Another vintage project from Great Britain, target Speed Week 2011

[octane]

Welcome back Patrick !
...and congratulations with your new blower.

IF IT AIN'T BLOWN IT SUCKS !

.. Had a go at it but it will take a better press than I have here in the garage to split the body!!!

P L E A S E   D O   N O T   DO   T H A T !!!!!!

...if it's build the same way as my AISIN 300



 and I'm pretty sure it is.

Please see this  ( and scroll down ):
CLICK
...where you'll find pics of the failed 'rebuild' of my (first) blower.
First problem: you will inevitably damage the bearing during dis-assembly
and they have the most wacky of wacky dimensions and they are NOT available.
As you can see ; that problem can be worked around.

BUT

The problem, to witch I never found a solution is that there is NO WAY
you can hold the rotors in ABSOLUTELY correct position during assembly.
I thought I could, using the method shown, but it never was perfect and it
needs to be bloody PERFECT.
The smallest of smallest of the smallest out-of-true will cause them to interfere with each other.
Now IF you have them in the correct position there is no way to
avoid that the position of one of the cogwheels ( is that the phrase ?) WILL move.
As you press it in with the nut it moves because of the 'angle' of the cogs in the cogwheel.

It's a VERY strange set-up.
BOTH wheels are pressed on ( you'll need a LOT of heat . It's EXTREMELY tight )
AND one (!) has a nut.



As you tighten up the nut the wheel clings to the lobe-shaft
and as the cogs are 'angled' ...the wheel turns ( in relation to the other wheel )
and drives the shaft with it...ever so slightly....
and the set-up gets out of wack.


The blower that I rebuild for my Honda didn't have that problem cause
the cogs are straight.



I really wish I could explain it better.

If need be, send me a PM with your phone-number and I'd be happy to give you a call
and maybe explain it better.

[ EDIT: just re-checked you pics. Appears that maybe your 500 isn't build the
same way as mine, so maybe you don't have the same problem (?) ]

[thefrenchowl]

Hi Lars,

Thanks for the tips and the link to your thread. My AMR500 looks a bit different than your AMR300... No nuts on the gear side, plus there's a timing mark on the gears. Only one nut on the drive side with woodruff key for the pulley. The drive bearing is as yours, wider than the slave lobe, and sticks out a bit...

The pulley is about 75mm, 3" pitch diameter... That would mean a 6" pulley on the engine sprocket, way too big cause of the KH clutch arrangement. The plan is to fit that 3" pulley on the engine and find a smaller one for the AMR. I plan to start with a 2 to 1 speed ratio...

On mine, I do not intend to part the gears from the lobes, just looking at pulling off the whole gear housing and lobes and turn it 180 degrees. The sticky point seems to be the 2 pins that locate that housing to the body casting proper.

I've googled this AMR500 till death recently, can't find anything about making it spin the other way. One drg I've found seems to show a small casting diff between the intake and exhaust chambers.

It does suck and blow whichever way I make it spin, but I'm a bit worried about spinning it at 11000rpm the reverse way from what it has been manufactured for!!! Swapping the drive from bottom to top will keep the chambers as intended.

All the best from Patrick

[jdincau]

I don't know if it applies to your supercharger but as I remember on our 6-71's Mooneyham put shims behind the gear so when it is tightened the indexing becomes correct.

[38flattie]

I love this idea for this bike!

Are you going to use the 'stock' cams, or are you changing cams for the blower?

[thefrenchowl]

jdincau: our 6-71's Mooneyham put shims behind the gear

Don't know yet if there's any there!!!

38flattie: Are you going to use the 'stock' cams

Bit of a quandry here... It's a KHK, high lift cams, .375 which is good, but lots of overlap, not so good...

I've tried to find a set of KH cams, they only lift .295 and would have less overlap but no luck so far... I don't have pockets deep enough for new cams, the supercharger was enough of a drain!!!

