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Re: The what if A65 67hp challenge. [Re: Mark Parker] #784521 09/16/19 11:44 pm
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Dave,that's quite interesting ...I like adapting exisitng parts..


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
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Re: The what if A65 67hp challenge. [Re: Mark Parker] #784529 09/17/19 1:49 am
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Dave, Peter Turner moved the outer studs in his cyl so he could use bigger pistons 82mm at least. His motor is 914cc or something like that. Maybe you could get a cyl from him they look fabulous. 9mm works well in the alloy block and though through bolting would be preferable it's not necessary. I made my cyls to be strong, though the base flange bolt location means cutting in for flats for nuts, I used flange nuts that suit a 12mm spanner to minimize that cutting.

Peter uses roller rockers in that new section, they give 1/2" valve lift from the stock cam. It's a very crisp sounding motor.

[Linked Image from i.postimg.cc]


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784543 09/17/19 3:51 am
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gavin eisler Offline
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Amazing work on that motor, the rocker box lift alone. Braw.!


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784545 09/17/19 4:20 am
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Looks like a Cylon BSA laughing

Re: The what if A65 67hp challenge. [Re: Mark Parker] #784546 09/17/19 5:28 am
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Gavin, is this the type of carb you bought? PKW $60au for a pair including postage?

If I get 34mm I can use them on the Firebird with either head.

[Linked Image from i.postimg.cc]


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784549 09/17/19 6:20 am
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If a new head is cast, besides making the chamber for the 80mm pistons, the valves could have buckets added so smaller stems can be used without the rocker side load causing problems. That would reduce guide and stem wear too. I would have to go back a ways to find a two valve head with buckets large enough for the springs, around the beginning of the four valve era.
Supertech has buckets up to 37.5mm diameter for BMW S14, 35mm for VW 16V.

Re: The what if A65 67hp challenge. [Re: Mark Parker] #784557 09/17/19 7:48 am
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Yes, of course you wouldn't be able to weld that centre plate, DURRRRRRR.
As well as the fact you couldn't get the crank in it wouldn't be able to leak oil would it????? Bloody shame, it would loose it's character.

The largest i ran was with 80.5mm pistons and 90mm crank. Around 920cc. (Similar to the Hanks' type setup.)
I did this as i lost a circlip and screwed one bore running 79.5. Normal was 79.5 or 80 x 89 (buttons after that!)
The shaped/stepped 3/8- 5/16 studs were ok using grade 10 just long and set in well. No head gasket problems really.
BUT, that barrel was really good close grained cast iron.
Used my own long 3/8 UNF/UNC barrel studs as far into the cases as they would go, grade 10.
I did have a through bolted barrel off an a65, as it was bored to +100 (T140+0.60 pistons) We just made tubular sleeves that
Screwed into the top 4 or 5 fins then ran half a dozen 5/16 allen bolts down into the base flange from the sleeves. It was OK but
the triumph pistons were not very good even after machining a fair bit, the basic shape wasn't really correct for the beezer head.
I ended up having the barrel lined and it was sold with the bike on the 650 spare engine. Getting the angle right for the drilling was
the thing, considering we did it on a pillar drill! It gave us an 840cc or so motor, and after shaving around 80 or so thou off the
barrel it was OK. A bit over 10-1 as i remember.

I never saw that big beezer of peter turner's at a track, was it any good?

Re: The what if A65 67hp challenge. [Re: Mark Parker] #784568 09/17/19 11:05 am
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That looks identical, jets are Keihin types. I have numbers somewhere


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784572 09/17/19 11:53 am
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It's his road bike Nick. He's even fitted an electric start. He works in motor sport so has flow bench and obvious skills. The carbs are 36mm from memory. He welded up a std crank and had it ground to 85.5mm?

I cannot use a flange plate on the port on the Thunderbolt to mount a manifold so welded up the bolt holes added some weld and drilled and tapped new mounting holes and made a manifold. I need a mill to do the gasket face frown It's pretty close with a file but a mill would be so easy.

I'm guessing the carbs suit 2 or 4 stoke motors.


