Honda-SOHC
Other Stuff => Misc / Open => Topic started by: haynes66 on September 03, 2015, 09:44:08 PM
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i'm working on a 750 f2 with only 22,000ish miles on the clock. condition of the bike reflects that and i have paperwork to confirm it. however, should i take a risk on not stripping the engine or go for 'better safe than sorry'? i have not heard it running and it was bought in a dismantled state. basically, i'm trying to save myself a lot of work!! advice please...
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I personally would stick the carbs on plus exhaust, minimal wiring - eg supply to points, earth etc then try firing it up, on my 500's this can be done on the bench or workshop floor, I think the 750 however might be rather different regards oil supply so check that first. If the engine is out of the bike do look carefully that any bits / covers or oil lines that might have been disturbed have been put back properly and that no dirt is lurking behind them if the cover was left off or removed in a dirty condition. If it all looks clean, I wouldn't do more than check the oil and turn it over by hand a few times, then check the tappetts and that the head has a good oil supply before firing it up. 20k is barely run in for a 750 if genuine, so long as the bores haven't rusted up through lack of use I would think it is fine. If being fussy, maybe test compression on all 4 cylinders, this will let you know if the bores, rings and valves are all ok, if there is a need to do more this will probably highlight it.
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as Mathew says,maybe as well,remove the plugs,a little light oil down the bores,and spin it over ,either by kicking,or starter,
has it got fresh oil in the sump/tank?
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At that mileage the exhaust guides will be worn out unless they have already been replaced
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Would they really wear out that quick Brian? Seems incredibly fragile to me, my 500's have done 10 times that with no attention to the valve gear. I geuss the answer might be to run the engine and see if it smokes or rattles at the top end?
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Well, I would normally tend to agree but I bought a bike from DK -'weather seized' through standing. The whole bike was in stunning condition and 10k miles only. I stripped it anyway to be on the safe side after freeing it up with some RS components release agent stuff. I stripped it down fully and found it to be in amazingly good nick but I found a mashed up large split pin ( no split pins used in a CB350K engine :o ) in the gearbox area plus a dried up wasp. Wouldn't have wanted that split pin roaming around in the gearbox.
See
http://www.hondatwins.net/forums/1-project-logs/34374-969-cb350k1-3.html
http://www.hondatwins.net/forums/1-project-logs/34374-969-cb350k1.html#post272350
I always question DK's philosophy 'we fed it a few snorts of ether and it ran but will need carbs cleaning'. How much damage are you doing running a bike left standing for eons and at least, not treating the bores etc first?
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At that mileage the exhaust guides will be worn out unless they have already been replaced
I'm with Bryan on that one. Mine had done a similar mileage and the exhaust guide's were knackered and two valve's bent. Intake valves are usually okay. Bottom end was good nick though. Obviously sump pan off and check the primary chains and any debris etc. Top end rebuild only will probably be the way forward.
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F2's are notorious for exhaust guide wear due to increased angle and higher cam lift, originals were lucky to reach 20,000 but the Honda used a harder cast.
First symptom is approx 350 miles to pint of oil and blue haze, this means guides are worn but stem seals holding-(also wont pull over 105Mph)
Second sympiom is less than 150 miles to the pint, plod in road at end of straight down from mountain left chocking in V large blue cloud---couldn't understand the cheering-- which is when stem seals let go.
If left to long valve in wandering in ecentric circles gets weak and the head falls off causing ooodles of expensive damage to discontinued parts
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thank you all. top end rebuild it is then. i think the bike was dismantled to restore rather than repair, so i'm hoping the bottom end should be fine.
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+ 1 with bryan and Roy, you can fit K-liners if the valves are not too bad.