lightweight pistons and Carillo rods on e-bay USA

Welcome, Mark.

Were you racing at Barber's, or spectating?

Hi Mark and welcome to the forum!

Just curious as to what the cylinder liners are made of with the nikasil treatment that you are using in in the billet barrels? (I'm assuming the barrels are billet aluminum.) What kind of clearances are you running on your pistons?

Since the mentioned piston weights made me curious I weighted my homebrew piston: its 234 gr complete with rings, pin and circlips. By the way - my homebrew conrod weights 380gr with the screws but without shells.
I once rebalanced my 850 Commando crank to 68%. Not very good unless you can race all the time. It seemed to me that the Isolastic rubbers couldn´t handle the vibes below 4000 properly - I had vibes in the handlebars which I never had before. They were not hard but I wasn´t used to it. The 68 % were good above 4500 - the engine was smoother than before. So I wouldn´t change the factor very much for a roadgoing Isolastic bike - unless you can keep it most of the time at 4k or above.

WEAL Norton said:

Since the mentioned piston weights made me curious I weighted my homebrew piston: its 234 gr complete with rings, pin and circlips. By the way - my homebrew conrod weights 380gr with the screws but without shells.

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Wow, that's light for 905cc's! It seems to me the stock 750 piston by itself is about 250 gr.

RennieK said:

Hi Mark and welcome to the forum!

Just curious as to what the cylinder liners are made of with the nikasil treatment that you are using in in the billet barrels? (I'm assuming the barrels are billet aluminum.) What kind of clearances are you running on your pistons?

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Getting slightly off topic, Nikasil is kind of old school now days and has a few downfalls, well probably a better description would be that there are new coatings that are far superior, so much so that cast iron looks like a bad wear surface in comparison. I would guess that the Nikasil was deposited directly onto the aluminium bore. The newer materials are usually plasma sprayed powders, that said there are even twin wire arc sprayed materials that will work better. The best ring/liner material combination (well second best) that I have come across was a Sulzer Metco plasma sprayed coating (if someone wants the actual powder designation I can dig it up) with TiN coated (PVD), nitrided 1.2mm stainless rings, the best combination wasnt so much a combination but a ring made from silicon nitride, not entirely practical for a piston engine though.

I'm trying to keep up with yo'all and seek smoothest operation over all else. I was wondering if anyone else notice Tim Joyce runing flat away from all else at Barber's. Kenny asked me if I'd seen him battling it out with two others, I did, but losing out to a missed shift??? This confused me no end because Kenny and the two others were about a 1/10 mile behind Tim's Triumph after a couple of track turns. Tim pulled almost vertical wheelie at race start snicking 2nd and nailing it before the 1st turn! Since Kenny didn't mention this at all, I assume Tim's bike was in whole 'nother formula class as its was no race contest at all to him.

D/t Jim's dang light kit shoving Ms Peel's BF into upper 90% Ken Canaga came up with solution to bore out ~1.5" slug in flywheel to bring down to 50's BF, that allows BF adjustment by just screwing in another mass. May not even have to split cases to access it either. Will be fun to hunt the sweetest BF for Peel.
Tracing engine orbitals shows ~75% vertical motion, ~25% horizontal with factory mid 50's BF.

Regardless of how road racers like it, I'm both fascinated and terrified of engine pulses on tire adhesion in skewed constant crabbed Gravel climbs and at max lean angle on increasing throttle. I sense there is some benefit from the isolastic dampening in thrust axis as well as engine turbo fan sense. Either I'm on to something or really stupid throttle user as slipping to spun tire is all too common an issue I'm had to come to terms with to enjoy or avoid.

Wow, that's light for 905cc's! It seems to me the stock 750 piston by itself is about 250 gr.[/quote]

Yep - just weighted STD Norton pistons - 750 is 342gr complete with rings, pin and circlips. The 830 is even worse: 396gr complete!
The Norton rod is no lightweight either: 450gr

Cheers

Hartmut

Hello all,

Thanks for the welcome. I'm in and out of town a lot so I mouth off when I see a interesting topic. Hard to keep up with all the forums but you guys seem to be a nice group.

