Conrod kits ?

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Conrod kits ?

Postby Scottish888 » Tue Jul 24, 2018 12:50 pm

Any thoughts on conrod kits suitable for a Ducati 250 mk3 that will be street use only.
I have been in touch with Lacey's here in the UK who were very helpful, they supply a race spec conrod kit around £600 plus tax, I understand this is a high quality item that they trust and I feel very confident in their product but are there any other alternatives with good quality that do not require the crankshaft to be machined to fit.
What have you fitted in your bike?
I thought I should ask on here before purchase.


Bevel bob
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Re: Conrod kits ?

Postby Bevel bob » Tue Jul 24, 2018 6:24 pm

Nigels kit will be A 1 but will need to be fitted by someone very competant to finish up with both the correct clearances and good alignment. New parts do appear on E-bay from time to time ,usually in the USA ,but you need to be very carefull to get the right size and quality, not easy.

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Re: Conrod kits ?

Postby ducwiz » Tue Jul 24, 2018 7:20 pm

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Re: Conrod kits ?

Postby Scottish888 » Wed Jul 25, 2018 10:18 am

Thanks for the tips folks,
After speaking with Nigel, he told me of the various quality issues he has seen with conrod kits, with one kit where the conrod is 5mm oversize requiring the crank halves to be machined -2.5mm.
I asked the rod supplier if the conrods could be machined instead but the bearing is same width as the rod.
I found a manufacturer here in the UK who would make rods for Ducati singles, prices at x1 £300, x10 £130, x100 £100 each, that is just a rough guide, obviously bearings and crankpins would need to be factored in but for standard street bikes this could be an option?
The manufacturer is
There will be many manufacturers out there
Nigel offers a superior product and I will likely go with that but I only need street spec at a lower cost if poss.
Maybe forum members could organise a manufacturer to do a run for us at various sizes with a rod manufacturer somewhere?
What did you folks choose when you have replaced a conrod kit?
More daft thoughts...
Are there any Japanese bikes with rods that could be machined to fit?
Does anyone have the the original rod dimensions for the typical sizes we have?

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Location: Stafford UK

Re: Conrod kits ?

Postby ranton_rambler » Wed Jul 25, 2018 4:40 pm

The various rod sizes are listed somewhere in this forum. I found it once and printed it off and put in my file. If you can't find it using the search facility let me know and I'll have a flick through my file.

double diamond
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Re: Conrod kits ?

Postby double diamond » Wed Jul 25, 2018 5:31 pm

The Mazzucchelli rod kits are probably adequate for your purpose. They offer the correct length 135mm rod with two options for crank pins: 27mm & 30mm. You need to verify the diameter of the big end pin bore in your flywheels. You probably have a 27mm pin but verify to be sure.

Manufacturing your own rods, big end pins and thrust washers and procuring the correct size bearing would be a very costly proposition.

I've had some success with replacing the big end bearing and thrust washers if the big end pin and rod aren't out of specification, but sounds like yours might be beyond this point.

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Re: Conrod kits ?

Postby LaceyDucati » Wed Jul 25, 2018 8:28 pm

Hi All
Thought I'd chime in here. Not seen/noticed the rod manufacturer posted, the prices quoted are pretty cheap compared with Arrow who require a 50 rod order nowadays. I might investigate myself, were the "quotes" for one piece rods with hardened eyes? Arrow themselves recon there is more issues and work in one piece rods, looks and first thoughts can be deceptive. I'm trying to stick with Arrow as we have a proven record with them and although seemingly expensive sometimes it's better the devil you know....

Info on Ducati Single rods

Narrowcase 125mm centres, B/E 39mm dia, 18mm wide, S/E 18mm dia

250/350 Widecase 135mm centres, B/E 39mm dia, 18mm wide S/E 18mm dia

1975- 250/350 Widecase 135mm centres, B/E 43mm dia, 22mm wide S/E 18mm dia

450 Widecase 140mm centres, B/E 39mm dia, 18mm wide S/E 22mm dia

1975- 450 Widecase 140mm centres, B/E 43mm dia, 22mm wide S/E 22mm dia

Yamaha XT/TT 600 rod is 134.5mm centres B/E 42mm dia 20mm wide, S/E I think 23mm dia

Honda XL500 rod is 140mm centres B/E 42mm dia 20mm wide, S/E 20mm ?

