Author Topic: My Dunstall CB750 (Read 51814 times)

scottly · « **Reply #75 on:** August 11, 2011, 09:43:35 PM »

While making new rearsets and controls to replace my Seeley/Tickle parts, I noticed the Tickle brake has very little leverage. Even with a Grimeca caliper and MC, the pedal had a "wooden" feel. You may be able to increase the effectiveness of the drum brake by merely drilling a new hole to anchor the brake rod closer to the pivot of the bell crank lever.

cafemancbdunstall · « **Reply #76 on:** January 21, 2012, 11:07:08 AM »

Hi im rick.I have one like it. Its a 1972 ,750k3 with a 1000 kit and all the #$%* on it. 2up seat. tank lesters k80,1s dickman fairing . clipons rearsets . Going to start to work on it this weekend .

Rookster · « **Reply #77 on:** January 21, 2012, 04:44:46 PM »

Hi Rick,
Post some pics. I'd love to see another one out there. There's only a few around.
Scott

Rookster · « **Reply #78 on:** May 13, 2012, 07:23:04 PM »

I was contacted a few months ago by moto journalist Nolan Woodbury about information on the Dunstall Honda as he was writing an article about Paul Dunstall. He asked if I would write something about owning and riding a Dunstall bike. His article is published on his website http://www.vintagemotorcyclesonline.com/features/stories/222-production-specials-part-ii

My contribution is on page 7 http://www.vintagemotorcyclesonline.com/features/stories/222-production-specials-part-ii?start=6

If anyone is interested in Paul Dunstall and the bikes he built then Nolan Woodbury has written the definative article on the man and his machines. And he made my pictures look awesome.

Scott

Rookster · « **Reply #79 on:** June 20, 2012, 03:37:34 PM »

Summer 2012 update:

I got a set of Dunstall Decibel replica silencers from Brituro to replace my crusty flat black originals. They aren't exact copies but they are great quality and sound awesome. Someday I may get the originals rechromed but for now the replicas will work just fine.

DunstallReplicaMufflers by Scott Rook, on Flickr

DunstallDriveway2 by Scott Rook, on Flickr

DunstallDriveway1 by Scott Rook, on Flickr

Scott

bert96 · « **Reply #80 on:** June 20, 2012, 04:08:49 PM »

Would it be possible to know the price of these brituro

Bert

Rookster · « **Reply #81 on:** June 20, 2012, 05:06:10 PM »

Sure. They are available on ebay for around $180 + $70 for shipping. They come in 2 different inlet sizes 1.1/2" (38mm) or 1.3/4" (44mm). I needed the 1.3/4" versions to fit the Dunstall exhaust. They don't come with clamps so you will need to get those.

http://www.ebay.com/itm/DUNSTALL-SILENCERS-SUIT-TRIUMPH-TRITON-BSA-CAFE-RACER-/370623787568?pt=UK_Motorcycle_Parts&hash=item564ae63230

Classic Bike Shop (UK)/ same as ebay seller: http://www.classicbikeshop.co.uk/index.php?route=product/category&path=143_151&sort=rating&order=ASC&limit=75&page=1

Mitch Klempf of Klempfs British Parts has a pair of them but he wanted $179 each. http://www.klempfsbritishparts.com/

British Cycle supply listed them on their website but they didn't have them in stock. http://www.britcycle.com/products/712/712_102a_b.htm

If you could get them in North America then the shipping wouldn't be so much. The ones with the black ends are made by Emgo and are only 1.5/8" inlet so they don't fit the Dunstall exhaust. The Brituros are made in England and sound awesome.

Scott

bert96 · « **Reply #82 on:** June 23, 2012, 04:30:08 PM »

I guess the hardess part is to find the down tube

Thanks

Bert

fishfreek · « **Reply #83 on:** June 25, 2012, 06:37:29 PM »

Man that's a sweet bike. I am just begining the process of my first build and bikes like these give me the inspiration to make it happen.

rtbmrgl · « **Reply #84 on:** August 31, 2013, 06:18:49 PM »

Congrats again on BOM (sept '13) win, man o' man i just went through your thread, I tip my hat fantastic job!

Rookster · « **Reply #85 on:** September 01, 2013, 07:02:26 PM »

Thank you. Great job on your CB500. It looks like it just came off the showroom floor.

Scott

Rookster · « **Reply #86 on:** February 08, 2015, 06:47:19 PM »

I started to get serious about a rear disk conversion for the drum brake. The Dunstall rearsets make the rear drum ineffective due to the reduced leverage on the lever. So to fix this problem I am converting to a rear disk. I explored some options such as a TLS rear brake plate but the mechanical leverage is just too small for a drum. In keeping with the theme, everything will be from the 70s. The goal is to replicate the old Hallcraft rear disk conversion or something similar.

HurstAirheartDiskReplacement by Scott Rook, on Flickr

Hurst Airheart caliper and master cylinder w/mounting bracket: chrome stripped, lightly polished and completely rebuilt:

HurstAirheartCaliper by Scott Rook, on Flickr

HurstAirheartMaster2 by Scott Rook, on Flickr

Its a start. Next up is the disk.

