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DB1 restoration
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Quadrasuarass



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

PostPosted: Mon Oct 01, 2018 4:15 am    Post subject: Reply with quote

They should both be 15mm; as posted above Marconi wanted the same look for each set of control - as in a mirror image. The correct fitting would have been 13mm clutch, 15mm brake. There is a record of this in the literature somewhere. I will see if I can dig it out.
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PaulDB2



Joined: 26 Apr 2014
Posts: 316
Location: Manchester

PostPosted: Mon Oct 01, 2018 11:15 am    Post subject: Reply with quote

Thanks Rocketron, I appreciate your efforts to measure the sizes. I will have a look for the numbers on mine later.
My DB1 was a Canadian bike, I imported from Ontario at the end of 2014.
Quadrasuarass, not doubting your info, interested to see if Rocketron can get rebuild kits and what part numbers they would be.
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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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2bims



Joined: 03 Apr 2010
Posts: 7289

PostPosted: Mon Oct 01, 2018 3:34 pm    Post subject: Reply with quote

And thanks also for the Laverda link......those "bespoke" masters now make sense to me how Bimota created them for the DB1.....removing the built in res pot and fitting a blanking plate for the tubed res pot on top of the forks....hadn't realised thats what they had done
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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Mon Oct 01, 2018 10:35 pm    Post subject: Reply with quote

The original plan was to figure out how to rebuild everything myself. I've changed that plan.
I've been in contact with my new found friend at laverda.ca. First by e-mail and now a chat on the phone. Typically, you don't know what you don't know until someone wiser than yourself tells you.
His biggest concern is corrosion within the cylinders. Apparently this is typical of older Brembo castings. He mentioned working on a Japanese car master cylinder of the same vintage. It was like new inside compared to what he's seen inside Brembos. Apparently something to do with crappy casting (materials?) and the difference in metallurgy with the piston. It can happen even with very little use, just time can do it.
He has a connection who can install brass inserts, which fix the problem. He believes mine should be ok with just a light hone. But he'll know better once he has a look inside.

OH, I just remembered he also explained he has special tools for inserting the pistons and seals. Without these it's very easy to drive them too far inside. This will possibly both distort the seals and it could also cause the piston to be travel limited. ie: not much brakes!

We discussed the calipers and he believes even a klutz like myself can't mess those up. So once he's rebuild the cylinders he'll send some new seals back in the package. With these he said just be VERY sure to clean out the groves where the seals lay. Any debris in there will stop the seals sealing properly. The metallurgy in the calipers, aluminium (body) and aluminium (pistons) keep corrosion to a minimum.


I've found someone with experience servicing the suspension. He even has the parts in stock for the forks! The shock however can be a problem finding spares. Next step is to remove the calipers and the forks.

Looking about here in the forum has made tire replacement seem quite easy. I'm going to go with the Shinko 16".


If I'd bought the core bike as a pile of crap, I would be looking to upgrade everything with new stuff. Wheels, brakes, suspension whatever needed to be renewed. That's not the direction I'm gonna go with this. Keeping it as close to when it came out of the box is what I want to do.
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PaulDB2



Joined: 26 Apr 2014
Posts: 316
Location: Manchester

PostPosted: Tue Oct 02, 2018 12:20 am    Post subject: Reply with quote

The calipers are pretty straightforward to re-seal.
The most likely issue with the rear shock (Marzocchi) is that the bumpstop will have gone hard and very brittle and just crumbles. I have found a place here in the UK that can replace the bumpstop (the eye needs to be removed from the piston rod) and rebuild the shock . I was warned however when removing the adjuster cable that it is easy to lose a small part from inside the adjuster mechanism inside the eye, it can just fall out, so be aware. Good luck.
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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: Tue Oct 02, 2018 12:54 am    Post subject: Reply with quote

Time to stop and ask for some advice and reflect. The top of the forks need to come off to allow removal. The top being the reservoirs of the brake and clutch.

The clutch side is turning reasonably easy but it feels like there is some pent-up force against it. Seems reasonable to assume the fork spring is pressing against it. The wheel is off and the forks are not pressing on anything. There is no preload adjuster apparent.

