Search found 220 matches

by CDB50MX
Sun Feb 19, 2017 4:04 pm
Forum: Tech
Topic: Mx fork mods
Replies: 21
Views: 8240

Re: Mx fork mods

1975 H*nda CR 250 forks with billet clamps adapted to a B50MX with a custom stem on BSA bearings .
by CDB50MX
Thu Jul 17, 2014 9:57 pm
Forum: Tech
Topic: Mikuni Carb Jetting
Replies: 13
Views: 5987

Re: Mikuni Carb Jetting

B50MX with VM34 mm Mikuni that I'm running : 159 series jets - Pilot 35 , Main jet 220 , Jet needle P-8 , Needle jet 6DP1 , Slide 2.5 with needle at mid clip .

Mike
by CDB50MX
Tue Jan 21, 2014 7:09 am
Forum: Tech
Topic: Factory Drawings......?
Replies: 14
Views: 4886

Re: Factory Drawings......?

The CD's I produced , was from blueprints found in a box of motor parts from the BSA comp shop in Duarte , California . The box also contained 90% of a B50 motor with prototype modifications . The prints were dated 1975 and the motor was labeled P92 . The CD of these prints , contain only the motor ...
by CDB50MX
Sat Jan 18, 2014 8:12 am
Forum: Tech
Topic: Factory Drawings......?
Replies: 14
Views: 4886

Re: Factory Drawings......?

946662_10200296972288979_701369952_n.jpg
Bill ,
It's been awhile since I shipped a CD out , but I'll check to see if I still have some in stock .

Mike
by CDB50MX
Sat Jun 02, 2012 7:23 pm
Forum: Project bikes
Topic: Help identifying this frame...
Replies: 95
Views: 34814

Re: Help identifying this frame...

Tim , we need more B50's at the vintage MX races . Get that thing race ready and bring her out .

Mike

www.americanretrocross.org

Facebook under American Retrocross
by CDB50MX
Thu Mar 29, 2012 11:45 pm
Forum: Tech
Topic: B50 Clutch
Replies: 8
Views: 3491

Re: B50 Clutch

It takes a puller such as this . Internet search for it or Ebay .

$(KGrHqN,!k0E68SV(UMEBP!pyZ4tS!~~60_1.jpg
$(KGrHqN,!k0E68SV(UMEBP!pyZ4tS!~~60_1.jpg (15.54 KiB) Viewed 3055 times
Mike
by CDB50MX
Wed Mar 07, 2012 6:46 pm
Forum: Tech
Topic: lightening rockers
Replies: 9
Views: 3417

Re: lightening rockers

I did the same thing to my rocker arms as Koncretekid , but on a MX motor , which has been raced every month for 8 years with no problems . Lightening the rockers may not have much effect by themselves , it's the combined effect of multiple improvements that's noticeable .

Mike
by CDB50MX
Tue Dec 27, 2011 7:09 am
Forum: Tech
Topic: High Level Exhuasts - What are the Benefits?
Replies: 9
Views: 4088

Re: High Level Exhuasts - What are the Benefits?

This is strictly seat of the pants feed back and very unscientific with no dyno results . I run an up pipe because I race vintage motocross on a BSA B50MX . I started out by fabricating and running different megaphones on the stock size up pipe , with no noticeable improvement . The megaphones were ...
by CDB50MX
Sun Dec 25, 2011 5:36 am
Forum: Tech
Topic: Factory Drawings......?
Replies: 14
Views: 4886

Re: Factory Drawings......?

I have CDs in stock of the P92/B50 BSA motor drawings . You can PM me for an order .

Mike Johnstone
by CDB50MX
Sat Dec 10, 2011 4:53 pm
Forum: Project bikes
Topic: Beat making a Tank
Replies: 156
Views: 53312

Re: ..........

Swiss made BSA ignition adjustment tools ?
by CDB50MX
Fri Dec 02, 2011 2:52 am
Forum: Project bikes
Topic: High MPG B50MX
Replies: 2
Views: 2229

High MPG B50MX

Custom one off BSA B50MX bicycle .
by CDB50MX
Fri Nov 11, 2011 6:45 pm
Forum: Tech
Topic: clutch preparation
Replies: 15
Views: 4954

Re: clutch preparation

I'd have to agree with Grouty my B50 clutch resides in the same place as my Amals . I struggled for years to harness the HP of a competitive B50 with a four spring Alloy BSA style clutch , finally giving in and installing a six spring alloy from ED V . I tried CCM springs , blocking flat the steel d...
by CDB50MX
Thu Nov 10, 2011 12:41 am
Forum: Off topic
Topic: Thanks Ed
Replies: 5
Views: 2708

Re: Thanks Ed

1st place trophies are either an award or 8 pounds ( $ 5 USD ) cash back to be used for the next races entry fee . Sometimes we have sponsored awards like chain lube or spark plugs for 1st place . Races are year round and normally draws 50 to 100 entries . We also get a few ex USA pro's from the 70'...
by CDB50MX
Thu Nov 10, 2011 12:22 am
Forum: Off topic
Topic: Thanks Ed
Replies: 5
Views: 2708

Re: Thanks Ed

110 B50.jpg
by CDB50MX
Wed Nov 09, 2011 10:58 pm
Forum: Off topic
Topic: Thanks Ed
Replies: 5
Views: 2708

Re: Thanks Ed

Lots of pictures of So. California vintage MX racing at Glen Helen Raceway on American Retrocross Facebook page or video at http://www.americanretrocross.org , hit videos button for the American Retrocross Youtube channel .

