Yellow Peril in peril

OK so it’s a long way from the Yellow Peril. After I bought my 1st Norton in 72 the 1st Norton owner I met had a heavily Norvilized yellow cafe. I always loved his bike and so when I saw this for sale locally it reminded me of my buddy way back and I had to have it. I’ve owned it for 2 years and finally got some time to try to get it running.



Appearently this bike had been running since being rebuilt but had a bad wet sumping problem. I was hoping to rebuild the oil pump or replace the conical seal in the tc and maybe fire it up but I discovered a pile of other problems now that I have the time to really look more closely. When I 1st saw the bike I remembered feeling some looseness in the header pipe bolts but they were nice and tight the 2nd time I saw it and took it home. After finding the swingarm bushes and rubber mounts are fried I decided to check the threads in the exhaust ports. They are real bad. Then I discovered the left side header had a lot of oil in it and there was a small pool at the mouth of the port.



I’m thinking worn guide, bad seal or a prob with an oil ring on that side. Peering in the spark plug holes you could see freshly honed cylinder walls and fresh valves. I took the rocker covers off to have a look, all 4 adjusters looked like this:



I’m thinking wrong valves or push rods. A compression check showed 120 on both sides but the motor/tranny was moving so badly in the loose isolastics I didn’t try putting oil in and re checking and I was happy with 120lbs anyway. A leak down test showed 25% leakage on the left side and mostly fom the ex. valve. There was nothing noticable from the crankcase. So I pull the head and the 1st thing I see is this:



tiny little ball bearing parked in the valve cut out on top of the piston, WTF? It’s .095” I checked my compression and leakdown testers but they don’t seem to be missing a check ball? The 40 over pistons are nice and snug in the bores. You can see the misty oil deposite on the piston top and where I wiped my finger around the perimeter. There is no patern on the cylinder wall from a gibled oil ring so I’m trying not to take the jugs off. I poured gas in all intake and exhaust ports and the valves are nice and tight with practically zero seepage. Now I think that ball bearing got caught in the exhaust valve when I did the leakdown test and that's why I had the 25% leakage reading. The bright side is it’s got new: pistons, valves, and guides.

Suspect the Heads been planed , half the ammount of half the adjustment . Me myself & I would pull the whole thing down , so Id know We did it . :shock:

Youre in for disassembling valves to check oil seal anyway ?

Pay to check cam lift , sounds like collets couldve clobbered seal ?

pulling the Timing Cover will reveal if theres other ' odd ' workmanship . Full strip would mean guesswork is eliminated , presume Zero Wrong .Pulling rods or stripping crank wil need new bolits.Such is life . :wink:

Don't you just hate it when shotgun or BB pellets work their way into your motor....
Is it steel or lead ?

No ideas, but buying something half done is always such a lottery.
Nice looking cycle.

Matt Spencer said:

Suspect the Heads been planed , half the ammount of half the adjustment . Me myself & I would pull the whole thing down , so Id know We did it . :shock:

Youre in for disassembling valves to check oil seal anyway ?

Pay to check cam lift , sounds like collets couldve clobbered seal ?

pulling the Timing Cover will reveal if theres other ' odd ' workmanship . Full strip would mean guesswork is eliminated , presume Zero Wrong .Pulling rods or stripping crank wil need new bolits.Such is life . :wink:

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Chriky Matt! Don't even go there! I just wanna ride!

Push rods and valves are stock combat lengths. Seals look new ( I pulled valves). I did check valve lift before pulling heads and it checked out ok, kinda hard to check intakes while in frame. I was thinking if it had an after market cam maybe it had a larger base circle than a combat and that was throwing the valve adjusters to the end like that. The valves are getting deep in the valve seats and although it didn’t leak gas the lapping in job doesn’t look fantastic to me for being new valves and all. From the deposits on the valves etc. it doesn’t look like this bike has run much since the rebuild.

