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Post by sjef on Mar 29, 2007 17:45:27 GMT -5
Hallo CJ
Also have a 91mm stroked crankshaft, normally this results in a 3,5mm shorter conrod.
how do you cope with the missing 3,5 mm?
i left my conrod the original length(rod/strokeratio) and placed a 3.5 mm baseplate under the barrel to compensate.
best regards
sjef
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Post by colinjay on Mar 29, 2007 20:30:15 GMT -5
Sjef,
I might be wrong about the rod length, it has been a while since I did any thing with this engine, I know it was stroked to 91mm.
CJ
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Post by joebar on Apr 12, 2007 13:28:50 GMT -5
Hi There....Sweden here. You can buy big bore kits and stroke kits from www.kedo.de or www.miles-motors.de. If you go over 540 cc you need to machine the engine housings. Then you can go up to 590 cc with parts from the links above. Miles motors make 700 cc SR engines and sell parts too. If you go that high you need to stroke the engine and mount a spacer under the cylinder foot. Sound like a lot of job.... / Joebar |
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Post by sjef on Apr 12, 2007 14:42:20 GMT -5
Hallo
both Kedo and Miles stroke the engines with an offset bigendpin
which result in a 88mm stroke.if you want more the crankshaft needs some machining, smith/kanrin sells 92mm crankshafts.
cu sjef
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Post by StewRoss on Apr 12, 2007 15:54:35 GMT -5
Hi, Yes Smith Kanrin also sell that large external flywheel. With the longer stroke and the heavier flywheel it'd certainly be a completely different bike to ride. SR  |
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lurch
Full Member
Posts: 217
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Post by lurch on Apr 13, 2007 9:53:52 GMT -5
Hi, Yes Smith Kanrin also sell that large external flywheel. With the longer stroke and the heavier flywheel it'd certainly be a completely different bike to ride. SR Hi Stew Have you got any more info on the Smith Kanrin heavier flywheel mod ? Ive seen there 4ls brake drums one the Discovolante website here in the UK but nothing else . I saw a bolt on plate that fits onto the magneto rotor on some Japanese SR site cant remember where though  Cheers LURCH |
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Post by sjef on Apr 13, 2007 11:21:10 GMT -5
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lurch
Full Member
Posts: 217
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Post by lurch on Apr 15, 2007 2:00:45 GMT -5
Thanks sjef
Thats the baby, I'm a little concerned about the heavier load/stress's put on the left hand main bearing though .
Should be easy to get a local engineer to knock one up I may give it a go !
Cheers
LURCH
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Post by sjef on Apr 15, 2007 3:38:04 GMT -5
Hallo Lurch,
don`t worrry, the original bearings are more than strong enough.
sjef
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Post by StewRoss on Apr 15, 2007 3:53:30 GMT -5
Hi Lurch, The Smith Kanrin one comes with the big alloy cover that you can see in the adverts... SR |
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Post by joebar on Apr 15, 2007 12:37:33 GMT -5
Hi guys
I have heard a lot of Daytona. The problem is that they don´t have any agent in Sweden.
I have seen their cylinderhead on the internet and hear about their big bore kits. Sounds like great parts
Does anyone know what the price is for those things ?
The cylinder head has 2 sparkplugs. Is there any other difference ?
I have heard about 600 cc and the problems that you get with the cylinder. KEDO has a special for that that looks like a locking screw into the sleeve. Daytonas cylinder is reinforced. How is that done ?
I have measured my cylinder and I see that there will not be much material left after fitting a big bore sleeve. PErhaps a billet cylinder will be the best way ?
Anyone that have experience about this ?
