More intake questions

Hey everybody!
My ol' 1982 XJ750 Seca is back from the grave! Just did valve shims, valve gasket, head gasket, cleaned carbs, and replaced intake manis. She starts like a dream now, but is suffering from a high hot idle (http://xjbikes.com/forums/threads/xj750-high-hot-idle.12020/). Didn't see an ultimate result there, but my situation is similar. She runs between 4k and 5k with the clutch in, after she's warmed up. Wanted to do a double check before my next order- she's getting a little expensive, with over $1400 in between parts, tools, and the bike itself.

I know that I've got a vacuum leaks- one at one of the four carb boots (P.O. put one on from another bike that doesn't even meet up with airbox. I also broke two of the exhaust studs in putting the exhaust back on (Hayne's specified 32.4 lb/ft, turns out it's 7.4 lb/ft). Wondering if this is enough to cause high hot idle?

Also important- I ordered the wrong carb kit when restoring the carbs- tried to save some money, received a full carb kit for a Euro Seca. So, while the carbs got a Church-style cleaning, all of the internals are 11000mi/33yrs old. About to go check throttle shaft seals with the ol' propane torch. Do I absolutely need to do the whole carb thing again with fresh bits?

 

haynes does have some errors in it
you may have to use carb cleaner to test the throttle seals propane does not always work for them.
the carbs are HS 32 you can probaly use the euro parts. my under standing is it was just for the epa

1400 including bike and tools isn't expensive i did 1200 on just parts

the same bike in different parts of the world got different jets
even US and Canada

http://xjbikes.wikidot.com/carb-specs

Years & Models: 1981-3 XJ750 Maxim, Midnight Maxim, and Seca USA models
Carb Manufacturer: Hitachi
Carb Series: HSC32
Carb Model ID: 15R00 (Maxim, Midnight Maxim)
Carb Model ID: 5G200 (Seca)
Main FUEL Jet Size: #120
Pilot FUEL Jet Size: #40
Main AIR Jet Size: #80
Pilot AIR Jet Size: #225
AIR COMPENSATOR Jet Size: #36
Starter FUEL Jet Size: #40 (non-replaceable, in float bowl)
Main jet NEEDLE ID: #Y-13
Main needle JET Size: #3.2mm (the main needle JET is also known as the "power valve" or "emulsion tube").
Fuel Level in float bowls: 3mm +/- 1mm (.118" +/- .039")
Idle RPM's: 1,050 rpms



Years & Models: 1981-4 XJ750 11M UK/Europe Seca models
Carb Manufacturer: Hitachi
Carb Series: HSC32
Carb Model ID: 5N100
Main FUEL Jet Size: #120
Pilot FUEL Jet Size: #43
Main AIR Jet Size: #80
Pilot AIR Jet Size: #195
AIR COMPENSATOR Jet Size: unknown if used.
Starter FUEL Jet Size: #40 (non-replaceable, in float bowl)
Main jet NEEDLE ID: #Y-14
Main needle JET Size: #3.2mm (the main needle JET is also known as the "power valve" or "emulsion tube").
Fuel Level in float bowls: 3mm +/- 1mm (.118" +/- .039")
Idle RPM's: 1,050 rpms

Years & Models: 1981-3 XJ750 Maxim, Midnight Maxim, and Seca Canadian models
Carb Manufacturer: Hitachi
Carb Series: HSC32
Carb Model ID: 15T00 (Maxim, Midnight Maxim)
Carb Model ID: 5H200 (Seca)
Main FUEL Jet Size: #120
Pilot FUEL Jet Size: #43
Main AIR Jet Size: #80
Pilot AIR Jet Size: #195
AIR COMPENSATOR Jet Size: #36
Starter FUEL Jet Size: #40 (non-replaceable, in float bowl)
Main jet NEEDLE ID: #Y-14
Main needle JET Size: #3.2mm (the main needle JET is also known as the "power valve" or "emulsion tube").
Fuel Level in float bowls: 3mm +/- 1mm (.118" +/- .039")
Idle RPM's: 1,050 rpms

 

Thanks XH550H! I did scan through that bit in the info overload hour- but felt unsure due to my inexperience. Should have asked earlier, but maybe I'll just go ahead and swap the euro bits in while I have the carbs out to get new boots in. Good confidence boost, man.

Damn dude! 1200 in parts? You must love that thing to death! For me, the 1400 feels like a lot- I'm in my twenties, and so deep in student debt that I live at mom's working on fishing boats for 3/4 of the year. Can't afford rent or much play time, but goddammit, I'm gonna have a functional bike.

 

it is an amazing ride responsive through out the throttle
i am working on a seca 550 now

 

When you initally set the idle speed after you put the carbs back on did you fully warm the engine?

$1200 won't buy a much more than a set of luggage for a new motorcycle. Old bikes are worth the relatiely small expense.

 

I ended up with a better bike than I could have gotten for 1200$ and lots of experience on the yamaha systems

 

K-moe,
No, set idle speed to 1100ish while cold, then backed off the screw as idle started to race. I take it that I should be controlling idle with choke while cold?

 

yes use the choke to keep bike running as bike warms up the rpm will increase from around 1000rpm up to 3 to 4 k rpm as rpm increases you can back off on the lever .
when you set your idle speed you should do it after a ride when bike is good and warmed up
otherwise you may chase your tail thinking you have a vaccum leak causing your rpm to climb.

 

^ What he said.

 

Roger! Thanks guys. I'm new to carb tuning/synching, and really appreciate the help. Unfortunately, flying to work in <1hr. Will post back when I get another chance to tinker in about 3 months.