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Post by mxmatt on Apr 30, 2016 17:59:28 GMT -6
From the way you describe what is happening I think its a bad THERMOSTAT so I would FIRST put in a new thermostat, it appears to me that sometimes it opens at the right temp and other times not so when it does not you get overflow. Alleyoop Did you mean to respond to s different thread here? |
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Post by mxmatt on Apr 30, 2016 11:53:29 GMT -6
Final Post!!!
Sorry for the bump guys. It's been a while. A huge thank you to all of those who helped me with this. At long last I believe I found and have fixed the overheating problem on my 250 Roketa 244cc.
I am posting this because in my attempt to find the solution to this problem I found almost no information about what fixed it.
After burping it for days, replacing a fully functioning thermostat and radiator cap, adjusting the idle, testing the electrical system, fan, temp gauge, water pump impeller, hoses and every other suggestion purposed on this thread, it turns out it was the head gasket. I suspected this early on but really didn't want to believe it was because I couldn't believe a four month old scooter that was babied and serviced to perfection (I have the records) could have a bad head gasket. Nevertheless it was. I replaced it over a month ago, but do to my busy schedule did not get the scooter back together until this week. I have now put 200+ miles on it and at least 100 on the freeway at 95% throttle. It never even came close to heating up and there are no more air bubbles in the cooling system. The following is what I experienced.
1) At 3500 miles. It was a cool AZ November night 2014. I rode it for 20 miles on the freeway (65mph) to buy some tickets to a game. On the return ride home, for the first time ever, I noticed my foot was covered in coolant and then saw the temp gauge redlined. I pulled over and let it cool down, added some water and then limped home. It kept heating up.
2) I drained and replaced coolant and proceeded to burp it. (Ultimately I did this a hundred times) It seemed to be ok, but if I got on the highway it would overheat. If I kept it under 45mph it would stay cool for 5-10 miles but eventually overheat. I would repeatedly refill and burp and try everything suggested on this thread to fix the problem. It did not work.
3) Symptoms include never being able to get all the air out of the system. Bubbles in the coolant tank and in the radiator cap cup. Coolant coming out of the overflow bottle. Repeated overheating no matter what you replace, adjust or test. There was no coolant in the oil and no oil in the coolant. *I don't know it it is related, but my muffler turned into a terrible rattletrap a month earlier and I'm wondering if some loose baffling plugged or restricted the exhaust causing back pressure.
4) This is not an easy fix! If you have no experience with engine repair, have someone who does do this for you. I don't recommend doing it without a manual. Form start to finish (body removal, disassembled, replace gasket and install, reassembly) over several days I'd estimate it took me 10-15 hours. I am not a professional, but I have rebuilt a 150 GY6 in the past. If you have an older bike with high miles, I'd replace at least the rings too. My piston and rings looked amazing (maintenance does a motor good).
5) I ordered the gasket on eBay for around $10.
I hope this post serves someone useful. Message me if you want more information or have questions.
I'm so excited to be back on the road. I should be back on this site more now as well. I've missed you guys!
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Post by mxmatt on Mar 21, 2016 1:19:33 GMT -6
I just replaced the head gasket on my scoot. I'll put it all back together as soon as I can and give an update. *crossing my fingers*
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Post by mxmatt on Nov 28, 2015 14:02:03 GMT -6
Well I figured out my brake issue. I had let a little Sil-Glyde slide lubricant from NAPA get on the brake cylinder and it caused it to hang once it heated up. Did a complete teardown and rebuild of my caliper and walls! Running perfect for over a month now.
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Post by mxmatt on Jul 1, 2015 16:37:35 GMT -6
I have the same issue with my Jonway 250. I am just curious, but have you changed the original brake fluid and do you notice if you have a hanging brake at all?
