Just can’t get it to run right

GaryF11 · 05-13-2023, 07:49 PM

Well this is probably my last post on this site because I’m about to give up and sell this bike… I have a 2021 rps hawk 250 with every mod done possible besides the big bore kit and porting the head other than that it’s fully modded. It ran perfectly fine up until about 2 months ago when I started having little issues here and there but most of the time they would go away on they’re own I just assumed it was the weather changing. We’ll fast forward to today and I just cannot get the thing to run right ever. Normally I would top out around 73 mph and could cruise at 55-60 comfortably now I struggle to even hit 61 most days and never see over 65 hard to cruise at 55 and it idles poorly most of the time will die if I open the throttle too fast and all of these issues ride to ride, for instance I can ride it somewhere and it run fine but next ride only 20 min later it’ll run terribly. The worst issues I’m having are hard starts, when it’s windy the bike starts choking and wants to die, immediately after coming off full throttle if I try to open it again the bike does nothing no revs rpm’s don’t increase it’s like it’s off but it will randomly just pick back up about 2 or 3 seconds after, the speed issue is a big one, it’s way less peppy, and the spark plug keeps getting black. Now before you start throwing suggestions let me tell you what I have tried which is pretty much everything. I have adjusted the valves to multiple different clearances, changed the filter twice, tried using a fuel filter, fully took apart my carb and cleaned it 3 times, messed with all the jet sizes that made sense, fixed my exhaust leak, changed the battery, changed the fuse to an actual fuse not one of the little glass tube ones, drained the gas tank cleaned it and refilled with fresh gas, and brand new spark plug. The jets I run are 35/125 in a nibbi pe28 fully open exhaust. The MAIN 2 issues are it being unresponsive after WOT and it just running very rough in general. I cannot for the life of me figure out what is happening it ran so good forever up until a few months ago and now it just will not run right at all this is my like 4th post addressing these issues and I just don’t know what to do at this point I’m about to give up and sell it… only thing I can think of really is maybe the cdi because it kinda does feel like a misfire sometimes but I cannot find a cdi that works for the bike anywhere online all of the ones that say they work in the reviews people say it doesn’t work so.

Big Bird · 05-13-2023, 09:09 PM

Have you tried a different carb?

GaryF11 · 05-13-2023, 09:24 PM

Quote:

Originally Posted by Big Bird

Have you tried a different carb?

I also have a PE30 and yes I’ve tried it bike still has the same symptoms actually little update literally just unplugged the cdi and plugged it back in and now I cannot go over half throttle or the bike starts doing unspeakable things

Big Bird · 05-13-2023, 09:42 PM

https://cscmotorcycles.com/zt10-106-...2016-up-tt250/

This might work.

GaryF11 · 05-13-2023, 09:51 PM

Quote:

Originally Posted by Big Bird

https://cscmotorcycles.com/zt10-106-...2016-up-tt250/

This might work.

Nope the smaller connector on my bike is rounded I appreciate you looking though

Big Bird · 05-13-2023, 10:01 PM

https://www.powersportsmax.com/produ...ducts_id/13010

Like this?

Oldenslow · 05-13-2023, 10:14 PM

For some reason, "I have thrown everything at it but the kitchen sink, now it don't work" is darned hard, if not impossible, to diagnose.

Big Bird · 05-13-2023, 10:16 PM

I normally wouldn't recommend the money bomb treatment but this stuff is so cheap on ebay you could probably replace all the ignition parts for $50.

Bikenut · 05-13-2023, 10:17 PM

I had very similar, actually almost exactly the same, symptoms with my Lifan KPR 200. Turned out to be a corroded battery post/connection. I see you changed your battery so perhaps your ground connection on the engine is bad. I don't know where the ground connects to the engine but you could follow the ground wire from the battery and check that connection too.

Cleaning the connection cleared up all the symptoms for my bike and is still running perfectly with almost 8000 miles on it. Hope this helps.....

GaryF11 · 05-13-2023, 11:17 PM

Quote:

Originally Posted by Big Bird

I normally wouldn't recommend the money bomb treatment but this stuff is so cheap on ebay you could probably replace all the ignition parts for $50.

I replace my ignition coil already with a nibbi one and my spark plug is an ngk iridium and my spark plug boot is a resistorless ngk boot so it’s all replaced pretty much

GaryF11 · 05-13-2023, 11:17 PM

Quote:

Originally Posted by Bikenut

I had very similar, actually almost exactly the same, symptoms with my Lifan KPR 200. Turned out to be a corroded battery post/connection. I see you changed your battery so perhaps your ground connection on the engine is bad. I don't know where the ground connects to the engine but you could follow the ground wire from the battery and check that connection too.

