CB250N top end engine queries

[Maffoo]

hello there ! I have a CB250N from 1981
i did some damage to the cam & am in the process of putting the top end back together after replacing the broken part

i have two questions, hopefully someone can help me
1 - how do i align the cam and the crank? what markers am i looking for & is there any secrets to it?
2 - what torque setting does the head have to be tightened down to?


any other help/advice/warnings appreciatted :rockon:

[Magua]

1 - how do i align the cam and the crank? what markers am i looking for & is there any secrets to it?

From the Clymer honda manual for 250 and 400 twins. "Rotate the engine until the "T" on the alternator flywheel aligns with the pointer on the crankcase".
...
"Install the cam with the notch straight up.."



2 - what torque setting does the head have to be tightened down to?


"Tighten the bolts in the sequence shown in figure 44. Torque to 22-24 ft.-lb. (30-33Nm)."
Top left, bottom right, top right, bottom left, top middle right, bottom middle left, top middle left, bottom middle right. Hope that's not too confusing.


I could try to scan the images or you could borrow the manual for the weekend.

[Maffoo]

hey awesome ! im hoping to put it back together tonight so i will have to go with what you said
that seems a low torque setting
i think the dude who put it together last time just used tthe 'as tight as you can & then a bit tighter' principle

i think i can figure it out from that....
now i just need a torque wrench ... now im really pissed off that mine got stolen

thanks for your help, ill get pics as i go along !!

[Maffoo]

i was also wondering about how to put the cam chain on the gear, but i guess i just split the chain & install the gear & then re-link it?

[Magua]

i was also wondering about how to put the cam chain on the gear, but i guess i just split the chain & install the gear & then re-link it?

"Install the cam chain sprocket onto the cam, but not onto the shoulder, with the timing line on the left-hand side. Position the sprocket so the line is horizontal and install the cam chain onto it."

"Slide the cam chain sprocket up onto the shoulder of the cam and install the 2 bolts. Toque the bolts to 13-15ft-lb. (18-22 Nm):

Hope that helps. Also there's a big warning message about the cam having to be pointed straight up and the line on the cam chain must be horizontal, likewise the T on the flywheel aligning on the crankcase.

[Maffoo]

dude you rock !

northcote huh? im in birkdale for two more weeks, then off to napier

[Magua]

To live or for a holiday?

[Maffoo]

To live dude
thats why i need to get his engine fixed asap lol
i have sold my car & will only have the bike as transport once im down there

[Maffoo]

i have finished the repair Magua

thanks for all your help :rockon:

[Magua]

No problem. Send me a pm if you need any more info from the Clymer or Haynes manual.
They both came with my bike. :D