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Post by 90GTVert on Jul 31, 2016 12:23:23 GMT -5
The valve seals came in yesterday. I went out today to replace them. The plan was to hook up a leakdown tester to fill the cylinder with air so I could do the job without removing the head. That didn't go so well.
I checked the rockers and there's clearance, so no simple mistake causing it there. I didn't really mess with the head while it was apart. The engine will be coming back out.
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Post by 190mech on Jul 31, 2016 12:56:02 GMT -5
Could be some crud on the Ex valve seat,,we pull the rocker cover and tap the rocker while the tester has pressure on it,sometimes thats all thats needed to get a pass,if that doesnt do it,I run the engine a few minutes,then check it hot,then its teardown time if it fails...
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Post by 90GTVert on Jul 31, 2016 14:49:19 GMT -5
Thanks for the tips John.
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Post by 90GTVert on Jul 31, 2016 21:16:09 GMT -5
I tried tapping the rocker with lower pressure and it went up from just above 50/100 to 65/100. I fired it up for a minute and then redid the test. Much better. I was able to get the valve seals swapped out then.  I fired it up and it didn't smoke. I don't trust it though. Last time it didn't smoke, so I put the panels back on. Then it started smoking again. I'll try it again tomorrow a couple of times before I put the panels back on. Just in case it's of use to anyone not familiar with this; I used a leakdown tester to fill the cylinder with air. That allows air pressure to hold the valves in place so they don't fall into the engine when the keepers, springs, and retainers are removed. It allows you to swap out the valve seals without removing the cylinder head. Another method that some use is to put nylon rope into the cylinder with the piston down in the bore just a little, and then move the piston to TDC. The rope should keep the valves from moving. A leak down tester lets you see how well the cylinder/head are sealing by pumping in air from an air compressor. It's basically a couple of pressure gauges and a regulator as well as connections for a hose from an air compressor and a hose with an adapter to screw in where the spark plug normally goes. One gauge tells the the pressure passing through. This pressure is adjusted with the regulator. The other gauge tells you how much pressure is holding in the engine (assuming all fittings on the tester are secure). You're hoping to see both gauges match, so you you know the piston rings and valves are sealing well. If pressure is low, you can listen for where air is moving. If you hear or feel air moving from the exhaust, then your exhaust valve is not sealing. If air is moving through the intake, then the intake valve isn't sealing. If air is pushing through the crankcase, then the piston rings aren't sealing.   You can get them from auto parts stores, and maybe even tool loaner programs. Be aware of the spark plug thread size that your engine will need. My tester was from Summit and did not include the 10mm fitting, but I used one from a compression tester set to make it work. I wasn't intending to check for leaks. I only wanted to fill the cylinder with air to keep the valves from moving. You don't need the leak down tester for this. You could come up with an adapter for your air compressor's fitting that would allow it to hook to the spark plug hole and then use the compressor's or other regulator to control pressure. I removed the valve cover and rocker assembly to give me access to the valves. Since I would be pumping air into the cylinder, I used washers and nuts on 2 of the 4 cylinder studs to secure the head. Then I put about 50psi into the cylinder while it was at top dead center and removed the keepers, retainers, and springs using THIS METHOD. Actually, I had to use a socket with a magnet in it for the exhaust valve, because the frame was too close to fit the tool. I used spark plug pliers to grab the seals and remove them, then just gently pushed the new seals on by hand. Then I put it back together and adjusted the valves.   |
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Post by 90GTVert on Aug 1, 2016 8:46:53 GMT -5
I started the scoot this morning and it's back to smoking. Perfect. I figured I should have ordered rings when I ordered seals, but I was trying to be as cheap as possible.
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Post by 90GTVert on Aug 11, 2016 15:04:02 GMT -5
The new piston rings have been here for about a week and the engine has just been sitting on the workbench all together. I finally got some motivation to work on it today and swapped the rings. There was a mild gold tint in the intake port, but just near the valve. The exhaust port had oil all over it. There was probably a teaspoon of oil sitting on top of the piston. The old rings didn't appear obviously bad to me. They weren't terribly scuffed up and the end gaps were decent. I think the rings are the issue, but my other thought was a worn guide in the exhaust... mostly coming from paranoia thinking back to having to run that valve in a drill to notch the 58.5mm piston for clearance. It's much more likely to be the rings since the head hasn't changed this whole time, but the cylinder and piston have, but I seem to like to worry myself.
