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305 engine mods.

Downunder dream
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305 engine mods.

Post by Downunder dream » Tue Nov 06, 2012 11:03 pm

Hi guy's,
Just wondering if anyone has modified their 305 with a cam and maybe some head work, and was it worth it. Not after a hi-po engine, I don't think the dreams pressed frame would cope too well. Cam's always sound good, and can you get one for the 305?
Cheers,
Scott.

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G-Man
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Post by G-Man » Wed Nov 07, 2012 3:16 am

Hi Scott

Everything is possible and most of the mods that can be done to CB72/77 can be done to the Dream engine. You could use the cam from a CL77, with mods to re-work the spline.

Mild porting will also help along with a slightly bigger carb. Some people have used a single CB77 carb, I think.

Your barrel could be modded with CB750 liners and bigger pistons to take it out to 350.

The big problem with these bikes is really the suspension and brakes so you might want to look at some improvements there.

Good Luck

G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

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Snakeoil
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Post by Snakeoil » Wed Nov 07, 2012 9:36 am

Not to argue, but more to better understand these bikes, I thought the Dream was a Type II engine, which would mean you cannot swap the cams with a CL77, Type I. Am I confused here?

As for hopping up your Dream, I'm a big fan of reliability over anything else on a small bike like this. Unless you are racing it, I don't see the benefit to upping the power on a bike like this. I'm doubtful it would do anything but detract from the value. If it were my nickel, I'd spend it on making the bike more correct.

Your bike, your nickel, your smile.

regards,
Rob

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davomoto
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Post by davomoto » Wed Nov 07, 2012 10:27 am

Rob,

The CL cams can be used by grinding the splines so the line up the same as a CA cam. As far as your other points, I agree!

Davo

conbs
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Not a Hi-po

Post by conbs » Wed Nov 07, 2012 11:19 am

Guys, the original post says he is not looking for a hi-po motor. I am not sure why the CL cam and carb with some porting would reduce reliability. Isn't the Scrambler motor reliable?. Everything else in the motor is essentially the same.

Jensen says these mods give a noticeable improvement in low end torque. I guess I will find out whether that torque will affect the frame because I am building a motor with these mods.

750 jugs are another discussion. Would the rods would handle the extra CC's? I would guess the big end rollers would be fine. However, I would begin to wonder if the combination of all of the above would start to be too much. Still, not really Hi-po.

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G-Man
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Post by G-Man » Wed Nov 07, 2012 12:20 pm

Personally, I think that a big-bore kit with lower compression might be the way to go. It could make the bike less buzzy and make the best of the 4-speed transmission.

I bought a CB750 barrel (STD bore) for £30 (about 50 bucks). That's going to be the basis of two cheap big-bore kits. One for my cafe racer and one for one of my Dreams. The pistons will be modified CB350.

By changing just the barrel and pistons, it is an entirely reversible modification.

Just my two cents....

G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

conbs
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750 jugs

Post by conbs » Wed Nov 07, 2012 4:44 pm

G, your comments are well taken. But, I am not sure I understand how to finish your mod of bigger pistons and have it be reversible.

How do you end up with the same centerline to match the rods if you use a bigger jug to get to 350cc? It would seem to me you would have to enlarge the holes for the bigger jugs - which would not be reversible.

I do see your thinking of making a bigger air pump going to 350 instead of more efficient with the porting and CL cams/carbs. I may be persuaded if it is not too involved.

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