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Post by captincvmn on Sept 29, 2022 20:12:43 GMT -5
Well, Sunday went for a ride, temps in high 200°’s. Around 270°, soft seize (maybe) at the end of a long uphill. Either way it shut off. I let it sit roadside for 3-4 minutes. I thought that’s bullshit, I had upjetted, it wasn’t hitting high RPMS, hanging around 8k, could it be fuel starvation again? It started, felt down on power, I went home.
FF to tonight. Pulled the bowl drain, ran 30 second drain test. Less than 75ml in 30 seconds. Still that should be enough to get me up a long full throttle grade. There’s no way I’m using 75ml in a 30 second period of full throttle. I’m not running a Top Fuel Funny Scooter. Swapped jet down to a 77 from a 79. Takeoff felt better, didn’t bog (as bad) when clutch engaged but it still isn’t that nice smooth entry into takeoff, it ramps up, engages, drops out of power and then eeks back into it. Not ideal. Went for a ride of the same path as Sunday. It’s cooler out today. I didn’t get as far before it shut down on my again. Temps were 260-275°F? First thought was fuel but I did try to kick it right away this time but no dice. I had to let it sit for 5 minutes before it would go. It started very hard and was down on power again to ride away. Rode more, back toward home. Past home, around a lap where there is a longer uphill grade. Made that hill no issue. Made a second lap. This time wider throttle setting, go to top of hill and throttled back to turn into my road. It died.
I did a little walking. Coasted down towards my house, 4mph in the dark. After 5 minutes it did start back up.
Rode into garage and shut it off. Disgusted.
Is it normal for temps to climb quickly after the motor stops while riding full throttle? It jumps from a steady 260-270° up to 360°ish within a minute of motor death.
What am I doing wrong with this thing. I no longer feel confident to ride it very far from home.
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Post by captincvmn on Sept 29, 2022 20:13:27 GMT -5
 30 second drain through carb bowl |
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Post by hippo008 on Sept 29, 2022 21:14:45 GMT -5
Well, Sunday went for a ride, temps in high 200°’s. Around 270°, soft seize (maybe) at the end of a long uphill. Either way it shut off. I let it sit roadside for 3-4 minutes. I thought that’s bullshit, I had upjetted, it wasn’t hitting high RPMS, hanging around 8k, could it be fuel starvation again? It started, felt down on power, I went home. FF to tonight. Pulled the bowl drain, ran 30 second drain test. Less than 75ml in 30 seconds. Still that should be enough to get me up a long full throttle grade. There’s no way I’m using 75ml in a 30 second period of full throttle. I’m not running a Top Fuel Funny Scooter. Swapped jet down to a 77 from a 79. Takeoff felt better, didn’t bog (as bad) when clutch engaged but it still isn’t that nice smooth entry into takeoff, it ramps up, engages, drops out of power and then eeks back into it. Not ideal. Went for a ride of the same path as Sunday. It’s cooler out today. I didn’t get as far before it shut down on my again. Temps were 260-275°F? First thought was fuel but I did try to kick it right away this time but no dice. I had to let it sit for 5 minutes before it would go. It started very hard and was down on power again to ride away. Rode more, back toward home. Past home, around a lap where there is a longer uphill grade. Made that hill no issue. Made a second lap. This time wider throttle setting, go to top of hill and throttled back to turn into my road. It died. I did a little walking. Coasted down towards my house, 4mph in the dark. After 5 minutes it did start back up. Rode into garage and shut it off. Disgusted. Is it normal for temps to climb quickly after the motor stops while riding full throttle? It jumps from a steady 260-270° up to 360°ish within a minute of motor death. What am I doing wrong with this thing. I no longer feel confident to ride it very far from home. I have had this problem on my Honda Dio 120cc stroker. In my case I had a lean condition at WOT because my vacuum pulse fuel pump wasnt pumpin'. It felt rich at WOT but I was getting high CHT and engine shutoff. It seems to me your jetting is in order, you richen up the main and you get a sputtering low power ride. You have leak tested and the motor passes. Could your carburetor bowl be running dry at WOT? Your tank can't flow enough into thr bowl to keep up? Could your exhaust gasket be leaking and air is being pulled in your exhaust port? I think you should start looking into unorthodox problems at this point. It seems like all your major bases are covered. I've seen some funky issues come from spark and ignition problems very similar to Brent's most recent video. I have had sparkplug and boots cause all kind of hard to diagnose problems like rich feeling at WOT but high CHT. You've done spark tests but are you 100% sure you're running the correct plug with a known good ignition source? Poor boot connection? Improper gap? Maybe grab a couple copper NGK plugs, gap em real small at .012" and let her rip. |
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Post by 90GTVert on Sept 29, 2022 23:07:06 GMT -5
Is it normal for temps to climb quickly after the motor stops while riding full throttle? It jumps from a steady 260-270° up to 360°ish within a minute of motor death. This is more common with coolant temp, because coolant flow stops so the coolant around the sensor is soaking up heat from the engine and not circulating to cool. A similar thing could happen with some CHT setups. If they experience much airflow during operation, the lack of airflow could cause the readings to be higher. I've noticed variations in CHT readings with different gauge and sender combos that I assume to be at least partially related to airflow exposure. The cylinder head itself should not be heating up after shutdown. |
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Post by captincvmn on Sept 30, 2022 6:55:44 GMT -5
I’m wondering if ring gap is too small causing heat bind under loaded conditions. I know what I’ll be doing this weekend. Tear down.
