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Post by sai on Jun 18, 2015 22:28:04 GMT -5
I have a Super 8 2T that's been modified to racing specs. Here's the detailed problem, please help:
1. Ever since I brought it to sportique, it's been making my spark plug black and even died in the middle of the road . Had to use a new dry plug to get home.
2. Happened again 1 time randomly and it's not happen again since. 3. SPortique washed my new air filter with Dawn and the performance dropped. 4. I washed it with carb cleaner and the power and speed dropped even more. 5. I went from main jet: 91 - 89 - 85 and the power hasn't returned at all , in fact it dropped even more.
6. A/F screw is STUCK, I can't screw it out and I'm not sure why. I saw a little white residue and I've been spraying it with PB blaster and no luck. I stripped the screw. Right now the screw is only 1/2 turn out.
7. Checked rollers, they are a little flat, but not bad I think. 8. When I start the engine the smoke is white with blue tint and finally clear. Once in a while if I open the throttle, I see clear / black smoke.
9. I opened the reed valve for the first time but the reed seater is stuck and I can;t pull it up. I can feel the reeds with my pinky though and they are flexing.
What the hell is going on here??? Right now I'm running at 38mph max while at 1/2 throttle I can already hit 40+mph.
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Post by Elektrey on Jun 18, 2015 23:05:15 GMT -5
if your going slower at full throttle than half throttle it sounds like your rich on your full throttle (WOT).
how does the plug look at the 85 Jet compared to 91?
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Post by sai on Jun 18, 2015 23:15:50 GMT -5
What I meant is normally at full throttle I get at least 50mph. But now I'm barely pushing 40mph.
The plug looks a little browner at 85 but today I changed it back to 89 because I know 85 is way too lean. I highly doubt it's the main jet at this point. The needle is also at 2nd leanest aka 2nd notch from the top.
What's going on with this bike...
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Post by 190mech on Jun 19, 2015 4:10:06 GMT -5
Ive had a few bikes over the years get richer and slower with time,its usually the airfliter is clogged beyond cleaning,installed new filter,power back,original jet reinstalled..Another possibility could be a stuck/worn piston ring..
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Post by 90GTVert on Jun 19, 2015 6:31:56 GMT -5
You've got quite a few miles on this one don't you? Any idea what compression is?
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Post by sai on Jun 19, 2015 8:11:01 GMT -5
Ive had a few bikes over the years get richer and slower with time,its usually the airfliter is clogged beyond cleaning,installed new filter,power back,original jet reinstalled..Another possibility could be a stuck/worn piston ring.. As I mentioned above, the air filter is brand new and it's been washed 2 times. Dawn and carb cleaner.
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Post by sai on Jun 19, 2015 8:12:23 GMT -5
You've got quite a few miles on this one don't you? Any idea what compression is? I don't have a compression tester but I can borrow one. The cylinder and piston were only 1 year old at most (7000 miles on it I believe), I seized the old one in 2014. Isn't it too early to have a low compression on this? Any other clue?
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Post by 90GTVert on Jun 19, 2015 9:07:03 GMT -5
Not really. You could definitely be at risk for ring issues with that many miles on a 2T.
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Post by sai on Jun 19, 2015 9:35:00 GMT -5
I need the bike to get to places today, but I'll open up the BBK in the afternoon and check if there's something wrong with them.
If they look fine, what's the next step? Also, what's the compression numbers should be?
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Post by 90GTVert on Jun 19, 2015 10:01:33 GMT -5
You want to see at least 120psi if it's going to run well. 150psi+ generally for a strong runner. Knowing what compression numbers really should be requires checking it when it's first built. Then you always have a reference of your setup.
If the rings aren't stuck or damaged you can check end gaps. Sometimes mine run well enough even beyond a service limit so while technically they should be replaced if compression is good it's prob not the issue.
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Post by sai on Jun 19, 2015 10:04:25 GMT -5
What are end gaps? And if the compression is below 120 does this always mean it's the rings? Is it ok to ride it while I wait for the rings to be replaced if it's indeed rings?
