Anyone worked on HD motors before?
Discussion
Been binge watching a lot of HD upgrade and repair videos recently out of curiosity.
Their reliability seems to fall in two groups. One saying they took their twin cam to 100k+ trouble free miles, others saying constant breakdowns, failed cam chain tensioners, excessive crank pin runout and some saying they scissored the crank itself from excessive engine braking and/or from adding more power.
In a lot of videos even the guys that work on HD motors for a living often bash the quality of components in HD engines. General consensus being that you buy a Harley to upgrade all the Harley parts to aftermarket to make it last, hence the immense aftermarket scene.
I don't know enough about engine assembly but one of the biggest moaned about things is how HD builds their cranks. Two pieces with a single crank pin which is pressed in - interference fit. Vs alternative stronger methods such as welding or bolted cranks. See here:
https://youtu.be/8I0gCjnu7DQ?si=Za7wLvwVq_Ezkarj
I'm curious do other motorbike manufacturers use press fit crank assemblies? Or is it just a Harley thing for 'cost cutting measures'?
Their reliability seems to fall in two groups. One saying they took their twin cam to 100k+ trouble free miles, others saying constant breakdowns, failed cam chain tensioners, excessive crank pin runout and some saying they scissored the crank itself from excessive engine braking and/or from adding more power.
In a lot of videos even the guys that work on HD motors for a living often bash the quality of components in HD engines. General consensus being that you buy a Harley to upgrade all the Harley parts to aftermarket to make it last, hence the immense aftermarket scene.
I don't know enough about engine assembly but one of the biggest moaned about things is how HD builds their cranks. Two pieces with a single crank pin which is pressed in - interference fit. Vs alternative stronger methods such as welding or bolted cranks. See here:
https://youtu.be/8I0gCjnu7DQ?si=Za7wLvwVq_Ezkarj
I'm curious do other motorbike manufacturers use press fit crank assemblies? Or is it just a Harley thing for 'cost cutting measures'?
Pretty much all modern piston ported two strokes have pressed cranks.
Built up crankshafts are more common than people realise, the pre war Auto Union V16 had a built up/bolted together crank using Hirth couplings as did the Pratt & Whitney R-2800 radial engine of WW2.
In Auto Unions case it was the easiest way of making a relatively long crankshaft without expensive tooling.
Pratt & Whitney did so so they could use a single piece master rod for strength as well as timing.
Built up crankshafts are more common than people realise, the pre war Auto Union V16 had a built up/bolted together crank using Hirth couplings as did the Pratt & Whitney R-2800 radial engine of WW2.
In Auto Unions case it was the easiest way of making a relatively long crankshaft without expensive tooling.
Pratt & Whitney did so so they could use a single piece master rod for strength as well as timing.
I have owned a few Harleys, some with big bore aftermarket engines. I even raced one.. 2litre with NOS.. The early twin cams had a few well known problems, which were corrected in later years. I am more familiar with the earlier Evo and Ironhead engines. The Evo 1340 and 883/1200 Sportster engines are good, reliable motors which come out of the factory in a mild state of tune, due to emission/noise regulations.
Its fairly easy to get an extra 50% more power from these engines with a different cam, pipes, ignition module and rejetted carb. After that things get expensive.
The crank of a 1340 Evo is designed to last 450,000 miles before it needs rebuilding.... they are built to last..
The tales of problems, and unreliability are often caused by poor servicing or ill considered engine mods.
Vibration does take its toll on the odd component, and all that chrome and polished alloy suffers in the UK climate..
While a lot of the aftermarket tat is ridiculously expensive, I found servicing / engine parts to be fairly priced and available. For example a few years ago I bought a complete gasket set for a 1979 XL1000.. It arrived in two days and cost just £60..Pretty much any part you may need for any post war Harley will be available from the aftermarket.
Its fairly easy to get an extra 50% more power from these engines with a different cam, pipes, ignition module and rejetted carb. After that things get expensive.
The crank of a 1340 Evo is designed to last 450,000 miles before it needs rebuilding.... they are built to last..
The tales of problems, and unreliability are often caused by poor servicing or ill considered engine mods.
Vibration does take its toll on the odd component, and all that chrome and polished alloy suffers in the UK climate..
