measuring the cubic capacity with head on

[duzatun]

been spending a lot of time on the 550, now before i bought it i was told somewere down the line a 610cc kit had been installed but im not sure of this and removal of the head to try and find the problem i have of number 3 plug running very black and do valves and check pistons and rings etc as i cant find anyone who can supply a gasket to suit the 610 cc means if i pull the head off and it is a 610cc i cant put it back together any one have any ideas on measuring the cc  or  bore width  without head removal or a contact for possible supply of such a head gasket
i have inquired david silvers and jerry collins with no luck

[Bryanj]

Cometic in the US will make a head gasket with any bore you like. I'm afraid the only way to be certain is to pull the head and measure the bore, most of the 610 kits had one piece scrapper rings which do let oil past, it is possible to modify the piston grooves, or rather have them modified, to accept 750 four standard size rings and fit the 3 piece ring.

You need to run this for a while and find out if the black is oil or fuel related before going farther

[duzatun]

bryanj
is the difference between oil and fuel related wet black for oil and dry black for fuel as i have rebuilt carbs and thought maybe swapping floats from another carb into no 3 to see if problem went with floats from that carb 3

[Bryanj]

Easiest way is to run it and check how much oil you need to add and get a miles per pint reading which should be a really high number I.E at least 400MPP

[matthewmosse]

I'll have a headscratching session, someone on ebay was selling cb550- 610cc conversions and had a few. I'll see if I can dig details out for you

[matthewmosse]

Hi, think this seller had the 610cc conversion
 http://stores.shop.ebay.co.uk/Gremlin-Racetech
Well worth asking if he can help.

[robrffr]

Saw on the net someone saying you can fit a CB650 crank, cylinders and head on a 550? To make 626cc? Might as well just fit a 650 lump isn't it?

[matthewmosse]

the stud patterning is the same but not got a cb650 motor to try parts interchageability. the 650 has no kickstart I think. coils might also be different, plus carbs Anyroad, if you had to remove the head and found the motor is a big bore conversion then sourcing a new gaskett might be needed.

[duzatun]

yep mathewmosse
thats what i will be doing soon almost finished all the customising to a criuser major buffing all over been through just about everypart on bike and fixed what had to be fixed
 rebuilt forks as it allready had  longer staunchens wich are bushed on bottom milled legs to take what i think were RD 350bushes for top of legs and all back together better than new just example of type of rebiuld  been doing
 except for the head valves and bottom end and will soon do that but after all this work need to ride her around for a bit before i go into her internals
 i also got given a cb400f that had been laying  in a paddock for some years as  some parts interchangable the 400 had oil cooler on it in good nick as the oil filter housing on 400 and 550 are same part number the adapter plate in between the filter housing and crank case which the oil lines came out of fits straight on the 550 and the sml radiator in good condition too
and the link you posted for ebay i had alook very interesting will have to look into that further for sure

[pae]

the 650 has no kickstart I think.

Correct, not sure about other differences but the 650 has electronic ignition (I suspect yours has points?)

Phil