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CBR4/6 seazed lump ?

Posted: Tue Aug 16, 2011 4:29 pm
by leopard_pagan
correct me if i have got this wrong...
i need to turn the engine by hand so that *I* know its not seazed.

1) remove spark plugs
2) removed starter motor in case it's seazed
3) put in to gear (2nd)
4) put a socket on the front sprocket nut & turn..

?

well thats what i did and i cant get anything to move! nor did the sprocket nut come undone!

starting to think the best way for this is to ditch the fitted (not) lump and get one that i know runs!
The valve stems look rusted as the carb/header ports were left exposed to the elements for what maybe a year.

Re: CBR4/6 seazed lump ?

Posted: Tue Aug 16, 2011 5:21 pm
by BillingCBR
leave it in neutral, if it has a timing mark cover on the right hand case, take that off and use that to turn it over.

Re: CBR4/6 seazed lump ?

Posted: Tue Aug 16, 2011 5:36 pm
by leopard_pagan
just done that and it eventually turned! its now moving as free as it gets. i cant feel any more resistance & i can now turn it on the sprocket in 2nd :grin:

thing is, if the valves are pitted as they are covered in rust.... cost wise may have to buy another lump as each valvle is £20 x 16..... more than a working lump of same year off ebay!

Re: CBR4/6 seazed lump ?

Posted: Tue Aug 16, 2011 7:31 pm
by BillingCBR
You might get away with having them blasted and lapped in, but if it's seized I'd definitely consider a new lump, the bores might be damaged from the rust, which could cause problems with the piston rings aswell. You won't know how good or bad it is until you get it into bits though :up:

Re: CBR4/6 seazed lump ?

Posted: Wed Aug 17, 2011 6:14 pm
by leopard_pagan
i know, just really didnt want to be doing that! lump is now moving/turning over freely :peace:

Re: CBR4/6 seazed lump ?

Posted: Thu Aug 18, 2011 11:28 am
by kiwi racer
leopard_pagan wrote:just done that and it eventually turned! its now moving as free as it gets. i cant feel any more resistance & i can now turn it on the sprocket in 2nd :grin:

thing is, if the valves are pitted as they are covered in rust.... cost wise may have to buy another lump as each valvle is £20 x 16..... more than a working lump of same year off ebay!

So pull the head and check it over , that way at least you know whats wrong . If you just presume its a crook valve set etc then thats not logical. Get in there and have a good look to confirm. As was stated above you can clean them up ok .

Re: CBR4/6 seazed lump ?

Posted: Fri Aug 19, 2011 9:17 am
by leopard_pagan
had a mechanic mate pop over the other day to take a look, due to the amount of rust inside, he said that i have probably scoured the bores when i got the pistons moving again.
yes you can clean the valves up but if pitted you still have to replace em.
the carbs are all seized up and not worth stripping & the headers are complete shite!
i am not happy with the loom so i'll get a whole one. that way if i need to cut stuff off, *I* know why.

SOOO i have decided not to use this lump at all now. getting it working will cost more than buying a 2nd working lump! i will be stripping parts off and selling to re-coop money towards buying another engine. eg side covers/rocker as they are polished, sump etc.