ascott 500 head swap onto a 350x.... with pics

[camatv1]

try contacting the people that did the original swap? maybe dirtwheels has an issue or can tell you the issue that had this swap in it? your best bet is to just figure it out on your own.. OR talk to someone thats done it before.. is it just the head thats going on? why not the entire cylinder and make it a 500cc? OR an xr600 engine?

[SWIGIN]

im realy about done with the swap....just a few studs and things like that im waiting for.

yes its just a head swap....from what iv read online you CAN use the 500 cly as well but the time it takes to machine it to fit ( its way to tall) makes it not worth it.

what im doing is putting a xr500 sleeve into my busted 350x cly. this makes it a 89mm bore (same as a xr500)witch is exactly what the head is made for and the early xr500/ft500 head gasket lines right up.

plus useing the 89mm sleeve lets me use the early xr500 pistons and all the over bores they make.

this 89mm topend combined with a 6mm powroll stroker crank will be 460cc ( witch should realy run great since the head is made for a large motor)

im not going with a whole motor swap since my aftermarket 250r frame is built for a 350x motor ....and whats the fun in just throwing a big motor in....lol

i was just wondering if anyone here had info on how this was done back i the day, but im thinking other then a few top motor guys building a few each this never realy was a do it yourself thing

[SWIGIN]

got some more parts to play with, thanks to jason hall for the rockers and cam

i had a problem with the 350x rockers only sitting about 1/2 way on the valve stems and in the first 2 pics you can see how much wider the xr500 rockers are and that they line up perfect with the ft500 valves. (in the first pic the xr500 rockers are on the left)

they go right in without any mods but the xr500 uses a little wave washer beside the rocker......for this swap they dont fit and are not needed. you just simply put them right in like a normal 350x rocker.


3rd pic shows the early xr500 (same as ft500) head gasket and the magic marker shows the last hole i need to make for this to be 100% bolt on.

the new hole is just inside the original hole and will work fine.... i like how all the head bolts or studs are close to the fire ring of the gasket (unlike a 350x )

4th pic shows the new 79-82 xr500 sleeve im going to be useing and as you can see the gasket is a perfect match since it is made for this sleeve.

the last pic shows the length of the sleeve is roughly a 1/2 inch to tall....this is one reason why useing the whole xr500 cyl is not a easy thing to do since it needs to be shortened and the timming chain area near the base gasket is way off and dont line up at all.

my buddy built a 89mm stroked 350x(460cc) like this one will be and all he did was put the new sleeve in a lathe and cut it down to the right lenghth....no big deal.

the last thing id like to say today is with a lot of big bores you need to ether buy a custom head gasket or mod and stock gasket to work. with this 89mm bore you would be cutting the main fire rind seal off of a 350x gasket and that can led to a head gasket leak.

but drilling the new hole in the cyl is all i need to do is run a off the shelf xr/ft500 head gasket with only opening a few holes up in the gasket.

now that i look at the 500 gasket on the stock bore 350x cyl the new piston isnt realy that much bigger

[Dirtcrasher]

I think it's pretty awesome, lots of things to figure out there. I am unfortunately still stuck without a Tig welder but this year will be the year I buy one, just so tired of not being able to do the aluminum welding.

I think it was Dale that has a TC 86 200X head (single plug though) and it had at least one huge valve. I'm not sure if he's done any talking with anyone on it though.

I can see bolting a head down and setting up the bridgeport to cut larger valve seats, but I have no idea how much of a press fit that valve seat needs to be? Thats the problem with most motors, no matter what you do to the ports, the valves are too small. But not for you anymore! Nice work Swigin.

BTW, what does SWIGIN mean? I always picture a big fat guy swigin down a bottle of whiskey, LOL!!!!!

