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jd750ace
Front Toward Enemy
Wow. 40 bucks and I can't even flip the pages? Kinda steep for clicking a download. JMO. I'd expect an actual BOOK for that kind of cabbage. A book don't get lost when my laptop craps out.
jd, for the kind of information that manual contains and the research that went into compiling it, the price is dirt cheap. The manual is in pdf; if you want hard copy just run it off.
Joe, "TT" stands for "Tourist Trophy," a term that hasn't had any real world meaning for many decades. In England it designated a street race on pavement, as in the Isle of Man TT. In the US it designates a dirt track race with right hand turns and at least one jump. I don't know WTF a street racer pipe is. TT pipes tuck under the motor in the middle. Stop fretting and use a pair of 1.5" pipes with good free-flowing mufflers. Straight pipes will only make a lot of noise, piss people off, and narrow the rpm range in which your motor makes power. Don't make the mistake of using straight pipes with baffles crammed in them, as far as flow is concerned they're the worst of all possible worlds. You're going to go after good street performance or image; don't get them confused.
Joe, "TT" stands for "Tourist Trophy," a term that hasn't had any real world meaning for many decades. In England it designated a street race on pavement, as in the Isle of Man TT. In the US it designates a dirt track race with right hand turns and at least one jump. I don't know WTF a street racer pipe is. TT pipes tuck under the motor in the middle. Stop fretting and use a pair of 1.5" pipes with good free-flowing mufflers. Straight pipes will only make a lot of noise, piss people off, and narrow the rpm range in which your motor makes power. Don't make the mistake of using straight pipes with baffles crammed in them, as far as flow is concerned they're the worst of all possible worlds. You're going to go after good street performance or image; don't get them confused.
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smg65
XS650 Addict
Performance costs money. If you're good enough, and there are too many folks out there who harbor that illusion, it'll still cost plenty. If you want the best performance that can be had, you might want to research and find who can deliver that to you. And it'll be expensive. Also, owning a flow bench is no guarantee of results. That book is probably a great starting point. Also, you need to define the "performance" that would be most suitable for you. So many variables.
650performance
XS650 Addict
Full disclosure: when I first compiled the engine build specs and tuning data used by the high profile XS650/750 race teams in the '70s and formed it into a how-to engine mod manual, I sent the first draft to Griz to review (especially the info about carburetion).
Therefore, the finished product is at least partially his fault. Just saying ...
Therefore, the finished product is at least partially his fault. Just saying ...
Port reduction is just a technique used to shrink the ports cross sectional area leading up to the seat,be it by raising the floor, lower the roof, adding material to crucial areas to redirect air flow or to aid in increasing port velocity or seeing an increase in both areas would be the ideal target . My intake ports for my particular needs has a volume reduction of roughly 4 to 5 CCs,which is a hugh amount, and still showed no signs of being choked off for the camshaft that I plan to use in my long rod motor, in fact it picked up flow and velocity through out the flow curve up from mid lift till .420, totally on target.
racerdave
^ Gone not forgotten ^
Jack do you add material by welding, or some form of epoxy? I know in the snowmobile 2 stroke porting world epoxy is sometimes used, but can come loose.
To be honest with you, I would never port another oval xs intake port again after the semi trial Hugh did on a partially modified D port,if done correctly the gains would of been overwhelming compared to my ported oval port. When you start mentioning adding epoxy to ports,people become real skeptical in it's ability to remain adhered to the floor ,etc.
About fours years ago,I applied some JB weld to my R90/S head with just lightly roughing it up with no type of anchoring pins( was 1/4 in thickness is some areas) and for those four years with thousands of hot and cold cycles to remove the epoxy, I needed the assistance of a burr cutter cuz I was unable to chisel it out,etc,it became solid as a rock and this is no BS.
It would be difficult for me to put a dollar sign on a passion VS making a profit.
racerdave
^ Gone not forgotten ^
Jack, I am just picking your brain here, so I understand if you choose not to answer. In your reply above, you stated, "adhered to the floor" was that just speaking in general, or is the floor more in need of material than the roof?
I can weld the walls but when it come to the floor it becomes real tricky near the seat cuz even with low amperage,it will sometimes burn through. A 110 welder is the best bet but it has to be a cold weld,weld a bead,semi shape,weld a bead,etc,etc. Your not adding structural strength just adding material for filling,so keep that in mind cuz sometimes the filling appearance isn't pretty.
racerdave
^ Gone not forgotten ^
Do you want a smooth intake, or rough intake to help break up fuel droplets?
