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A65L head's'
#480030 03/05/13 9:08 pm
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Greetings; first post, and I am certain not the last. Getting all the parts together to build a fire breathing A65L. AND a huge thank you in advance to all that keep this site alive and well. The information for the most part,is priceless. true story..
This is my first question. I now have two A65L heads; the casting # are as follows; head one.#(71-2202) head #2 (68-701)? Am I to take these casting numbers as manufacturing dates?? Both are in really good condition, of course new guides/valves/springs etc. are in order. Both are going to be soda blasted just as soon as I get my old tired butt out of the chair and into the garage. In any event, thanks for any and all info.
maxx40x

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Re: A65L head's'
MAXX #480034 03/05/13 9:50 pm
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Those are casting numbers. Under the BSA P/N scheme, 68- XXXX is a unit twin bit. Late parts started using the Tr*#mph P/N system, 71-XXXX is an engine bit. The 68-701 is pretty common and dates roughly 67 - 69 era. 71-2202 is a late head, probably has 5/16" rocker cover stud holes as opposed to the older 1/4" stud holes.


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Re: A65L head's'
#480041 03/05/13 10:40 pm
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Thank you for the response. Bothe heads are unmolested and I have the rocker box's for both, both correct.. no one has been into the intake ports and the exhaust ports are tight; not beat up, wobbled out etc..My next door neighbor runs Pro Stock NHRA, always in the top 10. except for last week.. blew the both motors in qualifying. In any event, both heads will go on the flow bench next week. Im not in a big hurry to build this bike; what I will do is promise to build the bike proper. Absolutely no short cuts. I love all things BSA and pre 79 Triumph.
thank you; more questions to come, I promise.

Re: A65L head's'
MAXX #480087 03/06/13 4:08 am
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Originally Posted by MAXX
...In any event, both heads will go on the flow bench next week...

MAXX,
I'd be interested in knowing how much difference the flow is on each side of the 68-701 head in its stock condition, before any porting is done.


1967 BSA Wasp
1967 BSA Hornet (West Coast Model)
1967 BSA Hornet (East Coast Model)
1968 BSA Firebird Scrambler
1968 BSA Spitfire Mark IV
1965 Cyclone Competition Build
Re: A65L head's'
Gary E #480175 03/06/13 9:07 pm
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Originally Posted by Gary E
Originally Posted by MAXX
...In any event, both heads will go on the flow bench next week...

MAXX,
I'd be interested in knowing how much difference the flow is on each side of the 68-701 head in its stock condition, before any porting is done.


First of all, Im ready for the snow in my backyard/driveway to go away.NOW!!! the older I get, the colder (it) gets.
In any event, I too am interested in knowing how well the stock ports flow and as soon as I get the heads on the bench I will give a full report. Years ago, (35+) I bought a few vary fast Triumph flatrackers; I would pull the motors and disassemble them, documenting/measureing everything that had been done to make the motor not only fast, but why it was staying together while being run as hard as these motors were run. Three of these motors were running 34mm Mikuni's that had been taper bored; the carbs were bored to 35.5mm, the intake spigots followed the same taper to the intake port on the head which was at 32.5mm on three of the four heads, and they were all about seven inch's ,center of carb to center in valve face... those motors were vary crisp; they sounded like they wanted, begged to be run hard; and trust me on this one little thing; in the days of my youth, I flogged each and every one of them on the street,(street trackers before they were cool) The 4th motor had a head that had been ported by Axtell, running 36mm Dellorto pumpers. that motor didn't come on the pipe until probably 6500rpm, like flipping a light switch on..! the ports were huge at 33+mm+ at the head. that motor never seamed to run as well as the heads with smaller ports, nor was it as crisp at lower rpm. Of course, It all makes sense now; I have all this info cataloged, just have to dig it out. valve size's/shapes/specs, cam' specs etc.. In any event, I never did get around to building a BSA motor; until now. I am thinking the BSA heads will respond as well or better than the Triumph heads, specifically when modern porting techniques and port shapes are used. What I am damn sure of, is this; Im going to find out. Im not silly enough to believe Im going discover an earthshattering/groundbreaking/heavens opening up/lightening bolt method of porting a BSA head. That has already been done..i think...?? Hell, Im 60 something years young, retired, and ; did I tell you my drive way needs plowed .sonofa%&#@@.....have to see if the tractor will start; what a xocksuxker.......I will keep all that are interested informed;
thank you again for the info and input. if you ever get this way, stop in and have beer, or coffee, or both.. I really don't want to go outside hear comes my wife and she wants the drive plowed NOW.... there is no longer any place to hide sonofa%^&#&......

Re: A65L head's'
MAXX #480207 03/07/13 1:26 am
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Midwest is pretty big Maxx! Can you narrow that down?

Bill


69 A65T
71 B50T
85 K100RS
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69 B44VS
71 A65FS
95 Trident
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Re: A65L head's'
No Name Man #480210 03/07/13 1:46 am
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Must be the offer of beer and coffee got Bill's attention laughing


Never underestimate the human ability to elevate stupid to a whole new level!.
Re: A65L head's'
No Name Man #480218 03/07/13 3:07 am
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I found a place to hide; and, by the time I got ready to plow the drive, the white stuff was melting, LMFAO.... my GSPs and I went to our woods,(German shorthair pointer's)my wife wont follow us into the woods. Then we got cold and hungry and had to come home..damn.
At any rate, our farm is in licking co. Oh. but I speed most of my time up on the lake (Erie). yup, I fish ,hunt, and shoot competitive archery, and center fire benchrest every chance I get, which ,by all accounts,(my lovely wife) is a lot. In any event; apparently Im not so far from either of you. the offer stands,,, beers and coffee, or Scotch, or Bourbon, or there is an ole boy back in the holler that produces a lightening that did not come from across the pond.. just sayin.

Re: A65L head's'
MAXX #480330 03/07/13 8:55 pm
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Yeah we should get together. Beer, coffee, BSA's...oh and don't forget food. Several on here near enough to do this. Somebody organize something.


69 A65T
71 B50T
85 K100RS
54/59 A10SR
69 B44VS
71 A65FS
95 Trident
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Re: A65L head's'
No Name Man #480397 03/08/13 3:08 am
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Agreed...

Re: A65L head's'
No Name Man #480512 03/08/13 11:53 pm
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Originally Posted by No Name Man
Yeah we should get together. Beer, coffee, BSA's...oh and don't forget food. Several on here near enough to do this. Somebody organize something.


I'll be out and about Sunday. It will be a Brit ride. Modern appliance type Brit, but still Brit laughing So you buying Bill? beerchug


Never underestimate the human ability to elevate stupid to a whole new level!.
Re: A65L head's'
MAXX #480570 03/09/13 11:40 am
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Hi Maxx, it would be interesting to see the flow bench results. I'd like to try one of my modified heads on one. I don't have access to one, but what I've done is to fit big valves and carbs and open the ports, the Lightning head is much better than a Triumph twin to hot rod because of the valve angles and that it was designed for a bigger bore and will fit much larger valves. After opening the ports which tapper from 38mm at the carbs and stay fairly large right through I fill the port floor to make it D shaped, that seems to retain the flow and give less drop in gas speed, thats what I'm guessing because of how it makes power. With a big bore kit (79.5mm) the breathing seems better again, seeing power increase is out of proportion to the displacement increase. This post shows a bit of stuff I've done to my A65:
http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=212693&page=all


mark
Re: A65L head's'
MAXX #480602 03/09/13 5:59 pm
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You wanna meet up somewhere? Zville maybe? I will ride a BSA as my almost modern bike isn't running right. Anybody else? Mark, if you left yesterday you could make it in time to meet us.


69 A65T
71 B50T
85 K100RS
54/59 A10SR
69 B44VS
71 A65FS
95 Trident
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Re: A65L head's'
Mark Parker #480603 03/09/13 6:04 pm
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Mark Parker; WOW>incredible build on your BSA. I will not be re-phasing my motor this time around; there just isn't enough time to get everything accomplished I want, and need, to get done. I know there are a few guys on the left coast (California) that have been D-shaping the ports on 650/750 Triumphs for quite some time, and have had varying degrees of success. I don't know at this point if I am going to weld/reshape the ports on my heads; I just have to wait and see what the flow bench tells us to do; what the head/valves/cam wants/likes. I have a SRM 750 kit on the way; I need to figure out what cam to run. This bike is not going to be a track bike. I will get it out now and then for the local bike nights in the area, ride it to a local tavern to have a beer or three, AND then, go street race. I have access to a pile of used titanium valves to cut down and shape. If I can stick to my schedule (6 hrs a week to work on the motor,and get the frame on wheels (a roller) I might have it done by end of summer. what I don't understand is why there is little or no flow information/numbers posted on this forum?? I would have thought that information would have been all over the forum??? maybe I haven't found that particular thread.. all I can do is post, with pix of the flow bench printout of the numbers I/we get. back to my cam selection, I'm going to run a big lumpy cam; I don't want a mild mannered/totally comfortable curser,, I have one of those. I'm building a little fire breathing BSA.I was going to use a Trackmaster frame, but the frame is old, and showing signs of fatigue. I could grind out and re tig all the bad welds; but what I have found is most of these old flattrack frames are rusting from the inside out. A new 4130 frame is not in the budget...So, Im going to use a 72,OIF, with a few modifications. any information on a good/great hot street (light to light)cams, I would be interested in the specific's. thanks in advance for any and all information.