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784573 09/17/19 12:00 pm
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Crikey! All this talk of giant motors makes my 650's seem like Bantams. I have enough trouble keeping everything buttoned down as it is. I have been using the John Hill barrels for a few years with good results. Using 5/16 bolts I have to be careful with the torque wrench though. I go about 26 ft/lbs and they stay tight with barely noticeable distortion in the bore. The turbo is undergoing a refit. The right cyl. gets hot and stresses everything. The left is ok. This has been an ongoing problem so if we can get 'er together we will have to measure each cyl to try and find n fix the problem. This spring we did at least 30 full power pulls at well north of 100 rwhp and it behaved perfectly. Of course a 3 second dyno pull is not the same as a mile or more at Maine!
As a side note, the original motor lasted for years with much abuse. The original 1966 5/16 studs and nut were never a problem. However, the motor we used for nitrous only use detonated and blew all of the 'special grade 8 nuts' right off the studs. Nuts were soft. Cylinder came up and hit the tank creating quite a leak. Very lucky. No flame! The adventure continues. I'm enjoying this thread! PRT

Re: The what if A65 67hp challenge. [Re: Mark Parker] #784579 09/17/19 1:10 pm
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8mm and 5/16 are the same size. By using metric threads I was able to simply tap to 9mm when I needed to, being the same pitch. 3/8 is 9.4mm.

Has Peter Crawford talked to you about his books on A65s Tom? Do you have power graphs you could share?


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784588 09/17/19 2:55 pm
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The carbs came with un numbered big jets, i think they are mostly aimed at twostrokes. i still havent tried mine yet.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
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Re: The what if A65 67hp challenge. [Re: Mark Parker] #784629 09/17/19 10:49 pm
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Originally Posted by Mark Parker
It's his road bike Nick. He's even fitted an electric start. He works in motor sport so has flow bench and obvious skills. The carbs are 36mm from memory. He welded up a std crank and had it ground to 85.5mm?

I cannot use a flange plate on the port on the Thunderbolt to mount a manifold so welded up the bolt holes added some weld and drilled and tapped new mounting holes and made a manifold. I need a mill to do the gasket face frown It's pretty close with a file but a mill would be so easy.

I'm guessing the carbs suit 2 or 4 stoke motors.


Ah, shame i thought that beezer may be used properly. It does look pretty though.
The first couple of heads we did used bolt on manifolds done in a similar fashion to the way you describe.
You have to cut off the whole back of the head really for a good job, it makes the welding easier even with
stubbs.
Those wing wong carbs look very good, and similar to the JRC type i think. (PWK, Kehin etc etc.)
You can buy jet kits for them, i suggest starting at around 135 as a main on your 750.

I still don't know about all this huge carb lark though, i suppose that at a squillion revs you may need bloody
great orifices to get a mixture in but on a typical race track you are flat out for only a short while, the ability
to accelerate quickly from 4-7k is far more important and gets better lap times than another 2mph on a straight.
I have a set of 36mm venturis here for my old weber but i only ever used them once or twice, 33-34 was the norm.
If i raced over on the iom then 36 may have been the way to go. In my experience, many racers tried huge carbs
and went back to smaller ones for the same reason, lower and mid-range.

No i have no records of any stuff i did on the dyno as it was nearly all back in the uk.
All binned when we moved here in '99. Most of it was on a 750 srm kit and the early 89x76 rig. There wasn't much
but i remember the big jump when we tested the 810cc motor, straight away we got upper 60's at the back wheel.
We struggled to get better than mid 60's with the 750 kit.
The last time we tried it (over here) we were getting the 80+ we had been chasing for a long time, but the only things
i got to ride against were bloody hondas.

Last edited by NickL; 09/17/19 10:51 pm.
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784637 09/18/19 12:12 am
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But, big carb and big port doesn't mean big flow 34-36 just means the carb will match the valve size, and the ports themselves are not huge but the flow is. I have this manifold 34mm, when the carbs arrive, slow boat from China, we'll see what the whole deal flows. The Thunderbolt head is better than the Lightning at this stage, and I put the guides back in the Lightning so will not mess with it anymore it has plenty of flow for a 650. I have some more twin carb heads I can mess with.


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784668 09/18/19 11:11 am
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Mark, Not aware of Peter Crawford. Most all of the test results are in Mikes computer.

Re: The what if A65 67hp challenge. [Re: Mark Parker] #784672 09/18/19 12:09 pm
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When comparing dyno readouts we all need to keep a few things in mind, Primarily,all almost use a Dynojet inertia Dyno, a good tuning machine but the power figures are about 10% higher than the eddy current or water dynos used by the manufacturers...An inertia measures how fast the vehicle drive wheel accelerates the dyno roller..An bike with a light flywheel will show more HP despite it really does not make more HP. Eddy current applies resistence to the dyno roller and can hold the engine from reving to full rpm.
A good example is this partial reading from my 650 Triumph race bike....The dyno is a Superflow , that is both eddy current and inertia..Through years of testing the machine's computer is programmed to show both readings...
The first two columns are Dynojet HP and torque, the second two columns are true HP and torque like the manufactuers use...A/F was disconnected.....Notice the power difference...My bike ran 133 MPH with less than 50 true HP at the rear wheel...

