|
|
Post by whitelinewarrior on Apr 9, 2012 8:08:08 GMT -5
Long story short, I rebuilt my 49cc 2T which ran super strong for a few days but I failed to pull the plug and check the tune. On the way home it over heated due to being to lean and seize. Ordered new piston, honed and ported on the the cylinder a little, put it back together and hooked everything up. It started right up and ran great so I took it down the road. Ran fine for about a mile then the old familiar feeling of slow down then lock up occurred. Just then I remembered that I forgot to prime the oil pump. Pushed it home, pre-mixed and made sure the oil pump was primed. Checked the compression and it was down about 10 psi from before (from about 120 down to 110 cranking compression). Screwed the plug in and she fired right up. Everything seems OK. I rode it 15 miles to work today with no trouble. I'm sure the piston and maybe the rings has some scratches. My question is should I tear it back down or just ride it? I'm a little tired of working on it for the moment. Thanks in advance for your input.
|
|
|
|
Post by whitelinewarrior on Apr 9, 2012 8:21:55 GMT -5
After reading some other posts it may have been my vaccum petcock the first time. It was in a long strech where I had it pretty well at WOT for a while. It may have just starved it for gas.
|
|
|
|
Post by 90GTVert on Apr 9, 2012 14:18:20 GMT -5
Could be. Could be the jetting or an air leak. Coulda been an oil issue. I've continued to ride after soft seizing plenty of times. Obviously it's safest to check it out, but as long as you fix the cause of the seize, you'll probably be alright. I'm kinda surprised it runs strong at 110-120psi.
|
|
|
|
Post by whitelinewarrior on Apr 9, 2012 14:31:33 GMT -5
What psi do I want 90GTVert? I need to raise the jug a bit to uncover everything at BDC anyway and can deck the jug and/or shave the head, no problem.
|
|
|
|
Post by 90GTVert on Apr 9, 2012 15:12:45 GMT -5
I like to see another 20-30psi anyway. I know the rings were getting bad on one of mine and it dropped from 150 to 120. It was an obvious difference in performance. Felt weak at 120.
|
|
|
|
Post by whitelinewarrior on Apr 9, 2012 15:16:52 GMT -5
Thanks 90GTVert. Got some new rings on the way. Hope that's all it is.
|
|
|
|
Post by whitelinewarrior on Apr 11, 2012 13:41:39 GMT -5
Ok, re-checked my compression using the method in your video and had 135 psi then measured the squish and got exactly .080. Should I try and tighted up the squish to .05-.07 as outlined in A. Graham Bell's book or just call it good as is? It's stock, 49cc.
|
|
|
|
Post by 2strokd on Apr 11, 2012 14:58:37 GMT -5
Sounds good to me.. Is it even a squish style head?
|
|
|
|
Post by whitelinewarrior on Apr 11, 2012 15:40:14 GMT -5
I thought it was 2strokd, idk, kinda new to this stuff. It's the 50cc two-stroke 1E40QMB Minarelli JOG type engine in a Moskito RX.
|
|
|
|
Post by 2strokd on Apr 12, 2012 7:17:37 GMT -5
Either way i guess what you did is going to help. Might see more gains with a squish style head.? Thats the only reason i asked. Here is a standard head.  Squish style head.  |
|
|
|
Post by whitelinewarrior on Apr 12, 2012 7:55:44 GMT -5
Ok, it's standard then. A squish is better right? Where can I get one? I've been getting stuff from Scrappy Dog Scooters but didn't see one on their site.
|
|
|
|
Post by 2strokd on Apr 12, 2012 12:14:48 GMT -5
Good question! I dunno exactly for a 39-40mm bore. This one came on a scooter i bought.
I think some come stock with these heads?.
|
|
