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Monza 250 (NC) restoration.

Posted: Wed May 19, 2021 3:58 pm
by Blaine.Hale
Howdy,

Wrapping up a Monza 250 here and I'm looking for Dellorto suggestion if y'all don't mind. I was looking at a Dellorto VHB 26 FD, as they're cheap and available on eBay but don't know if I should be looking for something bigger, maybe?
-Does anyone have jetting recommendations or should I stick to the chart here: http://ducatimeccanica.com/singles_carb_set_up.html
-What size Del should I go for?
-Any recommendations for a manifold to match that's bolt-on?'

Standard bore on the cylinder and stock pipe.
My searches on here didn't really lead to what I was hoping, so sorry if this a worn-out topic!
Pics, just because:

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Re: Monza 250 (NC) carb recommendations and jetting?

Posted: Wed May 19, 2021 6:25 pm
by Bevel bob
I would think a 26 carb is the biggest I would go with an otherwise unmodified Monza. A bigger carb would just lose mid range and not be able to make any gains without other alterations.

Re: Monza 250 (NC) carb recommendations and jetting?

Posted: Wed May 19, 2021 9:07 pm
by Blaine.Hale
Bevel bob wrote:I would think a 26 carb is the biggest I would go with an otherwise unmodified Monza. A bigger carb would just lose mid range and not be able to make any gains without other alterations.


Thank you! I was thinking the same...so looks like I can get a carb really cheap, then.

Also should add that I got the motor back together today...some things are slapped on just for photos, I find it easier to just drop the crankcase in the frame then bolt things on, so this will all come apart tomorrow.

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Re: Monza 250 (NC) carb recommendations and jetting?

Posted: Thu May 20, 2021 3:59 am
by Bevel bob
The motor looks like it has not been too abused , You may have to have several goes at getting the shimming correct, I would leave out the rockers so you can check the cam drive has no slack and no tight spots anywhere. Can't even expect the factory settings to be correct.

Re: Monza 250 (NC) carb recommendations and jetting?

Posted: Fri May 21, 2021 2:30 pm
by Blaine.Hale
Would you happen to know where to source the electrical bullet connector Ducati uses? I'd love to stick with the solder style instead of crimp, if at all possible. I noticed some Lucas electrics use very similar, if not the same, connectors.

Re: Monza 250 (NC) carb recommendations and jetting?

Posted: Fri May 21, 2021 3:39 pm
by nalimugmug

Re: Monza 250 (NC) carb recommendations and jetting?

Posted: Fri May 21, 2021 9:13 pm
by themoudie
Might I also suggest that you have a look at the site of Vehicle Wiring Products? I use them as a matter of course for my wiring and other requirements.

May not be the cheapest, but their 3.9mm connectors are all tinned that helps prevent corrosion and eases soldering. I crimp and solder my connections.

VWP_3.9mm_non_insulated_bullet_connectors

The older 4.7mm type of bullet connector are also available. Here is the link: VWP_4.7mm_ non_insulated_bullet_connectors

Enjoy wrestling with the multi-coloured spaghetti. ;)

Good health, Bill

Re: Monza 250 (NC) carb recommendations and jetting?

Posted: Fri May 21, 2021 9:24 pm
by Blaine.Hale
Awesome, thank you for the info guys! What gauge wiring do y'all recommend for the 6 volt system? I used 18 gauge with no issues in the past for most 6 volt looms.

Side note, looks like one of my oil rings is cracked on the piston so now I'm on the hunt for a ring kit for a standard bore 74mm borgo piston. Seems very hard to find since the Monza seems to be the only model with the extra oil ring on the piston.

Thought ya'll might appreciate this...another hobby of mine is photography and tintypes so I shot a plate of the motor before I dropped it back in the frame.

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Re: Monza 250 (NC) restoration.

Posted: Fri May 21, 2021 10:06 pm
by themoudie
Aye Blaine,

This is the cable that I use and if you use the formula; Watts divided by Volts = Amps, you can work out what cable cross-section you require.

Link: VWP_Single-core-pvc-thin-wall-cable

In my opinion wrestling with old cable and connectors is not worth the hassle and potential frustration if you are going to use the bike as intended. Get it dirty! :D

Good health, Bill

P.S. Rings? Give Nigel, at Lacey Engineering a call. ;)

Re: Monza 250 (NC) restoration.

Posted: Sat May 22, 2021 12:41 pm
by nalimugmug
Hi again,

When I made up a new loom not being exactly sure what wire I needed I spoke to these people.
https://www.autoelectricsupplies.co.uk/category/10

I was told that the best way was for me to count the strands of wire in one conductor in the old loom, so I ended up with this.
020101 14/0.30, 1.0mm², 8.75A, 3.7mm OD.

Hope along with Bills advice that this helps

Bob