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Post by sjef on Apr 15, 2007 16:07:58 GMT -5
Hallo Joebar, the cylinderhead has bigger valves, higher and bigger ports, will fit a 41 mm carb, better combustionchamber, stronger valvesprings,titanium valveretainers, valvelift +12.5mm. bigger fins for better cooling  the cylinder is stronger by design.it is designed to hold a 95mm liner.  the 546cc kit is sold out @daytona maybe there are some dealers (omc orange?)who can supply it.There are a few heads left @ Daytona. for prices etc you better ask www.vanem.com.aubest regards sjef |
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Post by Retread on Apr 18, 2007 13:22:08 GMT -5
Hi Guys,
I have read a lot of information on increasing displacement of an engine here, and while some is correct and some will cause some very costly mistakes. Let's try to learn about the relationship of bore and stroke and how it effects displacement. First of all a shorter con rod will not increase stroke or displacement. It will only move the area of displacement lower and dramatically reduce compression. A longer con rod also will have no effect on displacement but will increase the compression ratio (it is much cheaper and easier and safer to the engine to use a high compression piston to increase compression ratios.)
The stroke of an engine is controlled by the placement of the crank pin in the circle of the crankshaft. The further out from the center of the circle the longer the stroke. So the only way to change the stroke of an engine is to press apart the crankshaft and relocate the distance of the crank pin in relationship to the center of the crankshaft. A little can be gained by an offset crank pin, but the best gain for the effort is to weld up the crank pin holes and re-machine a different location for the pin further from the centerline of the crankshaft.
Engine displacement is determined by this formula:
bore X bore X stroke X .7854
This is the geometric volume of a straight walled cylinder. The engine specs must also be converted from mm to cm. a common up grade is to increase the bore to 90mm. Using this formula:
9.0 X 9.0 X 8.4 X .7854 = 534.38 cc
A common stroke increase to 91mm with the 90mm bore will result in a displacement of 579 cc. The use of a 91mm bore with the 7mm stroke increase will yield 592 cc. (Remember, a piston to fit the bore size will be smaller than the bore size for clearance purposes. It is a misconception that I have read in this forum that individuals claim that they installed a 90mm piston - they really bored the cylinder to 90mm and fitted a correctly sized piston for the bore.)
The use of a shorter con rod (does not effect the stroke) serves two purposes: prevent the piston that now rises 7 mm higher from hitting the head so a spacer plate below the cylinder does not have to be used, and many of the high compression pistons are not suitable for street gas so it also lowers an 11:1 piston to approx 10:1. The problem with a base plate is that there may be issues with the top motor mount because now the engine is taller.
It is my experience that the stock sleeve can be bored to 90mm, but any larger and the cylinder will have to be re-sleeved. New sleeves are slightly under sized in internal diameter because the re-sleeving process causes slight distortion. Re-sleeved cylinders still have to be bored to final size to remove distortion and fit the piston.
To the best of my knowledge,
Retread
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Post by sjef on Apr 18, 2007 14:10:45 GMT -5
Hallo Retread
guess you mean 3.5 mm?
one also can use a piston with a higher pinhole(strokerpiston)
I decided to use the original rodlength(baseplate 3mmthick) with a 91mm stroke in order to keep a reasonable rod/stroke ratio.
one other thing to concern is the piston speed, the longer the stroke the lower the max pistonspeed.
the length of the engine is no problem since the topmount can swing a little.
camchain can be an issue!
but there are suitable camchains available.
best regards,
sjef
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Post by Retread on Apr 19, 2007 8:34:13 GMT -5
Hello, I was referring to Powroll's service of a 7 mm stroke modification for these engines. www.powroll.com/P_YAMAHA_TTXTSR500.htmPart of their service is to also shorten the stock con rod 3mm. You make a good point about piston speed but the length of the con rod will not affect piston speed. Piston speed is a relationship of stoke distance and rpm. At any given rpm a stroked engine will have a higher piston speed because now the piston must travel further in the same amount of time (one revolution). The length of the con rod will not affect this, con rod length only moves the area of travel, not the distance of travel. The location of the crank pin to the centerline of the crank shaft determines the distance of travel (stroke). Check out Powroll's web site, they have a good animation that explains this better than words. A longer stroke will lower the maximum safe rpm of an engine because of the piston speed increase. Regards, Retread |
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