rm 125 help

mx4life92
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mx4life92
Edited Date/Time 1/26/2012 3:08pm
i know this is the wrong place to put this but no one ever checks the tech part



ok recently my top end seized up so i had to get it repaired, i had to have the cylinder bored to a 56.00mm (stock is 54.00mm) i installed a wiseco .80 piston. so i put it back together and added a new twin air air filter while i had the seat off, well now i went ridding today to break it in, after 20 mins of riding i blew a spark plug, so i put in another new plug and about another 20 mins i fouled that one to, so i put it away for about an hour then went back out put another plug in and fouled that one, so can anyone help me out here?

im running br9eix plugs, 50:1 oil mixture, and the bike idles perfect when started with a fresh plug..

heres the bike engine setup if it helps

wiseco .80 piston
56.00mm cylinder
bills racing pipe and silencer
twin air air filter
driven racing clutch
v force 3 reeds
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FastEddy
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FastEddy 2/13/2010 7:07pm
2/13/2010 7:07pm Edited Date/Time 4/17/2016 8:45pm
Did the plugs look golden brown when you them pulled out,or did they look black & wet?
mx4life92
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mx4life92 2/13/2010 7:09pm
2/13/2010 7:09pm
black and wet
Wolfman
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Wolfman 2/13/2010 7:09pm
2/13/2010 7:09pm
I hope that piston is a .08 and not a .80!

50:1? What kind of oil? Thats pretty lean on oil, which would make that gas to air ratio rich.
FastEddy
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FastEddy 2/13/2010 7:11pm
2/13/2010 7:11pm
Wolfman wrote:
I hope that piston is a .08 and not a .80! 50:1? What kind of oil? Thats pretty lean on oil, which would make that gas...
I hope that piston is a .08 and not a .80!

50:1? What kind of oil? Thats pretty lean on oil, which would make that gas to air ratio rich.
That's what I was thinking.
I always went with 32:1 on every 125 I ever owned.

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FastEddy
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FastEddy 2/13/2010 7:13pm
2/13/2010 7:13pm Edited Date/Time 2/13/2010 7:14pm
mx4life92 wrote:
black and wet
Hmmm,thats odd at 50:1.
Do you have your plugs gaped right?
Or did you change the jetting at all?
mx4life92
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mx4life92 2/13/2010 7:21pm
2/13/2010 7:21pm Edited Date/Time 4/17/2016 8:45pm
no its .80 its this one-http://www.motosport.com/dirtbike/product/WISECO-PROLITE-PISTON-080-OVE…

im running this oil- http://www.chaparral-racing.com/...4B9BA99F80812B32F050


no i havent change the jetting at all, the bike didnt foul plugs before the top end rebuild..
zippy895
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zippy895 2/13/2010 7:22pm
2/13/2010 7:22pm
how is it performing before the fouling. what oil are you using.using a ratio rite?
Cygnus
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Cygnus 2/13/2010 7:26pm
2/13/2010 7:26pm
Most times when you bore and engine the increased volume of air will make the carb actually draw more fuel with the original settings and you will have to go down a couple sizes on the jets.
ratonmacias
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ratonmacias 2/13/2010 7:28pm
2/13/2010 7:28pm
hey i was using motul 800 40:1 on my 04 rm 125 with a 54 bore then got an eric gorr 144 kit and that was a 58 mm bore still used the same jetting and oil so my guess is it might be sucking oil from the gearbox and fouling the plug with transmission oil.
zippy895
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zippy895 2/13/2010 7:32pm
2/13/2010 7:32pm
start w/ the easiest...get 1 galoon fuel(1 true gallon) and proper oz of oil for 1 gal.
drain out whats in your bike. start over. its posible that you mixed something wrong.do the obvious first.
zippy895
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zippy895 2/13/2010 7:33pm
2/13/2010 7:33pm
is it possible you added oil to fuel that already was mixed?
motodude72g
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motodude72g 2/13/2010 7:36pm
2/13/2010 7:36pm
check your stator. its usually a problem with symptoms like this..
neverwas 2/13/2010 7:41pm
2/13/2010 7:41pm
What caused it to seize the first time?
Wolfman
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Wolfman 2/13/2010 8:02pm
2/13/2010 8:02pm
mx4life92 wrote:
no its .80 its this one-http://www.motosport.com/dirtbike/product/WISECO-PROLITE-PISTON-080-OVERSIZE/?catalogId=107455 im running this oil- http://www.chaparral-racing.com/...4B9BA99F80812B32F050 no i havent change the jetting at all, the bike didnt foul plugs before the...
no its .80 its this one-http://www.motosport.com/dirtbike/product/WISECO-PROLITE-PISTON-080-OVE…

im running this oil- http://www.chaparral-racing.com/...4B9BA99F80812B32F050


no i havent change the jetting at all, the bike didnt foul plugs before the top end rebuild..
Oh right, you're talking MM, I was thinking inches.
mx4life92
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mx4life92 2/13/2010 8:12pm
2/13/2010 8:12pm
before fouling it runs amazing, and no the gas was fresh as i mixed it just before i went ridding. i followed the directions on the oil which say run 50:1, i use this same fuel mixture in my yz 125 and there is no problems at all. so which jet should i change it to

i dont know what caused it to seize.
newmann
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newmann 2/13/2010 8:14pm
2/13/2010 8:14pm
Okay, I'm going to play stupid here for a minute and ask if after the cylinder was bored, was it also replated?
mx4life92
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mx4life92 2/13/2010 8:22pm
2/13/2010 8:22pm
the previous owner had it sleeved.... and i didnt bore it myself i took it to a well know mx repair shop