Cleaning the connection cleared up all the symptoms for my bike and is still running perfectly with almost 8000 miles on it. Hope this helps.....

I have not checked that ground but I will tomorrow for sure I know the connections on the battery aren’t bad but I didn’t think about looking through all the wires for bad connections or corrosion

Thumper · 05-14-2023, 10:11 AM

It sounds to me like carb adjustment issue. Have you drilled the fuel/air mixture screw cap? If not, there is a reasonable chance that if you enrich the mixture slightly, things may get much better. That airmix screw CAN make a huge difference.

Mine was set way too lean and was causing all sorts of coughing, popping, even shut down. I thought it was electrical. But I adjusted the thing and WOW, perfectly well behaved now.

Megadan · 05-14-2023, 10:16 AM

Quote:

Originally Posted by Thumper

It sounds to me like carb adjustment issue. Have you drilled the fuel/air mixture screw cap? If not, there is a reasonable chance that if you enrich the mixture slightly, things may get much better. That airmix screw CAN make a huge difference.

Mine was set way too lean and was causing all sorts of coughing, popping, even shut down. I thought it was electrical. But I adjusted the thing and WOW, perfectly well behaved now.

he has a Nibbi PE carb on it.

Thumper · 05-14-2023, 01:06 PM

Yes...

So on the Nibbi PE carb, it is located just above the float bowl gasket on the same side as the slide height screw (idle adjust). It is that brass flathead screw on the left just above the float bowl:

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Quote:

Originally Posted by Megadan

he has a Nibbi PE carb on it.

GaryF11 · 05-14-2023, 02:25 PM

[QUOTE=Thumper;394712]Yes...

So on the Nibbi PE carb, it is located just above the float bowl gasket on the same side as the slide height screw (idle adjust). It is that brass flathead screw on the left just above the float bowl

What do you mean by drill it? If you just mean adjust it then yes I’ve tried adjusting it numerous times I pretty much have to mess with that screw everyday to get it to run but as of this moment I just went though and tightened all the grounds and still runs bad it’s only in high rpm’s on the main circuit and some on the needle but when I full throttle it almost feels like it just runs out of fuel the best way I can describe it is if I hold full throttle it’ll go for a few seconds and die out and BOOM pick back up for a few seconds and die then BOOM it picks back up again and it’ll keep going that as long as I hold full throttle but it works fine other than that also if at idle I snap the throttle open really fast it’ll die I really wish I had a better way to describe the problem I’m having but it’s very difficult I’ve tried going to a smaller main jet and still does the exact same thing I’ve tried a larger main jet and it’s even worse all around

05-13-2023, 07:49 PM	#1
GaryF11 Join Date: Oct 2022 Posts: 43	Just can’t get it to run right Well this is probably my last post on this site because I’m about to give up and sell this bike… I have a 2021 rps hawk 250 with every mod done possible besides the big bore kit and porting the head other than that it’s fully modded. It ran perfectly fine up until about 2 months ago when I started having little issues here and there but most of the time they would go away on they’re own I just assumed it was the weather changing. We’ll fast forward to today and I just cannot get the thing to run right ever. Normally I would top out around 73 mph and could cruise at 55-60 comfortably now I struggle to even hit 61 most days and never see over 65 hard to cruise at 55 and it idles poorly most of the time will die if I open the throttle too fast and all of these issues ride to ride, for instance I can ride it somewhere and it run fine but next ride only 20 min later it’ll run terribly. The worst issues I’m having are hard starts, when it’s windy the bike starts choking and wants to die, immediately after coming off full throttle if I try to open it again the bike does nothing no revs rpm’s don’t increase it’s like it’s off but it will randomly just pick back up about 2 or 3 seconds after, the speed issue is a big one, it’s way less peppy, and the spark plug keeps getting black. Now before you start throwing suggestions let me tell you what I have tried which is pretty much everything. I have adjusted the valves to multiple different clearances, changed the filter twice, tried using a fuel filter, fully took apart my carb and cleaned it 3 times, messed with all the jet sizes that made sense, fixed my exhaust leak, changed the battery, changed the fuse to an actual fuse not one of the little glass tube ones, drained the gas tank cleaned it and refilled with fresh gas, and brand new spark plug. The jets I run are 35/125 in a nibbi pe28 fully open exhaust. The MAIN 2 issues are it being unresponsive after WOT and it just running very rough in general. I cannot for the life of me figure out what is happening it ran so good forever up until a few months ago and now it just will not run right at all this is my like 4th post addressing these issues and I just don’t know what to do at this point I’m about to give up and sell it… only thing I can think of really is maybe the cdi because it kinda does feel like a misfire sometimes but I cannot find a cdi that works for the bike anywhere online all of the ones that say they work in the reviews people say it doesn’t work so.
	0