I took the swing arm off earlier and of coarse the tube in the cradle is where the slop is. Now I find the center stand was in place without the little spacer bushings and it and the bottom of the cradle are bent and banged up. I’m not budgetted for a bunch of repairs and parts right now. To avoid spending money on the swingarm spindle and fixing the cradle I decided to replace the swing arm and cradle with one I fortunately have from a parts bike that’s nice and tight. Taking off the primary I found the altenator nut and the clutch hub nut were torqued to about a whopping 10 ft lbs. Several of the through studs for the engine - cradle were also torqued in the 5 - 10 lb. range. I’m getting a bad feeling about the state of the bike inside the cases. I'm not going to fart around checking cam lift, I think I’ll pull the jugs to see what cam is in it and check the feel of the rods. I hope they’re torqued properly. Did I mention the cam nut was also in the 10 - 15 ft lbs. of torque range? I'm still not going to think about tearing into the bottom end yet.

Rohan, it's a steel ball bearing. It left tracks on the valve seats but nothing too bad, just enough to see. I'll have to make sure there's no more in the header, muffler and carb.

The wiring job is straight A to B with no disconnects anywhere and uninsulated spades. I've started snipping to remove components.

Hope the Rod bolts arnt in the 10 - 15 lb / ft Range :shock: . Meethinks pushrod length too , looking at it .

The radius on the adjuster ends Std. ? looks a bit flat , from here . Std .040 head gasket in it , 1 5/8 Inlet Valves . ?

Combat spec Head Ports & Carbs ? ?

Looks a good machine , would you like to borrow a Fine Tooth Comb . To go over it with . :|

' We ' thought it was your winter project . !

Is that a Dunstall seat? The tank looks fiberglass.

Push rods and valves are stock combat lengths.

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OK, which is it? Stock or Combat length? :mrgreen:

Since the Combat head is milled .040 shorter than the earlier head, the stock pushrods should have been shortened by .040. Rumor has it that none of them were.

Matt Spencer said:

Hope the Rod bolts arnt in the 10 - 15 lb / ft Range :shock: . Meethinks pushrod length too , looking at it .

The radius on the adjuster ends Std. ? looks a bit flat , from here . Std .040 head gasket in it , 1 5/8 Inlet Valves . ?

Combat spec Head Ports & Carbs ? ?

Looks a good machine , would you like to borrow a Fine Tooth Comb . To go over it with . :|

' We ' thought it was your winter project . !

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I don't have the figures in front of me but I wrote the pushrod lengths down on the bench top and checked them against specs and they are combat length.
I'm not sure about the adjuster radius. Stock as far as I know. Head gasket is paper with flame ring .030 and the inlet valves are 1 1/2".
It's a combat head with "C" stamp and 32mm inlet ports and carbs.
Regarding the fine tooth comb, I welcome all scrutiny and advice but this whole thing has taken such a turn it's going to be a long time before I eventually zip it up again. I have a very demanding schedule (over worked and under paid) so I'm time poor when it comes to working on my bikes.

Dave, the seat is not Dunstall but was offered as an alternative to the solo seat with number plate like you have. I think it's in Les Emery's catalog. The tank is fiberglass and I think it goes much better with the solo seat, specially with the yellow finish. I'd consider trading tanks with you: )

Hi Ron, I guess I gotta quit calling my combat stuff "stock combat" It's a 72 combat. I don't have the figures in front of me but I wrote the pushrod lengths down on the bench top and checked them against specs and they are combat length.

Cylinder base nuts were torqued to 10 to 30 ft lbs. The con rods have no up and down slop but I can rock them side to side more than I would like to. The cam is an SS in decent shape. The 2 machine screws holding the case together were barely finger tight.. The only fasteners that were torqued poperly were the studs going through the front mount. You were right Matt, I had to split the cases.

The main bearings are SKF 3NU06 11 roller tapered roller bearings with only 11 rollers. I haven’t done any mechanical work for 25 years other than tear down my burned out parts engines when i got them but from what I remember bearings were finished a lot better than these. The finish is rough right up to the actual race surface. Then there are lines running perpendicular to the race evry so often. I’m thinking if the outer races weren’t fully seated during instalation these impressions occured during buttoning up the cases as the cups were forced fully home. Somebody obviously didn't understand what superblends are to a combat commando.



