Csc sg250 clatter

Tennessee22 · 10-01-2022, 04:01 PM

About a month ago, I bought a second hand CSC SG 250 with 6,000 mi on it that was well maintained. The clutch started slipping and grabbing, so I bought the parts from CSC and put a new clutch in. On startup, I got a loud clatter that is strictly related to engine speed. Clutching or not doesn't seem to affect it at all. I immediately shut it down and tore it back down, couldn't find a thing. I put it back together, rode it about 10 miles, no change to the noise it was making. I convinced myself that the clutch basket was probably looser after me trying to get everything out, so tore it down again. Managed to tighten up the rivets a little, got it back together, still have the clatter. I put new pressure plates in and checked every shaft and bearing I could find, yep, still have that noise. I can't find any signs of wear or problems other than the loud noise which started immediately after I changed the clutch. I even adjusted the valves. I've got a short video of the noise but I have not figured out how I'm going to get it online yet.

I did waffle three pennies in an effort to get the castellated nut off of the oil spinner. All the pennies are accounted for. The nut is supposed to be tightened at 60 ft lb, but this one took way over a hundred foot pounds of force to get loose.

Any ideas anyone? This is driving me crazy!

Tennessee22 · 10-01-2022, 06:42 PM

Just posted a YouTube of the noise,

"Loud knock after clutch replacement"

Tennessee22 · 10-01-2022, 07:43 PM

Link to short video:

Mudflap · 10-02-2022, 05:37 PM

Sounds like one click per 2 revolutions. If that is correct it could be an exhaust leak, something related to the cam, rockers, valves since they move at half of crankshaft RPM.

Jeffrey boy · 10-02-2022, 09:06 PM

How did you lock up the driveline to get the basket nut off. There is a tool for that clutch replacement. If you just torqued it in gear you may have damaged something internally.

**JerryHawk250** · 10-03-2022, 07:40 AM

I'm with Mudflap on this one. Sounds like an exhaust leak.

grumpyunk · 10-03-2022, 09:22 PM

That sound does not exactly follow rpm. When revved, the sound goes up, but when you let off the throttle, the sound continues even as the sound from the exhaust drops, IOW, the sound lags behind the sound of the exhaust. IMO.
The sound reminds me of something being loose on a shaft and wobbling around. It at the same time sounds as if something was being skipped on like a playing card in the spokes of a bicycle. Another example is teeth of something impacting or being impacted(touched) by something else. Definitely not at engine rpm. I would look at the assembly of the gears on the of the crankshaft. OI think one goes to balance shaft, to the spin filter, there is an idler that is trapped by the clutch basket. It may be possible to put an idler on reversed, in for out, and may have interference.
I do not have a good mental picture, but I would take off the side cover, pull the spark plug, and rotate things manually looking for wobbly things and things that touched other things. I did post on site about doing a disassembly/re-assembly of an SG/CG250. I should look at the pictures.
Here http://chinariders.net/showthread.php?t=27837
The gear ratios point to the plastic gear here
http://chinariders.net/attachment.ph...1&d=1608303385
It is undergeared from crankshaft rpm, the balance shaft is at crank rpm, the clutch basket is way under engine rpm... my takie is something clanking around behind the plastic. I think the gear runs the oil pump. Could be something behind the gear. If the plastic gear got pressured by a lever as you removed the clutch basket, it could be running out of true, wobbling a bit and clonking into other bits or even the oil pump behind. It's been almost two years so this picture is my memory.
I did have problems removing the three Philips on the spin filter cover, but finally got the sticky one out using a hammer & chisel, replaced with 3 allen head screws. When I took things apart, I jammed something between the gear teeth on the crankshaft gear. Things were TIGHT, and I feared damaging something but it apparently worked out.

