Engine Modernization
- Thread starter chipdossjr
- Start date
- Status
comnoz said:
If you are not totally booked up, I have a list of projects for you. We will be transplanting lettuce and kale tomorrow...
Chip,
I think the issue with modernizing the Commando engine is that it is an archaic design and that is what makes it so likeable. One good kick and Karrumph, it is running. Wind on the throttle and it makes a great noise, and more than gets out of its own way. The motor makes the bike fun to ride. The rest of teh bike doesn't usually do anything evil in corners, but do plan ahead with the brakes. Park a bug spattered daily rider in a line of shiney Harleys and only the snobby ex-BMW riding orthodontists will not come over and say ' Cool bike. I ( or my brother, uncle, roommate, mom, etc.) had one of those and...'
A modern 50 hp engine would be an OHC water cooled 500 with 4 valve heads, six useable speeds, fuel injection, etc. but it will not be like a long stroke motor with small carbs. So, clearly, we are no help here. Please keep us in mind and let us know what you are doing.
All the best
Greg
- Joined
- May 27, 2013
- Messages
- 1,112
chipdossjr said:
I think if you read between the lines you will find the answers to your questions. It takes a bit to get there because the people on Access Norton are all very knowledgeable and many have been there and done that.
It really boils down to the technology of the British parallel twin engine which has it roots in Edward Turner's design for the Triumph Speed Twin back in 1937. The basic design was improved on by all of the British motorcycle manufacturer's through the 40's, 50's and 60's. Then the Japanese invasion created a period where the engines had horsepower and displacement increased to try and keep pace with the Japanese with an old engine design and even to the point of no return (Google Norton Commando Combat) and thus the limit was reached. The 850 Commando was detuned and the crankcase made stronger to get more life out of the old design. Study the history a little and you will learn much about the why and the wherefore's.
Many here understand the limit's and there are many who race these engines and have pushed every limit so listen to them.
Commoz (Jim Comstock) gave you the jist of it in an earlier post. The high performance pistons used in a CBR, are very tight tolerance to the cylinder bore...this is accomplished by controlling the expansion and contraction of the metals with water cooling. Too tight of tolerance on a Norton cast cylinder to an aluminum piston will cause a very quick seizure. Short skirt pistons in a long stroke engine also results in possible piston rocking which has the same end result. There are some techniques to overcome some of these problems...and that is why you should take the time to get to know the experts here...they will lead you in the right direction.
That's not to say you shouldn't try it yourself because invention comes from trial and error sometimes, but then many here have years into this so listen to them...they know.
chipdossjr said:
A lot of folks here might tell you that the FIRST thing you hotrod in a Commando is the brakes !
They weren't the best when they were new, and newer technology has made them distinctly 2nd rate.
A few minor and/or a few major upgrades can improve this, considerably, and increase your chances of being able to stop when needed.
Search for brakes or brake upgrades here, been discussed a lot...
- Joined
- Oct 19, 2005
- Messages
- 18,978
Besides the commerical level products made in significant quantity mostly covered above, there are a handfuls of private machinists innovators all over the planet and would have to ask forum for specific makers and specific items to find them or global search www to see how much you-me-we are missing out if this forum is only resource good as it is. More than upgrading to get a reliable Commando mainly means correcting some factory over sights that differ in each model, brakes to oil routes to sealing. Most the upgrades here only exceed the factory items in weight or for race excess use endurance. Still best not to waste good money on wine and women that do not last nor payback as well. Catch up here on on basic modernized crankshaft lore then get back when ready for more.
commando-crankshaft-porn-t8365.html
commando-crankshaft-porn-t8365.html
Fast Eddie
VIP MEMBER
- Joined
- Oct 4, 2013
- Messages
- 22,521
Orright Glen you got me now... reading the above text would seem you suggest the 'standard is best' approach...
How are we to balance that with your personal 1360cc nuterbastard Vincent approach...!?![/quote][/quote][/quote]
I sure wouldn't recommend trying to make a 100+ horsepower Vincent from a nice standard Vin like your or my Rapides.
I think the engine would shatter into many pieces somewhere well before 100 HP, many have tried and failed.
The 1360 was a complete new bike and engine, so no Vincents were harmed during the making of that bike.
