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Ryland · 03-23-2011, 10:48 AM

First off, does the engine turn over and does it have compression? if it does then it is not so much a basket case as it is a motorcycle that someone was doing a tune up on and quit.
A single carburetor is going to be harder to tune and is not going to give you any positive results.
So with what you have the first step is going to be to take the top domes off the carbs and make sure that the vacuum diaphragms are intact, these cost $140 each if you have to buy a new one so be careful! if those are intact and nothing on the carbs looks to be broken then order up a rebuild kit, they will cost you between $20 and $35 depending but include new gaskets, jets and needle valve, you'll have to look up what the adjustment screws all need to be set to but after you put the carbs back together they should treat you well for years, at least until you leave some gas in it over the winter to go bad, then you have to rebuild them again.
I've built new intake manifolds out of copper pipe soldered together, do not use plastic unless you want to set your motorcycle on fire, the only time you should use plastic or rubber is if it is labeled as being safe for contact with gasoline.
If you do want to play around with the intake tuning, building long straight intake runners between the carbs and the air cleaner can help with improving mileage, you can also get pre made foam air cleaners or bulk foam that you cut and sew to build your own air cleaners, in all the motorcycles that I have owned and worked on I like foam air cleaners the best, they trap the most dirt and they provide good air flow, to clean them you just use soap and water then oil them with high tack air filter oil.
Once you get the motorcycle back together and working then start looking at improving other parts of it, tires dry out with time and old dry tires don't grip as well, I find it well worth it for my own safty to buy good tires, if you can find touring tires that will fit they tend to be lower rolling resistance and are good all weather tires that will be safe and give decent MPG.
If you put synthetic oil in the engine remember that you have a wet clutch, the clutch is in the engine oil, so synthetic oil that is designed for motorcycles is a good idea or you might destroy the clutch.

03-23-2011, 10:48 AM	#4 (permalink)
Ryland Master EcoModder Join Date: Jan 2008 Location: Western Wisconsin Posts: 3,903 honda cb125 - '74 Honda CB 125 S1 90 day: 79.71 mpg (US) green wedge - '81 Commuter Vehicles Inc. Commuti-Car Blue VX - '93 Honda Civic VX Thanks: 867 Thanked 434 Times in 354 Posts	First off, does the engine turn over and does it have compression? if it does then it is not so much a basket case as it is a motorcycle that someone was doing a tune up on and quit. A single carburetor is going to be harder to tune and is not going to give you any positive results. So with what you have the first step is going to be to take the top domes off the carbs and make sure that the vacuum diaphragms are intact, these cost $140 each if you have to buy a new one so be careful! if those are intact and nothing on the carbs looks to be broken then order up a rebuild kit, they will cost you between $20 and $35 depending but include new gaskets, jets and needle valve, you'll have to look up what the adjustment screws all need to be set to but after you put the carbs back together they should treat you well for years, at least until you leave some gas in it over the winter to go bad, then you have to rebuild them again. I've built new intake manifolds out of copper pipe soldered together, do not use plastic unless you want to set your motorcycle on fire, the only time you should use plastic or rubber is if it is labeled as being safe for contact with gasoline. If you do want to play around with the intake tuning, building long straight intake runners between the carbs and the air cleaner can help with improving mileage, you can also get pre made foam air cleaners or bulk foam that you cut and sew to build your own air cleaners, in all the motorcycles that I have owned and worked on I like foam air cleaners the best, they trap the most dirt and they provide good air flow, to clean them you just use soap and water then oil them with high tack air filter oil. Once you get the motorcycle back together and working then start looking at improving other parts of it, tires dry out with time and old dry tires don't grip as well, I find it well worth it for my own safty to buy good tires, if you can find touring tires that will fit they tend to be lower rolling resistance and are good all weather tires that will be safe and give decent MPG. If you put synthetic oil in the engine remember that you have a wet clutch, the clutch is in the engine oil, so synthetic oil that is designed for motorcycles is a good idea or you might destroy the clutch.