another bad bottom end

[rmrider45]

well does anyone have a gun????lol. sons bike died last week now my 2003 rm 125 died.i left my son take it for a spin and as i was standing there after his second lap around it just died.got it home and was hoping the top end just went bad.top end looked good kicker was frozen . as i look down at the crank the connecting rod woulnt spin.sprayed a little wd 40 on the bottom of the rod put it back together and it runs but not like it should . it vibrates and sounds noisey.?is the only thing i did to the bike was leaned out the carb only one full turn out.could have this caused the crank too seize up or was it just time for it to go.thx:(:(:(

no warning it just died :(

 

[julien_d]

It was probably just time. Leaning out with just the air screw shouldn't cause any damage that quickly, unless you were already in a lean state to begin with. Sorry to hear. I just finished a bottom end rebuild on my KDX. It wasn't too bad, but it wasn't fun either.

 

[rmrider45]

ill just have to order the correct pullers to do the job and the bottom end rebuild should go ok.

 

[sharky243]

OUCH !!! It seems like this is the year for blown bottom ends !!! LOL !! I work on alot of dirtbikes here at home for the local kids. They can't aford to pay a shop to do it, so since I am a mechanic, I help them out and fix them at home. About 90% of the bikes i've worked on so far this year were all bottom end failures. They're not that difficult to do. Although you will need some tools to get it apart, ie: flywheel puller, case spliter, a 12t press, a heat gun, a freezer, and some chunks of 2x4. The heat gun and the freezer alow you to use physics to aid putting it back together. GOOD LUCK !!! take your time !!!

 

[Someone]

2x4's are for beating the kids? :)

 

[rmrider45]

i have to take the motor out maybe this week.when i start the bike it like raps really bad. is that because the crank is bent or is one of the bearings is shot?

 

[adam728]

Well you know one of the bearing is shot, you established that in the first post.

If the crank is out of true right now it doesn't matter. You'll either be putting in a new crank, or rebuilding the old one with a new rod and lower bearing, which requires the crank to be split, reassembled, and trued. Put in new main bearings when buttoning it all up. If the rod bearing went, they aren't far behind (and may already be damaged by debris from the rod bearing).

 

[rmrider45]

today i thought it was time to take the top end apart.i found the problem the lower connecting rod bearing has lots of movement up and down and thats what is causing the raping noise.in the morning ill take the bottom end out of the frame and take it over to the local machine shop. i called for a price and to put a new crank in and bearings and labor $609

 

[whenfoxforks-ruled]

INVEST in the tools! 300 to 400 dollars in parts, complete=1 fresh engine. Older bikes can be a pain, and some you can not get complete crank assemblies. But, Wiseco, Hotrods, and Motosport offer complete engine kits for most popular models. Not that 609 sounds too unreasonable. Crank, bearings and seals, 250? Usually the big end bearing going out takes the head and cylinder with it, and rarely the cases.

 

[m4i2k2e2]

i bought the kit from motosport. it gives you everything you need to do a complete top and bottom end rebuild. for my cr250r it was 430.00 bucks. get a clymer manual and do it your self.

-mike.

 

[rmrider45]

INVEST in the tools! 300 to 400 dollars in parts, complete=1 fresh engine. Older bikes can be a pain, and some you can not get complete crank assemblies. But, Wiseco, Hotrods, and Motosport offer complete engine kits for most popular models. Not that 609 sounds too unreasonable. Crank, bearings and seals, 250? Usually the big end bearing going out takes the head and cylinder with it, and rarely the cases.

i should invest in the tools .. i found a kit for the bottom

http://www.motorcycle-superstore.co...-End-Rebuild-Kit-2003-Suzuki-RM125-Parts.aspx


bottom end $181.99
top end $75-100


less than $300 in parts




the cylinder and head look good.

just strange how the rod has so much play up and down and how these bikes give no warning when they die


any i keep thinking i leaned the carb out too much thats why it just stoped because of lack of oil to the bottom

 

[whenfoxforks-ruled]

Oh it does give warning signs, if you know how it feels and sounds when it completely goes. Keep track of hours and maintenance schedules=running like new all the time. After its broke in, check the compression, and recheck frequently. A leak down test can show a seal in the bottom end going. The old saying"It ran the best ever, right before it blew" comes true a lot! And its not how it looks, measure it also! I have heard of brand new oem cranks being .010 on the flywheel run out, .002 is max. Check the thrust washer clearance, skirt, bridge and ring gap.

