Primary Side inner race

That's a really clever idea! Another one I've picked up here that would be a time saver.

I can't take the credit for the idea, although I read about this so long ago that I forget where it was that I picked it up, however I have used it lots of times and it saves huge amounts of time not to mention mitigating the risk of bearing damage from pullers, if you opt to put shims behind the inner race on the crank, or from accidentally overheating the bearing while putting it in and out, as some do for shimming the bearing outer from the crank case. Bearing manufacturing tolerances are very accurate and one inner is very much like an other, given the fairly wide parameters that we are aiming to achieve in terms of end float.

The only time I've seen something similar was at a shop where a guy sets up rear ends professionally. All the newer rings and pinions have to be set up by shims and since he did not have the super expensive measureing devices he had bearings slightly ground down for each type.
If one did Nortons a lot your method would save a ton of time.

This makes me think we should do a tips section. A while back someone posted making a clutch tool out of an electrical box. I did that when I did my clutch and it beat heck out of the way I did it lat time out of a fan pulley.

The next question is how do you distribute shims? I imagine that getting both rods centered in their bores would be best but how could one accomplish that?

hi maylar,as was posted earlier it not critical we are only talking about thousands of an inch, you could put equal amounts of shims behind both drive side and timing inner races

Centering the rods in the bores on a twin is of course a bit more difficult for us backyard bodgers than with a centrally split single cylinder crankcase.

My Mk111 had a fair old bit of float (about .035" as I recall) and shimming of the drive side would have pulled the drive sprocket keyway closer than I could measure to the crankcase oil seal. I don't think that this is such a problem on earlier engines where the seal is pushed in against a lip rather than held in by a wire clip.

On the basis that the timing side bearing is the one that's pulled up tight, I was able to convince myself that it was the logical side to shim and I've had no problems over tens of thousands of miles.

There is a fair bit of end float on the rods so they are able to find their own centres in much the same way as the camshaft seems to. (I hope :shock: )

I think the side clearances on the rods are: .013 - .016 ( .330/.406 mm) x 2 = .025 - .026 but if your crank is off by that much and you need to shim it to get the rods "centered" in the bores, you may have other problems. The crank endplay should only be something like .005 - .010. I assume there is virtually no play at the rod little ends?

Someone please make fun of my math, I don't mind.

hi swoosh, i think you will find there is more than that on the rods and even more on the little ends

chris plant said:

hi swoosh, i think you will find there is more than that on the rods and even more on the little ends

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Rod clearance was quoted from the Workshop Manual. I couldn't find numbers on the little ends.

If anything is too tight you should find it on your spin tests with the engine partially stripped.

MAIN BEARINGS: What again I hear you groan? A small point, quite often with the super-blend, the inner
race, especially on the timing side, comes loose on the crankshaft; this does not seem to be detrimental
in any way, so do not worry about it. The next time things are apart down there a blob of Retainer Loctite
is recommended. Clean both surfaces with Carbon tetrachloride or similar (Evostick Cleaner) degreasant
(not petrol, it leaves a faint oily film) and use Loctite-601 green Retainer fit, this is some four times
stronger than the 641 yellow Bearing fit. Bearing fit 641 is for use up to four thou. gaps, 601 for use up to
six thou gaps. While the ultimate is Studlock 270, stronger than 601 but it needs a minimum gap of two
thou. and will fill up to 10 thou.

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I'm new to Norton ownership.
At the risk of sounding totally naive, what is super-blend?
I've seen it mentioned a few times.

Just to simplify, when the Combats came out Nortons were having bearing problems. The so called Superblend was the replacement bearing then offered by the Dealers and fitted by the factory. My dealer sold the same bearing to replace both the ball on the timing side and the former rooler on the drive side. We are still arguing about exactly what made a "Superblend", in a civilized way of course.

There should be a recent thread on this you can get with the search engine. At least we all pretty much agree that oil is good.

Hey Jerry, Did you have a problem with the Megacycle cam? I think someone asked this question a few days ago and I don't think I saw a answer. Only reason I ask is I have a bike that is about ready to break in (not started yet) and just wanted to find out as to why it's coming out of your bike? Thanks for your time, Chuck.

but what oils DO you people recommend?

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Oh no!!! Not the oil thread!! :shock: :shock: :twisted:

Let's just say we all agree it must be liquid! :lol:

Hello all,

A bit more history to this. First the megacycle cam has been fun. It's been in there for 4 or 5 years with the radiused followers. I run 2 x 34 MM amal MK2 carbs as well. It runs great out on the open road. It takes me about 40 mins to get to any decent roads and here in Irvine S.California soccer moms are still driving SUV's like mad women; whilst phoning. That is important because it is related to the street lights here, there are loads of them before open road. I suppose there is the freeway, but still got to get off it to more lights then have to go over the mountains (Ortega HWY) to find the fun roads. Before the last rebuild I was contemplating changing cam, but decided not to at that time. The main reason is I cannot idle properly below 1000 and I like mid range torque. The reason for all the SUV talk is that here if you stall at a street light, they will drive right into you rather than stop, bad situation!! I have pushed the limits over the Ortega and other canyon roads here over and over again, riding like a mad man!!

During last rebuild I put the megacycle cam back in. Had the head totally re-done by a reputable company here, who shall remain nameless. Still wanted to ride like a lunatic some more. Since then I have been thinking more and more about perfection and mid range torque, nice idle etc. I was considering changing cam, but no way as only had 3000 since rebuilt and was beginning of the summer etc.

So I rode back home about a month ago , 60 70 MPH over the Ortega leaning over with 80 drops, taking the usual chances. Then 90 MPH up the freeway then home. Bike ran great, parked it and drank a beer. The next time I started it, (in garage 2 weeks later)-- terrible noise from head. Compression test and no compression on LH. Took head off and LH valve was stuck, RH valve sticking too. The reputable company probably did not ream the guides (Bronze, with blck valves). So then I decided to change cam, and of course found the spinning inner race.

So valve did not hit piston. I got to thinking what could have happened on the Ortega!!

So looking forward to my new line up where it will idle to perfection!!

Cheers

It's your baby but if it were mine I'd go to a smaller carb and a cam with a similar profile to the 70 standard. As I get older I appreciate torque more and RPMs that border on blowing less.
I also found the poor idle I had last fall a true irritation and the push the bike out of the traffic lane and restart gets old, as does the rev wildly and try not to stall trick. We have a few of those folks you mentioned here in San Mateo too although most of them are too busy on their cell phone to notice you.

You are going to do a nice job on that lower end but be sure to really put some miles on the beast before you spin it up. It take a long time to wear valve guides in if they are tight at all and if you set them up loose like you're going to race it you could burn oil.

Ron L said:

but what oils DO you people recommend?

Click to expand...

Oh no!!! Not the oil thread!! :shock: :shock: :twisted:

Let's just say we all agree it must be liquid! :lol:

Click to expand...

Just 1 simple question please.
Do you run detergent or non-detergent oil in your vintage bikes?

Heck I use Redline 20-60 in mine, a number of friends use use Mobil 1, a lot of folks here are using diesel oil. Rotella is hard to beat and I use that in some of my other stuff.