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DB1 restoration
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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Thu Oct 18, 2018 1:46 am    Post subject: Reply with quote

An unboxing!



The master cylinders returned the other day. I've been ill and then worked a few days. Have to pay for all this!



Front and rear caliper rebuild kits. Some reservoir hose, O rings for the reservoirs, crush washers. Old and a few new un-needed bits.



Front caliper kit contents.



Ready to reassemble.

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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Thu Oct 18, 2018 2:25 am    Post subject: Reply with quote

Correct me if I'm wrong but I believe the DB1 SR model is essentially what I now have. A stock DB1 kitted with carbs, cams and exhaust.

Does anyone have knowledge of DB1 SRs with a modification to add air cleaners?
There is so little room between the frame and the carb bellmouths, I suspect it will need some sort of curved rubber joint. Anyone seen anything like this?
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Quadrasuarass



Joined: 23 Aug 2013
Posts: 82
Location: New Zealand

PostPosted: Thu Oct 18, 2018 8:19 am    Post subject: Reply with quote

You will need 2x 45° Round Boots and 2x K&N Filters - the oval offset pattern,The round pattern are too restricted. I understand the DB1 RS had ø40mm carbs, the DB1 ø36mm. The example here is for 36mm carbs. I have no idea where you get the boots from these days. Mine were perishing so I used a piece of large diameter black electrical heat shrink to make them air tight again.





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PaulDB2



Joined: 26 Apr 2014
Posts: 316
Location: Manchester

PostPosted: Thu Oct 18, 2018 1:17 pm    Post subject: Reply with quote

Rocketron wrote:
Correct me if I'm wrong but I believe the DB1 SR model is essentially what I now have. A stock DB1 kitted with carbs, cams and exhaust.

153 DB1SR were built. The engine was improved with new camshafts, 41mm carbs and a 4-1 exhaust. Front brakes were uprated to 4 pot calipers and the rear brake was a 220mm (260mm standard DB1) rotor. Wheels were Marvic/Akront composite, 3 spoke magnesium centre bolted to an aluminium rim. The livery was also different being mostly red with white banding.
The previous DB1S (63 built) only differed from the DB1 by having 40mm carbs.
Not sure what the DB1RS used for an airfilter/box, but the standard one on the DB1 is so convoluted and restrictive that many are removed. mine came with some crappy cone filters but I currently have open aluminium bell mouths. Clearance to the frame is very tight. I will be looking at re-fitting proper cone filters as I am worried about any back-fires, and not seeing what could happen (fire!!) inside that gorgeous bodywork!
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Bimota DB1, Bimota YB5, Bimota YB6 Exup, Bimota YB9 SR, Ducati NCR Replica, Moto Guzzi 750 S3, Honda CR750 race replica, Seeley-Suzuki TR500
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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Fri Oct 19, 2018 6:05 am    Post subject: Reply with quote

Calipers all coming together again.







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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Fri Oct 19, 2018 6:10 am    Post subject: Reply with quote







Yea, seems like it would be best to remove the bell-mouths on the carbs. Then size them up for some sort of 45` boot. Maybe run the air cleaners, if I can fit something, on the street. Remove them for track use and replace the bell-mouths.

Hummm need to search out some sort of rubber boot....

https://www.google.ca/search?q=rubber+intake+coupler+45+degree&tbm=isch&source=iu&ictx=1&fir=sG2RvbkfXsPHDM%253A%252C_FUm5cj_vl2tEM%252C_&usg=AI4_-kQpdegZ77ASpvqPHdySDVY8kCZepw&sa=X&ved=2ahUKEwiJpZCQ35HeAhWzHTQIHYliBB4Q9QEwBXoECAUQCg#imgrc=_

Maybe not too difficult to locate something suitable... need do some measuring.
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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Sat Oct 20, 2018 3:39 am    Post subject: Reply with quote

Forks returned home today.

A few things of note.

Generally all good inside. Replaced one bushing on each of them. Replaced the seal at the top of the sliders. Unable to obtain new top scrapers and an internal plastic bush. So reinstalled the original parts.
The spring rate is left .57 kg/mm and right .56 kg/mm.
The oil viscosity was 5 wt, now installed 10 wt fluid, at 170 mm.
Rebound adjuster was seized, now working. Thought it was a compression adjuster. Turns out there is no compression adjustment. Right side fork rebound, left side compression.
The washer stack on each side differs.
There was some discussion among the "experts" and it was decided not to add the additional holes to the lower fork tubes. It was felt it would soften the suspension too much . If there was a plan to add a cartridge emulator it would make sense to do that.







Front brakes installed and began bleeding. Took a break (pun intended) to allow the calipers to fill. Will continue tomorrow.
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DB1 860



Joined: 23 Mar 2014
Posts: 177
Location: Sydney

PostPosted: Sat Oct 20, 2018 4:15 am    Post subject: Reply with quote

Im sure I was told that the adjuster on the right fork was for compression, I'll ask again then I get my forks serviced.