Mike
by CDB50MX
Tue Nov 08, 2011 3:31 am
Forum: Off topic
Topic: Thanks Ed
Replies: 5
Views: 2708

Thanks Ed

My B50MX likes it's new NEB clutch and three speed trans . The picture show the distance I was getting right after the first turn .
Mike
by CDB50MX
Thu Nov 03, 2011 6:05 am
Forum: Tech
Topic: B50 + Megacycle + Pazon = zero
Replies: 15
Views: 5738

Re: B50 + Megacycle + Pazon = zero

I run ARD mags on all my B50's , their shop was just 10 minutes from mine . Unfortunately , Allen of ARD lost the lease on his shop and at his age , I don't think he'll be coming back .

Mike
by CDB50MX
Wed Apr 27, 2011 11:15 pm
Forum: Off topic
Topic: March in So. cal , USA
Replies: 13
Views: 4370

Re: March in So. cal , USA

Hello for sunny Southern California .
by CDB50MX
Sun Apr 24, 2011 6:03 pm
Forum: Off topic
Topic: March in So. cal , USA
Replies: 13
Views: 4370

Re: March in So. cal , USA

Silly old fool on a B50 with trophy girls at Washougal , Washington , USA .
by CDB50MX
Sat Apr 23, 2011 4:33 pm
Forum: Off topic
Topic: March in So. cal , USA
Replies: 13
Views: 4370

Re: March in So. cal , USA

My local track in San Bernardino , California , Glen Helen raceway .

Mike
by CDB50MX
Sat Apr 23, 2011 3:07 am
Forum: Off topic
Topic: March in So. cal , USA
Replies: 13
Views: 4370

Re: March in So. cal , USA

Different race , one month later , same track and photographer , same table top , but riding it reversed direction .

Mike
by CDB50MX
Sat Apr 23, 2011 2:59 am
Forum: Off topic
Topic: March in So. cal , USA
Replies: 13
Views: 4370

Re: March in So. cal , USA

Not by me , this photographer likes to add a vintage matte to his pictures is all .
There's a 20 foot table top just out of sight under the bike .
Mike
by CDB50MX
Fri Apr 22, 2011 6:00 pm
Forum: Off topic
Topic: March in So. cal , USA
Replies: 13
Views: 4370

March in So. cal , USA

Year round racing here in Southern California , this was in March 2011 , temp a little chilly at 60 degrees .
Mike
by CDB50MX
Tue Dec 21, 2010 11:23 pm
Forum: Tech
Topic: footrests
Replies: 4
Views: 2088

Re: footrests

2002 Y*maha YZ foot pegs adapted to B50 mounts . Not a bolt on mod , requires fabrication and welding , but they sure work good .

Mike
by CDB50MX
Wed Dec 08, 2010 7:00 pm
Forum: Tech
Topic: B44 crankshaft lightening
Replies: 38
Views: 15531

Re: B44 crankshaft lightening

Roger, While not a 441 , my B50 MX bike runs a lightened crank . I machined 3 pounds off by turning down the thickness and diameter of the wheels , also removed the rotor crank stub . The crank was then balanced by Ed at E&V Engineering , all my reciprocating mass is lightened with alloy primary spr...
by CDB50MX
Fri Oct 15, 2010 5:27 am
Forum: Tech
Topic: Rear Wheel Alternative?
Replies: 5
Views: 2361

Re: Rear Wheel Alternative?

Mid 70's to early 80's KTM 250 rear hub . I have one one on each of my four B50's . Somewhere on this site , changing the rear hub has been discussed already .

Mike
by CDB50MX
Wed Oct 06, 2010 9:44 pm
Forum: Tech
Topic: B50 won't fly straight
Replies: 26
Views: 7008

Re: B50 won't fly straight

Thanks for the laugh lads , it was all in good fun .

