cecome Posted October 27, 2010 Posted October 27, 2010 Guy says he can't get more than 112 HP out of it. He said it should be 130+ with my setup. I have attached the report from the shop. Looks like compression is very, very low he did compression and leak down testing, some wear on the rings but not too bad from what he can tell, but then found out the head looks like it came from a salvage yard. Bike is a 97 with allegedly 20k on it. Can the head from later years fit on a 97 and if they did would they kill the compression. Please look at the report attached and give me any suggestions you may have. I will own and ride this bike till I die and want it to be right. Not sure what to do next. But want to do it right. Any and all feedback is greatly appreciated!!!!!! Quote
Redbird Posted October 28, 2010 Posted October 28, 2010 Where's Tomek? I know he did his head and said it was trashed, mileage was much higher than 20k, though. Any chance that's 120k? I'm not even sure if the XX's odo rolls over or reads above 100k. Perhaps not the original gauges, being salvage? Definitely sounds like a much higher mileage motor. Quote
HANKSXXX Posted October 28, 2010 Posted October 28, 2010 Guy says he can't get more than 112 HP out of it. He said it should be 130+ with my setup. I have attached the report from the shop. Looks like compression is very, very low he did compression and leak down testing, some wear on the rings but not too bad from what he can tell, but then found out the head looks like it came from a salvage yard. Bike is a 97 with allegedly 20k on it. Can the head from later years fit on a 97 and if they did would they kill the compression. Please look at the report attached and give me any suggestions you may have. I will own and ride this bike till I die and want it to be right. Not sure what to do next. But want to do it right. Any and all feedback is greatly appreciated!!!!!! Where did the leak down test show the problem to be? The mechanic running the test should have been able to hear where the air was going. As far as I know, all heads have the same combustion chambers so that wouldn't cause a loss of compression. Another possibility is a cam being a tooth off. Rings and valve jobs traditionally last a long time with these motors. Quote
cecome Posted October 28, 2010 Author Posted October 28, 2010 Guy says he can't get more than 112 HP out of it. He said it should be 130+ with my setup. I have attached the report from the shop. Looks like compression is very, very low he did compression and leak down testing, some wear on the rings but not too bad from what he can tell, but then found out the head looks like it came from a salvage yard. Bike is a 97 with allegedly 20k on it. Can the head from later years fit on a 97 and if they did would they kill the compression. Please look at the report attached and give me any suggestions you may have. I will own and ride this bike till I die and want it to be right. Not sure what to do next. But want to do it right. Any and all feedback is greatly appreciated!!!!!! Where did the leak down test show the problem to be? The mechanic running the test should have been able to hear where the air was going. As far as I know, all heads have the same combustion chambers so that wouldn't cause a loss of compression. Another possibility is a cam being a tooth off. Rings and valve jobs traditionally last a long time with these motors. cams were allegedly correct. he said leak down showed rings but not enough to explain the loss of compression to it's current levels. the attached report is what I have for the moment. I can ask more ??'s tomorrow. any advice? maybe the whole motor is salvage, don't know. Quote
cecome Posted October 28, 2010 Author Posted October 28, 2010 Where's Tomek? I know he did his head and said it was trashed, mileage was much higher than 20k, though. Any chance that's 120k? I'm not even sure if the XX's odo rolls over or reads above 100k. Perhaps not the original gauges, being salvage? Definitely sounds like a much higher mileage motor. really don't know about the motor any more, dmv said mileage was correct when I bought it with about 12k on it.. but what woud one expect in the way of compression?? Quote
mikesail Posted October 28, 2010 Posted October 28, 2010 Been a long time since I've looked at compression numbers, but my gut says that your rings are not too good if the wet number is 20 psi better than the dry. Is the leakdown tester calibrated to a bike motor? 10% numbers sound so-so for a big engine, not good for a small motor. the intake with 0.001 clearance is a big warning. If the valve(s) has not already burned, it will soon enough. Reshimming is critical for this tight a clearance. The valves which are off a couple of thou, or too loose are not such a concern, they will just have a minor effect on engine tuning. Did they really spend five hours on the Dyno??? Quote
cecome Posted October 28, 2010 Author Posted October 28, 2010 Been a long time since I've looked at compression numbers, but my gut says that your rings are not too good if the wet number is 20 psi better than the dry. Is the leakdown tester calibrated to a bike motor? 10% numbers sound so-so for a big engine, not good for a small motor. the intake with 0.001 clearance is a big warning. If the valve(s) has not already burned, it will soon enough. Reshimming is critical for this tight a clearance. The valves which are off a couple of thou, or too loose are not such a concern, they will just have a minor effect on engine tuning. Did they really spend five hours on the Dyno??? guy said 10% sould not explain the issues with compression. not 5 hours yet but they will be between tear down and the rest of the work, this just gets worse and worse as I go...... Quote
