Tim's XS project - 750cc rephased ported head titanium valve hot cam craziness
- Thread starter Tim
- Start date
Swagger
Putting boot to ass since 1967!
Re: Tim's XS project - October 2011 - ENGINE UPGRADES COMING 
I'm sure he's already added them, but if not you should ask you guy to add relief cuts to the intake manifolds to aid in retention. Don't need to be deep, just enough for the clamp to compress the coupler into the surface of the manifold a bit a bit.
May not need if you're planning to rack your carbs and provide a hard mounting point..
I'm sure he's already added them, but if not you should ask you guy to add relief cuts to the intake manifolds to aid in retention. Don't need to be deep, just enough for the clamp to compress the coupler into the surface of the manifold a bit a bit.
May not need if you're planning to rack your carbs and provide a hard mounting point..
midnightcafe
Been Around the Block
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
give Z1 Enterprises a call. Even if you don't buy from them, they will know and are plenty helpful.
- AUG 2012 SALT FLATS OR BUSTgive Z1 Enterprises a call. Even if you don't buy from them, they will know and are plenty helpful.
Swagger
Putting boot to ass since 1967!
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
What's the outer diameter on those manifolds? You might be able to use a common size silicone coupler (turbo market). I've used straight radiator hose cut down to suit as well....
- AUG 2012 SALT FLATS OR BUSTWhat's the outer diameter on those manifolds? You might be able to use a common size silicone coupler (turbo market). I've used straight radiator hose cut down to suit as well....
50gary
Under the Limelight
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
Just remember Overkill is good. I have a friend with 900cc XS(650) with an self made automotive plain bearing crank, titainium H-beam rods also self made, It's a water pumper, two added extra head studs, different valve angles, 14/1 compression, It is a race bike though. Yeah.. overkill is good.
Cheers, 50gary
Just need to keep telling myself the 750cc kit is overkill, even with the oversize intake valves...
- AUG 2012 SALT FLATS OR BUSTJust remember Overkill is good. I have a friend with 900cc XS(650) with an self made automotive plain bearing crank, titainium H-beam rods also self made, It's a water pumper, two added extra head studs, different valve angles, 14/1 compression, It is a race bike though. Yeah.. overkill is good.
Cheers, 50gary
Just need to keep telling myself the 750cc kit is overkill, even with the oversize intake valves...
Cornish Pixie
Ambitious but rubbish cafe builder
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
Hey Tim, cool motor build you've got going on. I'm watching this with more than a little interest
- AUG 2012 SALT FLATS OR BUSTHey Tim, cool motor build you've got going on. I'm watching this with more than a little interest
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
Today was a good day. Head arrived from Ryan at 707Racing.com. Had to sit it on my 750cc MikesXS cylinders to see how they looked together.
You're looking at ported and polished intakes, oversize titanium valves, springs and retainers from a NASCAR engine, custom bronze valve guides, heavy duty stem seals and custom carb manifolds.
Let the parts porn commence
- AUG 2012 SALT FLATS OR BUSTToday was a good day. Head arrived from Ryan at 707Racing.com. Had to sit it on my 750cc MikesXS cylinders to see how they looked together.
You're looking at ported and polished intakes, oversize titanium valves, springs and retainers from a NASCAR engine, custom bronze valve guides, heavy duty stem seals and custom carb manifolds.
Let the parts porn commence
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
Everyone I've spoken too, including racers running XS engines in sidecars etc. all say 34-36mm VM's are the way to go, and most suggest 34. My BMW 750 is running with VM32's, so 34's are plenty big enough.
Seeing as I have good 34's on the XS now, I might start with those along with some bigger jets to see if they work well before buying another set.
- AUG 2012 SALT FLATS OR BUSTEveryone I've spoken too, including racers running XS engines in sidecars etc. all say 34-36mm VM's are the way to go, and most suggest 34. My BMW 750 is running with VM32's, so 34's are plenty big enough.
Seeing as I have good 34's on the XS now, I might start with those along with some bigger jets to see if they work well before buying another set.
50gary
Under the Limelight
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
I wonder, did you increase the exhaust valve size? Most common consensus is the XS 650 exhaust is too big from stock. I'm running new VM 34 roundslides on my street 650. We made the manifolds from scratch and they look almost the same as yours (why wouldn't they) and ported the head myself, stock valve sizes, stock cam, two into one headers open exhaust, with Boyer ignition. Looking back at your donor engine the carburetors on it are CV carbs not VM roundslides even if they are 34mm they will not likely give the same performance level as the VM's? My bike is not over carburetor-ed by any means. With a 750 and big valves I would use 36mm VM Mikuni or even flatslides? I have some TM-38 flatslides on my CX500 Honda.
