Bobby Banshee Posted December 28, 2007 Report Share Posted December 28, 2007 I know the compression test is to be done at WOT. Why is this necessary? Is it so that the maximum amount of air is available for compression? If so, I should be able to do a compression test with the carbs off the engine. This would be a great deal easier to test because I have to remove the gas tank and pull the slides out of the carbs to remove everything to remove the head. Especially if I am going to remove the jugs. If I had a ring problem, wouldn't this make lower compression instead of higher compression? With a 19cc dome cut for a 4 mil crank i should be around 170-175 psi according the the builder. Indicating that the 190-195 psi cylinder is the one giving me a problem. Thanks. Shannon Shannon, i called Kevin earlier in the day. He seams to think its possible a air leak somewhere. I'm still having the same issue as well. I'm getting 185psi with 22+2 domes with a 4mil and woods port. Quote Link to comment Share on other sites More sharing options...
spurdy Posted December 28, 2007 Author Report Share Posted December 28, 2007 Shannon, i called Kevin earlier in the day. He seams to think its possible a air leak somewhere. I'm still having the same issue as well. I'm getting 185psi with 22+2 domes with a 4mil and woods port. I could see an air leak causing that side to run lean however, I can't understand how an air leak would cause high compression. Besides, I did a leak down test and didn't leak a needle width in over six minutes. I did this 3 times! I am going to switch domes and see if the problem follows the dome to the other cylinder. If not, I am going to pull the jugs back off and check them. I think the lean condition maybe a carb problem because I can't think of any single cause to result in both symptoms. :sad: Quote Link to comment Share on other sites More sharing options...
KEVSWS6 Posted January 8, 2008 Report Share Posted January 8, 2008 I could see an air leak causing that side to run lean however, I can't understand how an air leak would cause high compression. Besides, I did a leak down test and didn't leak a needle width in over six minutes. I did this 3 times! I am going to switch domes and see if the problem follows the dome to the other cylinder. If not, I am going to pull the jugs back off and check them. I think the lean condition maybe a carb problem because I can't think of any single cause to result in both symptoms. :sad: How did we make out on this? I forgot what our last step was. You got it right and are taking it over to the Dyno to see what it will do? Quote Link to comment Share on other sites More sharing options...
KEVSWS6 Posted January 8, 2008 Report Share Posted January 8, 2008 Shannon, i called Kevin earlier in the day. He seams to think its possible a air leak somewhere. I'm still having the same issue as well. I'm getting 185psi with 22+2 domes with a 4mil and woods port. The last time we spoke you just finished 22 miles of eating 4 strokes up. I will work with a motor I do until we get it right. If I have to ship out different domes or take the whole motor back and figure it out myself. I will try and do my best to make any wrongs right. Quote Link to comment Share on other sites More sharing options...
spurdy Posted January 9, 2008 Author Report Share Posted January 9, 2008 The last time we spoke you just finished 22 miles of eating 4 strokes up. I will work with a motor I do until we get it right. If I have to ship out different domes or take the whole motor back and figure it out myself. I will try and do my best to make any wrongs right. I did another pressure test and it held 6 PSI for over 15 minutes. The cases and intake are tight. Took it to the dyno yesterday and got the jetting dialed it. Everything ran well. The numbers came out at 55hp / 34 ft lbs tq. I don't know how much dyno numbers vary and this is the only motor I have ever had checked so I must say that the numbers don't disappoint me. I am still showing a consistent 190 psi with 19cc + 2 domes. I am going to run for a little this weekend. Maybe just put around for an hour or so and then recheck the compression. If we are still up there we should probably changed to a larger dome. I think we agree that we don't want it at 190 psi and I would really like to see it around 165-170 psi range. Props to Kevin and all his help! And thanks to the HQ for bringing it all together! :beer: SP Quote Link to comment Share on other sites More sharing options...
KEVSWS6 Posted January 9, 2008 Report Share Posted January 9, 2008 I did another pressure test and it held 6 PSI for over 15 minutes. The cases and intake are tight. Took it to the dyno yesterday and got the jetting dialed it. Everything ran well. The numbers came out at 55hp / 34 ft lbs tq. I don't know how much dyno numbers vary and this is the only motor I have ever had checked so I must say that the numbers don't disappoint me. I am still showing a consistent 190 psi with 19cc + 2 domes. I am going to run for a little this weekend. Maybe just put around for an hour or so and then recheck the compression. If we are still up there we should probably changed to a larger dome. I think we agree that we don't want it at 190 psi and I would really like to see it around 165-170 psi range. Props to Kevin and all his help! And thanks to the HQ for bringing it all together! :beer: SP I'm not happy with the PSI your at and really not happy with those Dyno numbers. Even if the dyno reads low it cant be that far off. Work with me here and we will bring those numbers up. With the PSI you are running along with the timing might be making the motor pre-detonate. I wanted to hit the static around 175-180 with the gas you are using. Please give me a ring this motor can do lots better. Cheers Kevin Quote Link to comment Share on other sites More sharing options...
spurdy Posted January 10, 2008 Author Report Share Posted January 10, 2008 I'm not happy with the PSI your at and really not happy with those Dyno numbers. Even if the dyno reads low it cant be that far off. Work with me here and we will bring those numbers up. With the PSI you are running along with the timing might be making the motor pre-detonate. I wanted to hit the static around 175-180 with the gas you are using. Please give me a ring this motor can do lots better. Cheers Kevin I want the compression numbers down as well. I have taken the jugs off and pulled the pistons. Sending Jugs, domes, piston, and plugs back to you in the AM for you to evaluate. If you say it should perform better then I believe you. Its your motor, your the boss. Again, thanks for all the help and your customer service is second to none! SP Quote Link to comment Share on other sites More sharing options...
KEVSWS6 Posted January 25, 2008 Report Share Posted January 25, 2008 No wonder you had 55 HP. This thing was ready to stick a piston. It was ugly. hard to believe that all it had on it was dyno time. This thing said it was hot and lean. Since I didn't put this motor together or tune it I'm not sure what happened. The plugs say fat and the one cylinder says fat but hot. The other cylinder says lean. I know the jetting on the carbs sounds way off. Hopefully with the new carbs setup by me and checking the stator out will kill this problem. Quote Link to comment Share on other sites More sharing options...
KEVSWS6 Posted January 25, 2008 Report Share Posted January 25, 2008 You just need one of these. Quote Link to comment Share on other sites More sharing options...
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