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Post by hippo008 on Sept 30, 2022 11:59:37 GMT -5
Thats an interesting theory. I have not heard of such an engine failure before but I dont see why its not possible. I would imagine the ring gap would have to be non-existent for that to happen though.
I wonder if your premix could be adding to your problems. I know at one point you were running 927 Castor or similar. As you already know that Castor will really gum things up unless you are pushing your engine HARD all the time. Maybe swap to a full synthetic alternative. I have used Belray Si-7, Motul 710, Motul 800, Amsoil Dominator, Klotz and liked them all.
EDIT:
This is a rarer problem but I have had it happen so I figured I should share. I have had an ignition coil and ignition boot start arcing to ground at higher temperatures. It was an intermittent problem that was really hard to track down, but it sounds pretty close to what youre experiencing. I would start the bike no problem but after a short time on the road it would start acting up with a rich sound but higher temps and it would randomly die at RPM. After a few minutes of sitting it would fire up again and be OK.
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Post by captincvmn on Sept 30, 2022 15:01:15 GMT -5
Hot coils are known to fail. Mine seems to be cylinder heat related though. Coil is mounted on frame highish above the engine.
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Post by Zino on Sept 30, 2022 16:55:35 GMT -5
I had a small head gasket leak that eventually blew .
First clues it was harder to start and my low and mid range power was down my top end was okish .
Small dark residue near one corner of cylinder head.
My temps did not spike as dramatically as yours when the head gasket fully failed but they did jump 50 degrees .
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Post by captincvmn on Oct 1, 2022 14:51:38 GMT -5
Nope. It’s toast.
When the rings stuck it scared up the cylinder walls. It won’t make good compression. It’s done for. I’m looking for my best options right now. Scooter Attack prices are very good until you add shipping.
I can get a new piston and hone the bore up. By then I’m almost up to a cylinder set. Aggravating that I’ve gone down this road yet again. I’m considering getting a new stage6 piston and honing my street/race cylinder and using my polini head. The stage6 head got a wrist pin needle ran through it.
Weighing my options.
Shoot, even Motoforce has a cast iron 70cc set that rivals Naraku but comes with a head. Maybe I’m not meant to go fast or far. Airsal makes a cheap aluminum 70cc set.
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Post by aeroxbud on Oct 1, 2022 15:36:22 GMT -5
That sucks Rob.
I know what you mean about prices of kits. The piston, rings, bearing and gasket were not far off the whole cylinder kit price for my aerox. So I just got a complete kit.
You could always get the motor force kit and port it a little. That's what I have done.
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Post by 190mech on Oct 1, 2022 16:03:27 GMT -5
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Post by captincvmn on Oct 1, 2022 17:06:51 GMT -5
What’s the worst that could happen right?
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Post by captincvmn on Oct 1, 2022 18:32:51 GMT -5
Generic slug ordered.
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Post by captincvmn on Oct 1, 2022 18:36:59 GMT -5
If the piston ring gaps line up with the holes in the bore I’ll drill holes and put new roll pins in.
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Post by aeroxbud on Oct 1, 2022 18:37:13 GMT -5
She will raise up again.👍
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