SOHC.co.uk Forums > CB350/400
My New Project arrives after a 44 year wait!
Laverda Dave:
Whilst the Triton is undergoing additional work due to a porous cylinder head I thought I’d crack on with the strip down of the ‘Rat’ CB400-4 mainly to determine if it is worth restoring considering its history (the engine being sand blasted in one piece and being painted black by the PO about 35 years ago being one concern).
So far it’s been a tale of woe and it’s not looking good. The PO had been riding the bike until it was pushed into the shed 20 years ago. I don’t know how he rode it, it was a death trap! Four engine mounting bolts were missing (front upper and front lower, both sides). The rear engine mounting bolt is a piece of studding! The ape hanger bars move backwards and forwards with just a slight push. When I drained the oil it was like thick black treacle with thick sludge in the bottom of the sump pan (that also has a stripped oil drain bolt thread with an oversized bolt fitted).
Stripping the engine has been a challenge; I thought I was going to break the fins trying to separate the head from the cylinder block as the black paint was so thick! I managed to split the cases today to check the crank and shells as this will determine if the rebuild is going to be worthwhile. The cam chain tensioner horseshoe spring and plunger was still in its fully compressed position, the horseshoe being completely seized due to the cam chain wearing a grove into it. Strangely the PO told me the engine has never been taken apart although the blue hylomer everywhere would suggest otherwise!
When I checked the crank journals four of them looked to be in good condition but when I inspected the centre journal I noticed a score mark deep enough to feel with a finger nail. The score mark does not go all the way around the journal and is about 4mm long at its deepest point. The corresponding shell bearing is equally scored in the same place indicating the bearing has picked up some grit and possibly sand from the sand blasting years ago. I’ve yet to measure the remaining journals with green plastigauge but I would value some expert opinion on the condition of the centre main journal before I start wasting my time (see photos).
I also noticed what appear to be several cracks on the lower main oil gallery with evidence of an overlong lower engine mounting bolt being fitted (and obviously removed as these were not fitted to the engine when I bought the bike). I only noticed the potential cracks when I scrapped the thick black paint from the area (see photo). When I say ‘cracks’ could these be casing marks as they appear to be proud of the surrounding metal. If they are cracks they will no doubt open up when the engine gets warm and leak oil. Has anybody had any experience of repairing these cracks if that is what they are?
In view of the above I could be looking at a scrap crankshaft and potentially scrap cases as well! If this is the case I will probably break the bike for spares otherwise it will become a money pit. Any thoughts welcome please!
McCabe-Thiele (Ted):
Ive sent you a PM about some parts I have.
Trigger:
The 400 has lot of casing marks on the engine and you will not know if they are marks or cracks until the engine is totally cleaned up and assessed. If they are cracks they are easy to alloy weld repair. I can't remember the members name but he lived in Peterborough who was in a panic with his 400 engine and thought it was cracked. After i had a good look at his cases, it was just casting marks.
Looks like something has got into that centre crank pin to make that deep score ;)
Bryanj:
I agree, with a light polish and new shells that would probably run ok fora bike not used flat out or daily driver.
Cases need good cleaning to asses and that has def been apart before.
There will be parts out there to rebuild it but as you say cost may make it unviable
AndyD:
Hi Dave
I feel your pain - guess it's the 'fun' of taking on a new project, hoping all will be well when you start looking closely while always knowing it's unlikely!
Deciding what is worthwhile is something I wouldn't dream of commenting on as my track record is awful - the 400/4 you kindly had a look at with the sidestand issue a while ago is the perfect example. A basket case with evident bodgery in all areas even before digging deep, but still thought I'd give her a go and have sunk far too much money and time into a bike I'm not even sure I really like!
Still haven't gone back to sorting what to do with it so just sits in the garage staring back at me!
I've got quite a lot of spare bits and bobs for the 400 including engine parts and lots of tools (and now time as well) so happy to help if I can if you decide to go ahead and try to save the bike.
Cheers,
Andy
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