NJ306E-M1-C3 Vs 6203 - C3

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Possum

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I am about to build a 650cc engine for club rally bike with a few country trips; no circuit or street racing.

Is the doubling the cost of main bearings by fitting a NJ306E-M1-C3 to the drive side justified?

One NJ306E-M1-C3 and one 6203 - C3, - the cost is about $115AUD, $87USD, 70GBP

As originally fitted with two 6203 - C3, - the cost is about $65AUD, $50USD, 73GBP
 
Are you sure the original fitment was two deep groove ball bearings? My understanding (and consistent with my '64 650SS) is a deep groove ball on the timing side and a parallel roller on the drive side.
for my latest rebuild I have gone to "superblends" both sides, wearing the additional work of ensuring end-float is correct, purely as insurance - this based on the superblends history.
Double or not, a $50AUD insurance policy seems cheap in terms of the total build price.
Cheers
Rob
BTW Possum I sent you a PM in late November requesting info on the 650 inlet tract inserts - I want to make a set
 
robs ss said:
Double or not, a $50AUD insurance policy seems cheap in terms of the total build price.
Click to expand...
Better insurance costs a lot more and deals with the crank and cases...
 
robs ss said:
Are you sure the original fitment was two deep groove ball bearings?
Click to expand...

This I think is the nub of this.
Even the earliest Model 7 dommies had a roller bearing on the drive side.
Same dimensions (externally) as a later 'superblend'*, it must be noted.
*which is just a heavier duty roller bearing

I think some previous owner/bodger has done an el cheapo, and used a ball bearing.
Probably last a while, especially if you were gentle on the throttle hand.
Lotsa old singles used ball bearings all round...

BTW, shop around for those bearings, one of the most heavily discounted items on the planet.
Even yer grandmother should get a 60% discount, and more if she jumps up and down enough.
A heck of a lot more if she buys 1000 or more !
 
The 650cc engine in question had two x 6203 ball bearings...

As my old tradesman often said, never assume the person before you did the job correctly.
 
Rob

I did not respond to your your questions as I assumed they were rhetorical, suggesting issues I should investigate further...

I have a collection of 600 / 650 bits that would like to be an engine, before I die.

600cc large inlet head with bronze valves & seats (it is already 28mm, so I do not require inlet tract inserts),
650 barrels,
650 - 10.5:1 Hepolite pistons,
270 / 450 cam & ignition, &
I am well down the road of a 90 degree offset crankshaft.
 
Possum
What I was after was the drawings you mentioned you got from Ben Gradler of the inlet tract sleeves.
I would love a copy if you have them
Cheers
Rob
 
The later 650 models didn't have the sleeves in the ports, so would you really want to go down that path ?
We diverge here from bearings, a bit....
 
Rohan said:
The later 650 models didn't have the sleeves in the ports, so would you really want to go down that path ?
We diverge here from bearings, a bit....
Click to expand...
Mine is a 650SS/1966 and has the sleeves installed.

Fritz
 
Rob

I don't recall getting any drawings from Ben Gradler. Are you sure you have not got me confused with someone else?

Possum
 
Rohan said:
The later 650 models didn't have the sleeves in the ports, so would you really want to go down that path ?
We diverge here from bearings, a bit....
Click to expand...

There appears to be some confusion over why Norton fitted split sleeves in the inlet ports on some twins. My Atlas had these fitted because when I originally brought the bike it came with a single Monoblock carb setup-these where probably fitted to the single carb 650s they are simply removed if you convert to a twin carb setup.
 
Don't recognize the # 6203 17x40x12mm as any bearing I would use on a NHT crank
I'd be looking for 6306 or some variant of 30x72x19mm

NJ306 brass cage C3 anywhere in the USA from a norton dealer is about $108 for 1 ea
I just bought some NTN brass cage C3 from the NY distributor for $59+ea delivered.
 
Fitting two ball bearings on a Norton engine was a dodge done to reduce friction losses, used on race motors it was effective. Sleeving the inlet ports was done to match up to the size of carbs found by testing to give the best spread of power for the anticipated usage of the motor. They really had no idea what sort of loons lived the other side of the pond.
 
How do the people on the smart side of the pond put a 6203 17x40x12mm on a 30mm crankshaft? Grind it down to 17mm? Even the cam drive gear shaft is over 20mm? :lol:
 
dynodave said:
How do the people on the smart side of the pond put a 6203 17x40x12mm on a 30mm crankshaft? Grind it down to 17mm? Even the cam drive gear shaft is over 20mm? :lol:
Click to expand...


Nobody either side of the pond mentions fitting a 6203 here, it's a simple case of Possum quoting the wrong bearing number (6203 instead of 6306)

(6203 being the original gearbox layshaft bearing).
 
Typo!...maybe I shouldn't be looking for gearbox & engine parts at the same time.

Just got home from my bearing supplier with a FAG NJ306E-M1-C3 and a FAG 6306-C3 for $84AUD

Possum
 
Possum
You're absolutely right
The member that posted about having sleeve drawings from ben Gradler was Possm, not Possum - my mistake
I did PM Possm but have not had a response
Thanks
Rob
 
dynodave said:
Don't recognize the # 6203 17x40x12mm as any bearing I would use on a NHT crank
I'd be looking for 6306 or some variant of 30x72x19mm

NJ306 brass cage C3 anywhere in the USA from a norton dealer is about $108 for 1 ea
I just bought some NTN brass cage C3 from the NY distributor for $59+ea delivered.
Click to expand...

Hi, do you like the NTN bearings better than FAG? Now that FAG is made in India, I am having my doubts. What do you think about running two rollers in star of the high capacity SKF bearing on the timing side? This is for an atlas head motor. NTN is Japan, I think. Chris
 
elefantrider said:
dynodave said:
Don't recognize the # 6203 17x40x12mm as any bearing I would use on a NHT crank
I'd be looking for 6306 or some variant of 30x72x19mm
NJ306 brass cage C3 anywhere in the USA from a norton dealer is about $108 for 1 ea
I just bought some NTN brass cage C3 from the NY distributor for $59+ea delivered.
Click to expand...
Hi, do you like the NTN bearings better than FAG? Now that FAG is made in India, I am having my doubts. What do you think about running two rollers in star of the high capacity SKF bearing on the timing side? This is for an atlas head motor. NTN is Japan, I think. Chris
Click to expand...

FAG makes stuff all around the world and has been for a long time.
FAG are $108, NTN are $59 Can't see or measure any difference in the product. I like NTN $49 better.

I do run two two rollers most of the time in NHT I build.
What does "atlas head motor" have to do with crankshafts & bearings :?:

NTN/Bower (USA) /BCA (USA)... yes is now Japanese owned.
https://www.ntnbower.com/
interesting bit of Ohio/Michign history:
https://www.ntnbower.com/About/history.shtml
 

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