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ProModeler Scorpion Power
HelicopterEngines Plugs Mufflers Fuel › Update on YS95.6sr-t
06-02-2010 03:35 AM  7 years agoPost 1
Gernejr

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Miami, Fl

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Hey guys here a quick rundown . The new mini lathe come in and got it setup up ,checked out, It's SWEET. So i grab up a SR liner chucked it up and when to work,it's taking a little longer then i thought to cut but worth it. Finished to with 220 cross hone finishes. I mod my honer for the liners.. Ok enough talk here's acouple pictures. Still have few more thing to do, may have running motor to breakin by the weekend if my life doesn't get in the way.

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06-02-2010 06:11 AM  7 years agoPost 2
GootyS

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Gauteng South Africa

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Looking good! what is the clearance between piston and sleeve? Are you still going to port it a little?

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06-02-2010 03:52 PM  7 years agoPost 3
CoronaL

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Winnebago IL

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now will that liner be as durable now? I am probably wrong, but I thought stock liners were coated in something that helped to harden the liner and protect against corrosion.

Randy!!! I am the liquor

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06-02-2010 08:46 PM  7 years agoPost 4
Gernejr

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Miami, Fl

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GootyS I set the liner to the same spec as ST motor. The Piston is 27.57mm and the bore is 27.70mm which works out to .06mm clearance per side. Both the ST and SR have the same O.D.
I'm going to break-in the motor with no port mods and see how it performs then I will do some porting and check performance again. I know there will be guys out there wanting dyno reads well if someone has one i can borrow I'll love to use it.LOL I understand there only about 5 grand . I guess i could setup a engine stand and use props to see how much more prop it could pull over stock and figure power incease in percents but I'm sure that will not be good enough for some. First I'm going to see how it runs and performs holds up.

CoronaL , If there's a coating thats news to me. I have honed many liners on rebuilds that like look new today.

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06-02-2010 09:17 PM  7 years agoPost 5
Ironhide

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dexter mi us

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Gernejr
Lookin good buddy !

I popped a enya 3 in mine just the other day much better !I'm still running the dual plug head with a OS 8 as well .

I'm very interested in the longer sleeve .

See if you can compare the vibs from a stock SR and your SRT for us .

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06-02-2010 09:43 PM  7 years agoPost 6
CoronaL

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Winnebago IL

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ok cool
keep us up to date

Randy!!! I am the liquor

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06-02-2010 11:02 PM  7 years agoPost 7
Gernejr

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Miami, Fl

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lronhide going to watch vibs if this goes as hope the next plan is SK720 for 700. was also thinking i'm going to weight both pistons and then again the ST after i clearance it for crank just to know the changes in the motor.

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06-03-2010 06:31 AM  7 years agoPost 8
GootyS

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Gauteng South Africa

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Awesome!! i shall wait for your feed back :-)

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06-05-2010 04:53 AM  7 years agoPost 9
Gernejr

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Miami, Fl

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here's a few more picturs. Shoved off the top of liner to get 12:1 with SR shim but with ST shim it's 12.5:1 , tHe stock SR is 13:1 . I can remove .004 from liner but that's it , will wait and see how she runs on rotor rage 30% . Still waiting on UPS man for new crank and Rear bearing. If you look close you can see the light between the head and Crankcase. it's .010.. this area is normally about .035 clearnace...

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06-09-2010 06:35 AM  7 years agoPost 10
GootyS

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Gauteng South Africa

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more...more...more..lol you saying the stock compression is 13:1 on the SR and with shaving some off the sleeve you getting 12:1? How much more can you go to get back to the 13:1 ratio or are you trying different compressions first?...or have a i lost the plot? :-)

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06-09-2010 10:46 AM  7 years agoPost 11
lightningrc

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UK

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Forgive me for being stupid just had a back opp and on loads of tablets .lol

What have you done used a larger size piston and over bored the liner ??

If so what piston is that from .

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06-09-2010 11:00 AM  7 years agoPost 12
Gernejr

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Miami, Fl

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Ok right now it is 12:1 with .2mm stock SR shim. Can change shim to ST .1mm shim yeilds 12.5:1 CR. Now i can still remove .1mm or .004 from top of liner and that along with .1mm shim get 13:1CR . Plan to work my way up on compression..

LighteningRC Yes it's YS91SR with ST piston liner has been bore/honed to 27.70mm from 27mm with long stroke SR yeilds 95.6..

Heliporz has got to be the slowest shipping around order crank on 5/31/10 still not here... not the first time on slow shipping.

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06-09-2010 11:12 AM  7 years agoPost 13
lightningrc

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UK

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Would at first be better just to over size liner and use wider piston first.

Whats the standard compression ratio ? as ive learned from the rossi engines when its to high it just makes it hard to tune and ups vibrations.

Or is it that with this mod it will lower the ratio so you need to up it again.

You could always add extra shims later any way it its to high.

Y do you need long stroke crank , in the photo the piston is right at the top , or is it not connected ?

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06-09-2010 05:26 PM  7 years agoPost 14
Gernejr

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Miami, Fl

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using ST piston in SR motor the piston is to lower at TDC causing to low of compression ratio. so i cut some from top of liner this rasied CR. I want to see how it runs at 12 for 15%, 12.5 for 20% and 13 for 30% . im mainly interested in tuning at 12.5 and 13 also smoothness of motor. using SR liner because it is longer means longer intake runners than using ST liner. equals more torque/HP. From what i figure SR stock CR is 13:1 but i want try 12.5cr as 13 may cause rough or bad idle . I wont know till its running hopevully that will be this weekend.

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06-09-2010 05:39 PM  7 years agoPost 15
lightningrc

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UK

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Right so you have kept standard crank for same stroke , but machined top of cyliner to regain compression ratio.

You could get the head machined have a grove cut into it so the liner sits into the head.

With that piston being lower do you think it may alter the port timing etc ?

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06-09-2010 07:35 PM  7 years agoPost 16
Gernejr

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Miami, Fl

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Port timimg should not change. I dont need to touch the head .

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06-09-2010 11:13 PM  7 years agoPost 17
lightningrc

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UK

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Let us know how she goes

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06-10-2010 02:23 AM  7 years agoPost 18
Gernejr

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Miami, Fl

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Man I just got my parts in But the ST shim is .020 or .008mm thick. Now i got to figure out where to get the .004mm or .010 shim that was in the ST motor i sold..... I need this to get 13:1 CR , if someone knows please inlighten me....Was going to start with 12.5:1 CR with .1mm shim and later shave .004mm more off liner to get 13:1 CR.. Guess i can email YS see what they tell me ... I'm Bummed

Looks like OS91HZ has .1mm shim and is 27.70 bore we may have a winner , Now i just need one in hand.... man this is getting to be like work.

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06-10-2010 06:19 AM  7 years agoPost 19
GootyS

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Gauteng South Africa

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Yip it does sound like work but its fin kinda work and when the motor makes good power im sure it will be worth it.

looking forward to hear how the motor runs on the different compressions.

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06-10-2010 09:45 AM  7 years agoPost 20
lightningrc

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UK

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Gernejr go to your local nut/bolts hardware supplier , I was amazed when I modded an engine last year and and we had them in a selection shims box in work exact size in all different thickness.

You will probably find those shims are standard sizes used in industry and not made by YS.

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