My Triumph cylinders are fully machined extruded 6061 billet with direct nikasil plating (no liner on this on). Piston is a 9.5-1 quench dome 2618 forging with nitrided stainless rings running .002" clearance. Its the predecessor (first test) to the current one Tim has on his racer.

I'm sure there are better ways to build a mouse trap but I personally like what I have. I believe it to be bullet proof. Before I got a chance to assemble it, I inadvertently left it overnight in the washing machine. Other than having to re-polish the fins the plating was perfect. Imagine a cast iron cylinder or liner.

Not sure what was seen by others at Barber but only on Sunday was there any challenge to 1st place in Formula 750 that was from a 2-stroke not even in the class and he was a few seconds behind the leader. Check mylaps to verify as I'm getting old and senile. Can you tell, I still like my Brit bikes.

Mark

WEAL Norton said:

The Norton rod is no lightweight either: 450gr

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The beauty of the stock Norton rod is its light small end weight, typically 75 - 78 grams. Most steel Norton rods are between 130 and 150 grams small end weight, although Jim has got his down a lot closer to the stock rod's weight. The alloy rod/steel cap is really a good design, with low reciprocating weight but strong big end. The extra weight in the big end is all rotating weight, and really isn't worth worrying about. It's the reciprocating weight that counts for the worst stress on the bottom end. The only problem with the stock rods is that they eventually fatigue and break in high horsepower race engines. It used to be standard practice for serious Norton racers to replace the rods every season. But that was back when Norton was still in business, and new factory rods were plentiful and relatively cheap.

Ken

grandpaul said:

Great story!

Since I plan on doing this till I retire, I wonder what I'm going to want to be doing AFTER that?

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I am retired (from 35 years in Corporate America) and 'ám having a blast working "ïn the industry" ;I hope that I can do this up until the day I die. I worked for Triumph, Norton and Honda, Kawasaki while in college; I should have stayed there...

The weight normally associated with the oil in the sludge trap is 105 grams IIRC.. I wouldn't bet my first born on this number, it just resonates.

RS

Give Stainless for the Holidays...

British Bike Guy said:

Hello all,

Thanks for the welcome. I'm in and out of town a lot so I mouth off when I see a interesting topic. Hard to keep up with all the forums but you guys seem to be a nice group.

My Triumph cylinders are fully machined extruded 6061 billet with direct nikasil plating (no liner on this on). Piston is a 9.5-1 quench dome 2618 forging with nitrided stainless rings running .002" clearance. Its the predecessor (first test) to the current one Tim has on his racer.

I'm sure there are better ways to build a mouse trap but I personally like what I have. I believe it to be bullet proof. Before I got a chance to assemble it, I inadvertently left it overnight in the washing machine. Other than having to re-polish the fins the plating was perfect. Imagine a cast iron cylinder or liner.

Not sure what was seen by others at Barber but only on Sunday was there any challenge to 1st place in Formula 750 that was from a 2-stroke not even in the class and he was a few seconds behind the leader. Check mylaps to verify as I'm getting old and senile. Can you tell, I still like my Brit bikes.

Mark

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You sound JUST like Marino.

I have Jim's set up in a standard 850. As Ji states there is no need to alter your balance factor, the ligher reciprocating mass alters the BF to approximately early to mid 60% which apparently Norton used on productio racer versions. The Carrillo's give piece of mind over 30 something year old alloy rods, and there seems to be a pretty good market for good second hand rods. I sold mine on ebay and recouped about $200. The rods apart from making it possible to use modern short skirt forged pistons, also run a trick small end with no bushing, so a special diamond like coated gudgeon (wrist pin) is used. All i the name of lighteness and durabilty.
Unfortuneatly I have had an engine problem, and am geting over Christmas bills before getting some more engine components, but I can honnestly say the Js piston and rod set up really smoothes out an 850. My main beef with my original set up was the shaking efore the iso units started to work, the above idel to about 2300 rpm. The bike was like most well fettled Cmd's smoth on the move. The new set up is smoother! I could notice much difference in before and after power, but I am sure the amals and other componets, along with the crank and cases will last much longer?
Oh I had the Total Seal second ring option, nowif you like to skite to your mates how mch compression your Norton has, and how it takes a real hard man to kick her over, well quiet simply you will not be dissapointd with this option. You can stand all your weight on the kicker statically and it will not deviate, honest. Should reduce down blow by significantly also.
The parts are very good qualty, much more sexy looking than the original pistons. I reckon this stuff would make it possible to make a nice Atlas or special 750 in a featherbed up?
Oh and Jim is a really nice guy to deal with, he is basically one of us, an enthusiast.