The drive train for the 4 cams makes it difficult to retard the inlet cams by the same amount, rear inlet is driven from the timing shaft by a 36 teeth gear (10 degrees per tooth) while the others 3 are driven from the rear inlet with 24 teeth (15 degree per tooth) gears. So it's probably easier to advance the exhausts to loose some of the overlap...

Patrick

[panic]

rear inlet is driven from the timing shaft by a 36 teeth gear (10 degrees per tooth) while the others 3 are driven from the rear inlet with 24 teeth (15 degree per tooth) gears.

I know it looks complicated with the cover off.
The #2 has 36 teeth on the driven row, runs at 1/2-speed off the 18 tooth pinion gear.
This sets the relative speed of the entire gear train, and the other gears are driven at this speed by their common 28 tooth row.
Since the all cams run 1/2 speed, each tooth on the big (36 tooth) row is 20°, each tooth on the small (28 tooth) is 25.71°.
Unfortunately, the overlap can only be addressed by moving the #1 or #4 (exhaust) cams relative to their drivers (#2 & 3), which is a huge change and leaves the overlap asymmetrical (I'm not sure what that will do here).
The exhaust duration has to go somewhere, and here it's removed from the working cycle by opening the exhaust 25.71° earlier which drops average BMEP quite a bit.

My KHK data shows timing as:
intake 30-57 (273) 98.5 CL
exhaust 65-33 (275) 102.5 CL
overlap 73, LSA 100.5.

Advancing the exhausts 1 tooth:
intake 30-57 (273) 98.5 CL
exhaust 85.7-9.3 (275) 128.2 CL
overlap 47.3, LSA 113.35

The overlap triangle area is reduced to about (using Vizard's guess) 42%, really huge.
Since there's no contact or interference problem, might as well try it.

[thefrenchowl]

Hi Jeff,

Thanks for correcting me on the teeth numbers  it's indeed 28 teeth on the train, not 24 as I recalled from my deficient memory!!!

You know I don't have much experience with superchargers, but I did see a lot of race engines over the years... As far as retarding the exhaust cams, it would follow most race cams I've seen. Per example, on the H-D/Aer Macchi CRTT, the H cam grind opens the exhaust 105 degrees before BDC, reason being they deducted from engine dyno tests that all the power from combustion is in the piston by that time and there's not much to be gained at the bottom of the piston travel. Could it also have to do with much higher revs than US built SV or OHV H-Ds??

So it don't look too outrageous to me with exhaust starting to open at 86 degrees before BDC.

I still think one still needs a bit of overlap in a supercharged engine to develop any power.

Surely, if one starts with a WL type cam, no amount of supercharging will compensate for the very mild timing one's stuck with???

My friend Gordon came to see me this afternoon to look at the supercharger, so we wheeled the bike out in the rain while the tea was brewing...







See you around,

Patrick

[bak189]

Question....do you think with gravity feed to the carb. the float bowl on the S&S is big enough using a blower.......We had to make some major mods. on our Turbo/Busa S&S carb. on a draw/thru system using gravity feed at 12lbs boost...it would suck the standard bowl dry in a 2mile run on the salt..................

[thefrenchowl]

Hi, bak189,

Good question!!!

I measured once the bowl capacity, it's 175cc... All I can say at this stage, it coped allright on methanol on my normally aspirated XLRTT!!!

My supercharger calcs tell me I will be using between 800cc and 1000cc of methanol per minute at 5500rpm...

Patrick

[wobblywalrus]

Patrick, that is a nice bike.  A suggestion if you run it on the salt, especially wet and rutted salt.  Use a shorter rear strut and lower the forks in the trees to give yourself more trail.  Run it and see how it works.  Assuming you get no wigglewaggle on decel, you can drop the front and use the long strut.  It is a good idea to be on the safe side at first.