Cheers, 50gary
- AUG 2012 SALT FLATS OR BUSTI wonder, did you increase the exhaust valve size? Most common consensus is the XS 650 exhaust is too big from stock. I'm running new VM 34 roundslides on my street 650. We made the manifolds from scratch and they look almost the same as yours (why wouldn't they) and ported the head myself, stock valve sizes, stock cam, two into one headers open exhaust, with Boyer ignition. Looking back at your donor engine the carburetors on it are CV carbs not VM roundslides even if they are 34mm they will not likely give the same performance level as the VM's? My bike is not over carburetor-ed by any means. With a 750 and big valves I would use 36mm VM Mikuni or even flatslides? I have some TM-38 flatslides on my CX500 Honda.
Cheers, 50gary
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
mmmm... soooo sexy.
anyway... is it just me or should the valve seats be in contact more with the valve springs? seems only half of it is in contact...
Not really sure if that would be an issue.
- AUG 2012 SALT FLATS OR BUSTmmmm... soooo sexy.
anyway... is it just me or should the valve seats be in contact more with the valve springs? seems only half of it is in contact...
Not really sure if that would be an issue.
t71ford
Over 1,000 Posts
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
Valve seats don't contact the springs...they contact the valve face inside the cylinder. If you mean the spring retainer caps, all is as it should be.
Looks awesome, Tim. Can't wait to see more!
- AUG 2012 SALT FLATS OR BUSTValve seats don't contact the springs...they contact the valve face inside the cylinder. If you mean the spring retainer caps, all is as it should be.
Looks awesome, Tim. Can't wait to see more!
Deviant1
Over 1,000 Posts
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
Yessir, that's mighty fine unobtanium parts porn, surely able to make even the most liberal members of the VJMC blush. Glad to see all of this goodness being mated together. With you going to the flats are you planning on making Barber this year as well?
- AUG 2012 SALT FLATS OR BUSTYessir, that's mighty fine unobtanium parts porn, surely able to make even the most liberal members of the VJMC blush. Glad to see all of this goodness being mated together. With you going to the flats are you planning on making Barber this year as well?
707racing
New Member
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
I think the intake velocity will be good. I ported/polished the intake ports to match up perfectly with the manifolds which I machined to match up to the VM34's. The intake should be a nice long smooth tube from the venturi's to the valve heads. I even "sharkfinned" the aluminum bumps in front of the guides!
- AUG 2012 SALT FLATS OR BUSTI think the intake velocity will be good. I ported/polished the intake ports to match up perfectly with the manifolds which I machined to match up to the VM34's. The intake should be a nice long smooth tube from the venturi's to the valve heads. I even "sharkfinned" the aluminum bumps in front of the guides!
Re: Tim's XS project - ENGINE UPGRADES COMING - AUG 2012 SALT FLATS OR BUST
Exhaust side hasn't been enlarged, just the intake side. I'm no engineer - Ryan from 707Racing (see his post above) did the head work and knows his stuff. Can't wait to see the crank and cam!
The donor engine is only being used for the bottom end - the carbs will end up in the trash along with much of the rest of the bike. Seeing as I am leaving my current engine intact, I'll probably hard-tail the new donor bike and put my old engine in it.
Will be running VM34's on the new engine. I'll likely test it out with my current VM34's before investing in another set. If I stumble across something more interesting for the new motor I'll grab them, but I have VM's on my XS650, my BMW R75 and my SR500, so keeping on with VM's makes some amount of sense.
- AUG 2012 SALT FLATS OR BUSTExhaust side hasn't been enlarged, just the intake side. I'm no engineer - Ryan from 707Racing (see his post above
) did the head work and knows his stuff. Can't wait to see the crank and cam!The donor engine is only being used for the bottom end - the carbs will end up in the trash along with much of the rest of the bike. Seeing as I am leaving my current engine intact, I'll probably hard-tail the new donor bike and put my old engine in it.
Will be running VM34's on the new engine. I'll likely test it out with my current VM34's before investing in another set. If I stumble across something more interesting for the new motor I'll grab them, but I have VM's on my XS650, my BMW R75 and my SR500, so keeping on with VM's makes some amount of sense.
