Author Topic: I finally got a bike!!! (Read 6401 times)

JoeyG · « **on:** July 31, 2013, 02:14:10 PM »

Well after months of searching and then just giving up on finding a bike, one just falls on your lap! I managed to pick up a 2000 YZ125 for a very good price. The top end is shot but that's no biggie. It has an FMF SST pipe, new rear tire, shifter and a few other little things so I'm very pleased.

I have a few questions, Previous owner installed the pipe and then cooked the top end. What is stock jetting and/or what is a good starting point for jetting? My elevation is around 1300.

Any other things I should look for? I did notice he had the CDI ziptied to the neck of the bike..is that where it goes?

Thanks!!!!

eprovenzano · « **Reply #1 on:** July 31, 2013, 02:19:58 PM »

What is the condition of the cylinder and head. Is there any (up and down) play in the connecting rod?

Start searching for a manual. It will become your best friend through the rebuild process

JoeyG · « **Reply #2 on:** July 31, 2013, 02:27:44 PM »

I don't know yet. I didn't get it till late last night but I'll tear into it after work. I'm going to check for main bearing slop as well as any rod bearing play.

eprovenzano · « **Reply #3 on:** July 31, 2013, 02:31:07 PM »

OK you're on the right track. Inspect, inspect, and inspect before deciding on what needs to be purchased...

Coop · « **Reply #4 on:** July 31, 2013, 02:33:34 PM »

Quote from: eprovenzano on July 31, 2013, 09:31:07 PM

OK you're on the right track. Inspect, inspect, and inspect before deciding on what needs to be purchased...

Yep. Then inspect some more. Never take a sellers word for what a bike needs.

Congrats on the new bike! Post up some pics when you can.

mj4trax · « **Reply #5 on:** July 31, 2013, 02:40:48 PM »

a 2000 yz125 is a wonderful model bike, lots of fun, neutral handling. It should treat you well.

c-slacker · « **Reply #6 on:** July 31, 2013, 03:33:03 PM »

From my research the cause of the meltdown was the SST pipe. The following is a quote from another forum:

"The FMF SST pipe is an amazing pipe.

Why is it amazing? Because in just about every case, it will work WORSE than the stock pipe that came on the bike.

The SST uses a restrictive reverse cone and pressure bleed to intensify the return wave and lower the initial flow out the stinger section of the pipe. What that in turn does is increase piston crown temperatures and make jetting difficult at best.

Now increased piston crown temperatures can be compensated for to some extent with richer jetting. But, by doing that you are defeating the purpose of the pipe, and negating any power gain you may have gotten from the pipe in the first place. Why are increased piston crown temperatures bad? Well, in some cases they are not. You see most bikes are jetted horribly rich from the factory, and raising the piston crown temps in this case will "fool" the engine into thinking it is jetted leaner than it is. Which will in some cases improve power. But in most cases, it will just cause slightly better throttle response and an increase in the spooge out the back of the pipe.

After all that you may be thinking: "well this doesn't sound so bad, why are they saying this pipe is no good?" Good question. Here's the answer. Because of the restrictive nature of the pressure bleed from the pipe, it does not evacuate as efficiently as it needs to. This combined with the piston crown temperature increase yeilds jetting that is too rich. So now you have a pipe that "fools" the engine into thinking it is leaner than it really is, but also makes it much richer than it was previously. Here in lies the second problem. It makes jetting a nightmare. If you jet it by feel, you will be jetting richer, and compounding the too rich condition even more, making the bike run like a slug. If you jet it leaner, you will be increasing piston crown temperatures even more resulting in an engine siezure. Catch-22 anyone?

If you are buying a pipe for your bike, get ANY other pipe. Or better yet, keep the stock pipe."

2 smokin RM · « **Reply #7 on:** July 31, 2013, 04:00:13 PM »

Congrats on the new bike! Should be a ripper. Just make sure you check everything out a few times before ordering your top end and any other parts you need. Pull the clutch plates out and check them while you're at it. They're cheap to replace and easy if need be.

Check the trans fluid.
Pick a premix that's readily available and fits your price and stick with it. Along with ratio. Should be 32:1

You'll be set for a while with a new top end and some new fluids. Get it running good and youll be addicted to riding it

JoeyG · « **Reply #8 on:** July 31, 2013, 04:36:20 PM »

Thanks everyone I'm really excited about this bike. I haven't been on a bike since 97 so the itch to ride is strong.

Slacker,
That may certainly explain why the top end went poof right after he put the pipe on. I think the SST may be up for sale!!

I have a pic but the file size is too big? Anyone help out with that?

What is a good pipe to replace the SST with? Fatty, PC, Stock??

eprovenzano · « **Reply #9 on:** July 31, 2013, 04:42:42 PM »

Quote from: JoeyG on July 31, 2013, 11:36:20 PM

What is a good pipe to replace the SST with? Fatty, PC, Stock??

Remember you are on a 125... where do you want the power to be bottom, middle, or top... based on that info you can choice a pipe to suit your riding style and terrain.

JoeyG · « **Reply #10 on:** July 31, 2013, 04:49:05 PM »

The bike will be used for MX. When it comes to a 125 I think you want your cake and eat it too type of pipe?? Bottom to mid? Heck a stock pipe just may be the ticket.

mj4trax · « **Reply #11 on:** July 31, 2013, 06:12:24 PM »

I've been pretty happy with the stock head pipe on my '01 yz125.

My brother put a PC platinum on his 2000 yz125, and we noticed very little difference. If anything it seemed to rob a bit of the bottom power to add to the top end. .... but it's barely noticeable.

eprovenzano · « **Reply #12 on:** July 31, 2013, 07:45:36 PM »

I think (someone please correct me is I'm wrong) (again) The fatty will rob some off the top, but will boost the bottom end, the PC will rob some of the bottom and will boost the mid to top. I'd go with a stocker at 1st (cheapest option) and then decide where you need more or less.

citabjockey · « **Reply #13 on:** July 31, 2013, 10:23:52 PM »

Open an account on phtotbucket.com.
Upload your photo(s) there.
Hover over a photo in your album view and you will have a menu popup, click on the "IMG" item.
Then go to you posting window over here. In the text area right click on you mouse and select "paste". Some gibberish looking kinda like

Code: [Select]

will show up. submit the post and there it is!

Quote from: JoeyG on July 31, 2013, 11:36:20 PM

I have a pic but the file size is too big? Anyone help out with that?

JoeyG · « **Reply #14 on:** August 01, 2013, 02:23:48 AM »

Ok, I found out its a 1999....No biggie. I did pull the cylinder head and found the leading edge of the piston cooked. Is that from running cheap gas? Isn't lean just burn a hole about center of the piston? Also noticed the cylinder is 55mm, does that sound about right? These are plated cylinders and can't be bored like a steel sleeve?

News:

Author Topic: I finally got a bike!!! (Read 6401 times)