Author Topic: Cylinder seating cb250  (Read 217 times)

Offline Fenderfreak

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Cylinder seating cb250
« on: May 13, 2019, 10:19:47 AM »
Hi all,

Finally getting round to rebuilding the motor on my cb250K3.

Quick question, just fitted the barrels and they do not seat all the way down onto the base gasket. Have lifted up numerous times to check what could be hanging it up but can not see anything.

It’s only sitting proud about 1mm, am now thinking it’s the o rings at the bottom of the cylinders.

If that’s the case this means it won’t close up until I torque everything down, also will this effect the valve timing once set prior to torquing it all together. 🤔

Any ideas.

Cheers

Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

Offline florence

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Re: Cylinder seating cb250
« Reply #1 on: May 13, 2019, 02:37:54 PM »
is the cam chain tensioner seated correctly with the rubber bits in place etc?
« Last Edit: May 13, 2019, 02:41:11 PM by florence »

Offline Fenderfreak

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Re: Cylinder seating cb250
« Reply #2 on: May 13, 2019, 08:46:10 PM »
Yep, everything where it should be 🤔
Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

Offline Bryanj

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Re: Cylinder seating cb250
« Reply #3 on: May 13, 2019, 10:15:16 PM »
Only thing i can think of is dowels bottoming out, there are two or three lengths on same diameter, parts book should give sizes. My ancient grey cells tell me cylinder shoulď go all way down.

Offline Fenderfreak

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Re: Cylinder seating cb250
« Reply #4 on: May 15, 2019, 04:15:30 PM »
Ok, have had the barrel off again checked seating of dowels and dimensions of dowels and all ok.

Measured gap between base of cylinder and cases with feeler gauges and found to be 1.2mm. Can slide Althea way through until I can feel the O ring at base of cylinders. Took barrels off again and found that the o rings stand 1.3 b 1.4mm proud of the cylinders.

So my conclusion is the gap is caused by the O rings and should disappear when all is torqued down.

Comments welcome.
Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008