The rods were torqued between 38 and 40 ft lbs (judging from my old beam wrench on removal. Unfortunatly there was some contamination in the oil and it will need new big end bearings inspite of it looking like these were new also. I’ll have to check the crank for run out because of the wear on the rod bearings and the TS main only touching at the toe of the rollers.





The cases are a matched set. These are not the original cases as they don’t have the little circle patterened mark before and aft of the serial number. It would seem this ticking time bomb blew previously. I noticed the oil pump feed drillway has the same dark staining as the rod bearings where the oil feeds from the crank. I think the oil tank was never cleaned out from the first mishap and is the cause of the abrasive wear on many of the surfaces.

The cam has notches for the timed breather and no drill ways for oil and no scrolls at the bearing surfaces. It’s been a long time since I’ve done any of this but shouldn’t either the bearings be scrolled OR the cam? Shouldn’t it be scrolled cam with plain bearings OR unscrolled cam with scrolled bearings? I have no scrolls on the cam or the bearings. (There is a short X pattern scroll out of the oil hole in the timing side bearing where oil can drip in from the top but this isn’t really scrolling like I would expect. The scrolls peter out 1/2 way, I thought they should go completely around.)



The op said it was wet sumping badly. The timing cover seal was badly worn and shy of the end of the spigot that it sits on on the oil pump by .200”.I don’t think it was seating properly to the timing cover.

I was hoping I had a runner here so I could experience riding a Norton again and take my time rebuilding my blue bike. Now I hope it snows.

My 69 wet sumps very quickly. In two days the tank is empty, but not to uncover the feed screen. I just start it up and the oil almost immediately returns to the tank. I think wet sumping is very over rated, or should I say over worried. The bike runs fine, plus it keeps the bottom end well oiled in the meantime.

Nelson recently had blowby in his 69S that was coming out the breather, but he found that was due to some bad scoring on the cylinder walls as I understand.

Good luck on your project. I didn't realize you don't have a ride-able bike at the moment. I just had a good 35 mile run up Naked Mt. and back. Feels so good but I got a bit chilled in the 60°F, not bad for November.

Dave
69S

Perhaps you need to read JoeS and Jim Comstocks comments on C3 and non-C3 bearings ?
Basically, if it wasn't C3 then the rollers can indent the tracks when squeezed on install, and be notchy to rotate.

I didn't take note of the numbers, are those superblend bearings anyway ?

Have fun...

RennyK. Here is a NOS Scrolled Camshaft Bushing. X pattern inside. Hope this helps to your question on the scroll. Combat motor you have. To my understanding, those bushing are suppose to last a long time?

Hey DogT, as I was leaving with the bike the PO made an effort to warn me about the severity of the wet sumping. Apparently after 20 minutes of riding it left a huge quantity of oil on the ground and that's why he took in the basement and drained the fluids. It sounded worse than most.

I don't think these are are the list of superblends. I think superblends have 12 rollers and these rollers don't look barrel shaped. All the superblends I've seen had brass cages too. I think some bearing supplier said "hey look, these will fit also and they're only $39.00!" The PO said, "they do fine" thinking "I'm selling the bike anyway" or maybe he just didn't know better. It seems to me the original combat bearings that were blowing up only had 11 rollers in them and they weren't barrel shaped either.

Yes TravellerJ, that's what I have in the TS. The DS bearing is just plain though. Are they supposed to be on both sides?

RennieK said:

I have no scrolls on the cam or the bearings. (There is a short X pattern scroll out of the oil hole in the timing side bearing where oil can drip in from the top but this isn’t really scrolling like I would expect. The scrolls peter out 1/2 way, I thought they should go completely around.)

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That is normal for the 06-2600 cam bushing. They appear as you describe to be 06-2600's

You can have,
1. Scrolled cam and scrolless bushing
2. Scrolless cam and scrolled bushing (which you have)
3 Scrolled cam and scrolled bushing
But not scrolless cam and scrolless bushing.
If you believe your cambushing are good, you can put virtually any scrolled or scrolless cam in there.

Looks like NO Television , for the next few weeks .

Seats NVT / Norvil . Is a US spec P.R. in Aus the same , and I recall cattledog picture somewhere .