Since it was all new stuff and the plan was for big power, I used some greatly uprated components such as
- Crankcases heavily fortified around main bearing areas in engine and trans and other known weak areas ( trans cam pinion boss)
-Quaife 5 speed rated for 200 bhp according to Rod Quaife
- One off Bob New by clutch with thin plates and extra plates. Said to be OK to 140 HP. Holds OK but just.
-crankshaft with oversized mainshafts, oversized bearings and oversized main pin. Main pin has 3 times the surface connection to the flywheels that the standard crank uses and has a 14 ton interference fit rather than 5 ton as for standard.
- the cylinders and heads look just like a standard Vincent but have approximately 35% more cooling fin area to deal with the increased horsepower.
- two start oil pump delivers twice the volume of the standard pump, and is a "must" according to Terry Prince, who supplied many of the steroidal parts.
There are other changes such as forged Pistons and rods and on and on.
With all of that it is a bit of a silly experiment as far as longevity. It would be a wonderful outcome if the engine stood up as well as a standard Vincent engine generally does.
No reason that one could not build a big bore big stroke Norton engine/trans in the same way. I the Norton engine/trans(TTI, 6K) would end up costing 20 or 25 k US$ , maybe more with assembly labour.
I think Jim Com stock has one almost together, he must have a good handle on what it would cost to start from scratch and build such a power train.
As far as hopping up a stock Norton engine, I have been mightily tempted and have had 920 kit in the drawer for years now.
The more I learn, the more I think it is not such a great idea, unless you start completely from new with beefed up parts hopefully capable of giving years of reliable running at the new higher power output level.
Glen[/quote]
Indeed Glen, I looked at building a super-duper 1007 motor and TTI set up. But (very) quickly concluded that was way to costly, and also kinda not the point (for me).
However, when ones pistons and bores are worn, cams and followers are shot, when one doesn't want to risk 40 year old alloy rods (having broken one previously) then, when in this position, the cost of 'upgrading' your engine is only as expensive as the price difference over and above stock parts!
After all, these bikes are now over 40 years old, and they were technically obsolete when new, and they were built down to a price, so, whatever kind of improvement an owner is looking for, there at least a dozen different ways to go about it.
To the OPs original question: Personally I would not experiment with CBR pistons etc. I'd rely on the experience of others who have already done so. Comnoz analysis of cams and there effect is a similar situation, changing things randomly / without deep knowledge can create many knock on factors that we are not aware of. Best to choose your idea of upgrades from those who have already learnt by trail and error!
A stock bike is a very nice thing to ride. But in my opinion, and for my own purposes, a hot rodded version is a lot more so!
How are we to balance that with your personal 1360cc nuterbastard Vincent approach...!?![/quote][/quote][/quote]
I sure wouldn't recommend trying to make a 100+ horsepower Vincent from a nice standard Vin like your or my Rapides.
I think the engine would shatter into many pieces somewhere well before 100 HP, many have tried and failed.
The 1360 was a complete new bike and engine, so no Vincents were harmed during the making of that bike.
Since it was all new stuff and the plan was for big power, I used some greatly uprated components such as
- Crankcases heavily fortified around main bearing areas in engine and trans and other known weak areas ( trans cam pinion boss)
-Quaife 5 speed rated for 200 bhp according to Rod Quaife
- One off Bob New by clutch with thin plates and extra plates. Said to be OK to 140 HP. Holds OK but just.
-crankshaft with oversized mainshafts, oversized bearings and oversized main pin. Main pin has 3 times the surface connection to the flywheels that the standard crank uses and has a 14 ton interference fit rather than 5 ton as for standard.
- the cylinders and heads look just like a standard Vincent but have approximately 35% more cooling fin area to deal with the increased horsepower.
- two start oil pump delivers twice the volume of the standard pump, and is a "must" according to Terry Prince, who supplied many of the steroidal parts.
There are other changes such as forged Pistons and rods and on and on.
With all of that it is a bit of a silly experiment as far as longevity. It would be a wonderful outcome if the engine stood up as well as a standard Vincent engine generally does.
No reason that one could not build a big bore big stroke Norton engine/trans in the same way. I the Norton engine/trans(TTI, 6K) would end up costing 20 or 25 k US$ , maybe more with assembly labour.
