Bore stroke ratio 107 vs 114 when you do a big bore?
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Intermediate
Joined: Mar 2018
Posts: 33
Likes: 4
From: SW Ohio
I can't help it. I like the M8, even better than the previous HD's. Let's face it, a lot of the problems come about when we start modifying them and don't do such a great job of it. On the other hand, they don't have enough power stock so we wouldn't have a lot of these issues if they'd give us what it needs in the first place.
Of course, what we want is really difficult, a stone-age, air-cooled V-twin design that produces great horsepower and passes the EPA requirements. If we do it on our own we don't have to worry about the EPA. If Harley does it, everyone gets arrested.
Of course, what we want is really difficult, a stone-age, air-cooled V-twin design that produces great horsepower and passes the EPA requirements. If we do it on our own we don't have to worry about the EPA. If Harley does it, everyone gets arrested.
Intermediate
Joined: May 2017
Posts: 37
Likes: 78
From: Rim Country
But you’re right, the MoCo did bugger things up for 3-long years on the M8; however, I wasn’t specifically discussing the oil sumping or tranny oil transfer problems.
I do believe poor cylinder sealing is one of the major causes of the M8’s oil sumping problems, due to the MoCo’s poor QC of cylinders, pistons and ring pack, and in some cases, the oil pump itself. The crankcase flywheel cavity design is also poorly thought out.
I remember during the Twin Cam’s introduction in summer 1998 how the MoCo was bragging up all of the wonderful benefits of using two cams (the engine will be quieter and have straighter pushrod angles, etc.). What a hoodwinking! And with the M8’s introduction, they bragged up the benefits of the single cam. Thank goodness they went back to a simple single-cam design.
You got to remember, though, that the MoCo is really a marketing company, not an engineering company. Their monster boutique dealerships are great at selling pinstripes, paint colors, blacked-out parts and T-shirts. Actually, in my opinion most of the touring bike color schemes since about 2015 have been horrible. And now the MoCo is trying to sell $30k ebikes. Good luck with that one!
Unfortunately, it takes some DIY creativity, mechanical skills, discipline, logical approach, and trial-and-error testing by M8 owners to fix up the MoCo’s mess ups, and hardball and stonewalling tactics. After all, someone’s got to pay for W!lly G’s retirement fund and the dealer’s expensive 50-bike vintage motorcycle museum…..why not the customer?
And to AbitNutz, post #11:
“If we do it on our own we don't have to worry about the EPA. If Harley does it, everyone gets arrested.”
PERFECTLY SAID!
Last edited by Mogollon; Oct 30, 2019 at 09:05 PM.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,861
Likes: 7,980
From: poway
The salient engine features I listed in the quoted paragraph were only pertaining to building a large displacement M8 engine. Point being that you can increase displacement much easier and for less cost than any of the predecessor Big Twins.
But youre right, the MoCo did bugger things up for 3-long years on the M8; however, I wasnt specifically discussing the oil sumping or tranny oil transfer problems.
I do believe poor cylinder sealing is one of the major causes of the M8s oil sumping problems, due to the MoCos poor QC of cylinders, pistons and ring pack, and in some cases, the oil pump itself. The crankcase flywheel cavity design is also poorly thought out.
I remember during the Twin Cams introduction in summer 1998 how the MoCo was bragging up all of the wonderful benefits of using two cams (the engine will be quieter and have straighter pushrod angles, etc.). What a hoodwinking! And with the M8s introduction, they bragged up the benefits of the single cam. Thank goodness they went back to a simple single-cam design.
You got to remember, though, that the MoCo is really a marketing company, not an engineering company. Their monster boutique dealerships are great at selling pinstripes, paint colors, blacked-out parts and T-shirts. Actually, in my opinion most of the touring bike color schemes since about 2015 have been horrible. And now the MoCo is trying to sell $30k ebikes. Good luck with that one!
Unfortunately, it takes some DIY creativity, mechanical skills, discipline, logical approach, and trial-and-error testing by M8 owners to fix up the MoCos mess ups, and hardball and stonewalling tactics. After all, someones got to pay for W!lly Gs retirement fund and the dealers expensive 50-bike vintage motorcycle museum ..why not the customer?
[snip EPA]
But youre right, the MoCo did bugger things up for 3-long years on the M8; however, I wasnt specifically discussing the oil sumping or tranny oil transfer problems.
