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545
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9/24/2013
Location
LA, CA
US
Edited Date/Time
8/15/2014 2:54pm
So as you guys may already know, I switched from a 450 to a 125 this month.. I took it out for the first time yesterday and it was a BLAST. I don't know if I was fast on it but I certainly felt like I was. I also sounded like it too. Sick. Anyway, The bike (05 YZ125) starts with 1-2 kicks everytime when cold, and idles perfectly (maybe even a tiny bit high). But if in between motos I kill the bike and bench race or take a break, when the motor is warm and I come to start it, it takes 5-6 kicks and idles SUPER SUPER low until I bring the revs up, then it idles fine.
Does this sound like a top end deal? Or is this how two strokes operate? I always thought it was the 4strokes that were harder to start when warm.. though I never experienced that with my Fuel Injected 450.
Any thoughts??
Does this sound like a top end deal? Or is this how two strokes operate? I always thought it was the 4strokes that were harder to start when warm.. though I never experienced that with my Fuel Injected 450.
Any thoughts??
Is it not wanting to easily start when warm indicative of a top end job needing to be done soon? What are the chances this is due to the bottom end? At this point I'm trying to decide if I should cut my losses and sell it or just hook up the motor and have a solid bike. I want to have a 125 that I can ride as my primary bike.
Also one more question, I seem to be hitting neutral when downshifting from second to first too many times for it to be user error.. Even a buddy that spun a lap on my bike yesterday hit that problem when he was only on the bike for 3 minutes. I know the 05 has a faulty shift stopper so I just replaced that last weekend.. do you think some of the bearings from the broken shift stopper are caught between neutral and first gear? I didn't see any bearings in the clutch basket or when I drained the oil but I just bought the bike so I don't know if they drained out when the last owner had it..
Would this affect the bike when it's warm? Because it seems to be working fine when it's cold but when warm we're talking a different story.
Thanks brah
The Shop
And mxrose, I'm not touching the choke lever at all, cold, warm or otherwise
Honestly if I just bought a used 125, I would plan on doing a top end with a good quality piston right away. You really don't know the condition of the motor till you tear it down and take a look around. You can check for any rod play at the same time. I did not do this when I bought my 125 and ended up with a shattered piston that left be stranded away from the truck. That's why its a 144 now.
You should never have to use 1st on an MX track. If you feel you need 1st gear, you either need to carry more momentum in the turns or get lower gearing. For reference, stock is 13/48. Make sure someone didn't put something weird on there.
When you removed the old shift stopper, was the bearing still intact? Where the balls and outer race still on it? If not, then those balls went somewhere in the tranny and that certainly won't help anything.
First thing I would do is ditch whatever fuel is in it and start over with a known good reference point. Get some fresh premum pump gas or low grade race fuel if you can find it and mix it 32:1 with a quality oil. Lots of people have good luck with Yamalube-R or Maxima Super-M in these bikes. Then I would open the carb, clean everything and make note of what jetting is in it. Stock pilot is 40 and stock main is 410 and the stock jetting is very close to perfect on these. Make sure some previous owner didn't jack something in there. While the carb is off, I would pull the reed block and inspect the reeds for chips or cracks.
Hitting neutral when downshifting from second to first.. changed the original shift stopper that had broken off, problem ensued. Thinking there may be some bearings stuck somewhere in the gearbox??? Knowing this information, would you still say it is worth rebuilding?
I was super pumped on having a 125 that is strong and reliable.. I understand there is some level of rolling the dice when purchasing a used bike, so what's to say I don't buy another bike that needs a rebuild.. but I just want to know that I won't be tossing countless wads of cash on a 9 year old YZ. I know they are virtually unchanged, but I don't want to spend more than $500 repairing this motor to be in tip top shape.. achievable???
When I replaced the shift stopper, it was broken with no visible bearings. I didn't see any when I drained the oil... I am now led to believe they are in the transmission.. what does this mean for me? How much damage (monetarily speaking $$) are we talking? Scrap this bike and just get a different one?
You guys are super helpful.
Pit Row
Given the way the previous owner is acting, I'd probably put in a good piston and rings as was suggested by someone else just to be safe. I know nothing about bottom ends except I've never had a problem with one.
And for a reference, I've been running a fuel mix of 50% 100LL (get it from a local semi-private airport) and 50% premium gas. Mix that with a 32:1 Bel Ray oil. Bike seems to love this mix. Getting the 100LL is a bit of a pain in the ass but I'm not going to change that for now.
sounds like a jetting/carb issue that everyone has already said, so try their advice and calm down a bit. lol.
125 top ends are so cheap i would have been ordering parts right when that thing rolled into my garage. you dont know how someone rode that bike last, its cheap insurance.
The half-assed way to "fix" it is to only remove the right side cover and fish out whatever bits you can see. The problem is you can't get at the tranny, especially the countershaft bearing and the blind bearing on the left end of the main shaft.
Read the threads about this on Thumpertalk. Lots of information and pictures.
http://www.thumpertalk.com/topic/512858-replace-your-shift-stopper/
If you are not opening the throttle any and just kicking it that is the problem.
Open the throttle half way and kick. It is not like a 4 stroke,it wont flood.
You sound like you have experience with this issue... your honest opinion on selling/keeping the bike? Any harm to ride it in the meantime? I have a practice day on Sunday I was hoping to ride at.
I had one go out in my son's 125 that year, and fortunately it didn't do any damage to the transmission. Replaced it with the new part # and it was great after that. Guess I was lucky.
Honestly, if it was me I would split the cases and do it right. But that's based on my personal situation of being able to do it myself and not being too worried about paying for whatever parts I might need. Your situation might differ and the cost of repairs or parts might be a bigger factor in your situation.
However, I would feel bad about selling the bike to someone knowing the tranny is already messed up and could potential get worse as debris moves around in there or even cause an accident if it was to lock up or let loose at the wrong time. So, I would either fix it before selling or be sure to let the new owner know what they were buying.
Read through that thread and it will tell you everything you need to know about the shift stopper. Then you can make your own decision.
What other parts should I get? Is this something that once I get in there and fix it I'll be good? Or is there a high likelihood of more and more crap coming up?
FGR, that is a huge weight on this decision.. I don't want to unload a bike off on someone that doesn't know what they're getting into.. and there is always that element of risk when buying a bike unless it's brand new.. so maybe I should keep it and try to fix it up..
Does $250 sound reasonable to have the cases split and go through the motor and carb? Any other parts I should order to do it right? Seals, etc from splitting the cases? Since I'm new to this I want to know what all I should get and then price it out from there.
Thanks a lot guys.. riding yesterday was bittersweet since it was so fun, yet I knew something may be off.
NOTE: There's also a leak coming from the drain bolt.. there was no washer on it so I put a fresh crush washer on and the leak slowed down a lot... but is still remaining... any idea on that? With all these little leaks etc it is just tough to think I can conquer it all and get a solid bike out of it..
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