running out of fuel after doing this, it seems like a huge jump to me considering my 660 came with a 155 main jet i know 2 strokes and four strokes have different characteristics but that still seems like a big jump, i wish i could find better info on jetting these things,
i want to know if it's better to upgrade to a vm20 carb? or will the vm16 work well with a pipe and filter? what's the biggest jet you can buy for the vm16?
the only mods i'm interested in is a filter, cdi, a pipe (probably the fmf fatty) and proper clutch adjustment i'm not looking for max power gains not planning on racing, and i can probably get a good deal direct from fmf i live about five miles from them and my friend knows a couple guy's in the r&d department
it seems when ever you have a ? you get the same reply telling you to call WRH i don't want to bother them based on the fact that i don't plan on buying anything from them at this time

 

My memory isn't as good as it used to be....

I think I remember reading a previous post (or someone's signature file) about their Pred-90 with K&N Filter with FMF Pipe with a 90 jet. As a suggestion, post with same type of "what size of jet with this combo?" question within .Press Here. to inquire what "starting" recommendations they come back with.

Hope this helps...

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For historical info on Pred-90 jetting & FMF pipe, surf:

http://forums.atvconnection.com/mess...did/386959.cfm

http://forums.atvconnection.com/mess...did/381752.cfm

Happy reading...

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