1995 RM125 slower than my 1978 RM125??? - Motorcycle-Journal Forums

03zq8 · 05-24-2005, 09:00 PM

Well, like the title says, my 78 (air cooled all stock) is faster than my 95. I'm in the process of diagnosing the 95 and could use a little advice.

-It starts up on the 1st or 2nd kick
-It *runs* flawlessly
-Compression is 155-160 psi, and holds all day, I couldn't find a spec anywhere, but I think this is good

The bike has absolutely no lower end power at all. I know it's a two stroke, and it shouldn't make much, but it's bad. I can't take off quick without feathering the clutch severely, or it just stalls or boggs. When I race my 78, the 78 kills it off the line. If we start from the top of 1st, the 78 pulls on it about 2ft per gear.

Any Idea's? I don't know much about the newer 2 strokes like this one (ie power valve, exhaust valve, etc.). Are the reeds worth pulling out and checking?

BTW the 95 has an FMF gold pipe on it, not sure if the carb was tuned for this.

Dave2122 · 05-24-2005, 09:24 PM

Here are some things to check

Air cleaner
Rear wheel bearings bad
Powervalves gummed up
Exhaust pipe header full of carbon buildup
What gearing are you running
What size chain areyou using

Jsut a couple simple things to check

03zq8 · 05-24-2005, 09:35 PM

Sounds like a start, thanks.

I know that the gearing and the chain are stock. I've just serviced the air cleaner.

I need to check the power valves, rear wheel bearings, and exhaust then. Whats an easy way to check the power valves and exhaust?

Sorry for the ignorance.

90rm125 · 05-25-2005, 01:07 PM

im almost positive its the rings or the exhaust valves my 90 rm125 was exactly the same and tore it apart and found the exhaust valve was broke

90rm125 · 05-25-2005, 01:09 PM

there is a cover right above the ehaxust port. u can un screw it and see if there any good but i suguest that u tear it all apart i will make alot easier in the long run

03zq8 · 05-25-2005, 04:07 PM

I'm going to check the reeds and the exhaust valve tonight. It's not the rings... 155psi and holding (compression check).

SuzukiRipper · 05-25-2005, 04:46 PM

maybe you should replace the gaskets you may have a bad one giving u an air leak and maybe a new set of piston rings also

Dave2122 · 05-25-2005, 05:41 PM

With 150-160 Compression the piston and rings are in great shape.

When you have the exhaust pipe off look into the header and scrape out all the blavk carbon that has built up in there.

If you have the Suzuki Shop manual follow the section on powervalve removal and inspection. Be careful not to break or strip any of the small parts. You need to clean them with brake cleaner and remove all the sludge and carbon buildup on them.

Also disassembel the carb and clean every piece individually and then set the float height to the correct spec upon reassembly. Use a good wuality carb cleaner and be carefull not to damage anything.

tkitna · 06-05-2005, 02:59 AM

It could be a bad crank seal. I have a 76' YZ125 in cherry condition that ran just like you described (no low end to speak of and when it came on, it still felt weak). Just a thought.

Dave2122 · 06-05-2005, 03:13 PM

If your crank seal is bad it will run like Dog S#1T and you will notice in most cases the motor will use up the gearbox oil as vacume sucks it through to the cylinder.

05-24-2005, 09:00 PM	#1 (permalink)
03zq8 Where Am I ? Joined: May 2005 Bike: 04 GSX-R600, 95 RM125, 78 RM125 Location: Van Buren, OH Posts: 39	1995 RM125 slower than my 1978 RM125??? Well, like the title says, my 78 (air cooled all stock) is faster than my 95. I'm in the process of diagnosing the 95 and could use a little advice. -It starts up on the 1st or 2nd kick -It runs flawlessly -Compression is 155-160 psi, and holds all day, I couldn't find a spec anywhere, but I think this is good The bike has absolutely no lower end power at all. I know it's a two stroke, and it shouldn't make much, but it's bad. I can't take off quick without feathering the clutch severely, or it just stalls or boggs. When I race my 78, the 78 kills it off the line. If we start from the top of 1st, the 78 pulls on it about 2ft per gear. Any Idea's? I don't know much about the newer 2 strokes like this one (ie power valve, exhaust valve, etc.). Are the reeds worth pulling out and checking? BTW the 95 has an FMF gold pipe on it, not sure if the carb was tuned for this.