These are the nearest Japanese rods, both can be used in widecases and are of obviously good quality. Bad bits - the crank needs modifying or special pins/side shims made. The rods are wider section and the wheels need machining to suit. The balance of the crank will be miles out and will need rebalancing. Yamaha prices are not as cheap as they used to be!

If you are doing the work yourself these rods are an option, but if you are paying me to do it as a one off it will work out expensive. If anyone is interested I think I have some 30mm pins to suit the Yamaha rods. I've used these rods myself years ago (recommended by Eldert in the early 90's), That was before I was doing larger numbers of cranks and had my Arrow rods manufactured. I also used to used Husarberg 125mm rods in the narrowcases, again no longer viable for me and no longer available except as aftermarket and not cheap.

Has anyone used Mazzucchelli rod kits? My experience of old kits has been of very bad quality. As far as performance and hard use I'd give them a miss, but I stand to be corrected if many have used them for normal road.

The other kits mentioned from Ducati Classics is the same kits from The Ducati Vintage Store (old scrambler club). I've fitted one, quality seemed okay and clearances/spec seemed the same as OEM (not as I would spec). Needed 2mm machined off each wheel thrust face, changes to balance unknown. Again if you are doing the job yourself or you've a mate that can.... probably okay.

You may question why I'm sharing all this info, when I'm selling my own rod kits. The answer is, selling the kits Is no big money spinner, regardless of the price I charge. The time/money taken to, procure, measure, clean, match and assemble the components together and the shear investment is questionable. That's not taking into account the investment in time to do drawings, check drawings and the investment in air gauging to measure the components.

This is not a moan, just a statement of what's available and where I'm at. Personally I think my kits are expensive for the cooking road bike and I would be more than happy to market quality cheaper kits if available. However I don't have an answer. Also things are not improving with manufacturing prices escalating. My Arrow rods have increased 27% since I last ordered 9 months ago, small batch quality engineering in the UK is an expensive business.

Just one other thing to remember when having crank work done, use someone you trust with a track record. Sadly I spend a lot of time rectifying/ condemning badly built/repaired/bodged cranks. Good used Ducati Single cranks are rare these days, the barrel has well and truly been scrapped.

Hope some of this helps

Best Wishes to all

Nigel Lacey
Lacey Ducati
Last edited by LaceyDucati on Wed Jul 25, 2018 8:37 pm, edited 1 time in total.

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Re: Conrod kits ?

Postby LaceyDucati » Wed Jul 25, 2018 8:36 pm

Forgot to mention that I will sell an Arrow rod on It's own if available without the rest of the kit, for the DIY enthusiast.

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Joined: Sun Sep 19, 2010 10:30 pm

Re: Conrod kits ?

Postby LaceyDucati » Wed Jul 25, 2018 9:11 pm

A few on Ebay....

NOS 27mm pin widecase Assembly. showing age from storage. ... SwHvpbI~tk

Remember these original kits were £350 in the UK when last available new in the early 90's (probably 25 years ago). Ducati parts were never cheap!

This ones a reconditioned (by Alpha) Late 32mm pin......I've not had any luck with these with Alphas own bearing. ... SwCAVa0yoD

No 30mm pin kits on ebay at the moment.

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Location: Scotland

Re: Conrod kits ?

Postby Scottish888 » Thu Jul 26, 2018 12:38 am

Thank you Nigel,

Very helpful and informative, Thought I would check all options before taking the plunge.
This looks like the only big expense on my bike and I only want to do this job one time, as I said most likely I will fit your rods as no other machining required, I would rather keep the crank original as once you have machined it then you must fit the oversize rods any other time.
I can see you have looked into every possibile solution, saves me from coming up with daft ideas, thank you for your work and advice.


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