B65 Mongrel

SteveS · Post by **SteveS** » Thu Sep 03, 2020 8:12 pm

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For various reasons I've had to temporarily abandon my other project so decided to proceed with another idea using various parts I've accumulated over the years. I've put this in 'Off topic' as it's got a twin engine
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: B50 SS Frame

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: A65 Motor

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: Showa Forks off a H*nda

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: Y*maha Monoshock Rear Suspension

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: Wheels, disc front, std rear

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I'm still busy sourcing a few more parts to flesh out my ideas. When that's done I can look at how to put it all together. An A65 in a B50/B25 frame has been done before so shouldn't be too difficult. The monoshock suspension seems to tie in dimensionally with the B50 frame but we'll have to see if it works or not. This is going to be a long term project, no hurry, I will be completing as and when time and funds permit.

beat · Post by **beat** » Thu Sep 03, 2020 8:42 pm

Post by **minetymenace** » Thu Sep 03, 2020 8:59 pm

very

, but sell me your frame and buy another with the dosh.....

malcward · Post by **malcward** » Fri Sep 04, 2020 8:37 am

Interesting mod to the front of the engine

Cheers Malc

SteveS · Post by **SteveS** » Fri Sep 04, 2020 1:20 pm

Gerry, I've got a spare B50T frame (damaged) if you're interested.

Malc, yes interesting mod. Looks like the PO had trouble removing the front engine bolt so took a BFH to it

SteveS · Post by **SteveS** » Sat Sep 12, 2020 8:24 am

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Got both the wheels blasted prior to powder coating. This identified a problem with rear wheel

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: Rear wheel, damage to sprocket mounts

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Milled out the damage and then welded by the local expert. Also repaired a crack in the bearing housing
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: Welding to sprocket mounts and bearing housing

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Local powder coater finished the wheels for me. Unfortunately we had a problem with outgassing which has spoilt the finish

I believe this is caused by the casting being porous. The trapped gas in the metal is forced out when the metal is heated forming little craters on the surface. I'm pretty sure it could be overcome by pre-heating the wheels for 30 minutes or so (prior to applying the powder) to purge the trapped gases.
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: Outgassing, has formed small craters on surface of coating

Feeling a little pi**ed off at the moment.

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SteveS · Post by **SteveS** » Sat Sep 12, 2020 3:13 pm

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Some better news, the engine arrived from Michigan US via Barrow-in-Furness

Sent over in a container.
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: A65 motor

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At some point I will need to strip the motor so I can get the front engine mount fixed. I've got a good set of A65 crankcases which I could use as a donor but I will try and see if I can get hold of a damaged set rather than sacrifice a good set

SteveS · Post by **SteveS** » Sun Sep 20, 2020 2:51 pm

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Afternoon all
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Found another local powder coating company that have done a much better job of finishing the wheels

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: Wheels fitted with Michelin Sirac tyres

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I wasn't sure about the original source of the wheels. Thought they could be Lester, Cambray, Morris. Thanks to Paul (Beesa71) for confirming they are CMA wheels.
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CMA were based in Suffolk and produced 'Mag' wheels for various bikes in the late 70's and 80's. Disc brake wheels were a complete casting. If you wanted a standard rear hub you gave them your existing hub and they shrunk fit into the casting. On my rear wheel you can still see the spoke holes on the BSA conical hub. The story goes that John Cerhan (the proprietor) was killed by one of the wheels he was working on coming off his lathe

Malcolms Lad · Post by **Malcolms Lad** » Sun Sep 20, 2020 4:31 pm

Love the idea behind this Steve, Look forward to seeing this one!

B44Claus · Post by **B44Claus** » Tue Sep 22, 2020 6:21 pm

Exciting project

I look forward to follow your progress!

Brgds,
Claus

SteveS · Post by **SteveS** » Sun Oct 04, 2020 2:18 pm

.Loosely put together a spare set of A65 crankcases, barrel and head. There's currently not enough room to sit the engine square in position.
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Looks like I need to stretch the frame by a couple of inches in length.

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: os

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Should be ok on the height
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: ns

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beat · Post by **beat** » Sun Oct 04, 2020 9:04 pm

SteveS wrote: ↑Sun Oct 04, 2020 2:18 pm need to stretch the frame

ore shorten the engine.... !

why using this engine

IMO, - it is the ugliest engine BSA ever made

unknow

SteveS · Post by **SteveS** » Mon Oct 05, 2020 7:56 am

Hi Beat (I know its you

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Hope your recovery is going ok

The A65 motor does seem to instill a love / hate reaction. As they say beauty is in the eye of the beholder

beat · Post by **beat** » Mon Oct 05, 2020 6:59 pm

hi Steve,

yes, - it's me

thanks,- recovery is going good so far.

and lucky, - you seam to be the right beholder

SteveS · Post by **SteveS** » Sun Oct 25, 2020 3:33 pm

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Initial butchery complete.