[panic]

Sorry, major typo in the KHK timing figures - used some from the next line in my .xls table (my edit expired, can't correct theoriginal post)

KHK data shows timing as:
intake 38-55 (273) 98.5 CL
exhaust 60-35 (275) 102.5 CL
overlap 73, LSA 100.5.

Advancing the exhausts 1 tooth:
intake 38-55 (273) 98.5 CL
exhaust 85.7-9.3 (275) 128.2 CL
overlap 47.3, LSA 113.35

Well, you're stuck with using K, KH etc. due to the lobe tapers so a 45 isn't going to help. I know people have used KH in a 45 (same angle, but reversed) for quite a while, but it wasn't at high speed or with bog springs, and it eventually eats the lobe (the roller corner digs in, then the hard-face comes off).
The LSA actually looks pretty good (certainly better than stock) and despite the low OL duration you have boost to help it out.
I can't think of anything else that doesn't require replacing cams.

[thefrenchowl]

wobblywalrus: Use a shorter rear strut and lower the forks in the trees to give yourself more trail.

It's already as low as can be on the rear end, 3.50 x 18" tyre is only about 1" from bottom of seat. The Cerianis tube ends are about 2" or 3" above the top tree so I can lift the bike a bit if needed. I just assembled it as it is on the principle that the lower the bike for a given wheelbase (55" for this frame), the more stable it should be???

Its rake is the same as std Sportsters or Ks, 29 to 30 degrees, and I certainly don't want to modify the frame!!! I'll AutoCAD the set up to see the rake/trail variations if I lift the front end.

Thanks for the tips!!!

Jeff, I will probably try the KHK cams to start with... I've had the bike for 27 years now and never put a degree wheel on it, but I will check these figures in the near future to compare with you data and calcs. Thanks again for your insights...

Patrick

[panic]

Are those 35mm mid-weight road race?
There are a few different fork tree sets for those, you may find one with a stem position closer to the tube center, which will add trail (same rake) in almost 7/8:1 ratio (move stem 7/8", get 1" trail).

This is going to sound odd, but using struts doesn't tie down the swingarm as well as it looks. You still have a bit of wiggle in the S/A pivot Timkens (just guessing: the normal adjustment is pre-load it until the bare S/A locks up, then back off until it barely falls of its own weight?); I'd increase the pre-load slightly.

[thefrenchowl]

Hi Jeff,

Yes, these are period 60's road race Cerianis, not the CNC type modern stuff, found them in France, with steel extensions to fit a tall Laverda twin... Bartered them for a set of 30s Guzzi race Brampton girders somebody else gave to me, I tell you, race on a shoe string!!!

  Yes, the swing arm adjuster nut is tight, real tight plus a bit of hammer at the end of the socket!!! Doesn't move up or down at all...

Patrick

[38flattie]

Sorry, major typo in the KHK timing figures - used some from the next line in my .xls table (my edit expired, can't correct theoriginal post)

KHK data shows timing as:
intake 38-55 (273) 98.5 CL
exhaust 60-35 (275) 102.5 CL
overlap 73, LSA 100.5.

Advancing the exhausts 1 tooth:
intake 38-55 (273) 98.5 CL
exhaust 85.7-9.3 (275) 128.2 CL
overlap 47.3, LSA 113.35

Well, you're stuck with using K, KH etc. due to the lobe tapers so a 45 isn't going to help. I know people have used KH in a 45 (same angle, but reversed) for quite a while, but it wasn't at high speed or with bog springs, and it eventually eats the lobe (the roller corner digs in, then the hard-face comes off).
The LSA actually looks pretty good (certainly better than stock) and despite the low OL duration you have boost to help it out.
I can't think of anything else that doesn't require replacing cams.

Patrick, this looks like a good place to start! With the wider LSA, and decreased overlap, you should see an improvement. The high lift and duration should help 'exhaust' the spent gasses. You could compensate some, I belueve, with a small increase of the boost.

Cool project, I'm subscribed!