Author Topic: The Jawa brand is back  (Read 12088 times)

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cyrusb

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Reply #60 on: November 22, 2020, 08:24:06 pm
I'd forgotten about that one. No fins on that either and they sold loads. Oddly, they have become popular as a basis for custom builders recently.  ???
I have seen some and they are interesting customs. I believe the CX was Honda's first v twin. And, If I remember correctly (correct me if I'm wrong) that motor was used turned 90 degrees to compete on the mile dirt ovals against the XR750's. I believe it had become obvious that the pulsed output of v twins worked better in the dirt.
« Last Edit: November 22, 2020, 08:31:39 pm by cyrusb »
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Keef Sparrow

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Reply #61 on: November 22, 2020, 11:14:17 pm
Yes, I believe they did do that to take on the Harleys on the dirt tracks. Obviously they had to chop the gearbox and shaft drive off when the turned the engine through 90°, but they couldn't take the engine capacity out to 750ccs so they were always down on power and had problems with coolant leaks.
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AzCal Retred

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Reply #62 on: November 24, 2020, 04:16:49 am
REAL Jawas! 500cc, 75 BHP, something to bolt on to your old Bullet primary of an afternoon!

https://www.speedwaybikes.com/cody/

https://www.speedwaybikes.com/cody/cody03.htm
Single cylinder, single OHC with a swept volume of 500 ccm. Air-cooled, four valve with a bore of 85 mm and a stroke of 87 mm, or a bore of 88 mm and stroke of 81.2 mm. Engine oil sumps, head and cylinders are made from aluminum alloy. The big-end and main bearings are of caged needle-roller type. The camshaft is seated inside the head on needle bearings and is chain driven. Valves are at a 35 angle with one tapered helical spring per valve. Valve seats are hot pressed into the head. The forged piston is made of light alloy with two piston rings. The engine has a circulation lubrication system. The oil tank is situated in the valve gear cover and right hand crank case. The engine holds .6 litre of oil. The oil can be checked at the oil level gauge. A 34 mm carburetor is used with electronic ignition.

Technical Data
Model 884 bore / stroke 85 mm / 87 mm
Model 888 bore / stroke 88 mm / 81.2mm
Swept volume493 ccm
Maximum power / RPM 63-70 bhp / 8500-10500 RPM
Compression ratio 13-15:1
CarburetorDellorto 34 mm
Ignition advance 30 -33
IgnitionPVL Electronic
Spark plugChampion G55R / G57R
Valve / cam timing10A13A17A 010203
Ex. valve open / close 69 /31 69 /31 67 /3062 /3066 /3362/30
In, valve open / close 37 /67 34 /67 39 /6231 /6839 /6237/68
(measured at a valve lift of 1 mm)
Valve clearance Int / ex .004" / .006"
Fuel Methanol
Oil (.6 litre) Silkolene Castorene R-50
A trifecta of Pre-Unit Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


Arschloch

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Reply #63 on: November 24, 2020, 07:26:37 am
https://youtu.be/g7GErOrxIX0

Can be done, these engines are made for speedway though, minimal weight. This means you have to rebuild them for pump fuel to have any practical use. How many hp's wil be left once that is accomplished? They don't idle either, the way to solve it would be 2 carbs, one at each intake port with one opening beyond 5000 revs. That's probably not possible because it has just one large intake port. So you would need to use a carb that limits the theoretical ability of the engine. The lubrication is an another troublesome area, does it even have oil filtering? Probably not...

After that surgery I doubt the engine will perform much better than a Fireball 535 single.


cyrusb

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Reply #64 on: November 24, 2020, 01:11:13 pm
Neat idea, but I would go with the J.A.P instead .
2005E Fixed and or Replaced: ignition, fenders,chainguard,wires,carb,headlight,seat,tailight,sprockets,chain,shock springs,fork springs, exhaust system, horn,shifter,clutch arm, trafficators,crankcase vent.


Arschloch

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Reply #65 on: November 24, 2020, 01:30:52 pm
https://en.m.wikipedia.org/wiki/ESO_(motorcycles

I wouldn't mind a eSo (= ACE in english), it was a company with very limited funds doing as good as they can out of the available stuff they could get their hands on. This is probably the root to the Jawa Speedway engines. Eso engines found on all sorts of vehicles....

https://youtu.be/_wSnU_4Wqag

https://youtu.be/ufQxnJV0xGI
« Last Edit: November 24, 2020, 01:33:12 pm by derottone »


cyrusb

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Reply #66 on: November 24, 2020, 02:00:04 pm
The way those engines idle it seems it would wear out it's throttle slide before its piston rings! Why the inherent lousy idle? No flywheels?
2005E Fixed and or Replaced: ignition, fenders,chainguard,wires,carb,headlight,seat,tailight,sprockets,chain,shock springs,fork springs, exhaust system, horn,shifter,clutch arm, trafficators,crankcase vent.


Arschloch

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Reply #67 on: November 24, 2020, 02:06:52 pm
The way those engines idle it seems it would wear out it's throttle slide before its piston rings! Why the inherent lousy idle? No flywheels?