While a lot of the aftermarket tat is ridiculously expensive, I found servicing / engine parts to be fairly priced and available. For example a few years ago I bought a complete gasket set for a 1979 XL1000.. It arrived in two days and cost just £60..Pretty much any part you may need for any post war Harley will be available from the aftermarket.
Merch131 said:
I have owned a few Harleys, some with big bore aftermarket engines. I even raced one.. 2litre with NOS.. The early twin cams had a few well known problems, which were corrected in later years. I am more familiar with the earlier Evo and Ironhead engines. The Evo 1340 and 883/1200 Sportster engines are good, reliable motors which come out of the factory in a mild state of tune, due to emission/noise regulations.
Its fairly easy to get an extra 50% more power from these engines with a different cam, pipes, ignition module and rejetted carb. After that things get expensive.
The crank of a 1340 Evo is designed to last 450,000 miles before it needs rebuilding.... they are built to last..
The tales of problems, and unreliability are often caused by poor servicing or ill considered engine mods.
Vibration does take its toll on the odd component, and all that chrome and polished alloy suffers in the UK climate..
While a lot of the aftermarket tat is ridiculously expensive, I found servicing / engine parts to be fairly priced and available. For example a few years ago I bought a complete gasket set for a 1979 XL1000.. It arrived in two days and cost just £60..Pretty much any part you may need for any post war Harley will be available from the aftermarket.
I love the sound of a low idling Evo. My dream bike is an Evo Fat Boy. Few and far between but common as muck in the states. Apparently 1998-1999 are the years to go for when they switched wiring harness to a more reliable water resistant one. But there's also a multitude of other things to look out for on such an old bike. Second project bike is more realistic Vs buying one as a one and only motorbike. I could only find two reasonable examples within 200 miles on autotrader. Its fairly easy to get an extra 50% more power from these engines with a different cam, pipes, ignition module and rejetted carb. After that things get expensive.
The crank of a 1340 Evo is designed to last 450,000 miles before it needs rebuilding.... they are built to last..
The tales of problems, and unreliability are often caused by poor servicing or ill considered engine mods.
Vibration does take its toll on the odd component, and all that chrome and polished alloy suffers in the UK climate..
While a lot of the aftermarket tat is ridiculously expensive, I found servicing / engine parts to be fairly priced and available. For example a few years ago I bought a complete gasket set for a 1979 XL1000.. It arrived in two days and cost just £60..Pretty much any part you may need for any post war Harley will be available from the aftermarket.
In terms of tuning, here are a few examples of a couple of my old bikes, before and after on the same dyno. A standard, just run in 1993 Evo 1340 made a whopping 49 bhp at the rear wheel. With an' after market 'touring' cam, ignition module, free flowing baffles and rejetting carb, the bike made 74bhp at the rear wheel.
A standard 883 Sportster made 37bhp on the same dyno, with a 1250cc big bore kit, standard top end, rejetted carb and home made pipes, it made 91bhp at the rear wheel. With a set of decent cams and some head work, the 1250 conversion is said to make 120bhp..
But if you want more, the aftermarket will sell you complete engines.. typically from the likes of S&S. Stock Evos are 80 cubic inches, while the aftermarket starts at 96ci, all the way to 145ci... I have had 96, 113, 120, 127 and 131ci engines in my bikes.. The latter I still have. That one has a relatively small carb so is tuned for road use rather than top end power... it still makes 130bhp / 150lb/ft torque at the rear wheel, the last time it was on a dyno. The bottom end of that engine is good for 220hp..
The most I've had from an Evo is 190hp from a 120ci motor, with made 127hp at the rear wheel plus another 60 or so with NOS. That was in a drag bike btw... The latest M8 engines can make more power, but are more complex and so more expensive to mod.
An old vid of my 131 on the dyno..
https://youtu.be/s2Jo-fipEAM?si=Xp72cidvp32Rng4_
A standard 883 Sportster made 37bhp on the same dyno, with a 1250cc big bore kit, standard top end, rejetted carb and home made pipes, it made 91bhp at the rear wheel. With a set of decent cams and some head work, the 1250 conversion is said to make 120bhp..
But if you want more, the aftermarket will sell you complete engines.. typically from the likes of S&S. Stock Evos are 80 cubic inches, while the aftermarket starts at 96ci, all the way to 145ci... I have had 96, 113, 120, 127 and 131ci engines in my bikes.. The latter I still have. That one has a relatively small carb so is tuned for road use rather than top end power... it still makes 130bhp / 150lb/ft torque at the rear wheel, the last time it was on a dyno. The bottom end of that engine is good for 220hp..