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Post by mxmatt on Mar 6, 2015 23:09:18 GMT -6
Ok, it's over heating. We are guessing that it's over heating because it's losing fluid. Do we know 100% FOR SURE where the fluid is escaping from? If not, then run the dye test and find out. If we do know 100% for sure where it's leaking at, then we need to know that. So.... Because this thread has gone so long and back and forth, please do the following; 1. Stop any guessing. *Sounds good* 2. Run the dye test (if we don't know 100%) *where do I get this stuff* 3. Give us the specs on the Rad cap. Rating #'s and the like. *16 lbs* 4. Give us an updated run down on what's been done. *replaced thermostat, tested old and new thermostats, both working, removed radiator and all hoses, flushed them and used compressed air to blow them clean/dry, burped the thing silly a million times, I can not detect any coolant escaping other than from the reservoir cap, scoot stayed cool for 3400 miles, even in brutal AZ heat but during a freeway ride last fall in cooler temps it started overheating and blowing coolant out of the reservoir cap, seems to do this when traveling at higher speeds on highway, around town under 45mph it doesn't heat up that I can detect, fan is completely operational, comes on at quarter reading and is on during overheating* 5. Post some pix so we can see what is going on. *I will when I get back* 6. Bypass the carb heater lines and eliminate it from the equation. *instructions please* There is too many ideas floating around and you've tried to check them in a fashion, but lets just do it once from the get go and diag this thing correctly. It's just possible it's a hunk of road debris keeping the fan from running. So, let's start at the top. Replies in your text above. |
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Post by mxmatt on Mar 6, 2015 22:56:13 GMT -6
Lets solve this once and for all. Get some black light dye and add it to your system. Run the thing around the block a few times till it overheats and then shine a black light in there and see where the frickin leak is coming from. Once we know that, we can decode why it's leaking. Where do I get said black light dye? I'm going to be outta the country for a week so I'll respond if I get wifi service where I'm at. |
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Post by mxmatt on Mar 5, 2015 21:57:05 GMT -6
It's not the radiator cap!!!!!  I'm about to lose my freaking mind! HOW DO YOU KNOW THAT?? DID YOU TEST THE CAP? No, but I doubt that both caps I've used have the same problem |
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Post by mxmatt on Mar 5, 2015 19:35:46 GMT -6
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Post by mxmatt on Mar 5, 2015 12:44:59 GMT -6
Lets solve this once and for all. Get some black light dye and add it to your system. Run the thing around the block a few times till it overheats and then shine a black light in there and see where the frickin leak is coming from. Once we know that, we can decode why it's leaking. It doesn't leak. It overheats. Pressure escapes from the overflow tank. |
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Post by mxmatt on Mar 4, 2015 22:20:17 GMT -6
Anyone had any experience with a faulty radiator cap? Doesn't it work like the thermostat?
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Post by mxmatt on Mar 4, 2015 12:57:49 GMT -6
I've gotten rid of the bubbles. In fact as long as I don't ride it hard, temp gauge reads great. Once I get on it for a little while I get intermittent cooling and a full reservoir. I think the cap is weak and letting fluid out too easily.
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Post by mxmatt on Mar 4, 2015 12:41:21 GMT -6
Sorry for the bump. So I haven't been riding my scoot since November when I stalked out on diagnosing my overheating problem. It was my daily motive transportation until then. So last Sunday I finally got around to pulling out the radiator and checking all of the hoses and the water pump.I found no obstructions whatsoever the impeller looked impeccable and there was nothing visibly wrong with the cooling system that I could detect. I blew the lines clean and reversed wash the radiator 20 times. I put it all back together and I'm still having the same exact problem.The cooling fan works. Both the original and new thermostat function properly. So guess what I am concluding? How long is a radiator cap supposed to last on these Chinese scoots? |
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Post by mxmatt on Nov 14, 2014 0:07:08 GMT -6
Thanks boys. I'll get on that. Do I have to take all the plastics off to do this job?
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Post by mxmatt on Nov 13, 2014 15:15:30 GMT -6
Yes. The top is hot the bottom is just warm. |
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? And again at 2033mi. 