tom
Looking a bit further down the post...
looked at this one: http://chinariders.net/attachment.ph...1&d=1608303830

the spin filter has a spring on it....you did put the spring on...?? Don't know if the noise ratio is right. If the spring was off, the spinnyfilter could move around on the shaft.
Actually, no it cannot move like that unless the castellated nut is not tight. Seems the spin filter had to be wiggled around on the shaft when installed from memory. Could the nut be tightened for the filter, but the filter not seated when the nut was tightened, allowing it to move on the shaft, spin, and keep spinning as the rpms drop off(as I think the noise does... in the vid, one case the engine revs drop, and the noise does not for a short while)
tom

Tennessee22 · 10-03-2022, 10:03 PM

Great input folks. The culprit turned out to be an exhaust gas leak. A couple of inmates on ADV Rider suggested it as well as here. I had tried the Hammer as a stethoscope trick, but I never put it against the exhaust header. When I did, bingo!

Why did the exhaust header gasket decide to give up at that time? Let's assume it was fragile. One of the things I did in an effort to get all the oil out of the right side case is tip the bike over pretty severely to the left side. It's possible that doing so worked the frame enough to cause the leak. Replacement part is $2.49, and does not require dismantling the engine, wahoo!

This community is amazing. Lots of thought experiments and input make all the difference when somebody is struggling alone trying to figure a problem out.

I must say, I really like the bike. It's sort of a miniature BMW R75/5, like I had back in the day. Except it has a disc brake up front instead of that evil, grabby drum brake. Neither are quick, but there is plenty of torque. The sg250 just rails around corners. I guess that's why those classic bike proportions are classic.

Tennessee22 · 10-03-2022, 10:06 PM

Quote:

Originally Posted by Jeffrey boy

How did you lock up the driveline to get the basket nut off. There is a tool for that clutch replacement. If you just torqued it in gear you may have damaged something internally.

This bike uses a snap ring instead of a basket nut. I stood on the rear brake to try to lock up the transmission while I was working on the oil spinner's nut. I was worried that I had done something ugly to the transmission, but I've ridden the bike and the trans seems to be fine.

10-01-2022, 04:01 PM	#1
Tennessee22 Join Date: Oct 2022 Location: Middle Tennessee Posts: 5	Csc sg250 clatter About a month ago, I bought a second hand CSC SG 250 with 6,000 mi on it that was well maintained. The clutch started slipping and grabbing, so I bought the parts from CSC and put a new clutch in. On startup, I got a loud clatter that is strictly related to engine speed. Clutching or not doesn't seem to affect it at all. I immediately shut it down and tore it back down, couldn't find a thing. I put it back together, rode it about 10 miles, no change to the noise it was making. I convinced myself that the clutch basket was probably looser after me trying to get everything out, so tore it down again. Managed to tighten up the rivets a little, got it back together, still have the clatter. I put new pressure plates in and checked every shaft and bearing I could find, yep, still have that noise. I can't find any signs of wear or problems other than the loud noise which started immediately after I changed the clutch. I even adjusted the valves. I've got a short video of the noise but I have not figured out how I'm going to get it online yet. I did waffle three pennies in an effort to get the castellated nut off of the oil spinner. All the pennies are accounted for. The nut is supposed to be tightened at 60 ft lb, but this one took way over a hundred foot pounds of force to get loose. Any ideas anyone? This is driving me crazy!
	0

10-03-2022, 07:40 AM	#6
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,551	I'm with Mudflap on this one. Sounds like an exhaust leak. __________________ 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
	0