Racing cams.


cyrusb

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Reply #68 on: November 24, 2020, 03:02:21 pm
Racing cams.
Been there, but instead of the constant goosing I just raised the idle accordingly. Yeah , it was frantic but for me easier to deal with.
2005E Fixed and or Replaced: ignition, fenders,chainguard,wires,carb,headlight,seat,tailight,sprockets,chain,shock springs,fork springs, exhaust system, horn,shifter,clutch arm, trafficators,crankcase vent.


AzCal Retred

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Reply #69 on: November 24, 2020, 04:24:07 pm
Derottone - thanks for the links!

Here's a back-up starting plan if you can't find a hill...
https://www.youtube.com/watch?v=_ALbtnnskdc

   I am amazed at the amount of power that was extracted from these old singles. I don't care that they burnt exotic fuel and ran crazy C.R.s, the fact that they held together at all under "drag strip" power loads and backyard engineering astounds me. Wikipedia shows FIM events in 1923, and suggests there were pre-WW1 events also. No dyno time, no flow bench testing, just keen observation, lots of file-work on ports, and a lot of inspired small-shop machine craft & welding. It's not like there were any large market forces supporting major R&D efforts, just enthusiasts having fun. I can't imagine Jawa, ESO, et al building any great industrial empire off of speedway engine sales.
   Years back CYCLE magazine got hold of a champion board track racing cast iron flathead motor. They flow bench & dyno tested it and eventually concluded it made about as much power as possible on the gasoline available at the time. They also said the cast iron work on the cylinder would be difficult or impossible to replicate today as all the folks with those specialized skill sets were long dead. The Burt Munro's of the world will always just use whatever is available and succeed brilliantly.

https://en.wikipedia.org/wiki/Motorcycle_speedway
A trifecta of Pre-Unit Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


Arschloch

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Reply #70 on: November 24, 2020, 04:40:42 pm
I can't imagine Jawa, ESO, et al building any great industrial empire off of speedway engine sales.

I can't imagine anyone building any great industrial empire without the know-how of what works and what not, although today it's more about selling visions.  ::)
« Last Edit: November 24, 2020, 05:04:49 pm by derottone »


AzCal Retred

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Reply #71 on: November 24, 2020, 05:56:56 pm
Selling corporate visions or hallucinations? A great chunk of the public apparently can't tell and difference between hyperbole & reality.
“It's easier to fool people than to convince them that they have been fooled.” Sam Clemens
Auto ads are full of the "comfort features" of their vehicles or touting tire smoking power and "net" connectivity. Hardly a word on what actually moves the vehicle forward or how it will hold up 10 years down the line. In their defense, I believe the bulk of Americans have only a hazy idea why the occupants of the ISS float about instead of just turning on the artificial gravity.

As far as I'm concerned, the Pre-Unit Bullet is about the highest level of mechanical transportation technology graspable by the current crop. There also seems to be no discernment between wants & needs. Fortunately for the auto industry there is no core competency test required of drivers. Talk about an industry based on a "vision". Those guys wrote the book on planned obsolescence to stimulate sales. Takes a lot of engineering talent to have the engine fail, the transmission fail, the car electrical fail, and the interior rot out all about the same time the monthly payments stop. Give me the Bullet & her 50 year long parts supply anytime. Every high school kid should have to successfully own & maintain a Pre-Unit Bullet or equivalent for two years before being allowed behind the wheel of 4,000 pounds of steel.
A trifecta of Pre-Unit Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


Arschloch

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Reply #72 on: November 24, 2020, 06:48:43 pm
Those guys wrote the book on planned obsolescence to stimulate sales. Takes a lot of engineering talent to have the engine fail, the transmission fail, the car electrical fail, and the interior rot out all about the same time the monthly payments stop. Give me the Bullet & her 50 year long parts supply anytime. Every high school kid should have to successfully own & maintain a Pre-Unit Bullet or equivalent for two years before being allowed behind the wheel of 4,000 pounds of steel.

I don't think anyone achieved that kind of a design perfection yet. The longer the stuff lasts the harder it's to predict when it fails.

https://en.m.wikipedia.org/wiki/Fatigue_(material)#The_S-N_curve

Nuts and Bolts are likely to never fail, although some are starting to use alloys screws, it has the advantage that once loosened it can't be reused and has to be replaced with a new one.

I certainly wouldn't sit in an ultralight aeroplane that was built like the GT535 when it came from the factory. It's just a bike, if a wheel comes off the chances of survival are still high.  :D
« Last Edit: November 24, 2020, 06:54:31 pm by derottone »


AzCal Retred

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Reply #73 on: November 24, 2020, 08:04:28 pm
De-Troit has a pretty good handle on it. Go test drive a Buick Park Avenue with 100K on the clock and then test drive a Lexus LS400 or LS430 with the same mileage. I know which one I'd buy second hand.
A trifecta of Pre-Unit Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


Richard230

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Reply #74 on: November 24, 2020, 09:40:58 pm
One of my favorite (not) automotive "safety" devices is the exploding crash pillows surrounding you in a modern car.  ::) Fortunately, I only have to deal with two of those things in my 20-year old station wagon (with an AM radio and crank-operated windows) and I sure hope they were not made by Takata (or whatever the name of that company that makes automobile hand grenades is called).   :o
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