[mikesnowman]

I am looking for input please. I bought a 99 t-cat with a Reichards 1108 (Same as Simons CPR) in it. 215 miles. Had low compression. 115 on each. Added oil and no change. Tried different gauge, no difference. Contacted Reichards and they have no dat on this since they have changed hands. Pistons rings and walls all look nearly new. After previous posts I was told to check the squish, which was close to .095. All the input I was getting was pointing me to cutting the heads, which I did. I had them cut down .015 to be on the safe side. I am now getting compression reading of 122. This still seems low. I had a conversation with an older master tuner who thought it may have low compression due to the height of the exhaust ports?
Should I cut more off to get more compression, or just go with it and not worry? I have not ridden this thing yet. Also what kind of horsepower am I losing with low compression? THis sled should be 215 to 235 hp I think?
Thanks

 

[94ZR580]

If you haven't ridden it yet I would not be cutting heads to address an assumed, unknown problem. Did you you look into the base gaskets? Maybe someone used fibre base gaskets and the cylinders are sitting too high. Exhaust ports should not effect compression numbers because you don't have any compression until the exhaust port is closed. Cutting the heads may have decreased the squish height, but did it adversly affect the squish shape? The shape of the squish band is important to proper combustion and, therefore, power and engine health. I hope you didn't make changes that will require more octane than premium pump gas to keep detonation at bay. I'd say don't cut any more until you know if you have any problems. Ride it and you'll find out if you caused a problem with indescriminent head cutting, or if it had issues when you bought it.

 

[bjankuski]

<div class='quotetop'>QUOTE (94ZR580 @ Jan 2 2007, 02:06 PM) <{POST_SNAPBACK}></div>

If you haven't ridden it yet I would not be cutting heads to address an assumed, unknown problem. Did you you look into the base gaskets? Maybe someone used fibre base gaskets and the cylinders are sitting too high. Exhaust ports should not effect compression numbers because you don't have any compression until the exhaust port is closed. Cutting the heads may have decreased the squish height, but did it adversly affect the squish shape? The shape of the squish band is important to proper combustion and, therefore, power and engine health. I hope you didn't make changes that will require more octane than premium pump gas to keep detonation at bay. I'd say don't cut any more until you know if you have any problems. Ride it and you'll find out if you caused a problem with indescriminent head cutting, or if it had issues when you bought it.[/b]

The exhaust port height does effect compression, the higher the port the lower the compression at cranking. What you do not know is what is the dynamic (running) compression the pipe design along with the max RPM of the engine will effect your dynamic compression. An engine with a high exhaust port and short pipes will have low cranking compression but it may have high dynamic compression and it may make a lot of power at high RPM. I would not modify your heads until you have determined how the engine runs. It may not need or want any more compression for trail fuel.

 

[mikesnowman]

<div class='quotetop'>QUOTE (94ZR580 @ Jan 2 2007, 02:06 PM) <{POST_SNAPBACK}></div>

If you haven't ridden it yet I would not be cutting heads to address an assumed, unknown problem. Did you you look into the base gaskets? Maybe someone used fibre base gaskets and the cylinders are sitting too high. Exhaust ports should not effect compression numbers because you don't have any compression until the exhaust port is closed. Cutting the heads may have decreased the squish height, but did it adversly affect the squish shape? The shape of the squish band is important to proper combustion and, therefore, power and engine health. I hope you didn't make changes that will require more octane than premium pump gas to keep detonation at bay. I'd say don't cut any more until you know if you have any problems. Ride it and you'll find out if you caused a problem with indescriminent head cutting, or if it had issues when you bought it.[/b]

First, thanks for the info!
I cut the heads after I spoke with the person that used to work at Reichards. he said I could safely go cut .02 that is why I went .015. The cylinders weere called viper??? they have huge castings at the exhaust side. The pistons are wiseco and they are domed. They come almost all the way even with the top of the cylinder. The base gasket appears to be the stock metal type and there is only one of them. It is all back together and runs fine in the garage. But I am just looking for input. I am not going to do anything additional yet, but I was curious as to if I am leaving much horsepower behind by not having 140 to 150 psi??
Maybe when Reichards did the heads they forgot to mill them??
Thanks