I think Jim Com stock has one almost together, he must have a good handle on what it would cost to start from scratch and build such a power train.
As far as hopping up a stock Norton engine, I have been mightily tempted and have had 920 kit in the drawer for years now.
The more I learn, the more I think it is not such a great idea, unless you start completely from new with beefed up parts hopefully capable of giving years of reliable running at the new higher power output level.
Glen[/quote]
Indeed Glen, I looked at building a super-duper 1007 motor and TTI set up. But (very) quickly concluded that was way to costly, and also kinda not the point (for me).
However, when ones pistons and bores are worn, cams and followers are shot, when one doesn't want to risk 40 year old alloy rods (having broken one previously) then, when in this position, the cost of 'upgrading' your engine is only as expensive as the price difference over and above stock parts!
After all, these bikes are now over 40 years old, and they were technically obsolete when new, and they were built down to a price, so, whatever kind of improvement an owner is looking for, there at least a dozen different ways to go about it.
To the OPs original question: Personally I would not experiment with CBR pistons etc. I'd rely on the experience of others who have already done so. Comnoz analysis of cams and there effect is a similar situation, changing things randomly / without deep knowledge can create many knock on factors that we are not aware of. Best to choose your idea of upgrades from those who have already learnt by trail and error!
A stock bike is a very nice thing to ride. But in my opinion, and for my own purposes, a hot rodded version is a lot more so!
What a concept,,,I could use a little help myself,,,,and we could all use a little change,,,, well the years start coming and they don't stop coming,,,,,,would you use SBR cases?Fullauto said:
or your own along with your new barrels and head....I'm just sayin' ........cuz time is a wastin' :lol:Fast Eddie said:
Nigel, I can't argue with any of that and have snuck the CR up on my bike just a tad for extra power. I suspect the stock non-Combat Commandos are already close to the edge of destruction as far as power output is concerned and one like yours may be right on the edge. Clearly the 880 Dreers were over the edge, even with the custom fortified crankcase half.
A lot depends on how the bike is used. I recall one Dreere 880 owner posting here that he lifted the front end on takeoff when showing off to friends and ended up coming down rather abruptly with connecting rods sticking thru the a giant hole in the bottom of the crankcases!
That same bike might have survived for a long time if the full power output was never put to use, or put to use in a more mellow way.
I've used my Commando full bore and heavily laden on long mountain passes many times now and it has been OK. Pulling up grades like White Bird Pass in southern Idaho or the 8 mile long drag up the Salmo Creston in SE British Columbia fully laden on a hot day really puts the test to a power train. I wonder if a hopped up version with extra output would hold together for such use. My tendency would be to utilize any extra power available. The trans is the big worry, but also the engine itself. Cracked crankcases are common enough with hopped up Commandos , so where exactly is the point of no return?
I'm thinking that given my type of usage it might be best to keep things pegged a few horsepower below that critical number, whatever it is.
Glen
- Joined
- May 8, 2015
- Messages
- 3
I really appreciate all the input, guys. I'm taking a look at what everyone else has to offer in the means of pistons and below before I decide how to do this.
The CBR pistons were definitely more for the concept of a lightweight slipper piston, I had complete doubt that they would actually be a viable option, with such huge differences in stroke, valvetrain, etc . I needed to get a better idea of what problems I would run into by running a shorter skirt.
Now, to answer the question of why, I still love the idea of an old bike that can haul as hard or harder than anything made from the time period. More importantly than that, I want something that is mine. Anyone can drop $$ on a full set of parts for everything that would be needed, but to me, that isn't as fun or as intimate as building a bike from the new parts of other bikes, or having them made for the specific build. I could care less about money and frustration, both of these are disposable, and we all know that these are part of the game.
The CBR pistons were definitely more for the concept of a lightweight slipper piston, I had complete doubt that they would actually be a viable option, with such huge differences in stroke, valvetrain, etc . I needed to get a better idea of what problems I would run into by running a shorter skirt.
Now, to answer the question of why, I still love the idea of an old bike that can haul as hard or harder than anything made from the time period. More importantly than that, I want something that is mine. Anyone can drop $$ on a full set of parts for everything that would be needed, but to me, that isn't as fun or as intimate as building a bike from the new parts of other bikes, or having them made for the specific build. I could care less about money and frustration, both of these are disposable, and we all know that these are part of the game.