Cheers Richard

grandpaul said:

Great story!

Since I plan on doing this till I retire, I wonder what I'm going to want to be doing AFTER that?

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I *am* retired, but wanted to do something that I actually liked. I spent 35 years slogging up the career ladder in Corporate America; it paid the bills. Funny that what they pay you is called compensation---for dummimng you down?

Any way: The reason to use a one piece forged crank, forged rods, forged pistons and get a proper balancing is RELIABILITY, it doesn't get any better, 7000+ RPM with no guilty conscience...

I believe that the weight commonly assigned to the oil in the sludge trap of the standard 3 piece crank is 105 grams, IIRC. (even if it appears a tad high). The one piece Falicon cranks have a gallery, not a sludge trap.

RS

If spin that built up crank at 7000 for extended pulls . . . . .
Yes, I get it, the lighter pistons/rods take some load off that built up crank but it's various parts are still flexing.


When you start spinning it up, what breaks first? Rods? Pistons? or Crank?

What breaks first and then next and next after that?"
I know I know!!

Assuming factory components. If cast iron flywheel don't shatter first then the valves float and hit pistons, show stops pretty soon after 7000.

With steel 5 lb lighter flywheel and race level valve train, the crank jump ropes and its ends pivot to allow alternator stator to rub/strike melt stator and crank can get permanent bent nearing 9000 rpm.

Done often and long enough the cases split through DS bearing and upper rear though bolt. Done dragster launch hi rpm clutch drops the cases can torque on their locating dowel and bind up like a constipated stubborn gorilla.

Vintage era dragsters preferred the thin 750 cases over the 850 as they tolerated more crank flex by flexing to relieve bearing bind. Going toward 11,000 and above the TS end of crank jerks on timing chain and oil pump snout to fracture pump and bend cam and destroy cam pensioner.

Long stroke is hard on piston jerk down from TDC so piston quality is a consideration. As pistons resist direction change the crank center is pulled upward/forward so its ends point downward/backward to strike or jerk on stuff.
Somewhat lesser crank flex hits with pistons jerked off BDC. Engine calculators have formula for piston G force, then plug in piston rating to find max rpm.

Some, maybe all crank cases have machined sharp stress risers in the mounting flats and can develop cracks there too.

At some rpm level ignition needs to slightly retard off max to give time to burn ahead of time. Don't know if any Norton twins can turn high enough to need it.

Superblend over flat rollers give some fudge factor on crank flex too.

I'd like to see a race level case made with the crank center offset rear ward to lower TDC jerk down some. Longer rods help lower sharpness of TDC jerk but more so on BDC dwell time G's relief.

The crank generally breaks first. Aluminum rods can also break (and all the various brands of after market aluminum rods are too heavy on the small end in order to keep them from breaking). You don't hear of Carrillo rods or forged pistons breaking. So lightweight pistons and lightweight rod uppers are at the top of the list. Bushless JS rods are proprietary and are lighter on the small end than bushed steel rods or the various brands of after market aluminum rods. I tried to come out with an aluminum rod but there was no way to make them lightweight AND safe on the small end. Remember - it is the small end of the rod that causes vibration and stress. I have heard the horror stories of aluminum rods breaking through cases, spilling the oil on the rear tire and causing crashes. No thanks!

The next high RPM problem is valve float and thats where the lightweight lifter camkit comes in.

There is also the option of additional piston lightening. JS 750 pistons are down to around 170 grams with the extra lightening. About 15 to 20 grams lighter. Extra machining is required.

Jim

Jim, what would the lighter modifications imply for heat and extra pressure tolerance as opposed to the smoothness and rpm acceleration tolerance gained?

I have not heard of Norton rod breaking unless something else let go first. If you know of such events I'd be interested to record them?

I can see racing fatigue from heavy piston jerking on Al rod, just ain't heard it reported in Norton's. The most maxed out dragster engines with boost that almost hydro lock at TDC use Al rods for the cushioning elastic properties over steel rods. Not likely needed in Norton style engines.