jon haney Posted October 28, 2010 Posted October 28, 2010 Could the motor have had a turbo on it at some point in its life? Turbo pistons produce lower compression. Quote
cecome Posted October 28, 2010 Author Posted October 28, 2010 Could the motor have had a turbo on it at some point in its life? Turbo pistons produce lower compression. Bingo that is what the guy at the shop just suggested. He said it is hard to explain any other way other than a previous owner lowered the compression on purpose. If that is the case what is my best course of action? Quote
ironmike Posted October 28, 2010 Posted October 28, 2010 The solution is fairly simple (assuming all is well with the bottom end); it sounds like you'll need a top end job - pistons/rings, assess and address valves/seats (replace/ resurface as needed), and new gaskets where appropriate. It's not an impossible situation, but you may have to do some parts chasing... Best of luck! Quote
cecome Posted October 28, 2010 Author Posted October 28, 2010 The solution is fairly simple (assuming all is well with the bottom end); it sounds like you'll need a top end job - pistons/rings, assess and address valves/seats (replace/ resurface as needed), and new gaskets where appropriate. It's not an impossible situation, but you may have to do some parts chasing... Best of luck! Thanks. Any suggestions on part sources? Or maybe I just sell her and get a stocker, but I would rather not start over. Quote
ironmike Posted October 28, 2010 Posted October 28, 2010 The solution is fairly simple (assuming all is well with the bottom end); it sounds like you'll need a top end job - pistons/rings, assess and address valves/seats (replace/ resurface as needed), and new gaskets where appropriate. It's not an impossible situation, but you may have to do some parts chasing... Best of luck! Thanks. Any suggestions on part sources? Or maybe I just sell her and get a stocker, but I would rather not start over. Yep, answered in your other thread (re:cam/head part numbers)... Quote
blackhawkxx Posted October 28, 2010 Posted October 28, 2010 Or maybe I just sell her and get a stocker, but I would rather not start over That sounds like the way to go. There is one in the For Sale section. Quote
cbrxxquad Posted October 29, 2010 Posted October 29, 2010 take the thick head gasket out and put a stock or thin one in it. Quote
cecome Posted October 29, 2010 Author Posted October 29, 2010 take the thick head gasket out and put a stock or thin one in it. any chance they could have put low compression pistons in it if there is such a thing?? mechanic said he could not tell if it was thick, would it be obvious? Quote
HANKSXXX Posted October 29, 2010 Posted October 29, 2010 take the thick head gasket out and put a stock or thin one in it. any chance they could have put low compression pistons in it if there is such a thing?? mechanic said he could not tell if it was thick, would it be obvious? Should be pretty obvious... Stock is .030"+ Mine is .075" Custom gaskets can be made to any thickness but for a Turbo, more is better... Quote
cecome Posted October 29, 2010 Author Posted October 29, 2010 take the thick head gasket out and put a stock or thin one in it. any chance they could have put low compression pistons in it if there is such a thing?? mechanic said he could not tell if it was thick, would it be obvious? Should be pretty obvious... Stock is .030"+ Mine is .075" Custom gaskets can be made to any thickness but for a Turbo, more is better... from the mechanic We don't know what the head gasket thickness is, we can only speculate until we pull the head. Besides, a thinner head gasket will barely make a dent in regaining the lost 60-65 psi cranking pressure. With 10-11% leakage at the rings, there's a lot more to be gained by replacing the rings.. perhaps 20 psi, but still a long way from the target 185 psi. Given these facts, I have to stand by my opinion that something else is amiss. Quote
HANKSXXX Posted October 29, 2010 Posted October 29, 2010 Stock head gasket is .032" My thick one is .075" and the difference, looking at the side of the motor where the head and case join, is obvious. With turbo's thicker is better, so I wouldn't worry about a .040" or .050" gasket being used. Nitrous doesn't need lower compression. When I installed the thick gasket, the cranking pressure went down to 150lbs. When my first motor ingested sand, the cranking pressure went down to either 125 or 135 lbs with 12% leakage past the rings. This was in the bad cylinder only. The others missed getting the sand...and no, I have no idea why. I just know what I found. Something else to think about...the markings on the intake sprocket are hidden by the frame. I don't think you can see them even with a mirror. Not sure how the mechanic did... If the cases were taken apart for low compression pistons, you might see some marks on the case bolts...That's about the only reason to put a socket on them... Quote
JB4XX Posted October 29, 2010 Posted October 29, 2010 Here is thicker head gasket... I wouldnt worry about it too much if you are not smoking/burning oil and valve clearances are right. Quote
HANKSXXX Posted October 29, 2010 Posted October 29, 2010 Here is thicker head gasket... I wouldnt worry about it too much if you are not smoking/burning oil and valve clearances are right. And Cecome, there is also a FI head... The difference between that and the carbed head is the pickup bolted to it... Quote
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