Rusty barrel cleaning?

[SteveC#222]

Not exactly a thumper question, Me and a mate are restoring an old Honda C90 over the winter. The bike is in sound but scruffy condition. My mate is going to get the frame and bits blasted and repainted and I am going to try and clean up the engine. Now the cast iron barrel is quite rusty (surface rust/flaky paint) but I don't really want to strip the top end as the engine has only done 8000 miles and has lots of compression ( for a C90) and it's an OHC so I don't really want to mess too much. Any suggestions for getting the rust off between the fins? Hasn't got to be showroom but we are trying to make a tidy job of it. Engine is coming out so access is not a problem.

Thanks

[themoudie]

Aye Steve,

Get the engine out and then bung up all the open orifices and seal with poly bags and zip ties. Then a good soaking in Jizer for 24 hours, followed by a steam clean and another Jizer/steam clean if required. Blow dry with either an air line or the leaf blower and then contemplate the next move!      You might want to try a vapour blast?

My regards, Bill

[timbo]

A long bristle wire brush and some rough sand paper folded over to fit in the grooves is as good as anything, if its just a quick spruce up. You would be surprised how easy and quick this is 

[iansoady]

Caustic soda solution will take all the old paint and caked oil off but it needs to be handled with care. And never used on alloy parts as it dissolves them.....

After use you can chuck it down the drain to dissolve the fatbergs.......