I put the engine in and fired it up and there was no smoke in 5 minutes of running and a little revving. I'm leaving it with wires hanging loose and so on till I start it again tomorrow. If it's fine then, I'll put it all back together.
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Post by 190mech on Aug 11, 2016 19:32:38 GMT -5
Most of the oil burning problems on 4T dirt bikes are usually the oil control ring taking a vacation.Those 3 piece oil rings really seem to be the ones that give the most trouble..Glad youve got it to quit smoking,thats a "no sale" item for most folks...
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Post by 90GTVert on Aug 12, 2016 15:02:07 GMT -5
I started it late last night, then again early this morning. It didn't smoke either time so I put it back together. I took it for a quick ride and again no smoke. It does have an exhaust leak. I didn't have any more of the good copper looking ring gaskets, so I used the metallic one that came with a gasket set. It's a little small and doesn't sound like it works very well. I've got some composite types left that should seal it for a little while before they disintegrate anyway.
I thought the 150 was slow as a 155 with tweaks, but I forgot what it was like stock. My max speed was 48MPH, with more like 40-45MPH cruising. The takeoff felt very slow, thanks to the lack of DrPulley variator as well. I may need to drop roller weight a little to get it going more quickly. The rear suspension sucks again with the bouncy stock shock.
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Post by iwannascoot on Aug 12, 2016 17:03:07 GMT -5
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Post by ryan_ott on Aug 12, 2016 18:01:00 GMT -5
I started it late last night, then again early this morning. It didn't smoke either time so I put it back together. I took it for a quick ride and again no smoke. It does have an exhaust leak. I didn't have any more of the good copper looking ring gaskets, so I used the metallic one that came with a gasket set. It's a little small and doesn't sound like it works very well. I've got some composite types left that should seal it for a little while before they disintegrate anyway. I thought the 150 was slow as a 155 with tweaks, but I forgot what it was like stock. My max speed was 48MPH, with more like 40-45MPH cruising. The takeoff felt very slow, thanks to the lack of DrPulley variator as well. I may need to drop roller weight a little to get it going more quickly. The rear suspension sucks again with the bouncy stock shock. Sounds like it's ready for craigslist, great!! Don't forget the China calibration to the vapor. |
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Post by 90GTVert on Aug 30, 2016 11:55:32 GMT -5
I did a small amount of tuning and gave it a 25 mile test ride a few days ago. Made a video the other day and finally listed it today. I had to cut the video down to 10 minutes because I was going over every detail and I figured no one would watch it. Prob too long now, but I'd love to see more people on craigslist going over details on video. Locals usually put a few photos and maybe a short paragraph, if they bother with more than 2 sentences and no pics. No speedo re-calibration or anything. Asking $750 OBO because I don't at all expect to get $750, but don't want to start it where I really want it to end up. Hopefully it doesn't scare people off, just thinking it's another diluted owner expecting near new prices. easternshore.craigslist.org/mcy/5757887502.htmlI'll probably sit it out in the yard at times as well. We've let other people sell boats and cars in the yard recently after craigslist ads went nowhere for them, because it's a high traffic road so hopefully one or the other will work. |
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Post by 190mech on Aug 30, 2016 12:03:09 GMT -5
Nice ad!!  |
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Post by 90GTVert on Aug 31, 2016 23:21:15 GMT -5
I have a guy that says he will pay me $500 tomorrow and really wants the bike. We'll see. He offered me $450 at first, telling me he's a war vet that needs transportation, and I just told him my bottom line of $500 and he jumped at it. That's what I expected to get out of it and I don't want to mess around with it for a long time, so hopefully it's not BS.
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Post by spaz12 on Aug 31, 2016 23:35:42 GMT -5
Lucky you. I've gotten one hit on my scoot  |
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Post by niz76 on Aug 31, 2016 23:52:09 GMT -5
Good luck with the sale! It's no fun waiting weeks or months for a scoot to sell so a quick sale is always nice.
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