The most I've had from an Evo is 190hp from a 120ci motor, with made 127hp at the rear wheel plus another 60 or so with NOS. That was in a drag bike btw... The latest M8 engines can make more power, but are more complex and so more expensive to mod.
An old vid of my 131 on the dyno..
https://youtu.be/s2Jo-fipEAM?si=Xp72cidvp32Rng4_
Like every manufacturer, H-D are affected by legislation, hence the change from noisy gears to quieter chains to drive the cams, and the camchain tensioner problems.
They are also driven by cost hence the move to a pressed up crankshaft which doesn't require skilled labour to assemble, true, and balance it, but is less tolerant of abuse than the old crank that was held together by tapers and big nuts tightened to "bloke hanging off 3 foot bar" lbs/ft.
The other problem is their customers, who want the big twin to have its cylinders in line, which means that they can't use a one piece crank and side by side connecting rods (although I don't know if "knife and fork" rods do actually force the use of one piece rods with roller big end bearings and prohibit detachable big end caps and plain bearings).
They are also driven by cost hence the move to a pressed up crankshaft which doesn't require skilled labour to assemble, true, and balance it, but is less tolerant of abuse than the old crank that was held together by tapers and big nuts tightened to "bloke hanging off 3 foot bar" lbs/ft.
The other problem is their customers, who want the big twin to have its cylinders in line, which means that they can't use a one piece crank and side by side connecting rods (although I don't know if "knife and fork" rods do actually force the use of one piece rods with roller big end bearings and prohibit detachable big end caps and plain bearings).
gareth_r said:
Like every manufacturer, H-D are affected by legislation, hence the change from noisy gears to quieter chains to drive the cams, and the camchain tensioner problems.
They are also driven by cost hence the move to a pressed up crankshaft which doesn't require skilled labour to assemble, true, and balance it, but is less tolerant of abuse than the old crank that was held together by tapers and big nuts tightened to "bloke hanging off 3 foot bar" lbs/ft.
The other problem is their customers, who want the big twin to have its cylinders in line, which means that they can't use a one piece crank and side by side connecting rods (although I don't know if "knife and fork" rods do actually force the use of one piece rods with roller big end bearings and prohibit detachable big end caps and plain bearings).
I don't think I've ever seen a 'knife and fork' rod assembly that didn't have detachable big end caps? Every one I've ever seen has been like this one from a Packard built Merlin but I would be very interested to be corrected!They are also driven by cost hence the move to a pressed up crankshaft which doesn't require skilled labour to assemble, true, and balance it, but is less tolerant of abuse than the old crank that was held together by tapers and big nuts tightened to "bloke hanging off 3 foot bar" lbs/ft.
The other problem is their customers, who want the big twin to have its cylinders in line, which means that they can't use a one piece crank and side by side connecting rods (although I don't know if "knife and fork" rods do actually force the use of one piece rods with roller big end bearings and prohibit detachable big end caps and plain bearings).
Tango13 said:
I don't think I've ever seen a 'knife and fork' rod assembly that didn't have detachable big end caps? Every one I've ever seen has been like this one from a Packard built Merlin but I would be very interested to be corrected!
As I said, I didn't know! 
In that case, I wonder why H-D didnt change to a one piece crank and plain bearings when they designed the twin-cam. Width considerations, perhaps? The "forks" of the rod are quite narrow (google says the current Milwaukee 8 engine's rollers are 0.360" lóng). How wide would they need to be in order to accommodate the big end bolts?
Edited by gareth_r on Sunday 6th April 17:21
The only HD lump that I've had apart is the Evo 1200 in my 1998 Buell. The big ends are cap-less knife-&-fork, the crank would have to be split to access the bearings.
This is basically the same motor as in the 1200 Sportster. Further to, and in agreement with Merch131's earlier posts above, Buell raised the power output to 94bhp from the equivalent Sportster's 66.
This is basically the same motor as in the 1200 Sportster. Further to, and in agreement with Merch131's earlier posts above, Buell raised the power output to 94bhp from the equivalent Sportster's 66.
Edited by TwinKam on Sunday 6th April 18:03
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