GaryJames
Veteran Member
With nothing better to do.......
I purchased some second hand CB350 items from a local Honda dismantler.
Cam box
Cam Shaft with a run bearing on the points end
Points end aluminium bearing cap with slightly scored bearing
Tach end Aluminium bearing cap.
The cam shaft was cheap at NZD$30 because of the run bearing. All the lobes are clean without any pitting and measured up within FSM specs so well worth saving.
The Points end bearing cap was similarly cheap at NZD$30
Had to pay NZD$ 60 for the tach end as it was in good shape.
Before I did the ball bearing mod I used the opportunity to practise a sleeve modification to the points end with a Phosphor Bronze sleeve.
Turned down the run bearing on the cam shaft to where the gouging disappeared and then mounting the bearing cap in my lathe, turned down the bronze stock I had to fit.
It worked well and I remembered to make sure the sleeve had a cutout at the top to match the existing oil passageway to the cam bearing.
all turning clearances were to 0.001 thou.
This shows the sleeve fitted but without the oil way cutout done.
When fitting this for actual engine use it will need some Loctite to make sure it doesn't spin.
It was a tight press fit but still...
Next was the ball bearing mod.
Using the same cam shaft I mounted it in the cam box with the cam sprocket fitted and centralised it.
Then used my digital caliber to measure the inside dimensions from the inside face of the cam box to the first cam lobe on each end.
Using these measurements I proceeded to turn down the cam shaft ends to suit. Increasing the measurement to give about a 0.005 thou end play.
I am using 6004 bearings with internal ID of 20mm and a thickness of 12mm and an OD of 42.
Stupidly I turned down the tach side to 20mm all the way to the lobe face. duh! I meant to leave a "step" for the bearing to butt against.
I them made an aluminium spacer to make up the distance. This actually turned out alright later as I needed to thin the spacer down to meet my 0.005 thou end play.
Turned down the Points end with a "step" correctly.
Then fitted the bearings and cam shaft with cam sprocket and spacer and centred the whole assembly again to make final end cap depth measurements before cutting off the end cap bearing end.
The ball bearings, 6004, I used were cheap no-name-brand from China but the 42mm OD finger press-fitted nicely into the Cam box ends. For actual engine use i will use SFK or NSK from Japan.
My cutting measurements were 4.43mm on the Points end and 6.03mm on the tach end, allowing 0.35 each for gasket thickness.
The spacer thickness ended up being 3.25mm.
All the component parts
Parting off the Bearing cap end.
I found it relatively easy to mount the odd shaped cap in the 4 jaw chuck, I just used the tail end stock press into the ID then gradually tightened each jaw until firm.
Aluminium cuts softly so doesn't need to be too tight. Had to make sure the face making contact with the Chuck was flat of course.
Showing the face with the bearing under cut.
You can see the ali spacer on the right hand end between the bearing and the first lobe.
Showing Tach end ball bearing with spacer and amount of protrusion into the cam box inner.
Showing the points end bearing with minimum protrusion in side.
Spinning the assembly by hand is very smooth, quiet and may I say satisfying.
Now I just need some miles on my CB350 with factory cam box bearings to wear out and I can then fit this...
Many thanks to all the previous members who posted CB350 Ball Bearing mod information on VHT and specially to Boomer 343 for his details step by step post which gave ideas and the confidence to do this mod.
cheers
I purchased some second hand CB350 items from a local Honda dismantler.
Cam box
Cam Shaft with a run bearing on the points end
Points end aluminium bearing cap with slightly scored bearing
Tach end Aluminium bearing cap.
The cam shaft was cheap at NZD$30 because of the run bearing. All the lobes are clean without any pitting and measured up within FSM specs so well worth saving.
The Points end bearing cap was similarly cheap at NZD$30
Had to pay NZD$ 60 for the tach end as it was in good shape.
Before I did the ball bearing mod I used the opportunity to practise a sleeve modification to the points end with a Phosphor Bronze sleeve.
Turned down the run bearing on the cam shaft to where the gouging disappeared and then mounting the bearing cap in my lathe, turned down the bronze stock I had to fit.
It worked well and I remembered to make sure the sleeve had a cutout at the top to match the existing oil passageway to the cam bearing.
all turning clearances were to 0.001 thou.
This shows the sleeve fitted but without the oil way cutout done.
When fitting this for actual engine use it will need some Loctite to make sure it doesn't spin.
It was a tight press fit but still...
Next was the ball bearing mod.
Using the same cam shaft I mounted it in the cam box with the cam sprocket fitted and centralised it.
Then used my digital caliber to measure the inside dimensions from the inside face of the cam box to the first cam lobe on each end.
Using these measurements I proceeded to turn down the cam shaft ends to suit. Increasing the measurement to give about a 0.005 thou end play.
I am using 6004 bearings with internal ID of 20mm and a thickness of 12mm and an OD of 42.
Stupidly I turned down the tach side to 20mm all the way to the lobe face. duh! I meant to leave a "step" for the bearing to butt against.
I them made an aluminium spacer to make up the distance. This actually turned out alright later as I needed to thin the spacer down to meet my 0.005 thou end play.
Turned down the Points end with a "step" correctly.
Then fitted the bearings and cam shaft with cam sprocket and spacer and centred the whole assembly again to make final end cap depth measurements before cutting off the end cap bearing end.
The ball bearings, 6004, I used were cheap no-name-brand from China but the 42mm OD finger press-fitted nicely into the Cam box ends. For actual engine use i will use SFK or NSK from Japan.
My cutting measurements were 4.43mm on the Points end and 6.03mm on the tach end, allowing 0.35 each for gasket thickness.
The spacer thickness ended up being 3.25mm.
All the component parts
Parting off the Bearing cap end.
I found it relatively easy to mount the odd shaped cap in the 4 jaw chuck, I just used the tail end stock press into the ID then gradually tightened each jaw until firm.
Aluminium cuts softly so doesn't need to be too tight. Had to make sure the face making contact with the Chuck was flat of course.
Showing the face with the bearing under cut.
You can see the ali spacer on the right hand end between the bearing and the first lobe.
Showing Tach end ball bearing with spacer and amount of protrusion into the cam box inner.
Showing the points end bearing with minimum protrusion in side.
Spinning the assembly by hand is very smooth, quiet and may I say satisfying.
Now I just need some miles on my CB350 with factory cam box bearings to wear out and I can then fit this...
Many thanks to all the previous members who posted CB350 Ball Bearing mod information on VHT and specially to Boomer 343 for his details step by step post which gave ideas and the confidence to do this mod.
cheers
