Bogging issues and clutch adjustment on 1980 RM 125
I am trying to get an old bike running for my son. It is a 1980 RM 125. I have put in a new piston and wrist pins/rings and now it has a bog when you try to excellerate and the clutch needs adjusting. ANY Idea's? Please explian how to adjust the clutch at both locations and what are the factory adjustments(turns on the carb screws) carb (Minkuno)
Re: bogging issues and clutch adjustment on 1980 RM 125
As far as your clutch adjustment ,I can't help you but the fact that the bike is older you might want to try removing the exhaust pipe at the baffel end and see if there is a difference in power ,if there is clean out your baffel and your good to go.
hope this helps
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What this sounds like is a carb issue. There are screws that are located on the carb that control the air and fuel mixture, if you are getting to much air then it will crank and run only for a minute or two then shut off. Have you tried adjusting it? It can take some time to get it right as each bike engine is going to be slightly different and all adjustments are going to be bike/engine specific. I would recommend adjusting the air and fuel mixture, that will probably work for ya. Hope that this helped.
First, try the cable adjustment at the lever end, if no more movement re-adjust inwards, then adjust at the clutch end.
If no joy, then it is either the lifter mechanism or the clutch its self.
Adjust the clutch cable to allow about 1/4" free play at the end of the clutch handle. Don't put the bike in gear until the rpms are near idle speed. The clutch is working fine if the bike does not lurch forward when going into gear at idle speed. Dirty, gritty oil in the gearbox can make the clutch grab. Consider changing oil if grabbing is the problem. The "crunch" you hear is the slider gear engaging into the driven gear. The higher the engine speed when being put into gear the louder the crunch. The slider gear engaging "dogs" can break. Crunching into gear is hard on the gears.
Post a comment to let me know how you come out on this.
Scatter gun approach > thoughts to check out > > >
Clean and dry the air filter? Go back to a stock main jet, at least to check things out? Are "O" ring seals on the main jet going bad?Partial internal collapse in exhaust (remove exhaust pipe & do a quick run down the alley), Install a new stock NGK spark plug, Be sure battery connections are clean and tight, Be sure intake manifold and carb are good and tight.
I am going to stick my neck out here and hope I can help.
The springs are not at all likely to be the problem. Any chance the cable is hanging up and not releasing fully? Disconnect the cable at the gearbox, put the bike in gear with the motor not running and see if the motor puts a major drag on pushing the bike. If pushing the bike makes the wheel lock up or the engine turn over it tends to say the cable is bad.
It could be you were given the wrong hub. Compare the old hub to the new one. Do the various measurements match? Contact the dealers parts department and ask how many fiber and how many steel clutch plates are in your clutch. Did your 9 year old son play with a funny looking frisbie and leave it in the back yard?
Ask what plate goes into the clutch hub first > Fiber or steel? Did you install the plates that way? Did the outer clutch cap go on properly and rest against the outer plate? Do any of the fiber disks have a gap wider than the other disks?
Food for thought. I hope this helps.
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