What does it mean if a dirtbike rolls when its in first gear?? The clutch is out, engaged. but the bike rolls

Question

The exhaust pipe is not letting any air out when you try to kick start it. Feels no compression. but, every now and then, the exhaust will backfire with compressed air only. bike will not start, but will start if you push start it. Once started it has power. it's a CR 125 two stroke. please help.

Answer 1

First gear is shot?

Answer 2

Yes 1 st gear out, likley clutch worn etc etc-typically indicative of 125 cc used bikes-they rev higher and incurr more wear than 250s or 500s-and they are usually owned by younger riders, which in some cases are less experienced mechanically.

BTW Honda introduced the CR 125 Elsinore as a 1974 Model. I know of some purchased in early 1974-may have been some pre production bikes circulating in late 1973. I know this, they obsoleted EVERYTHING else the moment they hit the mx track. I love my old Maicos, but this is the most important mx in history, overnight you either raced one or chased one. An advantage not overcame until late 75 with the 75.5 mid year RM 125.
The engines were basically the same until 1978, Honda painting it red and giving more travel in 1976, the bike was the same in 77 and 78 for the most part.
Now, your top end is quite worn-you admit you have to push it to even start it and compression is suspect. You need to do a leak down test-determine where all the air leaks are and remedy. I expect you will end up with a total rebuild, rod, crank seals, bore( if applicable) new piston, rings, reeds( if applicable), carb rebuild, repair of pipe/silencer=ignition may be bad if an early breakerless.

If it is your play bike, let us know the year-as it may easily be cheaper to sell it to a Vintage Mx racer who wants to put the $ into it, and get a later model bike with less wear. Again that depends upon the year of the bike. Any 74-75 is highly desirable, any 76-78 is desirable, any 79 or 80 is highly desirable, any 81-82 is somehwat desirable, any 83 is highly desirable-after 83 until about 99 is not yet collectable, but may othen still good bikes.

Answer 3

Always give year, make, engine size and model # when asking questions. We need all of that info to give an informed answer.
The CR125 has been made since 1976 and it has changed a lot along the way.
Re-read you question - "Feels no compression"
Probably time for a top end rebuild.
If you don't have a compression tester -
Remove the exhaust pipe.
Look in the exhaust port with a flash light and mirror.
If you see any scoring on the piston and cylinder wall, or dis-coloration below the rings, the engine will need to be repaired.
Also you said - it will start if you push start it.
That's another sign of a worn out top end.

What do you mean the bike rolls when in gear?
Do you mean - the bike tries to move forward when running, in gear, with the clutch lever pulled in?
If so -
The clutch cable may need to be adjusted.
The clutch push rod could be worn down.
The clutch activator could be worn.

Answer 4

on maximum of the folk of mototrbikes you purely could use the take carry of once you shy away or wanna end. all dirt motorcycles surprisingly have a canines engagement gearbox meaning there are no synchros and are designed to alter kit without using a take carry of, the only different reason for having a take carry of on a dirt bike is for stunts so which you would be able to lift the revs in a much better kit than 1st pop the take carry of and wheelie or dip the take carry of on the foreheadof a hill then wack the throttle decrease back whilst letting the take carry of out to spin the decrease back tire so it beds into the dirt givin lots extra suitable traction as you bypass over the hill and so on so in case you merely driving usually you dont could use the take carry of as quickly as your shifting i raced motocross for 4 years and that i no longer often ever used the take carry of and now im a bike mechanic