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TWIGGY - DB4 Trackbike
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hnracing



Joined: 15 Apr 2012
Posts: 42
Location: Gothenburg Sweden

PostPosted: Wed Nov 26, 2014 4:01 pm    Post subject: TWIGGY - DB4 Trackbike Reply with quote

Time for this winters project!
A DB4 based Trackbike with start date 2014-11-25, hope to be ready 18 April 2015 and must be ready 9 May 2015
Have got the frame and swingarm from DB4 and a Nitron Track rear damper.
A Ducati 1100 SS trackbike as donor that will give me a fully tuned 1100 engine, magwheels and fully reworked Showa forks. The weight of the complete donor is today 157kg without fuel.
Waiting for the delivery of custom made alu tank that I hope will fit. Rear subframe from a DB4 biposto. Frame plugs, chain adjuster and chain slider. Rear brake caliper and bracket
Hope that I will be able to source half fairings. And would love to have the Carbon tank-seat from Perfect-Fairings. But maybe I have to go with the fiberglass version.
Will post some photos later on with the weight of the parts.
Now I have to shorten the steam for the triples from the SSie so it will fit. And also enlarge the hole for the rear axle so it can get further backwards
for longer wheelbase.

/Henrik Nygren
Gothenburg
Sweden

Picture of donor bike below
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deebee4



Joined: 08 Jan 2011
Posts: 264
Location: Netherlands

PostPosted: Wed Nov 26, 2014 7:41 pm    Post subject: Reply with quote

"Now I have to shorten the steam for the triples from the SSie so it will fit."

????? You mean the pivot pin in the triple clamps of the front forks?
Should be possible, but check the front fork lenght, because it could become to tall. You even might halve to shorten the fork legs. If you want to I can measure of the fork lenght top to axle of the Bimota (Paioli RSU43) front fork.

"And also enlarge the hole for the rear axle so it can get further backwards for longer wheelbase".

Wheelbase is indeed short at 136 cm - 138 cm depending on the chain drive ratio, but when you look at the dimensions of contemporary 90's race bikes, even GP500 bikes, you'll see that this was quite a normal value.

With a maximum power output of around 100 - 110 HP the short wheelbase shouldn't become a big problem. The longer wheelbases (140 -147cm) can be found in more modern bikes with a lot more HP (like 150+ or even almost 200). A short wheelbase would make these powerful bikes hard to steer, the front end being up in the air all the time.
But a simple 2 valve air cooled Ducati engine will not give the handling too much trouble. Because of the torqueness of the twin the front end can become a little light and slappy under heavy accelleration, but a simple steering damper will be enough to calm it down.

Increasing the wheelbase will influence the agility of the db4 frame, and that was just one of its best characteristics.

So I would advise to just try the bike with the stock wheelbase before you put work in increasing the wheelbase and influencing the handling.

Ciao
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brian



Joined: 22 Aug 2011
Posts: 2415
Location: QLD, Australia

PostPosted: Thu Nov 27, 2014 12:39 pm    Post subject: Reply with quote

Welcome to the forum Henrik. Sounds like an interesting project for you. I'm interested to see how the transplant of the 1000cc engine goes.

Got any before pics of the db4 frame etc?
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Current rides - '99 Bimota DB4, '96 Bimota SB6, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250,
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hnracing



Joined: 15 Apr 2012
Posts: 42
Location: Gothenburg Sweden

PostPosted: Thu Nov 27, 2014 2:31 pm    Post subject: Reply with quote

Hi,
My first choice is to use the triple clamps from the 1000SS. The triples have 30mm offset and 50mm at the top and 54mm at the bottom for the forks.
The steam or pivot pin needs to be shortend 30mm.
I hope the length of the showa forks from the 1000SS will not be a problem. If so I will have to use Íhlins forks from my Monster that are little shorter.(taken from a M1100 -09)

I do need help with dimension of the frame and the the standard suspension settings.
I have read the workshop manual but can not find the information needed.
Dimension of the frame.
Is there a detailed overall dimension picture of the frame?
What is your distance from front axel to the underside of the frame?
Rear damper lenght should be 325mm according to the workshop manual and the spring 7mm preload.
What are you using at track?

When I look at the rear swingarm I just saw that there is 22m of aluminium at the rear where I could use another extra 10mm for the adjustment of the wheelbase. Not knowing if it would be needed.


Pictures and weight comparison with 1000SS will come shortly.
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Monster 1100 -96 for the road / 1100SS for the track / DB4 new track project
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vort28



Joined: 22 Mar 2010
Posts: 1782
Location: Northwest , UK

PostPosted: Thu Nov 27, 2014 3:16 pm    Post subject: Reply with quote

Welcome to the Forum Henrik.

