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CB400 Four special (Mr Sinx II )
Northy:
Right any purist please look way now before you go mad and say why wreck cb400f and make special out of it .
OH also long thread alert …if your bored just look at the pictures ;-) Oh will be lots of typos as well :D
Why a 400 four ,well back in 70/80 I created this and number of variations and still had standard yellow one VKK 333S.
I sold the bike in 1993 for £350 plus a mountain of spares (DOH !! ) well the engine had done over 150k, was on its second frame, iffy wiring and even the ARE alloy wheels where a bent in places. Ironically nothing I couldn’t fix now. So some 30 yrs on , my spannering skills are better than that poor cheeky kid on the “flying tampon” as mates used to call it. Its was called Mr Sinx, after our cat (bloody vicious thing!)
Well at the time of writing I have two other 400f that are rolling restorations. 2 frames and yet another mountain of part worn 400 bits. Also over the last few years done a few restoration to high standard and a couple of specials.(read I’m handy with spanner and a picky sod too)
So this will be a recreation of Mr Snix but I might move away from the clip ons etc , so more like the Mocheck Harrier (to save my back & wrists). So I’ve already have picture of how it will look in my head and I know what I need but finding them and making them fit is the fun bit (need a set of Alloys)
So where does ones start with just frame, engine and plie of bits …the carbs of course. I needed a clean set for one of the other bike which was suffering odd running.(turned out to be the coils). The Bike bits had been sitting for excess of 7yrs in garage (working one with sooty diesel, brake dust and damp etc ) So the carb where stripped right down
Tip one , don’t disassemble the rod mechanism if don’t have to. The rod that runs across the carbs to link them together runs in two bronze bushes. However there is also a brass pin in one mount that hold the bush in place and locates pin on the rod. To remove the rod you need to drill out this brass pin or the bush with break up if you try to remove the rod. However drilling out the pin a PTA its only 3mm dia and can easy go into the ally mounting. See picture even drilling the pin didn’t help cracked anyway!!
So some clean carbs , a with re-plated metal bits. I used stainless bolts and this not going to standard anyway.
Good job I've spare set of carbs
So next engine, I wasn’t expecting great things from this. The clock said it had done 43,000 miles and it showed signs of previous split cases and nasty bodges. As I was stripping this down to last bits, I didn’t bother deep cleaning it before hand
Ohh err
The thread on bolt that locks cam chain adjuster had been chewed up badly but managed to heli coil it. Phew
Spot the odd one out
Two head bolt where finger tight and the cam chain was starting chew its way into the adjuster (they all do that sir). Which is why there was no wear on the guides.
Then the good news the clutch looked like new. I even found my old home made clutch holding tool in the not use often “tool box” last used 25 yrs ago
The primary chain, is very sloppy and need a new one of those. The bore was OK , with marking where the piston had been and still on standard piston bit all looking a bit tied with one broken ring. I measured them all up and there just outside the recommended tolerances, could put new std piston and new rings and it would run but it deserves a rebore.
So do I go for the oversized 54mmbore kit or just take it 0.25mm OS. The cost using kits from Cruzinimage_uk is the same. I tempted by the big bore (sounds good and gains brownie point when talking bollocks at the cafe) but then reality kicks in and its only on a 400 if I need to go faster there’s an modern 750 in garage. However welcome your thought on this ??.
There was much sludge in sump and bottom of the cases but hardly any metal bits …all good.
Main bearings all Ok but the big end showing wear so they will be replaced ….bloody expensive at £10.74 per half shell ….
All the valves have been removed and the head looks in fine shape no damaged fins, rocker spindles with bit of wear and valve seats good.Cams all good , wear but nothing bad.
So no sheared screws or bolts, expect general wear no nasty surprises and only two threads required a helicol. I do them when I see on strip down as the stuff is going to be cleaned after so any bits of ally get washed away. Not bad at all it would have run no doubt but no very well.
Tip 2 Rotor removal is required for replace the end seal and best done once the crank removed,. you can’t do without splitting the cases due to the lip on the seal. You could take a hammer to it, dig out the special tool (if you have one ) with a 18x1.5 thread it to “pull” the rotor off. However the thread a size is the same of many car sump plug or Lamaba sensor plugs available for £2. Sorted !!
Next ……the case of clean the cases!!
Got quoted £140 to vapour blast the cases,head. barrels etc .......Sod that, out with chemicals.
SumpMagnet:
Personally..I have no issue with someone restoring an old bike in a less than standard way. The way I see it, you have put another old bike back on the road, rather than let it rust away in a shed somewhere. Or worse...restored it and then stuck it on a turntable never to run again...just to be looked at.
Back in the day, I hardly ever had a 'stock' bike and instead had aftermarket seats, bars, fairings, shocks, fork braces and all the other tat the fashion trends said you had to have.
On top of that...you are making something personal to you....Hope it ends up as good as you remember!
Trigger:
Nowt wrong with those crank case shells from the picture, measure them up ;) Much cheaper than new ones ;D
Northy:
its big end that have gone ...I'll get some piccy's of those.
Bryanj:
If the cranks worn its toast cos you cant regrind them or rather if you do there are no shells made
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