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just did a comp test on my 08 with 45 hours on it


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clean filter, both plugs out, WOT, 45m ASL and kicked as hard as i can with standard head/port i scored 103 and 102 (on cold engine with a new snap on guage)

 

reason for checking was, im about to install 20 cc domes and wanted to know the compression differance.

once its hot it will gain a bit of compression so it may be close to the noss compression chart, so with the 20cc domes i should see around 140-150 psi.

 

so tomoz im gonna stick the new head and domes in check the comp and start roosten !!

 

atleast whiles its apart i can see how much film the avgas has left.

 

im pretty excited :) i love mods.

 

You should have checked it warm to get a more accurate indicator of where your at. I dont see much reason to use cold numbers as a base.

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imo, if you are needing a rebuild after 45 hrs, then you need to look at your oil and filter. when you have the head off, you'll be able to check out your cylinders and excessive piston clearance/rock.

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im only too kind to my bike when looking after it, yes i give it hell but i make shaw its warm before i ride it, filter is always clean, jetting is as toomey recommended and i use motul 800 @ 40:1.

tonight ill test another lower hour 08 shee to see if it has the same results (im thinking it will), the comp guage adapter will come into play as daj said.

IM SAFE DAM IT haha, i wanted atleast 100 odd hours out of this thing.

 

yeh snop with a warm motor and same length adapter (as the plug) id see alot better results.

 

thanx for your input guys.

Edited by dirtydownunder
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Them are the numbers I like to hear, all my frinds are saying Im gonna be less reliable etc etc, cant do this and that, we will see when i get my 4 mill together thursday, *waiting on seals*

 

Ive been told that a long rod 4 mill is more reliable then a stock and 4 mill standard rod because of the angles of the piston travel. But who knows.

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Ive been told that a long rod 4 mill is more reliable then a stock and 4 mill standard rod because of the angles of the piston travel. But who knows.

 

 

Not really. Increased piston speed and travel increases wear on components and that is what you get from a stroker. However, I will agree that the 4mm motors can be built to very reliable specs. I think I have only seen one of our 4mm motors back for inspection this year. Probably did 75 of them last year. They hold up pretty well.

 

 

 

 

B

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yeh i made a few phone calls to some yami dealers and one said 30hrs and the other said every three races you do the rings and every 5 you do the pistons.

haha thats funny i reckon, banshee's are made of glass :) i still love em but.

cousin wasnt home last night so tonight ill check his, if my jugs are off i may aswell do this and do that so hopefully his is the same, if its only gonna last a few hours on top ends it may aswell rip for those hours.

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Are you kicking it just one time or are you kicking it until the gauge stops climbing? <ake sure you thouroghly inspect your bores and pistons while the head is off, look for excessive piston clearance and surface condition of the cylinder. Iknow Yamaha recomends changing pistons and rings quite often but you should get more than 40 hours out of it, I am going on 200 hrs. on mine and I started with 175 and am down to 170. All this being said, I do think your numbers are low. Pull yor head off, inspect it, and if everything looks good, put the new head on and recheck it. Good luck.

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bores are fine, still some good cross hatching going on, lil glazed but still good and tight piston to bore clearance.

sheebore.jpgbores2shee.jpg

flash always makes it look more glazed than what it is.

the heads on and im ready to go for a burn tommo.

 

yep, keep kicking till the guage stops. My quads a few psi down from a real low hour 08 shee so im still within spec, just my guage reads low.

 

thanx.

Edited by dirtydownunder
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