Bimota Forum

[mfennell]

Thought I'd contribute a few bits to the forum, which is an invaluable source of info even if it's not super traffic'd. I have a '99 db4, which I've had for a little over a year (sep '22) and about 850 miles. Last winter I pulled the bodywork off, found a fixed a broken fairing stay, and changed the headlight to the continental European projector style. I documented it elsewhere but I'll push the content here. Hopefully someone will find it useful.

It looks like I have to host pics somewhere so this might go a little slowly.

Anyway, I wrote the following LAST winter. I'll throw in some additional annotations.

So, here's my bike on the lift. This pic is actually from yesterday, rather than last year.



The db4 (and db2, db3, V-Due) uses a Yamaha FZR-style headlight. In the US (and the UK, I think), it's a single bulb but Continental Europe got a two light projector setup. H1 low beam, H3 high beam. Same as my Aprilia RS250.



Of course, I have to have it.

"FZR headlight? Just pop over to ebay for Germany, etc.. I bet they're 20EUR."
False.
It turns out this particular style was only used on a handful of Yamahas and none of them FZRs. Worse, the reflector ages with use and the light output dims, causing Germans to fail TUV so good luck finding NOS or even a used one. I never actually found a used 'Yamaha' light. I found a handful of 'Bimota' lights of the right style but they were asking crazy money. If I'm paying crazy money, might as well buy new. Paolo at Bimota Classic parts had (at least) two and my friend John with a db2 is at least as willing as I to spend money on useless things, so I ordered two @ 300EUR each. Shipping was expensive but DHL got the things from Italy to my house in something like 36 hours. Crazy.

I was thinking I'd have to make an ugly adapter from the headlight connector but it turns out there's a nice sub-harness and Bimota used AMPSEAL connectors, easily sourced for cheap.


PINS

CONNECTORS

CRIMPER FOR PINS

The lamps have spade connectors for hot and ground. I'm not sure how Bimota wires it up (I'll check out my Aprilia later) but I just bought a bunch of insulated ones from Amazon.

SPADE CONNECTORS

16GA wire

CRIMPER FOR SPADE CONNECTORS

Here's a shot of the connector, helpfully annotated for Future Me to remember what the hell I did.



I didn't have the correct crimping tools so this was a perfect opportunity to get some.



And here's the first one.


I ended up giving this one to my friend and adapting an Aprilia harness, in a later post

Just this morning I found that it's easy to get a dust cap for the 60mm openings. I need to go out to the garage and confirm there's room for them.


I discovered that the fairing stay is cracked, so that needs a trip to the impossible-to-contact-but-worth-it local welder/machinist for a fix and probably some reinforcement. I'm reinforcing some body mounts with fiberglass while I have it apart too.


Oh, and I'm going to put some Tyga LED turn signals on it. The mounting appears to all be identical to my Aprilia and, I assume, standard for both (and possibly Ducati) at the time. I never actually did this because I was reluctant to chop up my harness


And also pull the carbs. I'm thinking I need to go a tiny bit richer on the slow jet. Got it pretty close on my last ride. I remember those carefree days, when my FCRs just needed a tweak.
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Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Reminder that this was written for another forum (Ducati) where readers are not as familiar with Bimotas

Little update. I shipped the fairing stay off to a friend who had the nerve to move from the area about a year ago. There's a guy about 30 minutes away who's awesome but scheduling with him can be a chore.

About 1/4 of the mounting holes on the bodywork have cracks. The plastic on Bimotas is basically the same as the cheap Chinese fairing kits (actually, the kit on my 848 is better) and has been described as cracking "if you look at it out of the corner of your eye". It's a shame because the bike is otherwise immaculate. Anyway, I'm reinforcing/repairing with fiberglass and CA glue (rather than resin), a technique I stumbled on watching YT videos.


_________________
Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

I've been using fiberglass and CA glue to reinforce the fairing mounting holes. After sanding the area, I use a thick CA to glue down a small piece, soak it with thinner CA, dremel out the hole after it dries, then trim.



Then, Rustoleum flat black, which is just an oil-based enamel.




This is probably (certainly) not the best approach but it's really quick and surely better than nothing.

Since I'm waiting on the fairing stay, I put the Aprilia up on the lift for its own winter projects and pulled the fairings off.


_________________
Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Waiting on the stay to come back. My buddy did some work over the w/e. Meanwhile, I'm working on the Aprilia. New fork seals and stiffer spring (only has one in the left fork leg) and cleaning many years worth of dust and grime. Which brought me to the headlight.



