Erwin SR500 by BCM

Kim Boyle's personal SR500 lit up the innerweb last year after its debut at the Chop Meet. A year later he's built another one, this time for a customer. Broad-stroke basics like the stance are obvious, but under closer scrutiny lots of hand-made details emerge. Here's what Kim has to say about it:


Bike name: Erwin SR500

Year and make, model, modifications:  1978 Yamaha SR 500. Top-end rebuild with a little head work, Mikuni VM36 carb, stainless header pipe with a an open reverse megaphone

Frame: Stock SR

Fork: Stock SR shaved legs, lowered 2.5" Progressive springs

Chassis mods: Rear shortened 8" all unnecessary brackets removed and cleaned up, new fender mounts, hack the stock fender to fit. Progressive 1200 series shocks 1" lower than stock


Tire/wheel size and style: Stock Yamaha Mags 19" front 18" rear.  400-19" front- 450-18" rear, Firestone Deluxe Champion tires

Favorite thing about this bike: Probably the rear brake set up, My buddy Pat machined the rotor turning the center holes from rectangle to round and then drilled the rotor surface. then machined a brake stay, I cut down the caliper hanger by a lot, added a braided stainless line, trimmed the pedal down to a circle. It all cleaned up real well.

Next modification: Modifying it out of my garage and into the owner's hands


Other mods, accessories, cool parts, etc: two-piece headlight mount, Ductati monster front caliper & rotor w/ a Honda CR125 master cyclinder, SS brake line, hand-made brake line guide. Chain side case cover cut way down and a guard added. I fabricated the license plate/taillight bracket; Pat and I worked out the taillight, Biltwell supplied the reg tube. The tank is a Yamaha GT80 tank painted by Jaymes at Blue Moon Kustoms. Duane Ballard did the seat to the owner's specs. A ton of cleaning and polishing.


Thanks to:

Frances Bernal for the support and putting up with too much garage time.
Pat McCormick at Cutting Edge CNC, for the work & helping keep my head
on straight.
Rob Warren for being a garage mate & putting aside his own project to help
Paul Wisniewski--badge art
Duane Ballard--leather work
Blue Moon Kustom--Tank paint
Wes Drelleshack--wiring/photos
Olympic powder coating, Escondido, Ca
Thumperstuff, your SR headquarters


You can download a desktop background of The Erwin SR500, shot by Wes Drelleshak by clicking the photo above.

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Comment with Chopcult (38)

Commented on 8-2-2009 At 05:14 am

Makes me really miss my sr250. Not as cool as this bike but loads of fun.

Commented on 8-2-2009 At 07:51 am

And to think "some sites" would delete a post involving this bike. That thing is beautiful and puts a lot of American/Brit bikes to shame.

Commented on 8-2-2009 At 12:13 pm

great details!

Commented on 8-2-2009 At 12:53 pm

simple and clean. hell, that thing is a life motto! good work.

Commented on 8-2-2009 At 03:12 pm

Once again... absolutely beautiful.

Commented on 8-2-2009 At 03:59 pm

Damn it, i keep flip-flopping between a xs chopper or xs bratstyle type bike. Thought i had it nailed down. This does not help. Nice bike.

Commented on 8-2-2009 At 04:33 pm

that bike is smooth

Commented on 8-2-2009 At 04:35 pm

Saw this bike in carlsbad ysterday............sweet mo-cheen fer sure.

Commented on 8-2-2009 At 07:02 pm

ya i saw this thing too. there was a couple of em... bad ass ride

Commented on 8-2-2009 At 08:38 pm

beautiful, beautiful, beautiful

Commented on 8-2-2009 At 08:39 pm

beautiful, beautiful, beautiful

Commented on 8-2-2009 At 10:15 pm

Really sharp bike. Clean, concise and to the point.

Commented on 8-3-2009 At 12:15 am

Very nice! It looks like it would be alot of fun to ride. Nice job!

Commented on 8-3-2009 At 12:57 am

Again, Awesome!!!

Commented on 8-3-2009 At 04:59 am

Great Job as Always!

Commented on 8-3-2009 At 03:03 pm

Oh Man!
Thanks for all the kind words guys, I am grateful.

Commented on 8-3-2009 At 04:01 pm

Very nice. Love the blog. Keep it coming.

Commented on 8-3-2009 At 05:35 pm

love it love it love it, Kim...

Commented on 8-3-2009 At 08:17 pm

Slick as goose shit, and looks fun as hell to ride.

Commented on 8-4-2009 At 04:12 am

another home run.

Commented on 8-4-2009 At 02:13 pm

Nice looking ride.

Commented on 8-5-2009 At 04:56 pm

I would really like to find something like this for my girl

Commented on 8-5-2009 At 06:21 pm

very cool, nice to see some variety!!

Commented on 8-6-2009 At 04:38 am

Fantastic attention to detail. It's interesting how these bratstyle bikes start to grow on you.

Commented on 8-6-2009 At 04:58 am

looks rad very nice

Commented on 8-6-2009 At 06:11 pm

Nice. Love the mags.

Commented on 8-7-2009 At 03:54 am

Wow, that is a nice bike.

Commented on 8-11-2009 At 04:07 pm

wow - that thing is excellent!

Commented on 8-12-2009 At 11:23 pm

I've always liked those thumpers! Nice job!

Commented on 8-18-2009 At 08:33 pm

classy, thats alot of polishing

Commented on 9-13-2009 At 05:22 pm


Commented on 9-13-2009 At 05:22 pm


Commented on 11-20-2009 At 11:17 am

super slick, dick!

Commented on 1-16-2010 At 04:26 pm

after seeing your beautiful clean ride i know what my next projects gonna have to be. thanks for giving new life to a great old rice burner

Commented on 2-14-2010 At 12:16 am

Damn! Fantastic...

Commented on 2-15-2010 At 06:55 am

That's craftsmanship! Sweet motobike!

Commented on 2-7-2011 At 04:48 am

c lean and she must be a blast

Commented on 7-4-2011 At 02:33 pm

bravo kim!

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