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: Bottom frame rails removed

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I've kept all the removed parts in case I change my mind

beat · Post by **beat** » Sun Oct 25, 2020 6:23 pm

SteveS · Post by **SteveS** » Tue Oct 27, 2020 12:51 pm

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The point of no return
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: Point of no return

At least I've found the best way to get access to clean out the sludge and debris from the oil tank

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Spaced the frame with a piece of timber to gauge the stretch required.
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: Engine / Frame mock up

beat · Post by **beat** » Tue Oct 27, 2020 11:02 pm

do not forget to take out the pice of wood before welding....

Ian Hingley · Post by **Ian Hingley** » Thu Oct 29, 2020 3:44 pm

beat wrote: ↑Tue Oct 27, 2020 11:02 pm do not forget to take out the pice of wood before welding....

You can re-use the piece of timber underneath the sidestand...

Ian

SteveS · Post by **SteveS** » Fri Nov 06, 2020 5:53 pm

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Managed to get the crankcases welded

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: Front engine mount welded

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.............and the frame. I've now got an extra 60cc oil capacity

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: Frame stretched

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beat · Post by **beat** » Fri Nov 06, 2020 8:02 pm

SteveS wrote: ↑Fri Nov 06, 2020 5:53 pm I've now got an extra 60cc oil capacity

looking good...

if the pice of wood is out...

SteveS · Post by **SteveS** » Sat Nov 14, 2020 4:37 pm

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A little more progress
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: Cut out old gusset and tubes

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: Replaced straight tubes with bent ones to clear suspension

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: Mock up with s/arm and monoshock

malcward · Post by **malcward** » Sat Nov 14, 2020 6:03 pm

SteveS · Post by **SteveS** » Fri Nov 20, 2020 3:51 pm

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A bit more welding completed. Set up with wheels and suspension to check monoshock top mount location
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: Rolling chassis

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: Monoshock and front engine mounts in place

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: More frame brackets completed

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: Side panel mount holes reinforced

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: Side panel grommets

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The sleeved type grommet is useful during installation as it provides something to grab hold as you it pull in to place. Fitting is much simpler if you leave the grommets in hot water for about a minute to make them more pliable. You can leave the sleeve in place or remove with a sharp blade.
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: Side panel pins

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The B50T frame that I ended up using was missing the side panel mounting pins so I took the opportunity to make them a little longer than standard (3/4") so they locate more positively. They will be welded or brazed into position.
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: Folding Footrests

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Re-used the two frame / footrest lugs and got them welded to the new frame section. Fabricated the footrests from the base end of a pair of damaged T140 oif footrests brackets together with a pair of secondhand folding MX pegs. Also mounted an A65 side stand using a conventional frame mounted lug rather than the swinging arm mounted B50 type (old mount still in place at the moment)
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: Battery tray

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Standard B50 battery tray on left, modified A65/T140 battery tray on right to accommodate a smaller 7amp hr battery. There was insufficient room to fit the B50 battery tray and standard battery due to the rear suspension arrangement
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: Brake pedal

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Brake pedal shortened by 1.1/2" (as footrests moved back by same amount), drilled for lubrication and groove added to pivot bolt (bolt without groove courtesy of beesa71). Will probably fit an extended lever to the rear brake to compensate for the reduction in pedal length.
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: More brackets

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Frame seat loop cut and re-worked. A few more brackets welded in place, including supports for seat unit, relocated battery tray bottom mount, earth point, horn mount, side panel oddie mounts and silencer bracket mounts

SteveS · Post by **SteveS** » Wed May 19, 2021 1:47 pm

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Not done much with the project recently but last week I finally got the remaining welding completed on the frame. Today I got the frame back from the powdercoaters. After much deliberation I went with a dark metallic grey instead of the typical black. Looks better in the flesh than in the the pics
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: Frame R

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: Frame L

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: Frame accessories

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Now I have the rear engine plates finished I can start to assemble the engine as they need to be fitted to the engine prior to bolting the crankcases together. Ask me how I know

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SteveS · Post by **SteveS** » Thu May 20, 2021 4:38 pm

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I've been messing with the electrics. Made up an aluminium tray to fit on the left (where the air filter would have sat) to accommodate the regulator/rectifier, capacitor, horn relay, fuse box and the ignition transistor box
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: Electrics

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I am using the original o.i.f. electrical box to accommodate the dual ignition coil, conventional ignition / lighting switch and a couple of relays for the headlight.
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: Headlamp relays

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In case you're wondering I'm wiring the bike Negative Earth

beat · Post by **beat** » Thu May 20, 2021 8:59 pm

SteveS wrote: ↑Thu May 20, 2021 4:38 pm I'm wiring the bike Negative Earth

all the todays fast bikes are Neg Earth

B44Claus · Post by **B44Claus** » Fri May 21, 2021 10:26 am

Hi Steve,

Your project is coming along nicely, it looks great!

When you extended the top spine to get room for the bigger A65 engine you also moved the headstock up a bit, are you compensating that with a longer fork? If not you will lower the engine and reduce the steering rake a little. That will probably be just fine as the B50 frame has ample ground clearance and a steeper steering head might improve handling. Any thoughts about that?

