New Carbs on my 478

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Carts
Posts: 50
Joined: 18 Aug 2015 20:25
Location: Aberdeen

New Carbs on my 478

Post by Carts »

Hi all

My Morini getting a bit like trigger broom. The carb are leaking even after new seals. I was looking at getting a new set from Eurocarb. They recommended R3303. I have PHBH 26 on at moment. Would I be better going for PHBH 28. Or would I need to have some tuning done to the bike to get any benefits out of a bigger carb.

Also looking at new carb as bike is fluffy just of idal when moving from lights etc. the mechanic I had do the carb on his dyno put this down to old carbs with some ware.

Cheers

Carts
Steve Brown
Posts: 1390
Joined: 12 Nov 2007 23:44
Location: Leicestershire

Re: New Carbs on my 478

Post by Steve Brown »

I'd stick with the 26mm standard size. If you're not tweaking it for more power it would be a waste of time going large. At the least you would need to blend the joint of the rubber induction tubes to the bigger bore. If not the resulting step will lead to a disruption in flow at that joint. A poor idle and pick up would most likely result and I bet that's one thing you're trying to get rid of! The jetting of the bigger carbs as standard would not be right either so more work to do.
Even with standard carbs the original jet sizes may need altering to suit current fuels. The idle jets in particular seem to need looking at often (but not always) and lately some people are finding a tweak of the throttle cutaway is needed too. Certainly, having unworn carbs is a very good thing.
Of course your exhaust system and air filter set up will all play a part. Oh yes-the ignition too!
All donations to the rest home for old Camels, Leicestershire.
Carts
Posts: 50
Joined: 18 Aug 2015 20:25
Location: Aberdeen

Re: New Carbs on my 478

Post by Carts »

Thanks Steven.

You advise makes sense, just wanted to check before I bought.

I was going to get jetting advice by euro carb. Hopefully should be for current fuel. Then I will get my local dyno guy tweak the. To suit bike. Hopefully new carb will be better suited to latest fuel. A conversation I need to have.

For ignition I have a sax system, love it as stoped all the starting problems. My exhausted, no idea the make will put up a picture if anyone knows. I don’t know if it’s better or worse than a standard setup.

Cheers Dave
Carts
Posts: 50
Joined: 18 Aug 2015 20:25
Location: Aberdeen

Re: New Carbs on my 478

Post by Carts »

Umm I can seen to add pictures from my I pad. File size
Kamel
Posts: 175
Joined: 10 Feb 2020 22:31
Location: Zurich, Switzerland

Re: New Carbs on my 478

Post by Kamel »

I had exactly the same systems on my 500 Camel. On the advice of members here I changed the pilot jets from 45’s to 42 and It has transformed the bike. It is now much more controllable when pulling away, and the pickup much smoother throughout the whole rev range. I have som X8 needles on the way as well which are supposed to make further improvements.

Maybe worth trying that first before splashing out on new carbs?

Cheers,

Kamel.
'It must be a .....'
Posts: 364
Joined: 12 Sep 2010 12:25

Re: New Carbs on my 478

Post by 'It must be a .....' »

Hi, these are the 26mm PHBH settings I use on 478 engines

Pilot 42
Main 125 (depending on intake/exhaust it can range from 122 to 130)
Starter 48
Needle X8 (best) 4th groove or X1 3rd or 4th groove
Slide 40
Atomiser 264 CE
Float valve 200

The starter jet and both adjustment screw Orings need to be in good condition
Needles will wear especially the tip
The slides will wear more quickly than the carb body, so it is often worth replacing them; it takes 60,0000+ miles to wear out a carb

Good luck and enjoy the quest, Ian
Carts
Posts: 50
Joined: 18 Aug 2015 20:25
Location: Aberdeen

Re: New Carbs on my 478

Post by Carts »

Hi thanks all.

I had a good conversation with euro carb. I will be buying a set on Monday

Just need to strip mine down to see what sizes jets are etc. then We’ll agree what best.

Thanks for the info of what jets you have etc. I will compare to what I have and what euro carb suggest

Think may be a little different as jetting is set up at moment for worn carbs.

Agin thank for all your comments.
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