- Joined
- Nov 26, 2009
- Messages
- 3,320
chipdossjr said:
If you want to experiment and don't mind risking some money - more power to you. I like your positive spirit and enthusiasm. You've probably had enough advice already but if you want to take a chance on an experiment (and since no one has talked you out of it), I'll give a few pointers.
You'll need longer rods or shorter cylinders and that will be expensive. Watch the small end rod weight or you will be defeating your own purpose. Stay as light as you can with the reciprocating weight (piston, pin & upper rod end) to avoid crank breakage but don't go too short on the skirts - leave a safety margin. When you're talking about modernizing a Norton then don't forget about the soft cast iron cylinders. Today everyone uses Nikasil - thats impracticable because available Norton cylinders aren't set up for it. But you can send your cylinders to Bore tech for carbide hardening to prevent bore wear and if you go to extremely short skirts as in the CBR piston photo then you will have to avoid any bore wear and find the tightest clearance you can get without scuffing which will probably be about .0055" cold which should reduce to near zero when hot. The piston cam cut (out of roundness and barrel shape) is also very important and many people miss this but I won’t help you there because I spent a lot of time and money to get that right and consider it proprietary.
I had the same idea as you back in the mid 1980s when my race cranks and cases were cracking. I started with GSXR 1000 overbore piston blanks and modified them to work with stock rods and shortened cylinders. There’s been A LOT of development since then but its been worth it and now there are hundreds of Nortons on the street (and a few on the tracks) running these items.
Good luck and email me if you go ahead and let me know how it goes. Expect to make some adjustments to fit Norton air cooled requirements. Get a leak down tester and keep records as miles pile up. See example leak down test of short pistons at https://youtu.be/3S50Lvo9c-0
See photos below of your CBR piston photo with extremely short skirt.
And the compromises in skirt length below I had to make things practical for the air cooled Norton – over 20,000 miles so for in the test bike. Note the proportional difference in skirt length.
Photo below is of the first minimal GSXR 1000 overbore Wisco pistons I started with and the shortened iron cylinders for my 850 monoshock racer. Note missing fin.
The piston gets to maximum speed twice in every revolution. In one revolution the kinetic energy in the piston is returned to the crank twice, and twice the crank has to return it to the piston.
There are frictional losses in that energy transfer at bearings and at the piston where it contacts the cylinder. Over a full cycle (2 revolutions), about 25% of the time the piston mass is reducing that friction by opposing other forces.
I did a rough calculation for 1 lb of piston mass at 6000 rpm.
The piston reaches a speed of 5737.9 ft/min , and its kinetic energy is then 142.3 ft-lbs weight.
Taking estimated friction coefficients as
piston to bore friction 0.12
Small end bush 0.1
big end 0.0015
main bearings 0.0013 @ 30 mm
I came up with this for torque losses through friction.
Piston : 0.809 ft-lbs
Small end bush : 0.2573 ft-lbs
Big end : 0.0533 ft -lbs
Main bearings : 0.0312 ft-lbs
Total torque reduction from energy transfer : 1.1508 ft-lbs.
That's just a rough estimate, but about what you'd expect if you changed total piston mass by 1 lb. You could conceivably change it by 2/3 lb, so 0.762 ft-lbs change in torque.
At 3000 rpm, it would obviously be 1/4 of that amount of torque difference.
If you had 52 ft-lbs of torque from a 750cc engine, you'd be doing OK.
Just putting it all in perspective.
There are frictional losses in that energy transfer at bearings and at the piston where it contacts the cylinder. Over a full cycle (2 revolutions), about 25% of the time the piston mass is reducing that friction by opposing other forces.
I did a rough calculation for 1 lb of piston mass at 6000 rpm.
The piston reaches a speed of 5737.9 ft/min , and its kinetic energy is then 142.3 ft-lbs weight.
Taking estimated friction coefficients as
piston to bore friction 0.12
Small end bush 0.1
big end 0.0015
main bearings 0.0013 @ 30 mm
I came up with this for torque losses through friction.
Piston : 0.809 ft-lbs
Small end bush : 0.2573 ft-lbs
Big end : 0.0533 ft -lbs
Main bearings : 0.0312 ft-lbs
Total torque reduction from energy transfer : 1.1508 ft-lbs.
