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Baffles in 45 motors

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45Brit

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Post Wed Oct 29, 2014 2:56 am

Baffles in 45 motors

So, the 45 project has made a reappearance, what with the Grasstrack season being over and so on.

The stroker engine is with a new builder for final assembly

The question is this....

Right now, I have a stroked 54" crank assembly with T&O Pistons to suit. Crank cases have tbe baffles removed. Bike has a a Britush type oil tank with the tee for supply to the rockers - I see mention of using this to feed oilers. I also have several sets of spare cases so I could use a set with the baffles intact.

Bike is for road use.

What does the team think..... ?
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Cotten

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Post Wed Oct 29, 2014 7:49 am

Re: Baffles in 45 motors

I'm not a good 'team player', 45Brit,...

But the baffles significantly stiffen and strengthen the cases, and that is desireable.

....Cotten
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Pa

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Post Wed Oct 29, 2014 1:17 pm

Re: Baffles in 45 motors

They also prevent to much oil from reaching the pistons. Oddly, baffles were in both engine case cylinder registers in some engines. Other engines either had a baffle in the front engine case cylinder register or the rear engine case cylinder register. depended on the year and how the female and male rods were installed in a particular year. I don't recall the details off hand though. I am pretty sure there is discussions on the baffles in the archives. Shop Dope also explains them.
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45Brit

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Post Wed Oct 29, 2014 1:33 pm

Re: Baffles in 45 motors

Broadly speaking, the consensus in previous threads seems to be that the baffles were dropped as soon as the stock oil pump was uprated sufficiently to cope with feeding piston skirt oilers. Ohv motors don't have them, after all.

General consensus also seemed to be that the skirt oilers make a material difference to reliability and engine life

So I've been in touch with Cala's in Sweden to see about a new pump.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Cotten

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Post Wed Oct 29, 2014 2:17 pm

Re: Baffles in 45 motors

45Brit wrote:Broadly speaking, the consensus in previous threads seems to be that the baffles were dropped as soon as the stock oil pump was uprated sufficiently to cope with feeding piston skirt oilers. Ohv motors don't have them, after all....
45Brit!

If you lay pre-War OHV cases next to post-War without baffles, they will look delicate by comparison, as the later were beefed up.

If you've got baffles, keep 'em.

....Cotten
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knucklebolt

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Post Wed Oct 29, 2014 9:08 pm

Re: Baffles in 45 motors

It was my understanding that the rear cylinder receives an adequate oil supply from oil being flung off the flywheels, but that the front does not receive as much "flung" oil, and so the front cylinder is baffled so as to pull/suck oil into the cylinder on the upstroke of the piston...?? Is that not correct?

I didn't realize that the rear cylinder(s) was/were ever baffled, and it kind of baffles me that both would be. ?? I did not know they were ever there to restrict oil to the cylinders. ?

As I understand it, at least in terms of the big-twin, the reason to remove the front baffle, and install oilers is partly to gain a couple of HP because when the baffled cylinder is on the upstroke, it's sucking/pulling oily air and oil up past the baffle due to a suction effect...which costs a couple of ponies. ? Again, just my understanding of the whole baffle thing. Seems to me that the little and big twins are just about the same animal, other than the actual displacement, in terms of how the engine really works, or functions.

As I bought my big-twin engine as a already complete and rebuilt unit, I've never seen inside it, but I don't think I'd take any of the baffles out for that small a gain in HP. Unless one is really hot-rodding the engine, getting every last pony out of it, and reliability is not an issue, I'm pretty sure I'd stick with the baffles...Harley must have had some reason to do it that way. Also with the engine stroked to 54", seems like longevity and reliability would outweigh the cost of a couple of HP...assuming that the baffles in some way are good for the engine. But I guess it all depends exactly on how the whole baffle thing actually works. ??

Just brain-storming...or...trying to!

ken.
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45Brit

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Post Thu Oct 30, 2014 2:51 am

Re: Baffles in 45 motors

I've never owned a BT flathead so I don't know for sure, whether they have baffles. Broadly speaking the baffles create a partial vacuum under the piston, as the piston is on the upstroke, and draw oil mist into the cylinder.