Exactly the same configuration as the new headlight for my db4. Suddenly, my new harness and generic dust caps look amateurish. Long story short, I was able to track down a NOS Aprilia RS250 harness on at Speedwerks (via ebay), which is owned by the guy who connected me with my RS250 in the first place. All my messing about wasn't a complete loss - now I have the tools to swap in the correct connector. I have a little 'Euro Headlight Conversion' package set up for @Desmo55 but I don't think that's going to cut it now. For future information seekers, the Arilia part number is AP8124634.
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Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Fairing stay back from my friend. He does nice work with pretty basic equipment at home. He was a professional at one time but now he just dabbles.


He welded up the break, then cut and welded a reinforcing plate on the back side. I think we can call it 'fixed'.


_________________
Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Nice powder coating on the fairing stay at the shop my friend John uses.


Aprilia is ripping again (next up is to order a Zeeltronic ignition/powervalve controller) so the db4 is back on the lift. Normally, this time of year the weather sucks and the roads are a mess but it's been warm and the roads are salt-free so I've been getting a bunch of quick runs in. Originally written March 2023


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Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Finally put the connector on the Aprilia harness. It makes me irrationally pleased to have an OEM-appearing solution.



Still waiting on the lowers from Perfect Fairings. They finally shipped. 10 days later and I have no idea where they are. Bimota Classic Parts charges an arm and a leg for shipping but you get the stuff in less than 48hrs.

Placed an order for some jets based on feedback from Duati forum users and notes written in my owner's manual. That will be fun.
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Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

She's running again. After taking in all the input, my initial setup is:

155 mains
62 low speed
EMR needles, middle position (I have EMT needles too - leaner on low throttle)
1 1/4 turns fuel
1/2 turn air

It starts and idles immediately in my 45F garage, so it's pretty damn rich. The air and fuel screw settings are about where they were when I was trying to compensate for the lean throttle tip-in.

My carbon fiber lowers from Perfect Fairings are finally in the USA. Somewhere.


_________________
Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Lowers finally showed up from Perfect Fairings in Greece. 6 weeks or so. Quality is about what I expected. A few flaws in non-obvious places. They're not drilled but all the spots are marked , since the molds came from an original part. They only have fairings for two Bimotas. Someone at the company must have owned them.

Down to 3/4 turn on the fuel screws. My clothes no longer stink after I run it. I haven't been able to ride it though.


_________________
Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Double-sided chain slider from Bimota Classic Parts installed. I'm surprised that I can get bits like this.


_________________
Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Quick ride after work yesterday (Mar 17, 2023) minus fairings.



Carburation is better. Still with a lean stumble as I roll on but initial tip-in is nice. Going to raise the needles and give it another go.
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Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Raised EMR needles to 2nd slot from bottom. Opened slow fuel to 1.5 turns out. Still with the stumbles/backfires as I gradually rolled on.

Turned the slow speed needle in all the way to 1/4 turn (from 1) and it runs 100% better. No backfires. At tiny openings, it's not 'right'. I don't know how to explain it. I'll give another run.

Setting seems insane but that's where I am. Main air jet is a 200.

Thing I finally noticed this evening: one carb has a small shield cast into the bore around the main jet, one does not (or it was removed). Not sure how I didn't see it before.


This bike is an absolute joy to buzz around on, carb issues or not.
_________________
Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Current state of 'done'. (as of Mar 26, 2023)



Caught up with my friend John this afternoon and we swapped bikes for a quick ride. General agreement that my bike is a bit quicker. FCRs might be in the future for his db2. Hasn't happened yet. Thank God. Looks like a huge PITA on a db2


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Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[mfennell]

Phew. That was a PITA. Now at present day. Put about 650 miles on the db4 this season, just banging about. Never got the carbs right. Always felt like I had a lean condition on tip-in. Assumed I just needed to go one up on the slow speed jet. A couple weeks ago, I went riding on a cold day (45ish F/7C) and it was ... better?

Carbs are the worst.

Pulled the body yesterday and found I'm going to learn a bit about 2V Ducati maintenance. I guess I have a leaking o-ring.


_________________
Mike
db4, 848 Evo, 848, 701 Vitpilen, Aprilia RS250

[brian]

Hi Mike,

This is a great post. Nice info regarding the headlight. I’m in the process of looking for a headlight for my 2nd DB4 that I bought a few years ago with a lot of parts missing.

The fairing stay on my first DB4 also cracked and had to be repaired.

Cheers
Brian
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851