I did a search but didn't quite get the answer I'm looking for. I just received a UNI filter from Hetrick Racing (Good people!). The Predator 90 is completely stock but this weekend I'll be taking the stock airbox off and installing the new air filter and Hetricks aluminum filter guard. They gave me a 105, 110 and a 115 main jet.....which one do you think I should start with? I'm only at about 1,500 ft elevation and again, except for the new air filter everything is stock (for now). Any input would be great, thanks!

 

I'd start out with one size above what's stock... do a plug check and re-evaluate it... It's pretty easy to change out the main jet. Just adding a filter won't change it that much.. put a pipe on it and it will make a big jump (we run a 110 on our modified 50... it came with an 85).

Bryce

 

Thanks for the info. !!!!! Alyssa is one mean rider! How old?..... though my kids are JUST getting into riding, my 9 year old doesn't ride like that......awesome riding.

 

Alyssa is 6.. she's been riding for a year and racing for about 8 months or so.

She had a bad fall/winter racing season... first she got tangled up with a kid on a dirt bike at a pracitce and fractured her wrist and elbow...then surgery on that. After that, she started practicing again, but blew her engine teh weekend before the last race (Bent rod, melted rod bearing, shattered piston).

I just got it all back together and running tonight... gonna try to get her out for some break in on it this weekend and then Race on April 24th.

Give your kids some time and a lot of encouragement... let them do it their way (unless it's dangerous, then jerk a knot in 'em [img]i/expressions/face-icon-small-tongue.gif[/img] ) and try to lure them into the proper ways... they'll get there... we spent just about every weekend at the track last summer getting her ready for the fall season only to be filled with bad luck.

Oh well.. here come the next season... and this time there's a new Dinli Diamond back 90 up for a prize [img]i/expressions/face-icon-small-happy.gif[/img]

Bryce

 

as far as the jetting....I know some will argue but i always found that it is safer on the engine to start out higher than you think and work your way back down....it is better to be rich than to be lean...and 2 strokes love that fine ballance between lean and rich.....


Mike

 

Thanks Mike, I actually got a chance to put the 90 through it's paces after changing everything out and looks like I'll end up with the 110 or 115 jet. The 105 was leaving the plug a bit too white for me. After going to the 110 the plug started showing a more tannish appearance but I may throw in the 115 and a new plug and see what I get. Just to make sure I'm doing this correct.....I'm running the 90 around a bit, varying the throttle, and then goose it on the way back, cut the motor off and coast to a stop. Then I'm reading the porcelain a bit below the electrode where it goes below the threads (down inside). Am I doing this correct? Thanks.

 

thats how i have always done it!!!.....though some say you dont need to actually "chop" the throttle...but that is the way i learned and it seems to work...


Mike

 

You may want to put the bigger jet in to make sure it will not take it. You may also use the old plug so it will have residue to color up more quickly. I would also consider using a NGK B-8HS to tune with.
A plug chop on your mini-quad is not necessary. You will get better coloring if you let the kids ride it.
Just monitor the plug color every so often to see how it looks.

 

Thanks a lot for the info and peace of mind guys! This is all pretty new to me and I don't want to screw anything up.