I do believe poor cylinder sealing is one of the major causes of the M8s oil sumping problems, due to the MoCos poor QC of cylinders, pistons and ring pack, and in some cases, the oil pump itself. The crankcase flywheel cavity design is also poorly thought out.
I remember during the Twin Cams introduction in summer 1998 how the MoCo was bragging up all of the wonderful benefits of using two cams (the engine will be quieter and have straighter pushrod angles, etc.). What a hoodwinking! And with the M8s introduction, they bragged up the benefits of the single cam. Thank goodness they went back to a simple single-cam design.
You got to remember, though, that the MoCo is really a marketing company, not an engineering company. Their monster boutique dealerships are great at selling pinstripes, paint colors, blacked-out parts and T-shirts. Actually, in my opinion most of the touring bike color schemes since about 2015 have been horrible. And now the MoCo is trying to sell $30k ebikes. Good luck with that one!
Unfortunately, it takes some DIY creativity, mechanical skills, discipline, logical approach, and trial-and-error testing by M8 owners to fix up the MoCos mess ups, and hardball and stonewalling tactics. After all, someones got to pay for W!lly Gs retirement fund and the dealers expensive 50-bike vintage motorcycle museum ..why not the customer?
[snip EPA]
Poor ring sealing exacerbates the poor scavenging for sure. They forgot the issues they had with early twincam design and sumping.
2 Cams was always a WTF for me. Why add another cam? Going to chain on a single cam makes more sense. If they want to correct rocker geometry, go to 4 different rockers. It's cheaper. Chains an a decent hydraulic tensioner makes more sense as backlash noise won't be an issue. Springs only for tensioner on a 2 cylinder motor is plain stupid.
When you get right down to it any business is a marketing company. The only way it becomes less it if the technology is superior. Not sure you'll ever find that in HD. They used to be all nostalgia. Moving forward for them is a certainly a challenge.
NIce thing about a popular bike with issues is that the aftermarket will pick up the slack.
Still, I think that HD has improved their platform with each new motor version.
Seasoned HDF Member
Joined: Jun 2015
Posts: 8,054
Likes: 8,080
From: Canada
Regarding the number of cams, I don't see it as a bad thing at all. Quite the opposite if they did it correctly which starts with a crank that scissors if you look at it wrong. Look no further than the sportster with 4 cams and the Indian (oooops I said a bad word) has 3 cams, now that's different! If more cams means better pushrod alignment then Im all for that. Now if they put 4 up top even better. Sportsters even have a great sound in my opinion which cant be said for the M8.
Road Master
Joined: Mar 2018
Posts: 804
Likes: 92
From: Texas
I think you need to explain this. If the two engines are at the same RPM, they are reving the same.
Grand HDF Member
Joined: Jul 2007
Posts: 3,730
Likes: 8,484
From: Bates County MO
It's a function of time, Revolutions per minute- If they are at the same RPM, then they have the same time to get from TDC to BDC and back to TDC; the longer stroke piston has to travel 1/8" further in the same amount of time as the shorter stroke, so it has to be traveling faster. Not a whole lot, but there is a difference.
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Intermediate
Joined: Mar 2018
Posts: 33
Likes: 4
From: SW Ohio
As I understand it, the primary limiting factor on the traditional HD V-twin is that it's air-cooled. If it were completely liquid-cooled all kinds of problems would go away, Unfortunately, all kinds of ugly would pop up. At that point, you could double ugly it and go with an OHC arrangement and do away with pushrod angle problems entirely. The engine would now be unrecognizable as a Harley V-twin. Not to mention It would have to have radiators tacked on somewhere.
If the engine must be air-cooled and have pushrods, we're left fighting over detail changes with the only way to make more power is to increase the displacement or add some sort of supercharging. But everyone knows this. I'm afraid I'm just repeating the same thing that everyone has said countless times before.
If the engine must be air-cooled and have pushrods, we're left fighting over detail changes with the only way to make more power is to increase the displacement or add some sort of supercharging. But everyone knows this. I'm afraid I'm just repeating the same thing that everyone has said countless times before.
Seasoned HDF Member
Joined: Jun 2015
Posts: 8,054
Likes: 8,080
From: Canada
If they start using ceramics for engine components they can continue to be air cooled. No joke. Someone in Japan like Mazda I think (no surprise there) had a ceramic engine block and said it needed no cooling system. That was over 30 years ago. Not sure what happened to that idea.
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