tweaker
06-12-2007, 05:14 PM
First a little history. I had a Duncan Racing National Midrange setup with ALL the go-fast parts for about 10 years. I rode it almost exclusively at the dunes in Silver Lake Michigan. I sold that quad about 3 years ago and haven't had once since.
Yesterday i acquired a '94 300EX. The quad is in overall excellent condition, with the exception of the cylinder head. The original head was replaced with one off a donor engine, which I have the bottom end to. While they were at it they bored the cylinder 1st size over and installed a brand new OEM piston. They got about 5 minutes on it before a valve adjuster cam out of the rocker arm, jambed under the cam and broke through to the outside of the head right under the lobe. That's how I bought it. The hole is in a non-critcal area and is being tigged shut.
The donor engine the head came from had a 1st size over Wiseco 11:1 piston in excellent condition. I've miced it and the bore, and have a nice .002" clearance, so in goes the Wiseco for free. That leaves me with a left over OEM piston with maybe 5 minutes on it. The quad also has a White Bros muffler. I've yet to receive it so I don't know if the head pipe is OEM or not. Does WB make a muffler without a new headpipe, or can I assume it'll be an aftermarket pipe when I get it? I'm considering installing a cam but don't want to get too much money in this thing. Is there a cam worth dropping in that won't require replacing the springs? If not, which cam would give me the best all-around performance? I'd like it to be easy to ride for when my daughter gets a little older yet still have good power for dune riding. I've been looking at the Web Cam 254 with .310 lift and 242 duration. Is it worth doing? If not, I guess I'll have to go with something like the 236 or 254 and have to install springs and hardfaced rockers. What do you think? I can use your help because this is the 1st 4-stroker I've tweaked with.
Yesterday i acquired a '94 300EX. The quad is in overall excellent condition, with the exception of the cylinder head. The original head was replaced with one off a donor engine, which I have the bottom end to. While they were at it they bored the cylinder 1st size over and installed a brand new OEM piston. They got about 5 minutes on it before a valve adjuster cam out of the rocker arm, jambed under the cam and broke through to the outside of the head right under the lobe. That's how I bought it. The hole is in a non-critcal area and is being tigged shut.
The donor engine the head came from had a 1st size over Wiseco 11:1 piston in excellent condition. I've miced it and the bore, and have a nice .002" clearance, so in goes the Wiseco for free. That leaves me with a left over OEM piston with maybe 5 minutes on it. The quad also has a White Bros muffler. I've yet to receive it so I don't know if the head pipe is OEM or not. Does WB make a muffler without a new headpipe, or can I assume it'll be an aftermarket pipe when I get it? I'm considering installing a cam but don't want to get too much money in this thing. Is there a cam worth dropping in that won't require replacing the springs? If not, which cam would give me the best all-around performance? I'd like it to be easy to ride for when my daughter gets a little older yet still have good power for dune riding. I've been looking at the Web Cam 254 with .310 lift and 242 duration. Is it worth doing? If not, I guess I'll have to go with something like the 236 or 254 and have to install springs and hardfaced rockers. What do you think? I can use your help because this is the 1st 4-stroker I've tweaked with.