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General Category => General Discussion => Topic started by: Turin on January 04, 2025, 11:59:06 AM

Title: Breva 1100 Cylinders on older block
Post by: Turin on January 04, 2025, 11:59:06 AM
Someone else asked a couple of years ago, and I found the answer. The newer Carc 1100 cylinders (92mm pistons) do not fit on the older engine blocks. The oil passages are significantly larger on the newer blocks. the head gasket demonstrates the difference. If you shine a light at the base of the cylinder, it iluminates the oil passageway. Hopefully this keeps someone else from repeating my F' up.


(https://i.ibb.co/DgJNLs5/deck-ht-2.jpg) (https://ibb.co/DgJNLs5)


(https://i.ibb.co/9n2Vws4/breva-cylinders.jpg) (https://ibb.co/9n2Vws4)


I found a nice set of v11 sport cylinders and pistons and will be using the cylinders instead of the breva Units. These do fit, although they are a little tall.
Title: Re: Breva 1100 Cylinders on older block
Post by: John Croucher on January 05, 2025, 11:26:19 AM
I worked on this question recently.  You are right.  I wanted to use the twin plug heads.  No go.  The pistons?  The squish band is to narrow to fit in the combustion chamber on the head. Easy fix turn the piston dome diameter down an blend in. Valve clearance is o.k. 

The other problem with piston, the flame front does not propagate over the top causing detonate or pinging under wide open throttle. It can't be timed out.  Retarting the ignition timing affects idle. 

I got 230 psi compression. I got pinging  I got more h.p.  Using the stock map.  Had a fuel controller installed, but removed it.

2003 hydro motor. Lifters seem to hold up to the high compression. Starter turns engine over good. Some times on a cold start and lifters are not pumped up, I can hear a valve slam shut.

I ride the bike hard, disregard the occasional pinging.  I have an extra engine fully rebuilt if thing go wrong. 

Title: Re: Breva 1100 Cylinders on older block
Post by: Turin on January 05, 2025, 04:14:08 PM
I wanted to use the dual plug heads as well. Glad I didn't go that far. All I have to do is move on a set of V11 sport pistons and Breva cylinders.

That's what I get for not having the latest edition of Guzziology.  :grin:

A full engine transplant via Antietam Classic Cycle looks like the way to go.


Title: Re: Breva 1100 Cylinders on older block
Post by: johnwesley on January 05, 2025, 07:50:37 PM
I wanted to use the dual plug heads as well. Glad I didn't go that far. All I have to do is move on a set of V11 sport pistons and Breva cylinders.

That's what I get for not having the latest edition of Guzziology.  :grin:

A full engine transplant via Antietam Classic Cycle looks like the way to go.

What about using the dual plug heads off of a vintage?
Title: Re: Breva 1100 Cylinders on older block
Post by: Frenchfrog on January 06, 2025, 05:03:58 AM
Likely to be the same as the Breva...worth checking though.
If you want dual plug surely get your heads modified ? 
Title: Re: Breva 1100 Cylinders on older block
Post by: John Croucher on January 06, 2025, 08:50:07 AM
Likely to be the same as the Breva...worth checking though.
If you want dual plug surely get your heads modified ?

The same, I looked into that also.

The duel Coils will bolt up to the Stock location. and connector.  That is the easy part.  I haveca set of heads it started to duel plug.  Have oil feed completed.  Need to counter bore and drill and thread for plugs on mill. 

I put the pistons in and tested the set up. Was happy with the single plug heads and stopped on the duel plug heads.

Title: Re: Breva 1100 Cylinders on older block
Post by: Frenchfrog on January 06, 2025, 03:43:41 PM
I just hate the pinging in the  summer heat and do enjoy a good thrash then  :smiley: