cb350 to cafe' from scratch by a teen
- Thread starter alonb
- Start date
crazypj
Split personality, I fake being smart
That looks a lot better 8)
Heard an interesting story last night at bike 'club'
The 1970 (71?) Daytona CB750's broke down because Japanese engineers were confident the cam chain tensioner rollers didn't need replacing. The only one that finished (and won) was Dick Mann.
Engine was completely cleaned out then re-built before race ignoring the engineers recommendation. American team manager quit Honda and went to work for Kawasaki rather than apologise to the 'engineer's' for being right in ignoring them ;D
Heard an interesting story last night at bike 'club'
The 1970 (71?) Daytona CB750's broke down because Japanese engineers were confident the cam chain tensioner rollers didn't need replacing. The only one that finished (and won) was Dick Mann.
Engine was completely cleaned out then re-built before race ignoring the engineers recommendation. American team manager quit Honda and went to work for Kawasaki rather than apologise to the 'engineer's' for being right in ignoring them ;D
unfortunately the cam and followers are pretty much toast :'( they are supposed to be smooth can you see the pitting ? they weren't like that when new and the metal now is going to keep flaking off because thats what it wants to do now so you need to replace them .good used stuff can be found but you gotta make sure.. and the pistons look almost like the were close to a seizure at one time... it is not that expensive(less than 300) to just get new pistons and have it bored...you need to check the small end ,wrist pin bore of the rods and i would check big ends as well ,as per fsm procedure
also you need to check the clearance at the camshaft journals when you get another cam they are likely beyond tolerance ..be sure and set the cam endplay it can be done with a dry assembly of just the cam assembly in the rocker box on the bench
also you need to check the clearance at the camshaft journals when you get another cam they are likely beyond tolerance ..be sure and set the cam endplay it can be done with a dry assembly of just the cam assembly in the rocker box on the bench
I took the engine to a place that does top end rebuilds and I was told that my cylinders have rust and need to be machined. The guy there explained two options:
1. Machine the cylinders and insert sleeves to go back to factory size (64 mm).
2. Machine the cylinders and get oversize pistons.
What would you recommend doing? He suggested I choose the cheapest method. I'm not sure if oversize pistons will give me a significant improvement.
If I go with oversized pistons is there anything else necessary to do because of the piston change?
What are your thoughts about this? pls explain if possible!
1. Machine the cylinders and insert sleeves to go back to factory size (64 mm).
2. Machine the cylinders and get oversize pistons.
What would you recommend doing? He suggested I choose the cheapest method. I'm not sure if oversize pistons will give me a significant improvement.
If I go with oversized pistons is there anything else necessary to do because of the piston change?
What are your thoughts about this? pls explain if possible!
making do with what you have is impossible for someone like you, unfortunately, without spending plenty of money.. you need lots of new/at least good used parts you cannot escape thatalonb said:
if there is a popular small motorcycle in ilrasel with a parts network get one of those... unless of course,you have more money than what its worth by far to spend on what you have
For anyone who's been following this, I've been really busy the last 3 months because I joined the army so it's been really hard to find time for the bike. I finally got a a little time and closed the bottom end of the engine. I'm now waiting for a bolt from alloy bolts (they sent me the crankcase kit missing a bolt... And charged me 13.5 for shipping it). Anyway here's a picture to show a little progress 
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crazypj
Split personality, I fake being smart
As long as piston to cylinder clearance is good you shouldn't need to do anything to timing or carburation. You have done the oil transfer piece modification? It's dead easy of 350 as you don't need to remove complete clutch cover, just the little 3 bolt cover
you are doing fantastic man i of little faith should have known
stuff that is bad but you wouldn't know it
the pump arm ecentric drive off the back of the clutch ,very common to be worn ,any slop decreases volume of oil in theory .check it and its tiny feed hole you want minimum clearance there,the ecentric drive, i have seen them looser than an apricot fed gooses butthole
i mean if you have .25 mm slop thats too much ,see the extra clearance also makjes it run hotter cause the oil just cant stay in the eccentric if its sloppy
check the cam journals for overall clearance the specs are in the manual
dont bother even putting together pitted cam or rockers
replace them pay now or pay a lot more later
the mod that pj describes is good one in my opinion but no good if that ecentric is shortening the stroke and flow of oil before it gets there
be sure and replace the orings at the cylinder liners this keeps oil from getting in between the liners and the cast aluminum cylinder block inhibiting heat transfer amongst othe issues
make the camshaft endplay right at the minumum or a bit less its safe to do so .this will help keep oil up in the journals
i have have loads of excellent engine parts cant give them away but am happy to sell to you and ship at a fair sell price
the cam roller rubber wheells,and guides, none of them from a used 45 years old cb is any good you must replace them if original
there is an excellent aftermarket slipper tensioner well worth the money in my mind
you can set the cam endplay on the bench with just the cam the 2 gaskets ,end hgousings and the rocker box no need for anything else to set that dimension well before final assembly use a dila indicator axially at cam end points end,to chreck play
more will come to me
oh yah i will be posting my 350 build soon i am doing a cb450 clutch basketr and primary gear and pump eccentric
it gives about 10% more pump strokes for any given engine rpm and the ecentric is got more diameter and surface more durable
plus it is spinning the trans and clutch faster(10%) reducing loads on both,gearbox and clutch,it tightens up the gearbox ratios and allows more options for sprockets ,final drive
but that is not needed for you just make sure the oiling is up to tip top specs
make sure both ends of the cam followers are good many look fine on the large pad but are rusted on the valve tip end and you cannot do anything about it
it happens when sitting for years and the valve is open
i have nos and very excellent cams and rocker arms all i need is your lira or yen or whatever you call em shallooms ?
peace
stuff that is bad but you wouldn't know it
the pump arm ecentric drive off the back of the clutch ,very common to be worn ,any slop decreases volume of oil in theory .check it and its tiny feed hole you want minimum clearance there,the ecentric drive, i have seen them looser than an apricot fed gooses butthole
i mean if you have .25 mm slop thats too much ,see the extra clearance also makjes it run hotter cause the oil just cant stay in the eccentric if its sloppy
check the cam journals for overall clearance the specs are in the manual
dont bother even putting together pitted cam or rockers
replace them pay now or pay a lot more later
the mod that pj describes is good one in my opinion but no good if that ecentric is shortening the stroke and flow of oil before it gets there
be sure and replace the orings at the cylinder liners this keeps oil from getting in between the liners and the cast aluminum cylinder block inhibiting heat transfer amongst othe issues
make the camshaft endplay right at the minumum or a bit less its safe to do so .this will help keep oil up in the journals
i have have loads of excellent engine parts cant give them away but am happy to sell to you and ship at a fair sell price
the cam roller rubber wheells,and guides, none of them from a used 45 years old cb is any good you must replace them if original
there is an excellent aftermarket slipper tensioner well worth the money in my mind
you can set the cam endplay on the bench with just the cam the 2 gaskets ,end hgousings and the rocker box no need for anything else to set that dimension well before final assembly use a dila indicator axially at cam end points end,to chreck play
more will come to me
oh yah i will be posting my 350 build soon i am doing a cb450 clutch basketr and primary gear and pump eccentric
it gives about 10% more pump strokes for any given engine rpm and the ecentric is got more diameter and surface more durable
plus it is spinning the trans and clutch faster(10%) reducing loads on both,gearbox and clutch,it tightens up the gearbox ratios and allows more options for sprockets ,final drive
but that is not needed for you just make sure the oiling is up to tip top specs
make sure both ends of the cam followers are good many look fine on the large pad but are rusted on the valve tip end and you cannot do anything about it
it happens when sitting for years and the valve is open
i have nos and very excellent cams and rocker arms all i need is your lira or yen or whatever you call em shallooms ?
peace
crazypj
Split personality, I fake being smart
alonb said:
All that stuff is just normal when re-building and engine so I didn't add it
The transfer piece mod is pretty simple as long as you have a Dremel or similar
http://www.dotheton.com/forum/index.php?topic=43545.0
