Author Topic: 30DIC in my 650cc engine  (Read 423 times)

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JorgeMonteiro

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30DIC in my 650cc engine
« on: August 24, 2019, 12:37:18 AM »
As i said in my introduction, i'm trying to fit a weber 30dic into my 650cc engine.

I had lost my 1st gear, and my engine head was very damaged, so i bought a complete engine and gearbox. Didnd't bought it because it was in good shape, but mainly because it had some "abarth" components. Go figure...   ::)






The gearbox was ok, and its ready to go.



The head was very good and is also ready after some overhaul



The covers were cleaned




And the 30DIC is in the process





I didn't intended to upgrade the engine or use the weber carburetor, but the rocker cover has the inlet manifold attached and i can't avoid it


So, if you reached this part of the post, i'd like to ask for help to fit the carburetor without any other modification.

Since i'm not changing the camshaft or messing with the valves, i'm not looking for power increase, i only want this carburetor to work properly as close as possible to the original IMB28.


I've read some of Rusty's Uncle posts about this, and i guess the main jets are the thing i have to care about. Right now there are 105 main jets in it.


should i install it how it is?


Thanks in advance
« Last Edit: August 24, 2019, 12:45:42 AM by JorgeMonteiro »

Rusty's Uncle

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Re: 30DIC in my 650cc engine
« Reply #1 on: August 25, 2019, 06:05:11 PM »
Hi Jorge , I looked back at the jets I fitted. I had the engine running nicely with a 1.05 or 1.00 main jet and 1.9 air jet on the primary choke. A 1.00 main and 2.00 air jet on the secondary choke. As the Weber is a progressive carb you can drive the car on part throttle in town then give it the full beans when you get out on the open road  :)

JorgeMonteiro

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Re: 30DIC in my 650cc engine
« Reply #2 on: August 26, 2019, 03:04:38 AM »
Thanks

I dont know if i´m  identifying correctly the jets, but i opened the carburetor and saw 2x 105 and 2x 230, so i assume they are 2x 1.05 main jets and 2x 2.3 air jets. Is that true?

Does that mean i might have to reduce the air jets?


DEYAN IYI

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Re: 30DIC in my 650cc engine
« Reply #3 on: August 30, 2019, 09:41:44 PM »
Hi, Jorge!

Why do you assume that the carb is not properly jetted? It used to work on a 126.  It is hard to suggest by the size of the jets.  The easiest way is to fit it as is and get the idle mixture adjusted using gas analyzer. Then drive it and if it runs nicely and the spark plugs look perfect, gotta be ok. A temporary on board a/f ratio monitor would be great.

You said that the tuning is not your aim, but think about a better exhaust and electronic ignition. Just a bolt on upgrade, that will make a difference in performance and gas mileage.

Cheers.