[Linked Image from live.staticflickr.com]


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784690 09/18/19 3:40 pm
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This is the graph of the 883. The operator went to some pains to explain it's a ramp type dyno not inertia, he could adjust it to take longer to spin up the drum. It held the bike at a predetermined speed until the run was initiated when it hit the maximum speed or rpm we selected it again held it to that rpm. Except the first run, which indicated 85.4 on the screen with an inaccurate rpm count, so we ended up using speed rather than rpm to control rpm.

The graph is in KW frown even though hp was what was on the screen while we were doing it. 61.4kw is 82.3rwhp which realistically converts to 93.3hp at the crank, 50kw is 67rwhp-76hp @ crank. 40kw is 53rwhp -60hp. If I didn't have to pay to fix it if something broke I'd take it back in and try it with the correct mixture, the new freer flowing mufflers and maybe the extra 1000rpm the operator wanted to run it to. Why I envy the guys developing stuff at Umberslades where they were being paid to test engines and chase the best settings and find exactly what a configuration would deliver, without having to walk home if it all went wrong.

[Linked Image from i.postimg.cc]


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784693 09/18/19 4:38 pm
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I believe a ramp rate has a braking device to allow a a pre set rate of acceleration of the roller...An Eddy current is like a generator load device of sorts can can be programed to actually stall the engine at a given rpm...So the power readings having nothing to do with accelerating roller speeds...This is not to belittle anyones tuning , but to clarify why dyno readings can't be compared unless on the same machine..

This is a good example of a water or eddy current dyno...An 830 HP V8 is stalled by the dyno ..





79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784729 09/18/19 11:43 pm
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PES are selling 44.5 mm B44 inlet valves , i have just bought a pair, nice waisted heads and are roughly 2mm longer than a stock 71 valve i have lying around, should do the trick without having to sink the seat to prevent coil bind, has the same looking wee collet grooves too.,
I found them on that place,


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
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The poster formerly known as Pod
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784753 09/19/19 7:17 am
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Is spring pressure effected Gavin with the stems being longer?


beerchug
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784758 09/19/19 8:59 am
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Bigger valve heads sit further into the chamber, need longer stems to keep spring pressure equal. Or the seats need cut deeper.
I had to get seats cut deeper with the last set of big inlets from SRM, these PES types look more like the thing.


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56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784761 09/19/19 10:34 am
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I was in a discussion with several successful engine builders, auto drag racers....They claim from experience that if you have heads with identical flows rates, but one has higher velocity ports,when cammed and tuned for best power, the lower velocity ports will make more high end power and the vehicle will be faster on the track...


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: The what if A65 67hp challenge. [Re: gavin eisler] #784767 09/19/19 12:01 pm
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Originally Posted by gavin eisler
PES are selling 44.5 mm B44 inlet valves , i have just bought a pair, nice waisted heads and are roughly 2mm longer than a stock 71 valve i have lying around, should do the trick without having to sink the seat to prevent coil bind, has the same looking wee collet grooves too.,
I found them on that place,


Beware of piston contact, although you may get away with them with a standard cam.
You can always use shims under the spring cups to set the weight, had to do that with W+S springs anyway.
Used B50 exhaust valves at one time but they didn't do much good for me, and made cam timing more awkward.
I still reckon the PM +1.5mm inlets are a good valve. (Black diamond) Good shape, weight, length etc.

Re: The what if A65 67hp challenge. [Re: Mark Parker] #784768 09/19/19 12:11 pm
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That actually sounds backwards? If the port is low velocity power has to come in later with a narrower power range? I guess it may depend on exactly what that velocity is. From what I've read the BSA ports are low velocity in as much as the velocity can be increased without approaching any detrimental critical speed. Anyway we will find out, just trying to lace wheels for the '70 Firebird, does anyone know if the front has an offset or if the rim is just central to the forks and axle? The thing weighs a ton.

What I'm after with this head is a nice wide power range, so I'm chasing the best flow from the smallest ports to obtain this.


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784773 09/19/19 1:23 pm
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Yes ,perhaps backwards other than extreme drag racing.....I believe you would enjoy this this thread and the especialy the forum in general.... You may have to join the forum to see it. There a lot of pro US and Australian tuners, mostly cars but there are also some bike guys...A lot of it is beyond my knowledge level..

Speed Talk


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
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