08-11-2022, 04:15 PM | #1 |
Join Date: May 2022
Location: Hampton
Posts: 12
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Lost power at 55mph
So I went for a ride last Sunday I had been riding for about 30 mins so everything was nice and warm. I was doing about 55mph the throttle was at about 90%. Then all of the sudden it was like it was slowly losing power, I dropped the clutch rolled off then on the throttle came back to life. It did it again about 2 mins later so I turned around went home. Everything seemed ok it had about 75% of the tank of fuel. But earlier that week I had to turn up the idle to about 1250 or it felt like it was barley running. I did the valve lash about 900 miles ago and aside from this it had been running pretty well. According to the manual you only adjust every 3000km or 1800 miles i German spec’d
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08-11-2022, 04:18 PM | #2 |
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Join Date: Oct 2016
Location: Houma, La.
Posts: 11,708
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Recheck the valve clearance.
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08-12-2022, 04:46 AM | #3 |
Join Date: Oct 2020
Location: Flower Mound Texas
Posts: 904
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Might check your spark plug. Actually I'd replace it either way.
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08-12-2022, 10:09 PM | #5 |
Join Date: Oct 2021
Location: odessa MO; donna TX
Posts: 152
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Fuel contamination?
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08-15-2022, 11:04 AM | #6 |
Join Date: May 2022
Location: Hampton
Posts: 12
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So I redid my valves, the spark plug isn’t more than 1500miles old but looked good I replaced it after 500 miles, had a good burn color. Fuel cap gasket looked good. It might have been the valves but I have had a moment to open it up for a long period to see if it does it again. Thank you for the help
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08-15-2022, 11:17 AM | #7 |
Join Date: Mar 2021
Location: Ohio
Posts: 43
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As a motorcycle mechanic, that symptom is usually one of three things...a leaking vacuum petcock diaphragm, a failed tank cap vent, or a pinched fuel line starving the carb of fuel at WOT.
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08-15-2022, 11:18 AM | #8 |
Join Date: Apr 2017
Location: Omaha, NE
Posts: 8,100
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idle should be 1500rpm since nobody else stated so.
As for your issue - if it does the same thing again open the fuel cap immediately and see what happens. The fuel cap vent may be sticking shut and not preventing a vacuum buildup in the tank.
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08-17-2022, 12:11 PM | #9 | |
Join Date: Jan 2020
Posts: 277
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Quote:
We can rule out one big one on most of these Chinese bikes, as they have mechanical slide carbs and thus no diaphragm. I had a similar-ish issue on my Bashan that turned out to be the float height being set hella low from the factory, though. So that's something to check. Genuine imported Chinese sediment in the fuel tank blocking the screen on the pickups on the petcock is a possibility, as well. Typically these are pretty easy to remove and hose off with carb cleaner or similar. With the petcock removed and its mounting hole open, you can swish out any crud in there with a little gasoline or, if you're less brave, kerosene. Preferably directly into your fire pit or burn barrel. |
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08-17-2022, 12:50 PM | #10 |
Join Date: Mar 2021
Location: Ohio
Posts: 43
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Wasn't referring to the carb, I know they're not CV carbs...I was referring to a vacuum petcock...if the diaphragm inside is torn or otherwise leaking you'll have fuel starvation at WOT when vacuum is weakest. I'm not the world's foremost expert on Chinese bikes so I don't know if any are equipped with vacuum petcocks or not but it's worth a mention.
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08-17-2022, 02:53 PM | #11 |
Join Date: Jan 2020
Posts: 277
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Gotcha. Yeah, none of the Chinese bikes I've seen have a vacuum petcock, either. Manual only. (It's cheaper that way, I'm sure.)
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