Id set the SS 5 deg adv. , by the teeth .To tryn get the lift @ tdc for a 3S.(see the cam on ' for sale '
Definately stamped ' 3 S ' , if you read it upside down ) Got 3-500 to 7000 powerband , but I think
it was the 1 5/8 valves , Was ported to the Mk 3 Tapered type .( .17 or .27 in @ tdc I think it was )

AH Well , its not the end of the world . Just dont start polishing things , well be here forever then .

Haveing a dubious & suspicious mind , Id split the crank too . Bolts reusable perhaps , if not abused .
Pretty sure I did , but wernt butchered , ' we ' made titanium studs for the T 100 from aircraft bolts .

Good pictures , worth a thousand words . Thanx .

I thought the 72''s didn't use the side breather but vented out the lower back of engine. Don't know if the cam kept the notch though. Possibly an earlier cam?

Rennie, well, my wet sumping doesn't leave any oil on the floor, it just all goes into the sump. Yeah, if it all ended up in a puddle on the floor then I'd worry about it. Mine used to leak a whole bunch, but after my rebuild, the leakage is manageable, maybe a few drops every couple of weeks out of the crank flanges at the bottom of the engine. If you break apart the cases, use Hylomar Blue Racing formula on the flanges, it seems to work pretty good, it's like putting snot on though and it's about $15 for 1.2oz, but that's plenty for the whole bike. Carrier is acetone, so it won't last once you break open the seal.

Dave
69S

Matt Spencer said:

Looks like NO Television , for the next few weeks . Just dont start polishing things , well be here forever then .

Haveing a dubious & suspicious mind , Id split the crank too . Bolts reusable perhaps , if not abused .
Pretty sure I did , but wernt butchered , ' we ' made titanium studs for the T 100 from aircraft bolts .

Good pictures , worth a thousand words . Thanx .

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NO TV!!! but I just got cable hooked up! LOL on the polishing comment, that one cracked me up. I do have a bit of an aversion to polishing specially now that I have some buffing equip., that's something you can do while you're waiting for parts.

I'll definitely split the crank, the shell bearings have a very narrow stream carved in them in line with the oil way. The crank journals lost some sheen there as well so they need a polishing at least. I'll have to mic them to determine why I could rock the rods sideways. I'm thinking it should have been reground with oversize bearings.

htown16 said:

I thought the 72''s didn't use the side breather but vented out the lower back of engine. Don't know if the cam kept the notch though. Possibly an earlier cam?

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Yes that is correct, I guess the notches were never abandoned.

Rohan said:

Perhaps you need to read JoeS and Jim Comstocks comments on C3 and non-C3 bearings ?
Basically, if it wasn't C3 then the rollers can indent the tracks when squeezed on install, and be notchy to rotate.

Click to expand...

Thanks, I found the post on C3 or C? and I actually had seen it but at the time it had no bearing on my situation (pun intended). I just re-read it with all the links and it is interesting info.

Thanks also for the info and links on the cam bearings everyone. At 1st I didn't see any scrolling on mine and it wasn't until I was removing the main bearing races that I saw the X scrolls on the top of the cam bushes. I had been looking for scrolling similar to what is on the cams. Hopefully the left side has the same bushings too. (at work now).

DogT said:

Good luck on your project. I didn't realize you don't have a ride-able bike at the moment. I just had a good 35 mile run up Naked Mt. and back. Feels so good but I got a bit chilled in the 60°F, not bad for November.

Dave
69S

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Dave, thanks for the tip on the use Hylomar Blue Racing formula goo. I've been wondering what to use. Is it easy to get off later? When I 1st joined the site about 3 years ago Yamabond was getting the accolades. Back then I'd just gone up north to retrieve my bikes from storage in a barn on my brother's farm after being there 25 years. (just think, they could have ended up as barn finds). The only thing I'd kept with me was some special Norton tools in a box but all my other tools that were left up there were gone. In the last 2 years a lot of personal events have kept me away from the bikes again but I'm tooled up and have a place to work and I've just about worked past my obstacles to have more time to spend on the bikes. I'm really looking forward to having a running bike.

Yes, the Hylomar comes off with finger rubbing. I found tiny bits of it in my sump filter first oil change, but the stuff seems to disintegrate between your fingers like hardly feeling it.