Topic: FRANKENSTEIN

[popeye]

I bought a bike Frankensteined together from 4 bikes....engine is a '75 550...the bike has 627B carbs (500)....the bike ran ok from DSPO to my house (30 miles) except for a flat spot around 4000rpm...I got it home and took it to gas station to top off tank...it ran like feces on the way home..barely making it up my hill in low gear, full throttle...it seems that the DSPO had gotten much overspray inside the tank when he painted it...the fuel filter was totally plugged with gum...I cleaned tank and petcock and did the por-15 thing...cool...now it won't start...I have discounted any ignition problems and believe carbs are full of the same crap as the fuel filter was.....

Question 1)...after reading carb faq , it looks like the specs for 500 carbs and 550 carbs are very similar...I have 3 racks of 627B carbs but no 027(?) early 550 carbs...obviously I would like to rebuild what I got...but, if it makes a real difference I will buy a set of the 027's off of E-bay...Does it make a real difference ?...is anyone out there running the 500 carbs on a 550 motor SUCCESSFULLY?

Question 2)...does anyone know of a source (in the US) of 7/32 fuel line?     Thanks to all...

[SteveD CB500F]

I think the carb bodoes are the same, the 627/027 designation refers to the jet sizes and other internal parts. You can imagine that a 500 4-4 will need a different setup than a 550 4-1.

When you've got them apart, check the innards against the carb table in the FAQs:  http://www.sohc4.us/forums/index.php?topic=5410.msg26534#msg26534

[SteveD CB500F]

You might also like to PA grapppa as he's doing a similar job with his 550 at the moment.

[dusterdude]

popeye,for fuel line.try to locate an import auto parts outfit and see if the have fuel line for old vw beetles.it may be the cloth covered stuff and i believe it is 7/32.

[KB02]

Or, for fuel line, you do what I dd with my bike and get some 1/4 inch gas hose from the local parts store and a couple of 1/4 inch screw type clamps. The clamps may not be as pretty, but they will definately do the job.

[TwoTired]

I bought a bike Frankensteined together from 4 bikes....engine is a '75 550...the bike has 627B carbs (500)....the bike ran ok from DSPO to my house (30 miles) except for a flat spot around 4000rpm...

Question 1)...after reading carb faq , it looks like the specs for 500 carbs and 550 carbs are very similar...I have 3 racks of 627B carbs but no 027(?) early 550 carbs...obviously I would like to rebuild what I got...but, if it makes a real difference I will buy a set of the 027's off of E-bay...Does it make a real difference ?

Question 2)...does anyone know of a source (in the US) of 7/32 fuel line?     Thanks to all...

I believe the carbs you are looking fo are 022A.  I've never seen 027 carbs on a cb550.  From my research, I believe the primary difference between 022A and 627B carbs are the slide needle taper profiles, width and length, and the emulsion tube cross drilled holes used by the slide needles.  These parts will dominate the mixture equation in the 4000 RPM range.  However, they are matched to the engine reqs., stock 4 into 4 exhaust system, and air filter.  So, if these are changed, who knows what the final mixture settings need be.  Might just need to change the needle height.   If you can find them, some rebuild kits have the needles and tubes supplied in the kit.  If you put the 022A parts in the 627Bs, the stampings would lie but, the carbs ought to work....

7/32 fuel line (NOT vacuum line), is too hard to find these days.  What I do is go to a Honda or other Japanese motorcycle shop, and get them to sell me the correct size metric fuel line (5.5 mm) off their bulk supply in stock.
Cheers,

[popeye]

Thanks TwoTired and all......duh, when all else fails, try the Honda stealer, right?...got proper fuel line today @ $1.75 per foot...(happy to have it..even at ripoff price)...regarding carbs...I will just bid a set of e-bay 022a carbs   (thanks 2 tyres for correction...my memory fails me from page to page...oldtimers ya know)  ...(anybody got a good set of 022a carbs they want to part with...I'll swap ya a couple racks of 627B's)....BTW...did I say thanks?