10-03-2022, 09:22 PM	#7
grumpyunk Join Date: Jul 2018 Location: nw of atlanta Posts: 169	That sound does not exactly follow rpm. When revved, the sound goes up, but when you let off the throttle, the sound continues even as the sound from the exhaust drops, IOW, the sound lags behind the sound of the exhaust. IMO. The sound reminds me of something being loose on a shaft and wobbling around. It at the same time sounds as if something was being skipped on like a playing card in the spokes of a bicycle. Another example is teeth of something impacting or being impacted(touched) by something else. Definitely not at engine rpm. I would look at the assembly of the gears on the of the crankshaft. OI think one goes to balance shaft, to the spin filter, there is an idler that is trapped by the clutch basket. It may be possible to put an idler on reversed, in for out, and may have interference. I do not have a good mental picture, but I would take off the side cover, pull the spark plug, and rotate things manually looking for wobbly things and things that touched other things. I did post on site about doing a disassembly/re-assembly of an SG/CG250. I should look at the pictures. Here http://chinariders.net/showthread.php?t=27837 The gear ratios point to the plastic gear here http://chinariders.net/attachment.ph...1&d=1608303385 It is undergeared from crankshaft rpm, the balance shaft is at crank rpm, the clutch basket is way under engine rpm... my takie is something clanking around behind the plastic. I think the gear runs the oil pump. Could be something behind the gear. If the plastic gear got pressured by a lever as you removed the clutch basket, it could be running out of true, wobbling a bit and clonking into other bits or even the oil pump behind. It's been almost two years so this picture is my memory. I did have problems removing the three Philips on the spin filter cover, but finally got the sticky one out using a hammer & chisel, replaced with 3 allen head screws. When I took things apart, I jammed something between the gear teeth on the crankshaft gear. Things were TIGHT, and I feared damaging something but it apparently worked out. tom Looking a bit further down the post... looked at this one: http://chinariders.net/attachment.ph...1&d=1608303830 the spin filter has a spring on it....you did put the spring on...?? Don't know if the noise ratio is right. If the spring was off, the spinnyfilter could move around on the shaft. Actually, no it cannot move like that unless the castellated nut is not tight. Seems the spin filter had to be wiggled around on the shaft when installed from memory. Could the nut be tightened for the filter, but the filter not seated when the nut was tightened, allowing it to move on the shaft, spin, and keep spinning as the rpms drop off(as I think the noise does... in the vid, one case the engine revs drop, and the noise does not for a short while) tom __________________ vertical and above ground - my daily goal
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10-01-2022, 06:42 PM	#2
Tennessee22 Join Date: Oct 2022 Location: Middle Tennessee Posts: 5	Just posted a YouTube of the noise, "Loud knock after clutch replacement"
	0

10-01-2022, 07:43 PM	#3
Tennessee22 Join Date: Oct 2022 Location: Middle Tennessee Posts: 5	Link to short video:
	0

10-02-2022, 05:37 PM	#4
Mudflap Join Date: Sep 2014 Posts: 1,870	Sounds like one click per 2 revolutions. If that is correct it could be an exhaust leak, something related to the cam, rockers, valves since they move at half of crankshaft RPM.
	1

10-02-2022, 09:06 PM	#5
Jeffrey boy Join Date: Sep 2022 Location: Bucks co. Posts: 3	How did you lock up the driveline to get the basket nut off. There is a tool for that clutch replacement. If you just torqued it in gear you may have damaged something internally.
	0

10-03-2022, 10:03 PM	#8
Tennessee22 Join Date: Oct 2022 Location: Middle Tennessee Posts: 5	Great input folks. The culprit turned out to be an exhaust gas leak. A couple of inmates on ADV Rider suggested it as well as here. I had tried the Hammer as a stethoscope trick, but I never put it against the exhaust header. When I did, bingo! Why did the exhaust header gasket decide to give up at that time? Let's assume it was fragile. One of the things I did in an effort to get all the oil out of the right side case is tip the bike over pretty severely to the left side. It's possible that doing so worked the frame enough to cause the leak. Replacement part is $2.49, and does not require dismantling the engine, wahoo! This community is amazing. Lots of thought experiments and input make all the difference when somebody is struggling alone trying to figure a problem out. I must say, I really like the bike. It's sort of a miniature BMW R75/5, like I had back in the day. Except it has a disc brake up front instead of that evil, grabby drum brake. Neither are quick, but there is plenty of torque. The sg250 just rails around corners. I guess that's why those classic bike proportions are classic.
	0