Mike
by CDB50MX
Tue Oct 05, 2010 3:11 am
Forum: Tech
Topic: B50 won't fly straight
Replies: 26
Views: 7008

B50 won't fly straight

Any explanation on why my bike isn't going straight off of the jumps ? The rider should know what he's doing , I let Gary Jones , four time AMA national 250 MX champion race it .
Mike
by CDB50MX
Tue Sep 28, 2010 1:24 am
Forum: Tech
Topic: Alloy tank repair
Replies: 17
Views: 7237

Re: Alloy tank repair

Oh the advantages of living in Southern California , USA . Within 1/2 hour drive of me , are two craftsmen , who could lift those dents out with a custom dolly which fits into the fillcap . No cutting the tank open , no mess , I've had numerous knee dents lifted out for the reasonable sum of $ 30 pe...
by CDB50MX
Thu Sep 09, 2010 6:49 am
Forum: Tech
Topic: Oil change interval
Replies: 4
Views: 1581

Re: Oil change interval

Every meeting ( race ) , the bike may only have an hour run time on the synthetic oil , but the motor still runs strong ten years later .

Mike
by CDB50MX
Wed Aug 11, 2010 6:43 pm
Forum: Tech
Topic: alloy friction plates
Replies: 2
Views: 1434

Re: alloy friction plates

I'm with Stan on this one , I have four B50's , all with NEB alloy clutch baskets , all have alloy friction plates and steel drive plates . My B50MX race bike has eight years of hard racing on it without a clutch problem . :ban

Mike
by CDB50MX
Tue Jul 20, 2010 3:00 am
Forum: Tech
Topic: B50MX quick-release filler cap rubber seal
Replies: 7
Views: 2589

Re: B50MX quick-release filler cap rubber seal

Many years ago I replace my monza cap gasket with rubber , thinking it would stop the leak . It still leaked and also swelled up , cutting off the air vent into the tank , causing a vacuum and no fuel flow . I lost a big GP race because of that and now use rubber impregnated cork , which has been in...
by CDB50MX
Thu Jun 24, 2010 11:45 pm
Forum: Tech
Topic: Kehin PWK/T25
Replies: 5
Views: 2785

Re: Kehin PWK/T25

ScottS ,

It looks like you have a JRC Engineering adapted PWK carb , you can contact Bill Getty at JRC for jetting specs at 1-951-940-5410 west coast time . If your carb did come from JRC , it may be jetted very close already .

Mike
by CDB50MX
Tue Mar 30, 2010 4:24 pm
Forum: Tech
Topic: Comparing B50 Clutch Centre Assemblies
Replies: 11
Views: 3358

Re: Comparing B50 Clutch Centre Assemblies

Does anyone know if an alloy B50 clutch center exists and if not would fabricating one hold up to MX racing . I have a alloy NEB B50 clutch , friction plates and primary sprocket that do well with racing , an alloy clutch hub would cut a lot of weight .

Mike
by CDB50MX
Thu Jan 07, 2010 7:39 am
Forum: Tech
Topic: Mikuni VM30 on B44
Replies: 21
Views: 8768

Re: Mikuni VM30 on B44

I'd take a guess at : main jet 190
pilot jet 27.5
needle jet 159 series P-5
needle 6F4
slide 3.0 taper
by CDB50MX
Wed Jan 06, 2010 2:51 am
Forum: Tech
Topic: Mikuni VM30 on B44
Replies: 21
Views: 8768

Re: Mikuni VM30 on B44

Beat ,
The shocks are Progressive brand , alloy body with adjustable dampening , their produced here in Southern California . I got this set free , as Progressive used one of my B50 MX's as a demo bike in an advertisement which aired on Speed channel on American TV .

Mike
by CDB50MX
Mon Jan 04, 2010 10:42 pm
Forum: Tech
Topic: Mikuni VM30 on B44
Replies: 21
Views: 8768

Re: Mikuni VM30 on B44

Yes Beat , it does run good and like Stan said , I don't know what the air jet is , just what the carb was delivered with . I hope Bossy doesn't intend to "date me up" anytime soon , I'm done with long distance relationships . :oops: :laugh


Mike
by CDB50MX
Mon Jan 04, 2010 1:22 am
Forum: Tech
Topic: Mikuni VM30 on B44
Replies: 21
Views: 8768

Re: Mikuni VM30 on B44

Yes , this 30 mm Mikuni is on a fairly stock running B50 T motor . It has completed the L.A. to Barstow to Vegas dual sport ride twice ( that's two days and over 400 miles in the dirt ) , also been ridden on numerous BSAOC dual sport rides . It starts easily and doesn't run rich at all .

Mike
by CDB50MX
Sun Jan 03, 2010 8:25 pm
Forum: Tech
Topic: Mikuni VM30 on B44
Replies: 21
Views: 8768

Re: Mikuni VM30 on B44

This is the Sudco setup for a standard B50 with Mikuni carb :
VM 30 mm - 159 series jets
Pilot jet 50
Main jet 310
Needle jet 0-8
Jet needle 5L1
Slide 2.5
Needle clip at mid groove


Mike
by CDB50MX
Sun Jan 03, 2010 4:52 pm
Forum: Tech
Topic: Titanium bolts
Replies: 3
Views: 1264

Re: Titanium bolts

I use Ti bolts for the pinch bolt on cast alloy triple clamps with no problems .

Mike