How ugly is this gonna be? I'm hesitant to proceed for two reasons.
1. I don't want a hole in the roof.
2. I don't want the threads mangled as it pops off.
Anyone know how much thread is on the cap? Maybe before it's loose the pressure will be off? Maybe there is a tool for this?

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Bud977



Joined: 03 Mar 2013
Posts: 525
Location: Sydney

PostPosted: Tue Oct 02, 2018 8:05 am    Post subject: Reply with quote

Usually the preload on forks is 10mm so the cap isn't going to fly off too far. The resistance as you unwind is probably from dry threads, dried fork oil on the threads or the drag of the O ring. Give the threads a squirt with WD40 to lube them up and keep unwinding. Keep some pressure on the cap near the end so it doesn't fly off.
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2bims



Joined: 03 Apr 2010
Posts: 7289

PostPosted: Tue Oct 02, 2018 9:32 am    Post subject: Reply with quote

Yup...the reservoir tops aren't just reservoirs....they are the caps and tops of the forks keeping the springs in the tubes....so there will be some pressure until they come off...and the springs pop up....to remove the reservoir pots folk use rubber strap wrenches....that wind around the pots and have a steel bar for leverage...
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Quadrasuarass



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

PostPosted: Tue Oct 02, 2018 8:29 pm    Post subject: Reply with quote

Rebound damping is in one side, compression damping in the other. The caps will pop off with about 10mm of spring extension; the force is not that high and things shouldn't fly about unless someone has done something untoward with longer sprigs and pre-laod collars. There are two springs per leg, the main fork spring and and a smaller bump stop spring at the bottom that helps stop the fork bottoming out. Only one is shown in the M1R manual; a copy should be available somewhere on this forum; pm me if you want a copy. Other notes below:


The following information supplied by Marzocchi in Feb.1986
and should be use for the 1989-90 Ducati 851 and SP versions,
Bimota DB1, S, SR series motorcycles.

This what I have found and what actually worked well for me (170 lbs)
And my son (120lbs).

GENERAL INFORMATION
The right fork assembly controls rebound (knob at the bottom of the fork slider) and the left fork assembly controls compression (no control anywhere).

Different levels and different viscosities of oils can be used to suit conditions. This is the beauty of these forks. Adjustments on each leg will not effect the other. Only fork springs and oil levels need to remain the same. Oil viscosity can be varied on each leg if you are competent enough to judge and appreciate the differences.

Fork Springs
There seems to be misleading and inconsistant information on the springs for the M1R forks. There are 2 springs, one in each leg. Some parts breakdowns will only show one and even Marzocchi literature is misleading when it actually shows NO SPRING in the crossection of left fork tube. Trust me.......there ARE 2 springs.

Marzocchi has different fork springs for the 42mm M1R forks which are:
Light Spring-------30 inch/lbs---------Part # 18.0071
Medium Spring ---40 inch/lbs---------Part # 18.0072 (standard)
Heavy Spring-----50 inch/lbs---------Part # 18.0073 (standard)

Progressive Suspension has springs (Part # PS 1130). They work extremely well especially with the adjustable preload caps (no Part #) on pg. 7 of the Pro Italia, June 1994 catalog. These adjustable caps were made for the Ducati 750 Paso and the 907 Paso.


FORK TUBES
It appears that the right and left fork tubes are of different lengths as supplied on a motorcycle and there are different lengths available.

YOKES (Triple Trees)
Different offsets and stem diameters are available.

OIL LEVEL(s)
The oil level is measured from the top of the open fork tube (cap off) to the centerline (repeat: centerline) top of the oil inside the upper fork tube. Take the springs(s) out and compress the fork completely to
Make this measurement.

38mm tube models should have 160 mm of air distance from top
42mm tube models take 170mm of air distance from top.

I recommend you buy one of the many available fork oil measuring tools that look like a very large medial syringe with a long tube where the needle would be. On that tube there is a sliding disc that will rest on the top of your fork tube. The idea is to put a large amount of oil in the tube and then(with the tool) you suck off the unwanted oil and then repeat for the second tube. Simple and very accurate.....IFthe forks are vertical.

Use 5 weight oil for temps 10-15 centigrade (30-50 F)
Use 10 weight oil for temps above 15c (50 degrees F )
Adjust the oil viscosity to suit temps. There is 2 wt oil for colder temps and you can "play" with mixtures as you desire and learn.