Re: A65L head's'
MAXX #480617 03/09/13 9:37 pm
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PeteR gave some info about flow, but i don't remember the name of the thread. The summary was, ports of newer heads flow more air then valves, so I got a smaller port head for my bike just to check it up. Another reason was constant talk here how a small port head was so much better comparing to big ports head.
I've bought one such a head and realized it has tapered ports and now am installing kibblewhite valves + cast guides in it.
Looks like very expensive project to get perhaps some more hp in the lower revs range.
But some people here claimed this head is a business so I decided to try.

Re: A65L head's'
Adam M. #480623 03/09/13 10:57 pm
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If you do a flow test at a realistic valve-lift (about 3/8"),the big port doesn't help.
The bigger intake valves will help.
See how much you can reduce the port size without losing flow.I think you'd reduce it a lot between the guide and the seat,before it became restrictive.

Re: A65L head's'
MAXX #480661 03/10/13 4:11 am
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Originally Posted by MAXX
...what I don't understand is why there is little or no flow information/numbers posted on this forum?? I would have thought that information would have been all over the forum???...

I know, I know. I posted a thread months ago looking for A50/A65 head flow information and got few response. Most responses were ambiguous with 'probably', 'might not', 'not likely', 'little to be gained', etc. types of comments with no solid information. I felt like, those in the know aren't talking. After 45 years, it ought to all be figured out by now.


1967 BSA Wasp
1967 BSA Hornet (West Coast Model)
1967 BSA Hornet (East Coast Model)
1968 BSA Firebird Scrambler
1968 BSA Spitfire Mark IV
1965 Cyclone Competition Build
Re: A65L head's'
Gary E #480672 03/10/13 5:17 am
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Originally Posted by Gary E
Originally Posted by MAXX
...what I don't understand is why there is little or no flow information/numbers posted on this forum?? I would have thought that information would have been all over the forum???...

I know, I know. I posted a thread months ago looking for A50/A65 head flow information and got few response. Most responses were ambiguous with 'probably', 'might not', 'not likely', 'little to be gained', etc. types of comments with no solid information. I felt like, those in the know aren't talking. After 45 years, it ought to all be figured out by now.

Exactly. Those who know the numbers, are not talking, and Im okay with that. The only way Im going to understand what makes an A65/750 head breath, is to do it myself. I have two A65 heads, and should have one more on the way. I should be able to get it sorted out. I talked to a guy that had a quick A65/750 short rod motor; His thinking is I would I would really like the Megacycle 544-3 cam (380'lift @244/106 lobe center. All I can do is get the head on the flow bench and find out what works.
AND THEN, there are those that say run the TS bushing as long as its set up properly; AND THEN, there are those that say run the bearing set up.?? Im ordering the crank on Monday; that is a 10+ week waiting period. That should give me enough time to get the roller (frame) together, and the head sorted out. I bought three (71-71-72) bottom ends; all with titles. I will start posting pix soon. I also want to insure all the purest, that even though Im going to hot rod this motor/bike, It will be vary well cared for. I fully understand that there are vary few stock BSAs on the street. like the Triumph's, too many ,far too many, have been hacked up and left set to rust away; and hacked up to the point of no return. thanks again for all the information. priceless.

Re: A65L head's'
maxx77 #480686 03/10/13 11:08 am
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You obviously need some flow to keep the engine running.About 65-70 cfm at 10" vacuum would be enough to have it running well at 6000 rpm.
Equally important is to have high flow per square inch of port area.In a 100% perfect world,you'd get 87.25 cfm per square inch at 10" vacuum.You can't get more than that through the point of smallest cross-section area.You could get 95% of that.

If the port is too big at any point and you've only got 75% of that,you've killed the velocity.Compared to 95%,the kinetic energy per cubic inch of gas is down to about 62%.With less momentum,what keeps the gas moving into the cylinder after the piston has passed the point of maximum piston speed?Not much,especially around or just after BDC.

I did a test on a big port head.I wasn't particularly after CFM numbers,but just finding out where restrictions were in the port.
It flowed about 85-86 cfm at 10" vacuum,after removing some restriction near the valve guide.The valve-lift was a little over 1/2" (possibly 13mm) to get that.

At normal valve-lift,it probably flowed about 70 cfm.
70 cfm on a 30mm port is pretty slow,about 64 cfm per square inch.

