350X mods

[nat350x]

I am going to rebuild my stock 350X motor, and I was wanting some input on getting some more power out of it, but keeping it reliable and easy to start. I already have a dg krome power full exhaust and k&n filter, with air box vents. I was thinking of a mild cam and new piston and boring. Any suggestions would be greatly appreciated. :bounce

[Mobular]

Do not bore unless absolutely necessary! All it will do is remove any future life from the jug. Do only the barest minimum bore, and put in a 10:25-1 piston and a mild cam. You will be very pleased!

[ATC crazy]

My brither has a 350X in his TRX250R frame. Its bored to 372cc, whitebrothers E-series exhaust, Weisco piston & rod, a top-of-the-line cam from whitebrothers, clutch kit w/ kevlar disks, and titanium valves. It flat out hauled ass. It was geared down for the woods but would still pull about 60mph. It had torque like a diesel and plenty of HP. It would wheelie in every gear. I say go with those mods if you want to cause they are bulletproof. My brother and I rode it like that for a couple of years and then our nephew got on it; He was going along at 5th gear and droped it down to 2nd and dumped the clutch which snapped the wrist-pin (dumb ass) My brother still dosent have it rebuilt but he now has the high performance 372X engine with the parts to fix it and a stock 350X engine,,, so now its a ? of time. Start heading in that drection if you want bulletproof POWER :twisted:

[ATC crazy]

If you bore it anywhere above 380cc then its a reliability issue but if you stay below that then you are very safe. I got this from a friend that has been rebuilding ATC for 35 years.

[JohnR.]

For a play machine you won't need any more than a mild cam, a little port work, a 38mm Keihin PE, and a fresh Wiseco 10.25:1 piston. I have the same exhaust as you and run that set up on my woods bike and it is great. Does it still start easily? Well, three of us went out last month on a Saturday night, rode 10 miles down a frozen lake, we went into a bar (for hot chocolate of course, HAHAHA!!) and left our trikes sitting on the lake, in the wind in 15 degree weather for over an hour. When we went to leave the old X started on the first or second kick with the choke on. Hard starting is usually because someone is running a 18 year old stock carb and it has pretty much had it. Especially if you do some mods, mine would take forever to start with the stock carb, I ordered a new 38 from Duncan Racing along with a jet kit, tinkered with it for a few rides but now it is dead on.

[Joel85350X]

I just rebuilt my engine. Like others said, stay away from a large overbore. Mine was bored out only 0.5mm, or about 20 thousandths. I replaced the piston with a honda piston. I would highly suggest not using wiesco because their pistons are designed to be replaced after a few hundred hours; more of a race style piston. If you want something that you can bolt together for another 18 years of riding, go with a honda original overbore piston. They are available in 0.25mm increments up to 1mm over. I also put in a new set of titanium valves and dual valve springs and a mid range white brothers camshaft. During all of this I decided to have oil pump and shifter cam replaces to make the reliability and newness of the engine better. Besides this, a clutch might be a good idea, but then again yours might be fine. Play it by ear. These mods cost me about $900 professionally installed. The installer also checked all of the gearing on all of the gears with a stethescope. You can see if there are any cracks or broken teeth this way without splitting the main cases.

Best of luck to you.

[nat350x]

thanks for all the info :D I definetly will not bore more than needed. I didn't know white brothers made cames for the 350x. I'll check through them on prices, I have already checked powroll and webcams.

[nat350x]

thanks for all the info :D I definetly will not bore more than needed. I didn't know white brothers made cames for the 350x. I'll check through them on prices, I have already checked powroll and webcams.

[Joel85350X]

Yeah, white bros and powroll are weld/regrind cams. I think webcams makes their own originals. Can anyone verify this? Either way you are looking at a quality piece of hardware. Mine is a WB mid-range.

I might have the bike started by the end of the day...and maybe pics by Monday! :)

[Jordan]

Web Cams are also re-grinds... The only company I know of that makes brand new aftermarket cams is Hot Cams.