The right fork leg with the knob down on the bottom is for REBOUND and has 4 (yes only 4) positions. You can rotate past 4 and will go back to 1 after you get the oil and spring(s) installed you should be able to tell the 1 position from the 4 position.There are different springs in the REBOUND adjustment (knob area) to adjust the range of rebound dampening rates (not to mention you can play with oils).

Light rebound: Spring # 71.0050
Medium rebound: Spring # 71.0051 (nromal)
Heavy rebound: Spring # 71.0052 (normal)

Use no air in these forks. From time to time you will need to bleed off unwanted air that gets trapped in the forks.

MODIFICATIONS TO FORK LEGS (Tubes)

In March 1986 a Marzocchi service bulletin recommended:

Left tube: drilling a 6mm hole, 65mm from the bottom of the fork tube
Right tube: drilling a 6mm hole, 35mm from the bottom of the fork tube.

BE CERTAIN TO "DEBUR" THIS HOLE AND SMOOTH EDGES OF
DRILLED HOLE AS BEST POSSIBLE.

ricambi.spa@marzocchi.it has the Marzocchi service manual & parts book (one book) and spares.
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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Wed Oct 03, 2018 1:16 am    Post subject: Reply with quote

thanks for the info guys. This is what I was hoping when I began posting here. That there would be shared info both ways.



Took off the caps and no holes in the roof. I'm a little worried about remounting as the caps is gonna take some serious effort once the forks are back on the bike.



This is one of the areas I've not spent any time researching yet. For some reason a few years back this switch self-destructed. Seemed like it just became brittle. Maybe it was hit at some point but not sure. I've got the three pieces it decided it wanted to be. Some glue would get it together for the purpose of recreating it. One thought was to have it remade via a 3D printer. Good excuse to buy one maybe? Perhaps there is a source to purchase instead?

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Quadrasuarass



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

PostPosted: Wed Oct 03, 2018 1:47 am    Post subject: Reply with quote

That doesn't appear to be original switch gear, looks more like late 80's early 90's. Pic is what I would expect. I may have a set of the ones you show tucked away somewhere.

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Rocketron



Joined: 12 Jan 2013
Posts: 80
Location: Canada

PostPosted: Wed Oct 03, 2018 4:42 am    Post subject: Reply with quote

Yea, that's exactly the same switch. Just you've got the one slider that is broken on my left side.
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2bims



Joined: 03 Apr 2010
Posts: 7289

PostPosted: Wed Oct 03, 2018 8:32 am    Post subject: Reply with quote

Rocketron wrote:
Yea, that's exactly the same switch. Just you've got the one slider that is broken on my left side.



Look out for Suzuki GT380/550/750 Kettle LHS switchgear....they share the same units....1970's bikes...certainly the bit thats snapped off with the small Philips head grub screw is the same slider switch and fitment

https://www.ebay.co.uk/itm/Suzuki-GT380-GT550-GT750-Circa-1973-1974-Left-Hand-Side-Switchgear-Switch-Gear/332796580041?fits=UKM_Make%3ASuzuki&epid=15023487878&hash=item4d7c38d0c9:g:SbkAAOSwWo5bkm9N

https://www.ebay.co.uk/itm/Suzuki-GT750-GT-750-GT550-GT-550-1974-on-Left-Hand-Side-Switchgear-Switch-Gear/332826038143?fits=UKM_Make%3ASuzuki&epid=26024387204&hash=item4d7dfa4f7f:g:eM0AAOSwmNlbslTY
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2bims



Joined: 03 Apr 2010
Posts: 7289

PostPosted: Wed Oct 03, 2018 8:48 am    Post subject: Reply with quote

Or...…………….Because Suzuki are remanufacturing parts for old bikes....you can just buy the broken piece you need for the light switch brand new ...on its own

https://shopvintage.suzuki.co.uk/catalog/product/view/id/72595/s/57712-33012-000-knob-lighting/category/127/

Who'd have thought Bimota pieces could be bought so cheaply..... Laughing
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Quadrasuarass



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

PostPosted: Wed Oct 03, 2018 8:26 pm    Post subject: Reply with quote

Rocketron wrote:
Yea, that's exactly the same switch. Just you've got the one slider that is broken on my left side.


Opps; I need to clean my glasses more often.
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