3C exhaust.

M

MarkH

New member
Does anyone have experience of 3 into 1 exhaust fitment. I have just purchased a 1980 3C. The bike has damage to the rh silencer but comes with a 3 into 1 and a replacement centre stand. Also has k and n filters and bell mouths in a box of spares. I am worried that fitting one or all of these will muck up carbarretion.

The bike has high comp pistons and what appear to be jota type silencers and the standard air box at the moment.

Do I buy replacement silencer or use 3 into 1?
 
Hi Mark -Welcome to forum - Best to keep 3 into1 into 2 system and standard airbox for road use - a lot of the 3 into 1's were crap - some were good but need to make sure cam timing is correct. Try what you've got first - if it all runs Ok - then you've saved a few bob. - Regards - Phil
 
G'day Mark, welcome to the forum. How about a picture of your new toy? As always, Phil's advice is excellent, but if it doesn't run right with the air box the carbs are probably set up for one of the other 2 induction systems. It's a good idea to drop the float bowls off anyway if the bike's been sitting for any length of time, blow out the orifices with carburetor cleaner, while you're at it you can check the jetting.
With airbox you should have (thanks to Jean-Louis Olive, http://www.laverdamania.net/carbgb.htm)

Original carb setting for 1000 LAVERDA (Dell'Orto PHF 32, A11 camshafts):
Slide cutaway                   60/2
Pilot jet                              55
Choke jet                           70
Main jet                            120
Needle jet                    265 AB
Needle               K1, position 2
Pump jet                            35
Float height  18mm +/- 0,5mm

Original carb setting for 1000 LAVERDA (Dell'Orto PHF 32, C4 camshafts):
Slide cutaway                   60/2
Pilot jet                              55
Choke jet                           70
Main jet                            145
Needle jet                     265 AB
Needle                K1, position 2
Pump jet                            35
Float height  18mm +/- 0,5mm

Have fun!
Ken
 
Thanks for the replys guys. I need to get the thing MOT'd to register for the UK as it comes from France. I think I will get Roger Winterburn to do this and have a look at the settings, as a baseline.

I prefer the look of twin pipes as well. May well sell on the 3 into 1.

Haven't got a photo yet. But the bike is in the inevitable orange/ silver frame as it was renovated and resprayed these colours. I like orange though. Like KTMs too!
 
should I change them over to 145 then with my engine setup?
Click to expand...

Not with the lighter fuel that passes for petrol these days.  120 is a good place to start, may need to go a deal smaller...
 
Stefan, when I imported my Jota (4cs, high compression) from the UK it had 145s which were WAY too rich for US "petrol", even the highest octane stuff sold here. Just like Reggie, I dropped straight to 120, could probably have gone lower but swapped to Mikunis instead. But I think with the low compression pistons there's no way the combustion chambers could ever have achieved a clean burn with the amount of fuel from 145 mains, even back in the 70s.

Ken
 
When my Jota had the Dellortos on it, I was using 120 mains. I'd had the bike on the dyno to check air/fuel ratio and 120 was pretty well spot on. It had 135's in it when I bought it and was running way too rich.

Bike specs: 1000cc, 4C cams, H.C. pistons, updated ignition and large bore exhaust
 
Back in the 70's the production 1000 racer(s) we campaigned used 140, 145 or 150 main jets, depending on track temperatures and humidity. Put one Laverda production racer in storage till 2005..pulled it out of storage, took it apart and put it back together again..with all new brass it would not run on the 140 main jets anymore, not a chance. With modern USA high test fuel the engine runs fine with 122 mains.

I doubt we could of keep the engine running WOT on the 122 main jets back in 1976. Never tried..it would of been very lean.

Gasoline is different now.
 
Do you fancy a swap for a BIG bore collector and a pair of scabby original silencers ?  They do need work but will come up well with some attention !  PM me if of some use....  I quite fancy a rude loud three into one
 
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