45s have a full baffle in the front cylinder and a half baffle in the rear cylinder. The rear cylinder does indeed benefit from the oil flung from the flywheels.

Various members here report that piston skirt oilers combined with increased oil flow rates, greatly reduce piston wear and improve reliability. Posters with stroked engines using KR heads and barrels report satisfactory results. There hasn't been any mention until now, of the structural strength of the cases.

That would all be entirely consistent with my experience of older British engines

I'm very much inclined to spend the money for a Swedish oil pump conversion, because it is pretty much a bolt-on so the cost is a straight trade-off against shop time, and it is purpose-made kit.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Pa

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Post Thu Oct 30, 2014 6:51 am

Re: Baffles in 45 motors

Factory data on baffles.

Image
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Cotten

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Post Thu Oct 30, 2014 8:05 am

Re: Baffles in 45 motors

Just to muddy the water further, Folks,

The pre-War OHVs were prone to cracking the left case vertically to the rear cylinder deck, precisely where the half-baffle stops.

It could be argued that those should be removed!

Note also from the Shop Dope that removal of the rear baffles coincided with the reversal of the rods, and closing of the web on the forked rod.

....Cotten
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GuS

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Location: Bergen, Norway

Post Thu Oct 30, 2014 5:12 pm

Re: Baffles in 45 motors

Gents. My understanding of the baffles is the same as discussed above. If you look at the flywheel scrapers as well things add up.
The main scraper at the rear in combination with the breather moves the major part of the oil from the crankcase. Any remaining oil is by the next scraper vedged away from the rear cylinder. One wold then think this combined with the rear cyl baffle is to avoid overoiling of the rear cyl. The next scraper is rear to the front cyl and vedge the oil back towards the slot between the front cyl baffle. On the upstroke the vacume under the piston will draw the oil mist opp the bore.

My experience is remove the baffle and copy paste the K oiler system.
Woodys and Frankensteins posts are excellent reading.


GuS
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45Brit

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Post Thu Oct 30, 2014 11:53 pm

Re: Baffles in 45 motors

The scrapers are a slightly different question, for sure you need them in good order. I don't believe the baffles serve the purpose of controlling oil fling.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Pa

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Post Fri Oct 31, 2014 6:31 am

Re: Baffles in 45 motors

There was a topic on here years ago where a member was trying to figure out why his 45 was smoking so much and fouling the spark plug in his front cylinder. The fouling on the front spark plug was burnt oil. He eventually removed the front cylinder and found his front baffle had been cut out. If I can recall correctly, I think he resolved the issue with modern rings.
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45Brit

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Post Fri Oct 31, 2014 7:39 am

Re: Baffles in 45 motors

You have to remember that the 45s are an early-30s design; K and X series bikes were a next-generation design so yes, modern rings are an improvement.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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knucklebolt

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Post Fri Oct 31, 2014 11:02 pm

Re: Baffles in 45 motors

This is kind of off the wall, but I wonder if instead of removing the baffles, for whatever reason, if one could "swiss cheese" them. ?? Of course that could take a few cases to figure out just the right size of the holes, how many, and where to locate them...not to mention the time involved to road test the engines, dismantle, assemble, etc. Just exactly what this would accomplish I don't know, other than to keep whatever strength or rigidity the baffles add to the cases, if any.

Don't take any of that too seriously! :)

k.
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45Brit

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Post Sat Nov 01, 2014 12:04 am

Re: Baffles in 45 motors

The Motor Company obviously didn't regard them as worth keeping once they had the lubricating system upgraded. I haven't seen anyone reporting on here that they have suffered structural failures, and indeed there is one report in this thread of structural failure in BT at the point of attachment of the baffle - ie, the change of section - which makes sense in design terms, sudden changes of section serve to concentrate stress.

