Ever Heard Of NO Compression?

[York Racing]

So I got around to working on the Family Blaster and I put a new head gasket on it and had some problems with bad studs. Turns out that the kid before me that had it replaced the OEM studs with American threaded ones. He did a terrible job and 2 pulled out. He also ran it with a bad head gasket and just kept tightening the head studs. So I got them all rethreaded and put new studs in. Bolted everything down with a 1 time use head gasket and torqued it down. But when I went to kick it over, it went down with NO resistance. So I put the compression tester in and it wouldn't even register. So it literally had NO compression. None. It's a fresh rebuild and the reeds are fine. Not stuck closed or anything. Any ideas?

 

[hudack]

realy bad wall clerance

 

[York Racing]

Oh and the motor rolls over fine. It pushes air out of the tail pipe but barely any. The plug was perfectly dry and it looked like no gas was getting to the cyilnder but the intake boot was wet on the bottom.

 

[York Racing]

Oh...Maybe inproper piston size? I noticed a slight bit of slop between the piston and cylinder wall but it was tiny. Like barely 3 peices of paper wide.

 

[Kgibson]

Sounds like a huge airleak ...probably the head to have no compression, maybe the head or the cylinder isn't flat... leakdown will tell ya

 

[York Racing]

Ok I just talked to the kid and he said this. "I rebuilt the motor and I tightened down the head bolts and just rode it. I pinned it a couple of times and just ripped around a bit to break it in. I didn't retorque the head nuts or anything but I just kept tightening them everytime it would lose compression. Then I just kept running it until one day I was riding and it just bogged down and died and lost all compression." Help any?

 

[brandoz28]

Sounds like a huge airleak ...probably the head to have no compression, maybe the head or the cylinder isn't flat... leakdown will tell ya

hit the nail on the head......you've been around long enough to know a leakdown is imperative on a new build...

 

[York Racing]

Brando, the head is all I've had apart on this Blaster. I was just getting suggestions on possible problems. On mine I know it all because I built it all. This one is bone stock. I already feel like a noob for posting don't make me feel worse. lol

 

[brandoz28]

you stated it was a fresh rebuild.....leakdown test and report back

 

[York Racing]

It was also not my rebuild work. If it was my work I would know where the problem was. I take pictures of every step so I can look back if there are any problems.

 

[brandoz28]

without stating you "bought a freshly built motor" we don't know that



any ay around it, leakdown and report back

 

[York Racing]

Alright Slick sells them right? I still have yet to pick one up.

 

[MXsandracer]

uh... there's a piston in there right?? lol i have to ask. unless this airleak is a massive hole in the bottom of the cases that you could physically see, you would still have a compression reading. i call faulty compression gauge... check it by using it on something that you know runs (lawnmower, etc..) if it seems to work then try it on the blasty again with the throttle all the way open

 

[lowkhalbalr]

uh... there's a piston in there right?? lol i have to ask. unless this airleak is a massive hole in the bottom of the cases that you could physically see, you would still have a compression reading. i call faulty compression gauge... check it by using it on something that you know runs (lawnmower, etc..) if it seems to work then try it on the blasty again with the throttle all the way open

for real, so long as theres a piston moving up and down it will make something.


with cracked rings i made 60 something; not for very long though

 

[alex90]

So I got around to working on the Family Blaster and I put a new head gasket on it and had some problems with bad studs. Turns out that the kid before me that had it replaced the OEM studs with American threaded ones. He did a terrible job and 2 pulled out. He also ran it with a bad head gasket and just kept tightening the head studs. So I got them all rethreaded and put new studs in. Bolted everything down with a 1 time use head gasket and torqued it down. But when I went to kick it over, it went down with NO resistance. So I put the compression tester in and it wouldn't even register. So it literally had NO compression. None. It's a fresh rebuild and the reeds are fine. Not stuck closed or anything. Any ideas?

check the base gasket and the reeds and make sure it has rings, or the pistion has a hole it it

 

[bagds101]

sounds like new top end time. look at your piston like alex said and if theres no hole in it, while the head is off, slowly push the kicker down with your hand while looking down your top end. see if your rings are even touching your cylinder walls and if you have alot of play or not. but sounds like you need a bore and a new piston

 

[York Racing]

I had the same MXSandRacer. I tried both good compression gauges and the both read Zero. The piston is in one peice for as much as I can tell. The cylinder has slight scarring but it's barely anything let alone enough to make it read Zero. The rings have some play but it's so little I don't see why it would cause a zero reading. As for the cases, I think I would have seen a gaping hole and it ran good before when the kid before me owned it but it just sputtered and died. I checked the reeds and they are okay. Any more ideas? I'm still waiting for the cash for a leakdown tester. Thanks for all the help and rep will be handed out accordingly. =]

 

[Larry's Shee]

Couple things come to mind. There is a reason head gasket goes on one way. Being head was never torqued properly and just tightened whenever nuts were loose, head might be warped and will never seal. Also check that when studs pulled that it didn't mushroom up (up-set) around stud area. Good straight edge and light should answer that.