Not a problem, the floor leading up to the short turn is more crucial than the roof in this stage of the game. I wasn't in search of flow real-estate so I left the roof long side alone with exception of the valve guide boss which can be very beneficial in biasing the flow and velocity in the lower to mid lifts or increase port volume to enhance flow and velocity from mid to near max lift. You can raise the floor 3 to 4 mms but when it comes to re profiling the short turn lay it back with the corners rolling in from the wall*is the best I can describe it but really depends on how it flows. The entire port "MUST" align,meaning the roof wideness and radius leading to the walls and floor must align like hemi ports but still resemble a D shape,it that whats your searching for.
If you plan to D shape,get your floor corners cut first and take the cutter inwards to the corners near the seat but you must have the correct floor angle to do it correctly or the flow will aimed somewhat directly towards the roof . This'll open the port volume up given you room to weld in anchor pikes for the epoxy but build'em high enough for height gages when cutting the floor back down.
You want a rough texture to develop a high pressure point behind the low pressure front to enhance mixture vaporization. Developing a rough texture floor when using epoxy can be challenging as it most likely always turns to a powder,so just do your best but over time when the epoxy cures harder,it'll actually builds a rough texture,at least that's what I've experienced with JB Weld.
Nice of you to chime in Craig,wisdom and real life experiences become gold in my book
mseriously
Newb
650performance
XS650 Addict
Regarding the smooth vs. rough question as it relates to fuel atomization and flow, we discovered that with the CNC head it made no measurable difference whether the port was smoothed to remove the tiny marks left by the CNC bits or simply run "as-is."
Harry (Lillie's) hand ported heads were fairly smooth, but not polished, ditto with the Axtell ports. In contrast, the Branch XS head we dyno'd was very smooth. Not literally polished, but close to it. Shell's were much rougher, but they also had larger ports and didn't have the flow capability of the Lillie, Axtell and Branch heads.
Harry (Lillie's) hand ported heads were fairly smooth, but not polished, ditto with the Axtell ports. In contrast, the Branch XS head we dyno'd was very smooth. Not literally polished, but close to it. Shell's were much rougher, but they also had larger ports and didn't have the flow capability of the Lillie, Axtell and Branch heads.
Craig.....Did you ever have the opportunity to flow the Branch head ? and would it of been a street worthy ?
Regarding the the Shell ports size as being larger ,sometimes higher ports velocities can be troublesome is hooking up the rubber on certain track conditions and having a cushion to soften the power delivery can a viable asset wether you cross the finish line first or coming in third,this can be also applied to exhaust systems that enhance higher than normal velocities at the exhaust port.
Regarding the the Shell ports size as being larger ,sometimes higher ports velocities can be troublesome is hooking up the rubber on certain track conditions and having a cushion to soften the power delivery can a viable asset wether you cross the finish line first or coming in third,this can be also applied to exhaust systems that enhance higher than normal velocities at the exhaust port.
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650performance
XS650 Addict
Yes, I did Jack. It had the same basic approach Harry used, which was to absolutely minimize anything that would increase the port's cross section. All the work was focused upon the direction changes and, of course, the valve area.
I never obtained flow numbers on a direct comparison basis to Harry's heads, but we did dyno a XS "mule" engine with both of the heads. The difference was minimal, both in terms of the shape of the curve and absolute power/torque numbers.
The Lillie head works great on the street, so I can speculate that the Branch would also.
A street tracker I built in the late '80s had a Shell head and a #1 cam and it was pretty well behaved ... just had to give it a bit more rpm off a dead stop and if full throttle was to be applied it had to be done at a slightly higher rpm.
The Lillie head works perfectly on the street. Tony Guest's tracker has 69 RWHP (with race or av gas) and he says it is both docile at low rpm and ferocious up past 7000.
I never obtained flow numbers on a direct comparison basis to Harry's heads, but we did dyno a XS "mule" engine with both of the heads. The difference was minimal, both in terms of the shape of the curve and absolute power/torque numbers.
The Lillie head works great on the street, so I can speculate that the Branch would also.
A street tracker I built in the late '80s had a Shell head and a #1 cam and it was pretty well behaved ... just had to give it a bit more rpm off a dead stop and if full throttle was to be applied it had to be done at a slightly higher rpm.
The Lillie head works perfectly on the street. Tony Guest's tracker has 69 RWHP (with race or av gas) and he says it is both docile at low rpm and ferocious up past 7000.
Those D ports were not built by me and were not up to their full potential.
That Tony guest output just blows my mind,really super impressive.
You'd raise your eyebrows if you saw the cross sectional of my high velocity ports. It
ll be another year and I'll give you the opportunity to flow it but right now I saving up to take my grandson to Germany,so moneys tight right now, I haven't forgotten you.