05-13-2023, 09:09 PM	#2
Big Bird Join Date: May 2020 Location: California Posts: 169	Have you tried a different carb? __________________ 2020 Boom Vader Gen 2 2019 CSC TT250 2021 Kayo Fox 70
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05-13-2023, 09:42 PM	#4
Big Bird Join Date: May 2020 Location: California Posts: 169	https://cscmotorcycles.com/zt10-106-...2016-up-tt250/ This might work. __________________ 2020 Boom Vader Gen 2 2019 CSC TT250 2021 Kayo Fox 70
	0

05-13-2023, 10:01 PM	#6
Big Bird Join Date: May 2020 Location: California Posts: 169	https://www.powersportsmax.com/produ...ducts_id/13010 Like this? __________________ 2020 Boom Vader Gen 2 2019 CSC TT250 2021 Kayo Fox 70
	0

05-13-2023, 10:16 PM	#8
Big Bird Join Date: May 2020 Location: California Posts: 169	I normally wouldn't recommend the money bomb treatment but this stuff is so cheap on ebay you could probably replace all the ignition parts for $50. __________________ 2020 Boom Vader Gen 2 2019 CSC TT250 2021 Kayo Fox 70
	1

05-13-2023, 10:14 PM	#7
Oldenslow Join Date: Mar 2020 Posts: 153	For some reason, "I have thrown everything at it but the kitchen sink, now it don't work" is darned hard, if not impossible, to diagnose.
	2

05-13-2023, 10:17 PM	#9
Bikenut Join Date: Apr 2023 Location: Near Saginaw Mich. Posts: 178	I had very similar, actually almost exactly the same, symptoms with my Lifan KPR 200. Turned out to be a corroded battery post/connection. I see you changed your battery so perhaps your ground connection on the engine is bad. I don't know where the ground connects to the engine but you could follow the ground wire from the battery and check that connection too. Cleaning the connection cleared up all the symptoms for my bike and is still running perfectly with almost 8000 miles on it. Hope this helps.....
	0

05-14-2023, 10:11 AM	#12
Thumper Join Date: Feb 2021 Location: Kansas City Posts: 2,310	It sounds to me like carb adjustment issue. Have you drilled the fuel/air mixture screw cap? If not, there is a reasonable chance that if you enrich the mixture slightly, things may get much better. That airmix screw CAN make a huge difference. Mine was set way too lean and was causing all sorts of coughing, popping, even shut down. I thought it was electrical. But I adjusted the thing and WOW, perfectly well behaved now. __________________ -2022 5 speed Templar X Orange, OEM 51T rear sprocket, 14T front sprocket -NOS 2020 KTM 250SX (2-stroke motocross), less than 10 hours on it
	0

05-14-2023, 02:25 PM	#15
GaryF11 Join Date: Oct 2022 Posts: 43	[QUOTE=Thumper;394712]Yes... So on the Nibbi PE carb, it is located just above the float bowl gasket on the same side as the slide height screw (idle adjust). It is that brass flathead screw on the left just above the float bowl What do you mean by drill it? If you just mean adjust it then yes I’ve tried adjusting it numerous times I pretty much have to mess with that screw everyday to get it to run but as of this moment I just went though and tightened all the grounds and still runs bad it’s only in high rpm’s on the main circuit and some on the needle but when I full throttle it almost feels like it just runs out of fuel the best way I can describe it is if I hold full throttle it’ll go for a few seconds and die out and BOOM pick back up for a few seconds and die then BOOM it picks back up again and it’ll keep going that as long as I hold full throttle but it works fine other than that also if at idle I snap the throttle open really fast it’ll die I really wish I had a better way to describe the problem I’m having but it’s very difficult I’ve tried going to a smaller main jet and still does the exact same thing I’ve tried a larger main jet and it’s even worse all around
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