[SWIGIN]

lol
SWIGIN is from the HBO show deadwood

yeah i cant wait to see how a big cc 350x will run with this monster head....they run strong with the 350x head.


my brother had a dual sparkplug TC 200x (in a trx250r frame) and they really run strong but as far as the over size valves go they normally just go like 1mm larger and just open up the stock valve seat

[SWIGIN]

tonight i went to HRE and i cut the new sleeve shorter.... after makeing sure i had room to spare i left the new sleeve 1/16 longer then stock sleeve since the piston will be going farther down in the bore.

then we bored the old cly for the new sleeve... last pic just shows the stock sleeve in the big bore jug

[Louis Mielke]

looking good. I wanna hear the ride report

[SWIGIN]

thanks man, yeah id like ride report too...lol

i found what i thought was a 92 or 93mm long stud from a 400ex cly ( #5 on the microfische)

well it came and its way over 100mm long...what the honda guy told me is the length must be the installed highth.

so i ordered a #7 400ex stud that called 73mm long, i hopeing like the other it will be 20mm longer making it 93mm like i want.

[WLL]

more please!!! i like your motor work and thinkin . when can i buy the kit? please add sound in the ride report, i gota here her run!!

[SWIGIN]

i dont see me biulding another one of these even tho now i know what ill need .....the cost would be sky high.

i cant wait to run the thing too but that will be awile...never heard a big bore stroker with a monster head before...lol

[Tecate performance]

looks awesome, want to do another one

i have a ft500 head that i was planning on retro fitting. i thought about plumbing an external line into the rocker cover. are the xr/ft and 350x cams the same? i think the timing gears are.

you may want to calll FST and ask him what he did, i know he used to build them. also greenhuman on here said he's done one. i've got the 452 kit on stock stroke, stock head and valves and its pretty strong. i'd like to try the ft head for a stroker motor though, especially when you get around 500cc. make sure to check your deck height when you're done, most of the aftermarket pistons use the same compression height as stock and it puts the compression in the basement. i had cometic make me some thinner head and base gaskets to correct the deck and get the squish right and it was pretty cheap.

fwiw, the 04-05 trx450r pistons will fit the 350x rod, the rod small end is a little wider though and the compression height is about .120" shorter. the valve relief dia. and angles however are in the wrong place.

what cam, intake, and exhaust are you running? be sure to keep us updated!

[RideRed250R]

what i like is its a hemi... lol

[scrawny]

wow!!! cool stuff!

i cant believe the difference in valve size, are the exhausts that much bigger too? should be a screamer!!

[SWIGIN]

looks awesome, want to do another one

i have a ft500 head that i was planning on retro fitting. i thought about plumbing an external line into the rocker cover. are the xr/ft and 350x cams the same? i think the timing gears are.

you may want to calll FST and ask him what he did, i know he used to build them. also greenhuman on here said he's done one. i've got the 452 kit on stock stroke, stock head and valves and its pretty strong. i'd like to try the ft head for a stroker motor though, especially when you get around 500cc. make sure to check your deck height when you're done, most of the aftermarket pistons use the same compression height as stock and it puts the compression in the basement. i had cometic make me some thinner head and base gaskets to correct the deck and get the squish right and it was pretty cheap.

fwiw, the 04-05 trx450r pistons will fit the 350x rod, the rod small end is a little wider though and the compression height is about .120" shorter. the valve relief dia. and angles however are in the wrong place.

i'll be running a mega cycle xr500 #144-20 or a #144-21 cam with a 10.5 xr500 piston with a custom header and a aluminum intake

what cam, intake, and exhaust are you running? be sure to keep us updated!

from what iv heard FST used xr500 heads and cyl....this is not as good as the ft head and its easyer to use the xr500 sleeve in the 350x jug then try to get the 500 jug to fit a 350x.

im not worried about the compression highth at all since powroll knows about using the xr500 pistons in the 350x and when they shorten the rod for a stroker they take that into concideration.

the great thing about this combo is all the parts are made to work with each other....like the ft head and the xr/ft500 piston has the right valve releifes...and yes a 350x cam and a xr/ft cam will inter change

if you run a xr valve cover you can get the oil to the cam but not directly on the journals like a 350x cover......the 350x has a better oiling system

look at the xr500 valve cover that jason hall posted at the start of this thread....and then look at my first pic, its a 350x cover......you will see how on a 350x the oil gets pumped right on the cam journals

[SWIGIN]

wow!!! cool stuff!

i cant believe the difference in valve size, are the exhausts that much bigger too? should be a screamer!!

the ft500 exhaust valve is as big as the 350x intake valve.... 30mm