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Joe's 1976 CB400f


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Jeah, dont want to lose momentum...

 

 

What should a do about the carbon build up on the top of the bores?

I can get rid of the thick of it with some degreaser and my finger nails. Shoud i get the bores honed? Or just clean off the carbon and roll dirty... hah

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What should a do about the carbon build up on the top of the bores?

 

How I do it is wind each piston to BDC (I'm guessing on your motor it will be two at a time) and jam a rag down each bore good and solid leaving the top inch of bore clear.

 

Clean the carbon up with one of them green scotch pads you use on dishes. Don't get too anal because the carbon ring will come right back after a few rides anyhow. 

You just want to dislodge any sizeable chunks that may have been loosened by taking the head off. Take the rags out carefully by slowly winding the engine to TDC.

 

When you are done then clean each bore with a new rag that has been moistened with clean oil. Again no need to be too anal, the combustion will burn most everything in the first couple of revs anyway. 

Main thing is you don't want loose carbon getting right back under the valve seat again.

 

Oh yeah degreaser sprayed on the scotch brite will help soften the carbon. (don't spray it directly into the bore)

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  • 2 weeks later...

So yea,

 

Pulled head apart in the weekend. No pics. Cool story.

 

 

My barrels and the head are covered in some mega baked on oil and grime. Have tried scotchbrite but thats a bit futile.

 

Does anyone have any tricks for cleaning this stz? Apart from sand/soda blasting.

 

Alloy wheel cleaner? Has anyone used this?

 

Don't really want to put them back on looking all yuck tbh.

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ive heard drain cleaner/lye solutions work - but they dissolve alloy so be careful how long you soak for.

 

Or vinegar - http://www.bikeexif.com/custom-bsa-motorcycle its in there somewhere. cool bike too.

 

 

....To get rid of years of rust and grime, he dismantled the transmission and cases and bought 12 bottles of the cheapest vinegar he could find. (“I soaked the gearbox internals in my bedroom for about three days. It was pretty messy. I had to be extremely careful not to kick over a container in the night.”)....

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I'd try paint stripper. I'm pretty sure I've done it in the past but I can't actually remember for sure (I've had a lot of past you see)

 

EDIT: Oh, you mean the outside of the barrels? In that case oven cleaner is pretty good and relatively cheap/easy

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If you are going to pull it all apart to lap in the valves anyway just drop the head and barrels to an engine reconditioner (Headmaster on King St. is good) and ask if they can hot tank them for a day. Maybe ask them to give the barrels a quick hone while you are there.

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  • 1 month later...

Pictureless update fail.

 

So yea, Manu the GC put me on the the most epic GC ever who helped me clean my valves, barrels, head and lap in all the valves.

 

Got all that back nice and clean, and valves sealing now!

 

Got stuck in last night and put the head back together. And spent hours removing the baked on gasket from the bottom of the block.

 

Shits all clean and ready to go back on. Hopefully i will fit the barrels and head tonight. That leaves tomorrow for setting up the cam and putting other stz like carbs and 'zorst on. Then hopefully it will be a runner again (and without the blowing back through the carb).

 

Exciting times ahead. Looking forward to a bit more pep on my commutes than the GP125 can dish out!

 

Found a picture, cos pictureless updates are major lame tbh:

2677323228_dae1f47846.jpg

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So yeah,
 
I have actually got off my ass and did something for a change. Am pretty sick of my projects not doing anything and me just watching tv shows in the evenings. So bam:

Ready to go:
it1ehp3h.zem.jpg

Head with valves back in:
1rmt1ibx.5wv.jpg

This was a terrible job without ring compressors:
sfef5dpu.hy3.jpg
zkjdbt0c.oyb.jpg

Done:
wgeiysfb.xqy.jpg

Mmm, no carbon buildup:
nl2dbiip.iyi.jpg

Popped the head back on:
3e23iblj.axv.jpg


I need a tourque wrench to torque the head down. Will get that this weekend.
Put the cam in and timed it up. Super simple.

I did make an amature mistake though, i thought the cam chain tensioners could be put in after the head was on. Aparently not... Will have to come out again, no worries though. Shouldnt take long.

 

FULL STEAM AHEAD!!
 

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