 

[rmrider45]

:bang:

Oh it does give warning signs, if you know how it feels and sounds when it completely goes. Keep track of hours and maintenance schedules=running like new all the time. After its broke in, check the compression, and recheck frequently. A leak down test can show a seal in the bottom end going. The old saying"It ran the best ever, right before it blew" comes true a lot! And its not how it looks, measure it also! I have heard of brand new oem cranks being .010 on the flywheel run out, .002 is max. Check the thrust washer clearance, skirt, bridge and ring gap.

thats correct that bike that day ran so good and had such power (and it just stoped dead).the piston and ring that i had put in over the winter only had 4 or 5 rides on it.the cylinder wall and head look like new inside also the crank and rod look real good(i didnt measure anything yet.just the inside of the bike looks so good and died thats why i was wondering if the 1 turn out lean on the carb made it to lean and not get enough oil and seize up

:bang: :bang:

also some wiseco pistons on the directions tell you to drill 2 or 3 holes on the front of the piston(some)
the piston i put in was a vertex

?what is the reason for those holes on the front of some aftermarket pistons

thx

 

[julien_d]

the reason for the holes is to allow more lubrication to the exhaust bridge.

 

[whenfoxforks-ruled]

the reason for the holes is to allow more lubrication to the exhaust bridge.

I have seen plenty of seizures from skipping that step, and having enough clearance at the bridge,.0035"~.004". Way too many people doing bore jobs and not relieving the ports and bridges properly. 4 stroke bores are too easy?

 

[kawraper]

The hot rods complete crank with the rod already installed and crank trued is the way to go for sure. It may cost twice as much as just a rod and bering but it will save you the hassle of truing or getting the crank trued. In my mind its worth every penny after rebuilding one crank and just slapping the hot rods crank kit I chose the hot rods kit every time.

 

[rmrider45]

I have seen plenty of seizures from skipping that step, and having enough clearance at the bridge,.0035"~.004". Way too many people doing bore jobs and not relieving the ports and bridges properly. 4 stroke bores are too easy?

the stock piston i took out had no holes!!!!! and vertex never listed in drilling holes in the piston.and this bike was never bored

 

[GarbatyA4]

I purchased a Wiesco Crank shaft assembly with rod and piston. Cost me 300 with main bearings, all seals and top and bottom gaskets

BOO YAH!

 

[whenfoxforks-ruled]

the stock piston i took out had no holes!!!!! and vertex never listed in drilling holes in the piston.and this bike was never bored

YEP, not a fan of Vertex, yack gag, not as bad as oem Chinese? Maybe Vertex figured that black coating thats gone it a minute would save it? There are some ports that do not have bridges in the middle. You really need someone with a bore gauge, check all the ports for a bevel on the edge, and the bridge relief. Or, it will happen again. Maybe worse next time.

 

[rmrider45]

yes but the stock piston i took out had no holes drilled

 

[whenfoxforks-ruled]

Does it have a thin strip of cylinder in the middle of the intake or exhaust port?

 

[rmrider45]

just wondering before i do this job . most videos i watch on the net they take the transmisson out. do i have to take the kickstart gear etc and take the trans out or can i leave it be and just remove the crank.

http://www.youtube.com/watch?v=kYX-bOG9vR4&feature=related

 

[whenfoxforks-ruled]

Typically the left case is extracted, then pop the crank out of the right side. A lot of times the washers stick to the bearing race, shift fork rods stick also, be careful, and keep all the parts slid to the right side. Most the stuff that comes loose, only goes one way. Doubts about thrust washers, the manual and parts micro fiches give dimensions. Piece of cake. No steel hammers. Lead, rubber, wood and brass for pounding. The only thing you need off the right side is the crank drive gear and shifter shaft, but sometimes you have to yank the clutch to get them off. The rotor, sprocket and shifter on the left. I could not imagine replacing the crank main bearings and seals without taking the trans out. The clutch, idler, and kick starter gear. The shifter drum, and ratchet star staying in is fine.

 

[rmrider45]

i got it apart!!!!!!!! wasnt to bad.one of my old friends who use to be a bike mechanic had the flywheel puller that threaded in left handed.only had one small problem the kickstart gear poped off i hope it aint that hard going back on with those two springs.one other thing i didnt want to happen was one or two of the trans gears came off :( i am not sure if the one goes in with the 3 teeth up or down. i am sure in the manual it will show how they go on.btw no shavings in case and nothing blew apart .for sure tho the connecting rod bearing went bad.time to order new crank...


looking at this diagram i cant tell

http://www.bikebandit.com/suzuki-motorcycle-rm125k3-2003-transmission/o/m6559sch289649


it is #5 on the picture not sure if 3 teeth go up or go in with teeth down

 

[whenfoxforks-ruled]

3 teeth????????? On the side of some gears there are "dogs" that drive another gear? #5 shows no dogs on the left side, but it sure looks like #3 has dogs on both sides, its the one that the fork slides. They must mate. #6 has an oil hole that lines up on the shaft one way? Nice sharp edges on them dogs, or are they rounded over? Any wear or shiny marks on the fork slider surfaces? They can get checked with a micrometer.