I have seen pictures of a DB4 with Ducati ST3 motor's before so think should be possible, also seen a DB4 with 916 showa forks , so think the forks will be in the right ball park.
Very interested to see how the project goes also, and we love pictures so keep them coming.
Is this just to use as a track bike ?
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hnracing



Joined: 15 Apr 2012
Posts: 42
Location: Gothenburg Sweden

PostPosted: Thu Nov 27, 2014 8:35 pm    Post subject: Reply with quote

Hi,
Yes this will only be a trackbike.
For the road I have a Monster 600 - 96 that have been improved over the years.
Now running Íhlins fork with radial caliper from a Monster 1100S and aluminium swingarm with ÷hlins at the rear.
The engine is a M1000 engine that now is bored to 1078,
Pistal HC pistons, DP cam, TPO Beast R and 45/50 spagetti headers.

See enclosed frame dimension for 1000SS I am after something similar for the DB4.
http://user.tninet.se/~cmf606a/ducati/bilder/1000SS_frame_dimension.pdf

/Henrik
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deebee4



Joined: 08 Jan 2011
Posts: 264
Location: Netherlands

PostPosted: Sat Nov 29, 2014 1:03 pm    Post subject: Reply with quote

hnracing wrote:

See enclosed frame dimension for 1000SS I am after something similar for the DB4.
http://user.tninet.se/~cmf606a/ducati/bilder/1000SS_frame_dimension.pdf

/Henrik


I'll see what I can find for you... Smile
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brian



Joined: 22 Aug 2011
Posts: 2415
Location: QLD, Australia

PostPosted: Sun Nov 30, 2014 1:33 am    Post subject: Reply with quote

Sorry, but i have to ask since i've seen no clues yet... why TWIGGY?
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Current rides - '99 Bimota DB4, '96 Bimota SB6, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250,
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deebee4



Joined: 08 Jan 2011
Posts: 264
Location: Netherlands

PostPosted: Sun Nov 30, 2014 12:14 pm    Post subject: Reply with quote

Maybe this will be of some help: haven't found the frame dimensions yet.

If you want to I can measure things up, just give me the reference points and values you need.





Which came from this book:


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hnracing



Joined: 15 Apr 2012
Posts: 42
Location: Gothenburg Sweden

PostPosted: Sun Nov 30, 2014 12:15 pm    Post subject: Reply with quote


The bike is named after the english model that was initially known for her thin build. http://en.wikipedia.org/wiki/Twiggy
A friends rainbike is named "Indra" - the god of rain and thunderstorms!
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Monster 1100 -96 for the road / 1100SS for the track / DB4 new track project
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hnracing



Joined: 15 Apr 2012
Posts: 42
Location: Gothenburg Sweden

PostPosted: Sun Nov 30, 2014 12:18 pm    Post subject: Reply with quote

deebee4: Fantastic!
That is the drawing I am after.
Will come back shortly with the dimensions that I want.
Thanks!
/Henrik on his way out take some photos!!
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brian



Joined: 22 Aug 2011
Posts: 2415
Location: QLD, Australia

PostPosted: Sun Nov 30, 2014 12:29 pm    Post subject: Reply with quote

hnracing wrote:

The bike is named after the english model that was initially known for her thin build. http://en.wikipedia.org/wiki/Twiggy
A friends rainbike is named "Indra" - the god of rain and thunderstorms!


Ahh, that Twiggy... right
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Current rides - '99 Bimota DB4, '96 Bimota SB6, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250,
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deebee4



Joined: 08 Jan 2011
Posts: 264
Location: Netherlands

PostPosted: Sun Nov 30, 2014 1:47 pm    Post subject: Reply with quote

hnracing wrote:
deebee4: Fantastic!
That is the drawing I am after.
Will come back shortly with the dimensions that I want.
Thanks!
/Henrik on his way out take some photos!!


I just took off the rear shock (has to be rebuilt, because it was not working properly anymore after 10 years of track use.....Embarassed

Ohlins B18230. Distance between holes (center to center) 32 cm, can be adusted up to 35 cm. Being short legged in lowered the bike a bit in the past to be able to reach the ground better. Now since it's only used on track I gradually raise the bike a bit.

Spring: 1091-21/80 079. Free spring lenght: 160 mm. Spring preload: 10mm

Embarassed
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hnracing



Joined: 15 Apr 2012
Posts: 42
Location: Gothenburg Sweden

PostPosted: Sun Nov 30, 2014 10:27 pm    Post subject: Reply with quote

Finally some photos Smile




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hnracing



Joined: 15 Apr 2012
Posts: 42
Location: Gothenburg Sweden

PostPosted: Sun Nov 30, 2014 10:29 pm    Post subject: Reply with quote

DB4 frame vs 1000SS frame






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