73 Sport Carb help

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ajay809
Cucciolo - the Lil Pup
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73 Sport Carb help

Post by ajay809 »

Heys guys, I've been out of the Ducati game for some time so i come to the best place I can think of for some help. I have read through some of the relevant posts that seem to address my issue and gotten some really great info, but like I said, I've been outta the game for 10+ years and just thought I'd ask before I drive myself crazy.
I bought a period bastardized 750 Sport in 1993 for $1500. I rode it on the street for a while and raced it for a period of time (got some parts from Ray Donahue who I've seen post here).Vee two rebuilt the motor in 2000 and it's been through a few mods but barely ridden since then ( I really think there's less than 300 miles on the rebuild). About two years ago I had some folks I raced with build a frame for it and added modern Yamaha front end and wheels, custom race tech single rear shock, custom tank and a bunch of other stuff. It was what I wished I could have done in the past but couldn't afford it. So bike is complete now and I have personally not done alot of the work. It starts and runs but has a cough on the front cylinder and when I tried to ride it yesterday it had a hard time getting out of it's own way.
I'm running pretty much straight high pipes with very little baffling. Dyna ignition, Ricks regulator/rectifier. PHF 36 carbs with pumpers disabled. K18 needles (3rd position), 58 pilots, 150 mains, which from my reading on here seems a bit much. It runs starts and kinda idles but will start an intermittent "cough " on the front cylinder almost immediately and that doesn't seem to go away.
I've owned the bike for what seems like forever and I just finally want to take it for a ride. I just haven't worked on this bike in some time and was just hoping for some well-informed help.
I deeply appreciate any input, Thanks.
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BevHevSteve
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Re: 73 Sport Carb help

Post by BevHevSteve »

Assuming you have checked valve adjust is right, timing is right I would think carbs need rebuild and properly syncronized.
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ajay809
Cucciolo - the Lil Pup
Posts: 5
Joined: Wed Aug 25, 2010 4:36 pm
Location: Chicago

Re: 73 Sport Carb help

Post by ajay809 »

Thanks Steve, I took the carbs off to check all the settings and jet sizes, but not before i checked synchronization. They are essentially brand new and the synch seems spot on. I suspect timing and valves are correct but will try to dig in this week just to confirm.
Hopefully more better updates to come!
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BevHevSteve
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Re: 73 Sport Carb help

Post by BevHevSteve »

Ok also check that the exhaust nuts are tight (check when cold only) and also the intake manifold insulators are tight and not cracked. Next time you start the bike once warm spray just a quick bit of carb cleaner around them so see if the RPMs increase which would confirm time to replace as they are leaking.
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Steve Allen (925)798-BEVL[2385] Ride'm, Don't Hide'm
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ajay809
Cucciolo - the Lil Pup
Posts: 5
Joined: Wed Aug 25, 2010 4:36 pm
Location: Chicago

Re: 73 Sport Carb help

Post by ajay809 »

right on...the exhaust gaskets are brand new and the nuts tight but I will confirm...the intake rubbers are old but appear to be in pretty good shape...I may just order a new set to cover all the bases.
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