'77 RM125 won't start - Motorcycle-Journal Forums

Ukraine Train · 06-07-2005, 06:31 PM

There's fuel on the plug so I know it's getting gas and I've cranked it over while the plug was out and I could see it sparking across the gap so it's getting spark. I've tried a spare coil and that didn't help. I've tried push starting too and it doesn't sound like it's even trying to start. Any ideas?

Dave2122 · 06-07-2005, 09:40 PM

Simple formula...Air+Fuel+Spark= Running bike.

Now if you have all 3 of the formula then you have to much of one of them.

Check you are not flooding the plug out with fuel? Check for a bad foat or a bad needle valve.
Check for a major air leak around the head and base gaskets and the intake manifold.
You have spark but is it enough spark?

Just some things to check out to get you going.

Good Luck and take your time.

stingray_69 · 06-10-2005, 04:46 PM

do you know what you are getting for compression?

Ukraine Train · 06-10-2005, 04:48 PM

I don't have an exact number but compression is good, I just rebuilt the engine. It was running strong and then over the course of about 10 minutes it started to run weaker and weaker. I limped it to the garage, shut it off and after that it wouldn't start again.

stingray_69 · 06-14-2005, 06:04 PM

Check your float hight. Mine was starting real hard. Sometimes it was starting at all. I thought it was because it was to rich and I checked the hight with a pair of calipers and thought it was good. It was kind of akward measuring them that way so I went a got a small pocket ruler and found that the float level was to low so I readjusted the level and now the bike starts right up even though it still running a little rich.

03zq8 · 06-14-2005, 08:58 PM

I'm helping UT with his bike...

I adjusted the float height last night. The bowl was full of gas when the carb was pulled off. I pulled the plug and I though it looked dry.

It's really boggling me.

FYI Compression is ~140ish, very good.

Dave2122 · 06-14-2005, 11:03 PM

Make sure your main jet is not glogged with crud. Make sure every passage is clean and clear. I am glad your helping with the bike!

06-07-2005, 06:31 PM	#1 (permalink)
Ukraine Train Newbie Joined: Apr 2005 Posts: 4	'77 RM125 won't start There's fuel on the plug so I know it's getting gas and I've cranked it over while the plug was out and I could see it sparking across the gap so it's getting spark. I've tried a spare coil and that didn't help. I've tried push starting too and it doesn't sound like it's even trying to start. Any ideas?

06-14-2005, 08:58 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 helping UT with his bike... I adjusted the float height last night. The bowl was full of gas when the carb was pulled off. I pulled the plug and I though it looked dry. It's really boggling me. FYI Compression is ~140ish, very good. __________________ 2004 GSX-R600 1995 RM125 1978 RM125

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06-07-2005, 09:40 PM	#2 (permalink)
Dave2122 Sprocket Pilot Joined: Sep 2004 Bike: Which one of the 9? Location: USA Posts: 887	Simple formula...Air+Fuel+Spark= Running bike. Now if you have all 3 of the formula then you have to much of one of them. Check you are not flooding the plug out with fuel? Check for a bad foat or a bad needle valve. Check for a major air leak around the head and base gaskets and the intake manifold. You have spark but is it enough spark? Just some things to check out to get you going. Good Luck and take your time.

06-10-2005, 04:46 PM	#3 (permalink)
stingray_69 Newbie Joined: May 2005 Posts: 22	do you know what you are getting for compression?

06-10-2005, 04:48 PM	#4 (permalink)
Ukraine Train Newbie Joined: Apr 2005 Posts: 4	I don't have an exact number but compression is good, I just rebuilt the engine. It was running strong and then over the course of about 10 minutes it started to run weaker and weaker. I limped it to the garage, shut it off and after that it wouldn't start again.

06-14-2005, 06:04 PM	#5 (permalink)
stingray_69 Newbie Joined: May 2005 Posts: 22	Check your float hight. Mine was starting real hard. Sometimes it was starting at all. I thought it was because it was to rich and I checked the hight with a pair of calipers and thought it was good. It was kind of akward measuring them that way so I went a got a small pocket ruler and found that the float level was to low so I readjusted the level and now the bike starts right up even though it still running a little rich.

06-14-2005, 11:03 PM	#7 (permalink)
Dave2122 Sprocket Pilot Joined: Sep 2004 Bike: Which one of the 9? Location: USA Posts: 887	Make sure your main jet is not glogged with crud. Make sure every passage is clean and clear. I am glad your helping with the bike!

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