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Big Bore Build - Part 1 - Cylinder (Read 130 times)
DragBikeMike
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Re: Big Bore Build - Part 1 - Cylinder
Reply #15 - 06/30/20 at 18:54:58
 
The finished product was gratifying.  It was round and straight within a few ten-thousandths of an inch.  Not pro-stock quality but easily good enough for sweet-street performance and a decent life expectancy.
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DragBikeMike
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Re: Big Bore Build - Part 1 - Cylinder
Reply #16 - 06/30/20 at 18:55:40
 
I must discuss my observations on cylinder rigidity.  This thing gets real thin when you poke it out to 97mm.  I could tell right away that it was flimsy.  The bore diameter would change dramatically when I released the torque plates.  The skirt of the cylinder would expand by about .0007”, the center got smaller by .0010”, and the top went oval by .0011”.  Reinstall the torque plates and everything went round & straight again.  If you compare the stock cylinder to the 97mm you get a good feel for the reduction in liner thickness.
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DragBikeMike
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Re: Big Bore Build - Part 1 - Cylinder
Reply #17 - 06/30/20 at 18:56:35
 
The 97mm cylinder weighs 1 lb. 3 oz. (538.641 grams for Armen) less than the stocker.  That’s a lot of iron.  The skirt is thin.  As I previously mentioned, the skirt expands outward when you release the torque plates.  This thing is nowhere near as rigid as the stock cylinder.  I think if there is any sort of reliability issue it will center around this thin cylinder wall.
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DragBikeMike
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Re: Big Bore Build - Part 1 - Cylinder
Reply #18 - 06/30/20 at 18:57:14
 
Bumping up the bore size will require a special head gasket.  The stock multi-layer steel (MLS) gasket is too small.  Head gaskets that overhang into the bore can cause hot spots with associated pre-ignition and detonation.  You want to use a true 97mm gasket.  This picture shows the stock gasket overhang.
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DragBikeMike
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Re: Big Bore Build - Part 1 - Cylinder
Reply #19 - 06/30/20 at 18:57:53
 
Copper Gaskets Unlimited (CGU) in Phoenix, AZ offers a true 97mm copper head gasket for the LS650.  They also offer cylinder base gaskets.  Their gaskets are available in a variety of thicknesses which will allow slight adjustment of deck height and combustion chamber volume.  I’ll be using their .026” thick copper head gasket.  As you can see, it fits perfectly.
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Re: Big Bore Build - Part 1 - Cylinder
Reply #20 - 06/30/20 at 18:58:31
 
After I was confident that the cylinder bore was good-to-go, I dressed up some of the broken stuff and cleaned it up a bit.  I’m debating whether or not to paint it.  Hey, it’s only gonna get dirty.
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DragBikeMike
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Re: Big Bore Build - Part 1 - Cylinder
Reply #21 - 06/30/20 at 19:01:05
 
So, was boring out my cylinder worth all that trouble?  For me, yes.  It was interesting and I improved my skill set.  It took a long time and required a lot of effort, but the finished product was very gratifying.  It’s amazing what you can accomplish with a little tenacity and patience.

Would I recommend a project like this for any of you hobbyists?  Absolutely.  Get a junk cylinder and give it a whirl.  It’s a terrific learning experience.

Did I do a better job than a bonafide machine shop?  Probably not.  I imagine I may have done a better job than you could get at some sketchy machine shop or a motorcycle shop with a cheap boring machine, but I doubt that my finished product is as good as what’s expected from a top quality engine rebuilder.
   
In Part 2 of this report, we will go through the cylinder head, install the bigger valves, modify the ports, flow test, and set it up for a big cam.
 
Part 3 will inspect and setup the bottom end.
 
Part 4 will cover engine assembly.
 
Part 5 will install and test the engine.

As usual, I hope you find this report informative and I look forward to any comments or questions.

Knowledge is power.

Stay safe out there.  Respect the Vid19.