That's just a rough estimate, but about what you'd expect if you changed total piston mass by 1 lb. You could conceivably change it by 2/3 lb, so 0.762 ft-lbs change in torque.
At 3000 rpm, it would obviously be 1/4 of that amount of torque difference.
If you had 52 ft-lbs of torque from a 750cc engine, you'd be doing OK.
Just putting it all in perspective.
- Joined
- Aug 10, 2014
- Messages
- 2,222
looks like no one has tried fitting a yamy 850 tdm engine
https://www.google.ca/search?q=yamaha+t ... =0CBwQsAQ#
http://en.wikipedia.org/wiki/Yamaha_TDM850
https://www.google.ca/search?q=yamaha+t ... =0CBwQsAQ#
http://en.wikipedia.org/wiki/Yamaha_TDM850
- Joined
- Oct 19, 2005
- Messages
- 18,978
all racers and outlaws like hobot know the basic power rule of thumb equation Is Always
parts + labor x time in hours divided by number of hoped for hp + tq peak number for a total of $$$,$$$.oo
The ultimate bullet proof modern old school isolastic Commando is start with proven Steve Maney or equivalent bottom end and 920 alloy cylinder, JSM piston/rod kit @10.5 CR (+ JSM optional BSA lifters) an aggressive cam, maybe even Norris D+ drag only, Fullauto head massaged by Comstock or equivalent, then call Bruce McGregor for his proven upgraded Lingskogs balanced, thermal compensating spring loaded hi end turbocharger bearings, belt driven Drouin supercharger with dialed in flat side Lectron type 40 mm carb mated to TTI 4 WIDE Ratio gearbox mounted in tri-linked chassis lifted a bit for more leaning. No matter what all Norton twins are highly allergic to hi rpm so above combo even is devil may dare 1007 size would put an end to question of hooking up tq or hp wining road races.
private mail to hobot to encourage pulling trigger on last two known available improved version. Only one available now.
lookie here to get itchy wrist restless very very restless...
https://www.google.com/?gws_rd=ssl#q=dr ... ercharger+
parts + labor x time in hours divided by number of hoped for hp + tq peak number for a total of $$$,$$$.oo
The ultimate bullet proof modern old school isolastic Commando is start with proven Steve Maney or equivalent bottom end and 920 alloy cylinder, JSM piston/rod kit @10.5 CR (+ JSM optional BSA lifters) an aggressive cam, maybe even Norris D+ drag only, Fullauto head massaged by Comstock or equivalent, then call Bruce McGregor for his proven upgraded Lingskogs balanced, thermal compensating spring loaded hi end turbocharger bearings, belt driven Drouin supercharger with dialed in flat side Lectron type 40 mm carb mated to TTI 4 WIDE Ratio gearbox mounted in tri-linked chassis lifted a bit for more leaning. No matter what all Norton twins are highly allergic to hi rpm so above combo even is devil may dare 1007 size would put an end to question of hooking up tq or hp wining road races.
private mail to hobot to encourage pulling trigger on last two known available improved version. Only one available now.
lookie here to get itchy wrist restless very very restless...
https://www.google.com/?gws_rd=ssl#q=dr ... ercharger+
lcrken
VIP MEMBER
- Joined
- Mar 15, 2009
- Messages
- 5,057
hobot said:
I feel obligated here to point out that those horsepower curves are clearly bogus. I've never seen any Commando produce such nice, smooth curves, with no dips or peaks along the way to max rpm. The peak HP numbers might be right (although I really doubt it), but the curves are clearly just something drawn up for a sales pitch.
Ken
- Joined
- Oct 19, 2005
- Messages
- 18,978
Yeah Ken definitely pure PR sales pitch I posted to tease someone else to try on a Drouin and get back to us. I'll find out someday in mean time how else can we encourage spending someone elses money faster? In between ongoing mechanic failures, I hit pychological blocks with Peel progress - right now waiting for mood to strike to saw my modernized swing legs about off. Car dying like mass air senor or throttle position or idle valve motor turned out to be fuel pump intermitent failure. About 3 days $300 wasted getting back to level again. Ain't just me I know others more overwhelmed but delays are that much less life time left and even Peel is couple-3 levels down my attention list.
- Status
Similar threads
