+7mm Crank OEM Cylinder Porting
Moderator: rztom
Re: +7mm Crank OEM Cylinder Porting
Okay. Seriously...
Has ANYONE ever actually built a +7mm OEM cylinder engine???
Has ANYONE ever actually built a +7mm OEM cylinder engine???
Re: +7mm Crank OEM Cylinder Porting
Too bad Kel Caruthers isn't a member here.
Re: +7mm Crank OEM Cylinder Porting
Yes I have!!!!
If I remember right you end up with around 2mm (maybe a little more) positive piston to deck height as appose to 1.25mm for a +4mm stroke so nothing amazing there! Just be realistic with your power goals, 80-83 hp is a very achievable number below 10k with out the need to think about it to much.
Re: +7mm Crank OEM Cylinder Porting
Nothing stopping me from going for insane power, just a personal preference. I always thought riding with small engines would force me to get faster by learning good technique. Learning has always been more important to me than winning. Funny (or, not) how that philosophy seems to be reflected in my bike projects.Questo vecchio rz wrote: ↑Tue Dec 04, 2018 12:37 pm I know what your saying /thinking though, It would be nice to have the YPVS setup. I think I would have paid to have one built.
Hope you build it, and we can follow your progress and how you make out on your build.
Not using the OEM cylinders because I want the power valve, although I would prefer to have it.
Bottom line is, I want to use the OEM head. To me, it's one of the most beautiful motorcycle heads ever made - and I was lucky to get a billet copy.
Then, there's the part about doing something different. There are tons of super fast bikes and engines out there, already.
Re: +7mm Crank OEM Cylinder Porting
Kinda-sorta understand a little about a "square" engine.
This statement is very encouraging!
Re: +7mm Crank OEM Cylinder Porting
SWEET!!slinger wrote: ↑Thu Dec 20, 2018 9:10 amYes I have!!!!
If I remember right you end up with around 2mm (maybe a little more) positive piston to deck height as appose to 1.25mm for a +4mm stroke so nothing amazing there! Just be realistic with your power goals, 80-83 hp is a very achievable number below 10k with out the need to think about it to much.
Doesn't mean I can get it done, but I have considerably more hope. Just wish I had more time.
Onward then....
- Questo vecchio rz
- Posts: 1116
- Joined: Sun Aug 16, 2015 5:55 pm
- Location: Reconquista of California
Re: +7mm Crank OEM Cylinder Porting
Heres a quick video on Kel, narrated by none other than Dave DeSpain!
He's into his 80s now , and was getting it done likley before most of us were born!
https://youtu.be/jUCebazy8zs
It's been a few years, but last I knew, Kel was working over here at Chapparael Cycles in San Bernardino.
I met him there and once at Laguna Seca. Got a handshake and autograph.
I think he was or is in charge of the new bike aeembly division, they likley sell 1000s of bikes a year. My guess is he's retired as this was 10 years ago or so when I met him there.
Banshee (Baja) race bike,+ 2 A Arms,L.E.Ds, Toomey, +4 stroker IMS tank, run flats.
96 GSXR SRAD, Future Yoshimura rep.
85 custom Tri-Z
RZ/YZR bike(project)
86 VFR750 RC24 Merkel replica (project)
Royal Enfield Bullet 500
96 GSXR SRAD, Future Yoshimura rep.
85 custom Tri-Z
RZ/YZR bike(project)
86 VFR750 RC24 Merkel replica (project)
Royal Enfield Bullet 500
Re: +7mm Crank OEM Cylinder Porting
And I always had the impression that you want your bikes as queer as possible
Bye
Martin
Martin
Re: +7mm Crank OEM Cylinder Porting
On that note...
Got a feeling Kel would think my projects are a big waste of time.
Got a feeling Kel would think my projects are a big waste of time.
Re: +7mm Crank OEM Cylinder Porting
Kel Caruthers did an interview in the last issue of Cycle World.
I think he's an enthusiast with a very curious mind and I feel certain that he would not look at your projects as a waste of time.
By the way, I am fairly certain he was the guy that made those over stroked over bored 680cc Daytona 200 Specials for Kenny Roberts and Eddie Lawson back in 1983.
I think he's an enthusiast with a very curious mind and I feel certain that he would not look at your projects as a waste of time.
By the way, I am fairly certain he was the guy that made those over stroked over bored 680cc Daytona 200 Specials for Kenny Roberts and Eddie Lawson back in 1983.
Re: +7mm Crank OEM Cylinder Porting
made a drawing and I ended up with 3mm
the liner also sticking out is because I will start with blank liners in Banshee cylinders, so I can make a double exhaust port as wide as possible at the top to get good blowdown, and using the liner as bridge in the middle.
if it runs, you can race it !
Re: +7mm Crank OEM Cylinder Porting
If the domes are cut, so the piston can travel 3mm higher, that means an OEM gasket can be used at the base of the cylinders, right? No spacer.
And, so... the port timing will not be messed up in any way. Correct?
And, so... the port timing will not be messed up in any way. Correct?
Re: +7mm Crank OEM Cylinder Porting
change the stroke and port-timings will change off course. but that's just a question of placing the cylinder at the best height and make changes to the ports.
as in our RZ/RD's the ducts are straight up, you can hardly mess-up the transfer-flow if you alter the bottom of the port as in this case it has next to no influence on the inflow into the cylinder.
as in our RZ/RD's the ducts are straight up, you can hardly mess-up the transfer-flow if you alter the bottom of the port as in this case it has next to no influence on the inflow into the cylinder.
if it runs, you can race it !