05-24-2005, 09:35 PM	#3 (permalink)
03zq8 Where Am I ? Joined: May 2005 Bike: 04 GSX-R600, 95 RM125, 78 RM125 Location: Van Buren, OH Posts: 39	Sounds like a start, thanks. I know that the gearing and the chain are stock. I've just serviced the air cleaner. I need to check the power valves, rear wheel bearings, and exhaust then. Whats an easy way to check the power valves and exhaust? Sorry for the ignorance. __________________ 2004 GSX-R600 1995 RM125 1978 RM125

05-25-2005, 04:07 PM	#6 (permalink)
03zq8 Where Am I ? Joined: May 2005 Bike: 04 GSX-R600, 95 RM125, 78 RM125 Location: Van Buren, OH Posts: 39	I'm going to check the reeds and the exhaust valve tonight. It's not the rings... 155psi and holding (compression check). __________________ 2004 GSX-R600 1995 RM125 1978 RM125

05-25-2005, 05:41 PM	#8 (permalink)
Dave2122 Sprocket Pilot Joined: Sep 2004 Bike: Which one of the 9? Location: USA Posts: 887	With 150-160 Compression the piston and rings are in great shape. When you have the exhaust pipe off look into the header and scrape out all the blavk carbon that has built up in there. If you have the Suzuki Shop manual follow the section on powervalve removal and inspection. Be careful not to break or strip any of the small parts. You need to clean them with brake cleaner and remove all the sludge and carbon buildup on them. Also disassembel the carb and clean every piece individually and then set the float height to the correct spec upon reassembly. Use a good wuality carb cleaner and be carefull not to damage anything. Last edited by Dave2122; 05-25-2005 at 05:47 PM.

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05-24-2005, 09:24 PM	#2 (permalink)
Dave2122 Sprocket Pilot Joined: Sep 2004 Bike: Which one of the 9? Location: USA Posts: 887	Here are some things to check Air cleaner Rear wheel bearings bad Powervalves gummed up Exhaust pipe header full of carbon buildup What gearing are you running What size chain areyou using Jsut a couple simple things to check

05-25-2005, 01:07 PM	#4 (permalink)
90rm125 Newbie Joined: May 2005 Posts: 3	im almost positive its the rings or the exhaust valves my 90 rm125 was exactly the same and tore it apart and found the exhaust valve was broke

05-25-2005, 01:09 PM	#5 (permalink)
90rm125 Newbie Joined: May 2005 Posts: 3	there is a cover right above the ehaxust port. u can un screw it and see if there any good but i suguest that u tear it all apart i will make alot easier in the long run

05-25-2005, 04:46 PM	#7 (permalink)
SuzukiRipper Newbie Joined: May 2005 Posts: 12	maybe you should replace the gaskets you may have a bad one giving u an air leak and maybe a new set of piston rings also

06-05-2005, 02:59 AM	#9 (permalink)
tkitna Newbie Joined: Jun 2005 Posts: 1	It could be a bad crank seal. I have a 76' YZ125 in cherry condition that ran just like you described (no low end to speak of and when it came on, it still felt weak). Just a thought.

06-05-2005, 03:13 PM	#10 (permalink)
Dave2122 Sprocket Pilot Joined: Sep 2004 Bike: Which one of the 9? Location: USA Posts: 887	If your crank seal is bad it will run like Dog S#1T and you will notice in most cases the motor will use up the gearbox oil as vacume sucks it through to the cylinder.

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