New to 300 ex wanna make a nice trail quad

[300ex965]

OK guys so i recently got my hands on a 1998 300ex, the quad already has the following modifications.
-HMF full exhasut
-Supposedly its jetted.(Im not sure cause it pops whenever u let off at high rpm's not sure if thats good or bad:()
-k and n air filter with box lid still on.
I kno not many mods but I plan on adding to it alot, im looking to add some mods that would make it great for trail ridin and the occasional jump. It already has great bottom end, but i need more on top to try to keep up wit my buddies z400.
Well anyway I already have 400ex shocks on the way and plan to make my own relaocation bracket, and i also have a 2001 raptor rear shock in the mail.
Well what im looking for is a lil help on wat kinda stuff to put on it to give me some more top end and help with handling and such. LMK wat u guys think. :) Thanks in advanced

[m0t0xk1d]

well if you already have 400ex shocks then i would get 400 ex a arms but use the stock 300 spindles so you dont ruun into a camber probelm. the shock reloactor is a little harder then you think it would be to make. i would suggest buying one. for more power i would suggest a good port and polish and a cam and a 400ex carb and a high compression piston like 11:1.for a cam i would recomend a web cam or sparks cam but with the sparks cam you would need hardweld rocker arms and HD valve springs or maybe even a hot cam.. take the airbox lib off and for a main jet run a 130 with the mods you have now with a good port and polish i would run a 150. be careful with the raptor shock as it tend to blow the liquid out of it. the poping is back firing. there is a few solutions i learned. ! make sure the pipe and silencer is tight. i mean this as in tight the nuts and bolts that connect the head pipe to the head and the head pipe to the silencer. another solution is put some high temp silicone between the head pipe and silencer. this will eliminate the pipe sucking in air in any gaps. also check the air fuel mixture screw. and another thing would be take the heap pipe off and check the copper flange gasket you may neeed a new one.


. read up on the previous threads and learns all about these. it will become your best friend

[300ex965]

Around how much would a good port and polish, 11:1 piston, and cam run me? And where should i go to get this done.

[m0t0xk1d]

cam and piston will be around 200 each if not lower and port and and polish can be from 100 to probably 600 depends on where you get it down most people send them to sparks racing or tc racing for post polish

[300ex965]

Ok well i was just on powroll.com and valve springs, hardfaced rockers, and a 11:1 compression piston is gonna cost me about 400.00 and then theres a cam on ebay for like under a hundred wat u guys think?

[m0t0xk1d]

post the link to the cam

[dirtdawg]

don't forget about sprockets. i got the 12 tooth front and it is better for acceleration on trails. 400 front end is a great mod. make sure it is jetted AFTER you put in the cam and piston and all that junk, don't want to ruin brand new rings cuz it runs too hot. that would suck. i got the g-force axle too. adjustable for better stability.

[dirtdawg]

as far as the popping, that is the slow jet/ pilot on the decel. i have had experiences with that one before. change it to the 42 and try it again. if not, fuel screw like the other guy said. i've spent a lot of money on jets in the past. :rolleyes:

[300ex965]

My quad has alot of bottom end already I was actually planning on puttin a 14 tooth sprocket on to increase my top end. here is the link to the cam. http://cgi.ebay.com/ebaymotors/300ex-webcam-cam-300_W0QQitemZ280371731218QQcmdZViewItemQQptZMotors _ATV_Parts_Accessories?hash=item4147751b12&_trksid=p4506.c0.m245 And as for the jetting i plan on putting a 400ex carb on it so that should give it more fuel.