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Discussion Starter #1
Heres the situation: I replaced intake manifold off the sled as it was cracked, put new plugs and fuel in for the season, and I can't even get a kick out out of the thing, soo I poured fuel down the cylinders, and still nothing! After that poured some oil in the cylinders and I finally got'er going, so I took her for a drive and it was losing power, didnt feel like it was all there, and finally pulled her in for the night and she just quit. Is this a compression problem or what? I dunno :sos:
 

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I would be leaning to it not being a compression issue, but the only way to know for sure is putting a tester to it. Do you know why the manifold cracked? I have had an issue similiar to this in the past, and there was just simply gas in the block, the fluid down there was creating too much compression and the motor was just working too hard.
 

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sorry dident answer the question,

I would be worried if you had less than 120 psi in the cyl.
also be worried if there was more than a 10% difference between cyl's
 

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Discussion Starter #4
There was a peice of the manifold broke of where it mounts to the stud and it just happened to break around the port, also why they break I was told people over tighten them. At first I thought this was was the problem cause it was sucking too much air but I replaced it and I got no futher at all. There shouldnt be a block in the fuel lines just put all new ones on at the first of the season. Also when you pull it over feels like theres nothing there. :eek:
 

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you are really not going to know until you put a tester on it.


If you dont have one, you can borrow one from a local pep boys or place like that, you will have to put money down on it, but they will give it back when you give it back. harbour freight sells them cheep as well.

either way if you plan to do any amount of work on motors you neeed a compression tester. get the numbers, and post them we could help you more after that.

good luck
 

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Discussion Starter #6
Yeah not going to pull it apart until I get them readings and I'll post them to see what you guys think?
 

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Discussion Starter #7
Well got a compression tester and got the readings, but one thing: dont think it the comp tester is worth a :turd: :lol: I got a reading of 0 and 30, so to confirm i checked other sleds and I got 60 - 60 on a 440 jag and 50 on all three cylinders on a mach z, so I think the comp tester is only reading half of what it should be it seems. Anyway I think im gunna pull the cylinders off and check them out myself.
 

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Make sure you have a good seal with the tester. Hold throttle wide open and pull over till you get highest reading, usually 3 pulls. That'll let you know what you really have.
 

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Discussion Starter #9
<div class='quotetop'>QUOTE (88eltigre @ Dec 23 2009, 04:14 PM) <{POST_SNAPBACK}></div>
Make sure you have a good seal with the tester. Hold throttle wide open and pull over till you get highest reading, usually 3 pulls. That'll let you know what you really have.[/b]
Tried holding it wide open and still got the same readings, so i think the compression tester is fried for sure now, but atleast it gave me an idea of what cylinder to look at. I am gunna pull the cylinders of tonight and see whats there might get some pics to and post them up so you guys can have a look and see what ya's think. :D
 

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you seem real anxious to pull the heads apart, I still stand by using the appropriate equipment to test with first. Remember that you will not get a better seal on the head than a factory seal. They are able tighten all head bolts at the same time. I usually look to break that seal as a last resort, also once you pull the heads, if it is not it, you are wasting time and money on replacing the gaskets.

I can not stress enough you can not use the old gaskets no matter how good they look. The most common problem with re-using head gaskets is bypass between the cylinders, this will cause uneven compression, and blow out the crank bearings, if not the crank, then your problems will be tripple what they are now.

I understand that the snow is flying, and you want to run, but skiping the simplest step may put you several dollars and weeks behind.

This is an older sled, and there is bound to be some wear, puting undue stress on these parts is sure to cause aditional problems.


If you do end up pulling the heads i recomend following these tips.

after pulling the heads, cylinders and pistions. lube all holes where the bolts were. there was bound to be some sort of lock tite. Now that the air can get to it it will harden like steel in just a few days. Also coat all combustion surfaces with a light oil. this will stop it from "Flash rusting"
If you do not see obvious signs of wear on either the rings, pistions and cylinder walls use a set of calipers to measure the diameter of the pistions, and the inside diameter of the cylinders. the bottom of the cylinders should show the most wear. make sure to measure as deep into the cylinders as you can reach with the calipers. a set of ID micrometers work best if you can get your hands on one. but not alot of people have them in their garage. you are looking to have the pistions about 5 to 7 thousenths smaller than the cylinders. you can go up to 10 thou, but will need over sized rings.

Before you re-assmeble the cylinders you shoud have a "kiss up" done to them. you can do it with a honing stone, but most sled shops will do it for real cheep. I had a tripple that a local sled shop kissed up the cylinders on for me and they charged $10.00 per cylinder. If you do it with a honing stone, please remember all machining marks need to run horizontal, not up and down. This will give you maximum compression.

now re-measure the pistion and cylinders. this will tell you what size of rings to order. make sure that the pistions and cylinders are the same temperature. alot of guys make the mistake of keeping the pistions in the house and the cylinders in the garage, and they will end up with bad readings because the colder parts will shrink a little. Also take 3 or 4 measurements in different places, the parts could be out of round.

Before you put the motor back together. Keep all of the parts together including the gaskets for at least 24 hours, again so that everything is the same temperature. This is the most common cause for new gaskets failing. Even after you torque the heads if the block is 30 or 40 degrees colder that the heads and cylinders, the warm parts will shrink when they cool and can cause gasket bypass. Even a small 2 thousanths shift after it is torqued will result in bypass.

When puting it all back together, use locktite and folow the torqueing requiremens of the gasket manufacturer. Most times these are the same as the book values, but if they are different go with the gaskets.

hope this helps, and good luck
 

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What do the cylinders look like?
are they as scored as the pistons?

I recomend replacing the pistons, from the pics they look heat scored, and chances are they are brittle. Before you remove the piston lay the motor on its side. this way if the bearings are shot none of the needles can fall into the block.

Clean up the cylinders and measure them this will tell you what size of piston to order. If you like measure them and post the readings. ill let you know what part numbers you can choose from. also let me know what places you have in your area, i can find out what after market parts they supply. Most likley Parts Unlimited (Lemans)
Weisco is a good piston, but they are a hotter type and a little more pricy, but depending on your riding will depend on your best application.

good luck and happy holidays.
 

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Discussion Starter #13
I have a Weisco piston and rings now so i think im gunna get another one just to match the other cylinder so they are the same
 
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