Re: A65L head's'
MAXX #480721 03/10/13 3:38 pm
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MAXX, If you want a real 'wild' cam, I have a Megacycle X-8 Gathering dust. Didn't care for it much on my 650. PRT

Re: A65L head's'
MAXX #480723 03/10/13 3:45 pm
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Greetings Maxx, welcome to a great forum and thanks for starting this thread. Looks like it's going to be very informative!

Just bought a cabinet and in the process of soda blasting a couple of 68-701 heads myself,

Which crank are you ordering?


BSA
Matchless
Triumph
Re: A65L head's'
MAXX #480733 03/10/13 5:10 pm
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Maxx, I'm restoring/building my first BSA (A65/L) Enjoying the great thread on heads. I,m looking foward to the next on. I'm from down south and around here geyying some of that "white lightening" is not a big problem. If I get a chance I'll bring some up your way and you can enlighten me on flow characteristics. In tha mean time plow that driveway.

Re: A65L head's'
pushrod tom #481154 03/13/13 7:13 pm
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Originally Posted by Mezz
Maxx, I'm restoring/building my first BSA (A65/L) Enjoying the great thread on heads. I,m looking foward to the next on. I'm from down south and around here geyying some of that "white lightening" is not a big problem. If I get a chance I'll bring some up your way and you can enlighten me on flow characteristics. In tha mean time plow that driveway.
Originally Posted by pushrod tom
MAXX, If you want a real 'wild' cam, I have a Megacycle X-8 Gathering dust. Didn't care for it much on my 650. PRT

(pushrod tom)That's a lot of cam. cam choice is what's holding me back from making aluminum dust around the flow bench . As always with aftermarket cam choice's, seams like you have to sacrifice either the big end or the little end. never seams to be a cam that will pull from idle to the stratosphere without sacrificing the mid range. I will however keep in mind that you have the cam. What did you not like about the cam.? Granted, you were running it in a 650, that's a lot of cam for a 650; Im assuming the motor was/is set up for class specific rules?? road race? _(Mezz) LMFAO..yeah I only get into that stuff once maybe twice a year. hopefully we can get together and compare notes on not only the A65, but the delicate balance of grain's and gunpowder used to make that stuff.
thanks again for the information.

Re: A65L head's'
maxx77 #481166 03/13/13 9:45 pm
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Maxx, The X-8 just didnt seem to give much for the amount of work it took to get it in the motor. Had to clearance the case and the lifter guides to make room. I have used 4 different cams and have another one in the wings. So far the stock cam set up at 105 I and 101E lobe centers has given me the best hp and speed. My current setup looks good but will have to get on the track (ECTA Willmington, Ohio April 26-27) to see how it really pulls. The development started last summer and included several set ups of a new build. One significant change is a Mega X-2 Adjusted for best results on my motor. I don't ride it around as a street bike but it sees some miles for breakin and tuning. In a (mostly) head to head comparison with the stock cam in the same motor, it picked up almost 4.5 hp and 2lbs. torque across the range. Maybe, with camshafts, less is more? Cheers, PRT

Re: A65L head's'
pushrod tom #481183 03/13/13 11:20 pm
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Originally Posted by pushrod tom
Maxx, The X-8 just didnt seem to give much for the amount of work it took to get it in the motor. Had to clearance the case and the lifter guides to make room. I have used 4 different cams and have another one in the wings. So far the stock cam set up at 105 I and 101E lobe centers has given me the best hp and speed. My current setup looks good but will have to get on the track (ECTA Willmington, Ohio April 26-27) to see how it really pulls. The development started last summer and included several set ups of a new build. One significant change is a Mega X-2 Adjusted for best results on my motor. I don't ride it around as a street bike but it sees some miles for breakin and tuning. In a (mostly) head to head comparison with the stock cam in the same motor, it picked up almost 4.5 hp and 2lbs. torque across the range. Maybe, with camshafts, less is more? Cheers, PRT


you guys are killin me. OK, with the information Im getting, I'm now not really sure how the SRM750 is going to respond to, or what the 750 is going to want in regards to a cam; in regard to the Mega x3 cam, my best thinking tells me its going to like it. Its like the carbs, I would love to run GPs, but I don't know if that is feasible with this motor; again my best thinking tells me to set-up a pair of Mikuni's and call it a day. I am certain I am going to have a blast building/researching/picking the knowledgeable brains on and off the forum. Many, many years ago I had more than a few conversations with Earl Bolwbe ; at the time I didn't think I was going to be building a BSA; needless to say, I should have paid attention.
thanks for the confusion, er, I mean information pushrod tom.

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