Mike
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kamelryttarn
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Re: Big Bore Build - Part 1 - Cylinder
Reply #22 - 06/30/20 at 23:33:21
 
As always I am in awe of your great work. You have done an amazing job there. Thank you so much for sharing it with us!
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Re: Big Bore Build - Part 1 - Cylinder
Reply #23 - 07/01/20 at 04:33:29
 
Awesome!
Great work, well documented (as always!).
Can't wait to see the performance testing!
thanks for sharing
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srinath
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Re: Big Bore Build - Part 1 - Cylinder
Reply #24 - 07/01/20 at 04:34:48
 
When the skirt is so thin don't it run the risk of breaking at the bottom of the stroke - as in - in the old days the 89 GSXR750 connecting rods were used in a lot of hopped up GSXR motors regardless of what the build was. Those had longer rods - they were super short stroke but had the longest rods of all GSXR air oil cooled. The thought was there is less stress side ways at the bottom of the stroke - and we're only talking a 2mm longer rod.

Some thing some thing angularity something they used to say.

Cool.
Srinath.
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LANCER
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Re: Big Bore Build - Part 1 - Cylinder
Reply #25 - 07/01/20 at 11:19:08
 
I don't recall anyone posting about a break in the wall at the bottom of the cylinder.   I've not had that issue to date.  

Thanks for the data DBM.
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Re: Big Bore Build - Part 1 - Cylinder
Reply #26 - 07/01/20 at 12:35:17
 
LANCER wrote on 07/01/20 at 11:19:08:
I don't recall anyone posting about a break in the wall at the bottom of the cylinder.   I've not had that issue to date.  

Thanks for the data DBM.




Yea savage probably has longer rods than the GSXR or any year, and spins slower than any GSXR … besides, those likely already had thin sleeves being 4 cyls. Bore em and thin becomes wafer thin.

Cool.
Srinath.
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Re: Big Bore Build - Part 1 - Cylinder
Reply #27 - 07/01/20 at 13:04:40
 
Great job DBM.....anxious to read about your results.  I have been running a 95mm Wiseco for the last 10,000+ miles and I am well pleased with it.  A larger 97mm might be even more fun!

When the piston is down in the bore below the aluminum......the rod is not at much of an angle and there likely aren't large sideways forces like there is in the mid bore when the rod angle is high.

I have never heard/read of a Savage cylinder of any bore size breaking.

Most cylinder failures are related to running the bike out of oil.  I have read of 2 piston/cylinder failures from improper boring (1 too tight and 1 too loose).
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Re: Big Bore Build - Part 1 - Cylinder
Reply #28 - 07/01/20 at 16:19:36
 
This is going to be exciting! The forum members here are phenomenal!
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DragBikeMike
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Re: Big Bore Build - Part 1 - Cylinder
Reply #29 - 07/01/20 at 23:34:27
 
I am not worried about the cast iron liner breaking.  My concern is over circularity & rigidity.  The entire cylinder, top-to-bottom, is very flimsy now.  I have never seen a cylinder that distorts this much when you release the torque plates.  It's probably not a big deal.  I'm just saying that if it's gonna misbehave it will probably be related to the flimsy cylinder.  Stuff like elusive ring sealing, seizures, rattle & resonance, stuff like that.  No one is reporting those problems so I suspect it's gonna work just fine.

Srinath, long rod engines make more power.  You want to run the longest rod that you can reasonably fit into the engine.  Probably not an option for us since there isn't exactly a cornucopia of speed parts available for the LS650.

I believe the desired rod ratio is 1.75 or better.  For instance, an engine with a 6" rod and a 3" bore has a rod ratio of 2.  The LS has a 3.7" bore and the rod is about 6.6" so our rod ratio is around 1.78.  Good but not best.

The longer rod geometry increases dwell at TDC so combustion pressure has more time to build, improves the angle of the rod in relation to the piston which reduces piston thrust, and improves the angle between the crank journal and the wrist pin which results in better mechanical advantage.  All good stuff if your looking for more horsepower and torque.

Dave, encouraging to hear you've logged over 10K on the Wiseco.  I'm not sure how many miles I have on the Wiseco 94mm.  Will have to check.  I am satisfied with it so far. It's a very easy way to grab a few more ponies.
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