Just finished putting the sled back together after polishing the tunnel and doing new rings and bearing. I noticed the previous owner had the top end apart for some reason (no gasket on water rail, RTV instead). Noticed he sed 2 head gaskets stacked on top of each other. Any reason why he would of done that? Lower Compression?
I replaced the head (jug) gasket with a new one from yamaha. She seemed to run great after getting everything back together, although she didn't run bad before. Just a little low on compression.
I replaced the head (jug) gasket with a new one from yamaha. She seemed to run great after getting everything back together, although she didn't run bad before. Just a little low on compression.
Am I correct in assuming that the sled your talking about is the SRX in your profile?I can't see how 2 o rings could possibly fit one on top of the other like you say but I am sure your aware of the 2 separate o rings,inner and outer,that seal these cylinders/heads together.One is orange and the other is black so it is easy to distinguish them.I hope I'm not coming across as being a smart a** but I'm just not sure what sled your talking about.
If it's a Viper then people have modded the head gaskets on them for compression reasons like you say as well as the red head V Max,this is quite a common mod actually for them.
If it's a Viper then people have modded the head gaskets on them for compression reasons like you say as well as the red head V Max,this is quite a common mod actually for them.
bluebandit98
New member
gotta be an sx
Nope 00 srx. Not the dome gaskets, but the gasket under the jugs.
crazykid
New member
Sounds to me like the previous owner may have done the lift and cut mod. Thats where you double or triple the base gaskets and cut the head the same amount, its also called a poor mans port job, it raises the ports for a little boost in power.
mopar1rules
Active member
snopax said:
the previous owner was simply raising the cylinders, to increase the port timing. its only .010", which isn't even noticable, or worth the time IMO.
Ah yes,I never thought about the base gasket mod for these sleds.I should have too because I did this once but I can't remember what if any difference I actually felt in performance.snopax said:
Should I worry about going down to one head gasket? I wonder if he had the heads shaved.
If you have the heads off it now check them to see how much of a gap between the combustion chamber and the flat part of the head is left.If the heads were planed there will be almost no gap or very minimal one plus the outside edge of the head itself may have a sharp edge to it where it was planed off.I hope I explained myself enough for you here if not I'll try to take a pic of what I'm talking about with a head I have here and it point out for ya.
Pictures would be great. I didn't bother taking the domes off when I replaced the rings. I've heard horror sorties of the bolts breaking
mopar1rules
Active member
snopax said:
What do you mean 1 head gasket? The only "head gasket" on a srx, is 2 o-rings......1 outer and 1 inner. The 2 stacked gaskets that you are talking about, are called "base gaskets". You would be ok to drop down to 1 gasket, if the squish clearance isn't too tight (could re-cut head), cc volume too little for octane of fuel being used (could cut head again), or if the previous owner didn't have the cylinder bases decked. Maybe the previous owner had the cylinders decked .010" for cleaning up surface imperfections, and then needed to add another .010" base gasket, to get the port heights back to stock. Without measurements, no one knows for sure if you are safe w/1 base gasket.
Hi Mopar, thanks for the heads up on the correct terminology. Yes I am referring to the base gasket. Judging by the number of mods on the sled when I purchased it, I am pretty certain the previous owner was trying to adjust to advance the port timings by raising the jugs. I do not want to pull the domes out because I do not want to snap a bolt. With the new rings and a few test runs I am at 123 psi on a trusted compression gauge. I guess Ill wait for the rings to seat and see where the compression ends up. I'm assuming anything over 135 - 140 psi would indicate shaved domes, and too much compression for pump gas. I'll have to research a little more. It's hard to tell if the engine is running nay better. It's far too warm out and she is running rich. Only 150 more days or so until the trails open and I can try her out 
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mopar1rules
Active member
I have never had problems w/the head bolts, or heard of people breaking the head bolts. Never the less its your sled and your choice to do on it and work on it how you choose. If it were me, I'd pull the heads and see exactly what I had, especially if you say there were many mods done on it. Also, 123psi w/2 base gaskets is very good, as my MAC gage will say 115-118 on my single base gasketed srx. Then again, every gage reads different. Also, don't get caught up and use compression gage readings to dictate what octane to run.