I've just got back into Dirt Bikes and picked up a 86 RM125 to ride around after my son after having some exhaust issues the bike is back in one piece and I was exicted to get my first full ride out of it today. Well I was disappointed to say the least. The issue was If I got on the throttle WOT in first or second the bike basically shut down no real bog just no real response. If I roll on the throttle thru first and second all seems well until I hit third and crack the throttle open at which point I get no response and it doesn't seem to pick up unless I back off the throttle. This just gets worse the farther into the gearing I get and If I get to trying to WOT on top gear it kind of sputters along. When I had the bike in getting the pipe fixed up I asked the guy if he could test the compression to see if I needed a top end in this bike and he asked me how the bike started, I told him the bike started 1st or 2nd kick everytime and idled just fine he replied that the top end was fine then. One of my friends suggested this was a lean condition and I am currently without a tool to view a plug as some of the informative threads have talked about earlier in this forum. I did run this tank of gas at 28:1 against Suzuki's recommended 20:1 for this bike but I doubt that would make this much of a difference to performance. I am running the recommended B9EGV plug for this bike. Any ideas where to start to troubleshoot this problem would be appreciated. I also spoke to the guy I bought the bike from and he said he had no performance troubles with the bike while he had it and I somewhat know this fella and doubt he would lie to me although I also have seen him ride and it's unlikely he ever had the bike past 3rd gear or at WOT so that could explain that. I am going to start to work on it tomorrow as one of my first ever home wrenching projects as I'm tired of paying big money and downtime to mechanics. Sorry for the long post but I wanted to include as much of the limited information I had.
Poor Performance Older RM125
- Thread starter Chili
- Start date
marcusgunby
LIFETIME SPONSOR
- Jan 9, 2000
- 6,450
- 2
Sounds like it is lean on the main jet-maybe its blocked-get that carb apart-also the float level maybe too low.
- Thread starter
- #3
Looks like we are on the right track Marcus. I took the carb apart and the mainjet is pretty much clogged with a hard green deposit. Now the next question is what is the best way to clean this jet? I've tried spraying contact cleaner through it several times and it still has deposits that don't want to come loose. I don't have anything small enough to run through the bore of the jet at home and I would be reluctant to do so until I know how sensitive it is. Am I better just getting a new main jet? It appears based on the stamping on the jet that it is a 280 main. Not sure what stock was for this bike.
marcusgunby
LIFETIME SPONSOR
- Jan 9, 2000
- 6,450
- 2
Yes buy a new one, try one the same size.
- Thread starter
- #5
Thx for the help marcus I really appreciate your time! It makes it so much more confidence inspiring as a newbie wrencher to have someone at least point you in the right direction. I bought a new one before your reply when I stopped at the Bike shop on the way to the hardware store to get carb cleaner to try to clean the jet. $3.07 tax included for a new jet or $4.95 for a bottle of carb cleaner, going new made sense to me :) Just got in from testing the bike out after getting the carb back together and can rip it wide open without hesitation now. Thanks again and enjoy the mojo!