My DB1 was converted to a S by the dealer here in Sydney thirty years ago, It runs open 41mm carbs... up to this point there has been no problems... although Id like to fit some rock catcher mesh on them... like you see on the Ducati Bevels
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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Sat Oct 20, 2018 4:48 am    Post subject: Reply with quote

Yes , I agree, it would make sense that it's a compression adjustment. However Ellis told me it made no difference what the adjustment was when compressing the fork. It did make a difference when pulling it however.
We were both surprised by this fact.
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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Sat Oct 20, 2018 8:51 pm    Post subject: Reply with quote

The solution to the front end problems was new constant rate springs with the correct preload and some internal mods. Because these old style, right way up forks have no internal valving cartridge, and not being that much more sophisticated than an old ‘75 SS is, there really isn’t much you can do without changing things substantially. The LH leg on the M1R forks has only a compression damping cone fitted, which is a mechanical way of increasing the compression damping as the forks get closer to bottoming out. The RH leg has both compression and rebound valving, and the rebound adjuster. So it got nearly all the attention.


A quote from here..... http://www.bikeboy.org/851workinpro5.html

Of course everything you read on the internet is true. But it seems like it probably is a rebound adjuster.

I had a 851 back in the day.

Interesting you've not had any problems running without air cleaners. How many kms per year about? You do frequent oil changes?
I just assumed I'd be sand blasting all the engine internals.
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rpo83



Joined: 28 Oct 2008
Posts: 387
Location: Melbourne, Australia

PostPosted: Sat Oct 20, 2018 10:04 pm    Post subject: Reply with quote

I noticed something weird with your front calipers, as i've just rebuilt mine it is all fresh in my mind, it appears you have got the banjo and bleeder in the wrong positions, the banjo is on the outside of the caliper... At least it is on mine, so to check the DB1's i went to some images i have, here is a pic of a low mile DB1, which confirms the same orientation as mine.... Maybe check any images you have before you started...

I've just checked your pics on page one, and yes, you have them around the wrong way....


DSC05951 by Motorbike Owner, on Flickr
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Steve

YB5 #130, YB5 #196, YB7 #302, SB6 #949, Laverda RGS Executive, Laverda RGS Corsa.
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DB1 860



Joined: 23 Mar 2014
Posts: 177
Location: Sydney

PostPosted: Sun Oct 21, 2018 12:03 am    Post subject: Reply with quote

You know Steve I don't have my old Brembo P8 anymore so I cant check, but the later model calipers like the P4 both holes are M10x1.0 with a bevelled seat to take the bleed nipple, which is handy when doing brake conversions.
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rpo83



Joined: 28 Oct 2008
Posts: 387
Location: Melbourne, Australia

PostPosted: Sun Oct 21, 2018 12:13 am    Post subject: Reply with quote

That would make bleeding a little more convenient Gerald... I didn't inspect mine, i simply put them back the same as they were.. As they are not blumbed yet, i may inspect them and swap them if i can, thanks for the heads up Smile
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Steve

YB5 #130, YB5 #196, YB7 #302, SB6 #949, Laverda RGS Executive, Laverda RGS Corsa.
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DB1 860



Joined: 23 Mar 2014
Posts: 177
Location: Sydney

PostPosted: Sun Oct 21, 2018 1:30 am    Post subject: Reply with quote

My thoughts as well that it makes more sense for the adjuster to be for compression, once rebound is set to comfortable speed you can leave it alone.

I bought My Db1 18 years ago to race in the national Bears series that runs here, owning a new 996 SPS I was concerned about the lack of adjustment in the front forks but was surprising happy with them and still am,
they are thirty plus years old and I think well suited to a DB1.
I hadn't read Brad the bike Boys article on the forks, he's not so keen on them , I know Brad well he knows his stuff, maybe the forks don't work so well in a heavier bike, These days there is a company in NZ making internals for M1R's.
I have since fitted a new Wilbers rear Shock and the forks are feeling their age a bit, but I'll leave them and enjoy the Bimota experience

I had a big bore kit fitted 12,000 klm ago, with the heads coming off earlier this year to redo the squish , everything internally was fine. Oil changes every 5,000

Gerald
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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Sun Oct 21, 2018 4:02 am    Post subject: Reply with quote

Quote:
I've just checked your pics on page one, and yes, you have them around the wrong way....


Well Steve, it's either funny or sad, I've not decided which just yet. It does explain why the brake lines haven't rubbed any paint off the fork tubes. I was trying to figure that out while bleeding the brakes.
Two steps forward, one step back.
Thanks guys for keeping me from messing up! I was being very diligent taking pics before and after disassembly, just obviously not looking at them for reference upon assembly! Smile

More later....
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