Thanks,
Claus

SteveS · Post by **SteveS** » Fri May 21, 2021 11:35 am

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Hi Claus
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Yes it had crossed my mind about the change to frame geometry. The steering head is about 1/2" (12.5mm) higher than before so I don't think there will be much effect (?). However I need to make up some steering stem spacers for the fork yokes I am using, so I can adjust their size to compensate, as required. Additionally the holes for the fork legs in the yokes I am using are straight (not tapered) so I can move the legs through the yokes a little if required.
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Made up a new lid for the Electrics Box incorporating readily available M6 rubber mounts (unlike the unobtainable [at a reasonable price] original type metal / rubber mounts) and M20 cable glands in place of rubber grommets to hold the wiring in place.
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: Electrics Box Lid

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Purchased a dual output coil which I have bolted to the lid. Don't have any experience regarding the longevity and / or performance of these cheap coils; we'll have to wait and see if it works ok......
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: Dual output coil

SteveS · Post by **SteveS** » Thu Jun 10, 2021 4:44 pm

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Made some progress with the chainguard. The OEM Y*maha product is quite rare, very expensive and made from plastic so I decided to make one from some aluminium 'U' channel - 1.1/4" x 2" x 1/8" x 600mm. First I radiused the two long edges
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: Radiused corners

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Next I slit the edges of the channel so I could form a curve at the end of the chainguard
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: Slit

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Made up a former to make the curve. The timber was a tight fit in the channel so was helpful to support the chainguard while carrying out the work.
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: Former

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Curve welded and blended
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: Curve welded

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: Curve blended

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Alignment checked
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: Checking alignment

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Brackets to mount to swinging arm
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: Brackets

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initial trimming to size
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: Trimmed to size

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Complete - ready for powder coating
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: Outside

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: Inside

beat · Post by **beat** » Thu Jun 10, 2021 8:46 pm

SteveS · Post by **SteveS** » Sun Jun 27, 2021 12:52 pm

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Got a few more parts back from the powder coaters. This has enabled me to get the rolling chassis together:
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: OS

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: NS

SteveS · Post by **SteveS** » Tue Jul 27, 2021 3:43 pm

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Not been able to spend much time on the bike, but finally got round to completing further engine assembly so the bottom end is nearly done, (clutch to adjust, timing to complete) and top end nearly done......
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: OS

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: NS

Post by **minetymenace** » Wed Jul 28, 2021 8:03 pm

Sweet!

beat · Post by **beat** » Fri Jul 30, 2021 7:52 pm

minetymenace wrote: ↑Wed Jul 28, 2021 8:03 pmSweet!

+ 1

( eaven as this is the ugliest engine BSA ever made, -- IMO )

SteveS · Post by **SteveS** » Sat Sep 25, 2021 10:58 am

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I have been unable to do much work on the bike recently mainly due to delays with getting hold of parts etc. However the brake discs have now arrived

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They had to be made especially as there was nothing 'off the shelf' available to match a 1970's CMA wheel to 2021 H*nda upsidown forks, no surprise there

If I ever attempt a fork swap like this one again I will try and ensure I use as many stock parts as possible as custom parts are soooo expensive

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: Front face

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: Rear face

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: Twin Discs

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I need to plumb in the hydraulics for the discs but I will leave that until a bit later as I want to get on with the exhaust system. If all goes to plan I should have the initial exhaust system laid out by end of October. I intend using 1.5mm stainless tube incorporating standard mandrel bends. I was planning on a twin exhaust exiting on the right but have now decided to go with the conventional route i.e. one on the left, one on the right, probably without a balance pipe.

beat · Post by **beat** » Sun Sep 26, 2021 6:47 pm

SteveS wrote: ↑Sat Sep 25, 2021 10:58 am probably without a balance pipe.

I am still scraching my heat what is the balance pipe for ??

if you make one, - you may tell me the answer

beat

SteveS · Post by **SteveS** » Sun Sep 26, 2021 7:44 pm

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Hi Beat
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The balance pipe was introduced around 1969 /70. The balance pipe is a horizontally fitted tube that links the two exhaust headers as they leave the cylinder head. I understand the idea was to balance the pressure within the exhaust system to give more even and slightly improved performance (and reduce noise slightly)............
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: A65 Lightning 1969 with balance pipe

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JB · Post by JB » Thu Sep 30, 2021 4:52 pm

I'm not sure if BMW were using balance pipes first, but I do know that the first British twin to use them was on the Thruxton T120 race bikes as they were found to give more power. I remember reading somewhere that they worked best with a smaller 1.375" diameter exhaust pipes rather than larger 1.5" pipes, I think T120 & T140 balanced pipe sizes were 1.375". An A65 with 1.5" pipes probably doesn't get the full benefit, if this information is correct!

B44Claus · Post by **B44Claus** » Thu Sep 30, 2021 8:26 pm

Hi Steve,

That looks absolutely super!
The A65 engine is ugly? No way! I like the design much better than Thr....h's. The cylinder head and valve cover also have a more functional layout where you have access to all valves. I would reconsider the routing of the exhaust pipes, in my opinion twin high level pipes exiting on the same side looks so cool:

Or the OIF variant:

Keep up the good work!

Regards,
Claus