I'm not trying to jack this post, but will the 400EX top end bolt on to a 350X lower end? Are the 350X and 400EX the same stroke? A friend of mine picked up a stock 85 350X that was run without oil, and it messed up the cam bores in the head and cam cover. We were just thinking that an ATC400X would be a lot of fun.

 

Stock intake, unported head, and stock cam. I have a 10:25 piston but have not put it in yet. How id the reliability with the 12:1 if I use the 104/93 mix gas? What cam works good with these pistons for dunes and trails? Will head porting make a noticable difference?

 

as far a s reliability goes, it's not the gas that necessarily makes the difference although it's always better if it does not suffer from dtaonation or pre-ignition. 12:1 or even higher is not what seems to hurt these engines, but when you take the bore up too high without redoing the stud positions in the upper and lower cases. The stock arrangement will go up to 89 mm, but that leaves a pretty thin walled sleeve. Like with any other engine if you push the performance way up, the relaibility goes way down... just math...........

Porting really does help these things as will a good exhaust. The valves aren't overly large on the 350X so it can use all the breathing help you cna give it. Polish the exhaust and open it up a bit and have the head done by someone like TC racing or similar who knows these motors. The cam will depend not just on the application, but what porting work you do as well. You can go up to a 39 or 40 mm carb on these too. I use 44/38 Lectrons on mine and like them, but they are kind of built for the motors too so I am not "dialing them in" contantly.

 

The motor is still in a ATC so can I even fit a bigger carb? The 36VM was tight. I do have the stage 3 DG X-Cellerator exhaust on it. What is TC's phone number? How much does it cost for a full port job?

 

MDE3 do you use the stock intake to mount the 38mm Lectron or a different one? I'm fixing to put a 38mm Lectron on my 350x/250x conversion. Also how did you get the air box to hook up? The don't have to have a airbox because I'm setting it up for 300' sand/dirt drag racing.
Later!

 

Hi.I use a custom built intake, but most just used a modified version of the stock intake.

I made a billet aluminum intake that was port matched to the head port diamenter as well as to the 44 mm outlet on the Lectron (44/38 Taper-Jet). Then I had special Viton couplings made to stand up to the heat and race gas(114). The taper in the runner was the same angle as the stock intake, but this makes the intake runner around twice as long as stock(depends on your carb diamenter at the outlet and the diameter of your intake port). I machined the last 5/8" of the outer surface of the intake to be circular, with about a 1/32" lip on the end. I had some small weld spots touched to the outside of the carbutaror oulet to stop the Viton coupling from slipping off when it was clamped in place.

The coupling provides both a seal and a cushioning effect, as well as providing a small buffer between the aluminum of the intake and the aluminum of the carb. When you tighten the coupling it swells and separates the two components slightly.

Based on a street time trial on both units I did this to, we saw about a 25% gain over the stock intake in terms of acceleration. Basically we hit top speed in 75% of the time it took using the stock intake.

As for the carb intake, we used a stock 250X intake and just heated the end with apropane torch to soften it then slipped it onto the carb. The I made a coupling to attach the K&N filter, and just supported it with large zip ties, also put one around the back to pull it in tight(wrapped around the gas tank collets and the back of the filter) Not very professional but easy to service in a hurry. In fact we attached all the plastic with zip ties so we could get everything opened up quick. Never rerally had a problem with it on flat track, or MX. On the MX (intake) conversion I didn't put a lip on the intake (first one) and the coupling did come off a few times.......not good) Also using standard rubber for the coupling will not work....the race gas (certain ones) will soften the rubber along with the heat, and the coupling will get sucked in between the carb and the intake manifold.

 

Sorry to go off subject and ruin this thread, but I have a really nice 350X motor for sale, I was thinking about putting this into my 250R frame but I decided to mod my R engine so im selling this -

http://cgi.ebay.com/ebaymotors/ws/e...item=2439489994

Will end auction early for the right price

Check my other auctions for more 350X parts.

Thanx,

Email me at Live2Ride300@yahoo.com

 

MDE3, Thanks for the info! now I have an idea were to start.
Later!

 

sorry to interrupt this lovely chat...lol

but do you know any mods to stick on a 200x for a good price? i would like it to be able to run about 60-65.

and would i need a extended swingarm or new shock to handle the new power?

would wheel spacers help handling?

sory for all the ?'s thanx

 

Well I spoke to Tom over at TC racing. He recommended a cam, springs, CDI box. Should be good for about 30-32HP (rear wheel) with my current mods. Or about 8hp more than now. Gonna be cool.