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Post by 90GTVert on Jun 19, 2015 10:16:17 GMT -5
It wouldn't have to be rings for the compression to be below 120psi, but with a 2T it's common as well as head gasket leaks. You'd likely hear it now if the head gasket leaked or at least see evidence of the leak when you take the shrouds off. It can heat up and a piston crown starts caving in but doesn't form a hole so it totally fails. That will also be obvious if the head is off. Could be issues with the bore and you should be able to see that it's in rough shape if that's a problem. I'm not sure on the exact service limit on the end gaps, but I'd guess roughly 0.030". If you meant what are they and not what's the spec : you can move on to setting the piston ring end gaps. Piston ring end gap is the distance between the two ends of a piston ring while in the cylinder's bore. Improper settings can lead to poor sealing or excessive wear. Piston ring end gap should be 0.10-0.12mm per inch of bore according to A. G. Bell's book, Two-Stroke Performance Tuning. Since most scooter big bore kits are measured in mm, we first need to determine the bore size in inches. This is done by dividing the bore diameter by 25.4. 47(mm) / 25.4 = 1.85039" Bore Diameter i usually multiply the median number from Bell's equation (0.11), by the bore diameter. 1.85039 x 0.11 = 0.20354mm End Gap If you wish to use SAE feeler gauges, you can convert the end gap figure in mm by 25.4 to get the end gap in inches. 0.20354 / 25.4 = 0.008" End Gap Begin by placing a piston ring into the cylinder as shown. Use the piston to make sure the ring is level inside the bore to get an accurate measurement. Place a feeler gauge in the end gap. If the gap is smaller than the desired gap you calculated, remove the ring from the cylinder and lightly file the ends. Re-install and re-check the end gap until it is correct. If the gap is too large you can either try to use a new ring or if it's very close, don't worry about it. Repeat that process on the second ring, if your kit has 2 rings. If it's running then I guess you can ride it. Obviously you're at greater risk of a potential issue (breakdown) riding a scoot that's less than 100%.
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Post by niz76 on Jun 19, 2015 15:30:08 GMT -5
I have been a Maintenance Supervisor for property Management Co.s for years now (apartment complex(es)). One of the huge parts of my job is A/C mtc. and repair. Imagine trying to keep 200+ residents happy in the hot FL summer and you get some of the magnitude of the job haha. -And the A/C's are just the tip of the iceburg! Being a Mtc. Super is kinda stressful- I wouldn't suggest it. lol. Anywho- over the years I've trained lots of guys and I always tell them that when it comes to A/C calls I'd much rather be working on an AC that is broken and won't work than to troubleshoot one that's "Not working good enough." With something that's just simply not working you might find the problem, fix it, and badaboombadabing it's working again and all are happy. With something that's "not working good enough- or good as it used to." well that's where it becomes a huge PITA because you have to have lots of experience and check over EVERYTHING! You gotta test everything- make sure everything is working up to it's full potential- not just spot one problem and fix it... I guess my point is, it's probably going to be way more work inspecting everything and getting it tuned back to 100% than it would be to just simply find the one thing wrong that's making it not work...
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Post by thatcrazyguy on Jun 19, 2015 21:41:16 GMT -5
I suggest not driving your scoot, I had same problems my friend, and the final result was an hour tow to no76's house to split cases and pull the shattered piston and cylinder out check compression and replace those rings asap!!!!
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Post by Sitticuss on Jun 19, 2015 22:08:34 GMT -5
It's time for a new top end and reeds. You've got 7k on it. These little engines will run forever before the compression is to low for them to start usually before then It's KABLAMO and your walking. I run mine hard and at 5k miles I just swap the top end out. Their not that expensive. If you go to the trouble of just inspecting the piston your like 15 minutes away from just tossing and replacing it. A couple taps with a RUBBER mallet will free a stuck intake.
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