Scott

Retro Rocket · « **Reply #87 on:** February 08, 2015, 06:55:38 PM »

Why not just use a cb750 F0/F1 spoked rear disc brake hub...? Saves all the screwing around...

scottly · « **Reply #88 on:** February 08, 2015, 07:02:45 PM »

Quote from: Rookster on June 20, 2012, 03:37:34 PM

Summer 2012 update:

I got a set of Dunstall Decibel replica silencers from Brituro to replace my crusty flat black originals. They aren't exact copies but they are great quality and sound awesome. Someday I may get the originals rechromed but for now the replicas will work just fine.

Scott

That bike is just plain beautiful.

SOHC4 Cafe Racer Fan · « **Reply #89 on:** February 08, 2015, 08:50:51 PM »

Quote from: Retro Rocket on February 08, 2015, 06:55:38 PM

Why not just use a cb750 F0/F1 spoked rear disc brake hub...? Saves all the screwing around...

++++++1

Rookster · « **Reply #90 on:** February 08, 2015, 08:52:37 PM »

Thanks Scottly, I feel the same way about your Seeley.

Quote

Why not just use a cb750 F0/F1 spoked rear disc brake hub...? Saves all the screwing around...

Well I'm running Lesters so I would absolutely love to use an F rear Lester with the 6 bolt disk but they are very few and far between. So, in the mean time the plan is to make a conversion for the drum. If an F Lester shows up for reasonable money in the next month, then I will probably be all over it. I even found a 10" disk that runs the same 6 bolt pattern as the Honda so the conversion would be very easy. At this point the disk needs to be surfaced and a spacer needs to be turned, so that's next on the list regardless of which wheel is used. BTW the screwing around is half the fun.

Scott

Retro Rocket · « **Reply #91 on:** February 08, 2015, 09:14:29 PM »

Scott, what disc shares the same pattern..? I have an old Hearst Airheart disc on an F spoked wheel but I'm chasing another disc for another F wheel i have, the old Honda rear discs are huge and heavy...

Rookster · « **Reply #92 on:** February 09, 2015, 01:05:21 PM »

Drum to disk conversion part 2: Disk and Spacer

I am using a 10" AP Lockheed cast iron disk from a Triumph. Norton and Ducati used the same disk. The plan is to get the disk conversion operational then swap the disk out for a lighter version.

Triumph_disk2_zps72gpzfym by Scott Rook, on Flickr

This is the new wheel spacer that also acts as the sliding surface for the bushing in the caliper holder. It is stainless and has been bored out for the 20mm axle size.

StainlessWheelSpacer1 by Scott Rook, on Flickr

Scott

Retro Rocket · « **Reply #93 on:** February 09, 2015, 02:45:14 PM »

Thanks Scott

Rookster · « **Reply #94 on:** May 22, 2015, 02:43:38 PM »

The rear disk conversion is up and running.

photo 2 1_zpseo3005q3 by Scott Rook, on Flickr

The disk is a 10" AP Lockheed disk that was used on Triumphs and Nortons in the 70s. It is cast iron and 1/4" thick. The caliper is a Hurst Airheart unit that was made integral with the mount. The master cylinder is a 3/4" Hurst Airheart item. The conversion is still in the testing phase. I plan to replace the disk with a new lightened version and source a shorter brake line. These things are never done.

Scott

Lefthook · « **Reply #95 on:** May 22, 2015, 02:57:33 PM »

Man that looks great, very nicely done.

SOHC4 Cafe Racer Fan · « **Reply #96 on:** May 22, 2015, 03:09:18 PM »

Quote from: Rookster on February 09, 2015, 01:05:21 PM

Norman Hyde full floating T140D disk

Scott

The Norman Hyde floating disc looks darn close to the EBC floating rotors.

Rookster · « **Reply #97 on:** May 24, 2015, 02:40:29 PM »

Thanks Lefthook. I'm Diggin your build as well.

Cafe Racer Fan: I have no idea if the Hyde rotor is made by EBC. It could be but it is only available through Norman Hyde's website so IDK.

A ride report: The rear disk works much better than the rear drum did with the Dunstall rearsets. It is by no means an excellent disk brake set-up though. This is due to the Hurst Airheart master cylinders which are notorious for being weaklings. There is an old joke that the Hurst Airheart braked flat trackers could run in the brakeless class. The disk setup gives just enough feel and doesn't have that clamp down effect that the front does. It comes on progressively but never hits the locked wheel threshold. At least not yet. I haven't really been doing panic stops either. I can stop the bike with the rear disk only, which is something I could never do with the rear drum. Here are some detail shots of the master cylinder and the caliper.

photo 3 1_zpsrnjdmdjs by Scott Rook, on Flickr

photo 2 1_zpseo3005q3 by Scott Rook, on Flickr

DunstallTrain3 by Scott Rook, on Flickr

What looks relatively simple actually involved a bit of work. The master cylinder is actuated by the stock brake pivot. It is a pull actuated master cylinder. The disk carrier runs a 6304 bearing. I still need to have a shorter brake line made up and a new disk full of holes added. I wanted to do some finish work to the setup as well.

Scott

SOHC4 Cafe Racer Fan · « **Reply #98 on:** May 25, 2015, 12:31:37 AM »

There are slight differences between the Hyde and the EBC. I was just surprised at how close they look.

moraarcher · « **Reply #99 on:** May 25, 2015, 05:20:30 AM »

Very, very nice. I really like the color. I haven't worked on mine for awhile but got the bug bad this spring and have made lots of progress. I will be posting pics soon.

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Author Topic: My Dunstall CB750 (Read 51814 times)

fishfreek