There have also been several posts to the effect that engines run at racing speeds seem not to suffer from having no baffles.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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37ULH

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Post Sat Nov 01, 2014 1:25 am

Re: Baffles in 45 motors

I'm thinkin the front baffles continued in the 45 engines through end of production, did they not?
If you look at the inside of your cases it is obvious they thought they were channeling the oil to the front slot and using vacuum to carry it up the cylinder.
I guess the durabilty of these engines proven over 75 years was a fluke and they had no clue.
To me it seemed to work...and i don't think the pumping loss is dramatic...my 45 (not stroked) has them and went a timed 96mph on a rough tune...

IMO if adding piston oilers then, if desired, cut them out. I wouldn't do it, especially in a stroker, unless you find some other way of oiling the front cylinder. I don't believe they were ever an oil deflector in the front position or that over oiling results when they are not there.
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45Brit

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Post Sat Nov 01, 2014 4:35 am

Re: Baffles in 45 motors

"Splash lubrication" and "oil mist" were widely used in engine design up to the 1960s. Their effect is greatly overestimated, as any British bike owner will tell you.

Harley realised when they were designing the knucklehead that greatly increased lubrication was required. They employed the same principle to the K and X series engines. The ongoing development of the Big Twin incorporated piston skirt oiling and the K had it from the outset

So, really, increased flow rates and pressure, piston skirt oilers and no baffles are only copying the Motor Company's own thinking and development work. The builder finishing off the stroker for me, has insisted on late-style Hastings rings with the 3-piece oil control ring.

Don't forget, also, that stroked engines may well require removal of baffles to provide piston skirt clearance. Mine uses the T&O pistons supplied for the purpose, so I could retain the baffles, but there are well-known limitations in that direction.


I don't believe the longevity and durability of the 45" engine is a fluke. I've remarked before that 37-45" seems to be the optimum size for engines of this sort; the 30.5" Indian can hardly get out of its own way, and the big 61" -plus flatheads from Indian, HD, Enfield and others suffer from rapid wear in service. My personal view is that the big flatheads of the late 1930s over-reached the technology of the day.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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45Brit

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Post Sat Nov 01, 2014 4:53 am

Re: Baffles in 45 motors

Re Pa's post showing baffle configurations, I find that the two case sets in my shed - both showing the half-baffle at the rear - are mismatched sets.

I've been told that these case sets have appeared in the UK in recent years, since the late 1980s. Possibly due to the importation of engines and spares that might have been "difficult" to register or dispose of in the US. Previously, virtually all WLs in Europe were ex-military and so, all manufactured between 1942-45
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Frankenstein

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Post Sat Nov 01, 2014 7:18 am

Re: Baffles in 45 motors

As the baffles appeared with the advent of recirculating oil, were first modified with the change of orientation of connecting rods, and disappeared (on OHV's) with the introduction of real oil control rings, the conclusion is obvious. Baffles were meant to limit the amount of oil reaching the cylinder walls. Supporting evidence would also be Flatheads not having a real oil control ring, and what passed for one was fitted only to the rear cylinder as the front naturally received less oil as it was further from the source of oil, i.e, the sump. I might add that this explanation was given me from a dealer who attended the service schools during the era that these changes were made and received it at those schools.
A further rationale might be made along the lines of marketing the "new" recirculating oil systems. The older constant loss systems were noted for the faint (or sometimes not so faint) blue cloud they left in their trail from their exhaust.
To bolster the claims that the new system was indeed an improvement, they were making whatever efforts necessary to minimize the "blue cloud" emitting from the new machines. True oil control rings were not in common use in 1936, having only been introduced by Hastings in the year 1935 specifically for the Ford V8. See " http://www.fundinguniverse.com/company- ... y-history/ " Thus the mechanations with baffles, rod orientation, etc.
Of course, this is only one man's opinion, "your results may vary"
DD
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45Brit

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Post Sat Nov 01, 2014 10:34 am

Re: Baffles in 45 motors

My Jawa and JAP engines have total loss oiling systems and it's considered quite normal for them to emit varying quantities of blue haze, up to a dense white smoke if the engine is cold. Riders gauged the effect if the lubricating system by that, having no other real information other than a small gauge glass in the feed line.
Shoot, a man could have a good weekend in Dallas with all that stuff...

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