big bore 350x mods

[lndy650]

sorry if theres already a thread about this....
i was wondering what you guys with big bore 350x's do for exhaust carbs ect...
i use a 400ex carb but my exhaust is a cobra and i dont think the head pipe is big enough for 452cc's.... i did my own porting based off a TC head which worked very well. also like everyone knows with these bb's i cant get my clutch to grab:( .
i have heard with a few mods these engines are over 40hp what do you guys think?:Bounce

[SWIGIN]

i like 2'' pipes...it seems to work real well, the 1 1/2'' (not just cobra but all aftermarket headers) is to small.

i know guys who say '' but what about low end.....or....youll lose low end'' this is total BS...with the big motor youll have more then enough

just get a length of 2'' exhaust pipe at avanced auto or someware like that and add it to your header....you can see my weld where i cut it. (the rest of the welds are ground off smooth)

the header just has 1 bend but from the header to the silencer is at least 12 peices, just cut little cones and weld them together




as far as carbs go throw that 400ex carb as far as you can...its a stock carb built for a stock motor and its 35mm. you need at least 38mm but a 39 fzr would be better (crf 450 carb)

honda changed the way they measure carbs some say that the 400ex carb is 38mm.....its still the same old 35mm carb


as fr as the clutch goes i would try the normal springs first...if it does slip then look at my ascott thread for info (we are working on this right now)

as far as HP goes....my ascott headed 460cc big bore stroker will see a dyno when it gets done ....and my buddys 350x headed 460cc BB/stroker will go as well as soon as we get the clutch to hold

stock is 27hp my buddy thinks he is in the 40s....we will see

[lndy650]

thanks for the info! does a 39mm fcr fit in the stock intake boot? you did a very nice job on that header i figured i'd have to make my own:naughty:
ive been enjoying the ascott thread. i had a brand new clutch and my first ride it started slipping so i havent even got to feel the power yet but this motor has more power with the clutch slipping than a stock 350x with a good clutch:lol:

[SWIGIN]

yeah with the sliping clutch my buddys 460cc motor smokes worked up 450's ....lol

i have no idea if the carb will fit the intake....probaly not...but you can try a different intake or make one

im running a aluminum intake i made... it tilts the carb down and to the left so the air box tube lines up better (this is on my quad)

[SWIGIN]

on second thought...... the 38mm round slide carb im running now is working fine on my buddys 460cc motor and they do fit in the intake

id just get one of them since they are made to fit and i know on a trike carb clearence is more of a problem
http://denniskirk.com/jsp/product_catalog/Product.jsp?skuId=16256&store=Main&catId=111&productId=p16256&leafCatId=11101&mmyId=#fitment


this is the one im running...its made for a 350 yamaha and the large side of the carb is turned down some so a smaller air tube will fit...and it came jetted perfect

http://denniskirk.com/jsp/product_catalog/Product.jsp?skuId=16259&store=Main&catId=111&productId=p16259&leafCatId=11101&mmyId=