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newmann
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newmann 2/13/2010 8:53pm
2/13/2010 8:53pm
mx4life92 wrote:
the previous owner had it sleeved.... and i didnt bore it myself i took it to a well know mx repair shop
If it had been sleeved it probably had a pretty major meltdown that made the cylinder unrepairable, therefore it was sleeved. If the bottom end didn't get torn down at that time, there could have been some scattered metal down there that damaged a seal. Could be sucking some tranny fluid as mentioned above.
newmann
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newmann 2/13/2010 9:01pm
2/13/2010 9:01pm
One more question. Since it was sleeved, did the piston kit come with rings for a cast iron bore or a chrome plated bore? I'm not sure what the difference is but know it was always an option with a lot of the Wiseco's.
project racer 2/13/2010 9:09pm
2/13/2010 9:09pm Edited Date/Time 4/17/2016 8:46pm
Ever put a new needle and seat in the carb, checked the float height? As Cygnus mentioned, on a two stroke, as the bore size increases, they tend to run richer. If the RH crankseal was leaking, you would probaby be leaving a smoke stream that would rival a locomotive, on top of that, the bike would never "clean out".

I've puked many a two stroke engine,and have never had metal from a top end failure get past the bearings to actually damage a seal.
mx4life92
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mx4life92 2/14/2010 1:19am
2/14/2010 1:19am
when i got it the top end and bottom end were brand new i actually picked it up from the repair shop, so it was running good, then i put about 30 hours on that top end before it went out, and everytime before the spark plug goes out it runs but no smoke at all, but right when i put a new one it, it starts smoking again, it came with cast iron.
NetMXer
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NetMXer 2/14/2010 2:13am
2/14/2010 2:13am
What year is the bike?
zippy895
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zippy895 2/14/2010 6:20am
2/14/2010 6:20am
would bad reeds come into play?
roughneck
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roughneck 2/14/2010 8:10am
2/14/2010 8:10am
mx4life92 wrote:
i know this is the wrong place to put this but no one ever checks the tech part ok recently my top end seized up so...
i know this is the wrong place to put this but no one ever checks the tech part



ok recently my top end seized up so i had to get it repaired, i had to have the cylinder bored to a 56.00mm (stock is 54.00mm) i installed a wiseco .80 piston. so i put it back together and added a new twin air air filter while i had the seat off, well now i went ridding today to break it in, after 20 mins of riding i blew a spark plug, so i put in another new plug and about another 20 mins i fouled that one to, so i put it away for about an hour then went back out put another plug in and fouled that one, so can anyone help me out here?

im running br9eix plugs, 50:1 oil mixture, and the bike idles perfect when started with a fresh plug..

heres the bike engine setup if it helps

wiseco .80 piston
56.00mm cylinder
bills racing pipe and silencer
twin air air filter
driven racing clutch
v force 3 reeds
Its nothing more then jetting...You are running way to rich....

Go a few sizes smaller on your main jet....Put your needle clip in the 3rd notch from top..and run your mix at 32:1

If need be you might have to go one size smaller on your pilot if the above does not work..

Depending on where the bike come from..and what they had it jetted for....Its best to go back to stock jetting or close to it and start from there....

50:1 is to lean..32:1 is safe..
mx4life92
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mx4life92 2/14/2010 11:02am
2/14/2010 11:02am
bike is a 2000 rm 125, and on the oil it says do 50:1, i use it in my yz 125 my brother uses it in his 05 rm 125 and theres no problems at all. i will try changing the reeds, and will take a look at that jetting guide
project racer 2/14/2010 11:21am
2/14/2010 11:21am
For what it's worth, make your jetting changes one step at a time, and test. Would be kind of a bummer to drop too many sizes on the main all at once and end up sticking it. Especially being at .80 over on the bore already. Not a lot of bores left at that point to be risking huge steps in leaning out the jetting.


zippy895
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zippy895 2/14/2010 11:33am
2/14/2010 11:33am
inspect the reeds.see if they are flat .see if the ends are tore up. if it looks ok,just flip them over and install.cant hurt to see if theres a difference.
dont rule out rejetting
roughneck
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roughneck 2/14/2010 12:41pm
2/14/2010 12:41pm
zippy895 wrote:
inspect the reeds.see if they are flat .see if the ends are tore up. if it looks ok,just flip them over and install.cant hurt to see...
inspect the reeds.see if they are flat .see if the ends are tore up. if it looks ok,just flip them over and install.cant hurt to see if theres a difference.
dont rule out rejetting
When flipping old reeds over they tend to break...They are use to opening one way at a million miles an hour...

New reeds would be better......but...thats not why you are fouling plugs...Jetting is the problem..
Rooster
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Rooster 2/14/2010 1:42pm
2/14/2010 1:42pm
The overbore on my CRF required a few sizes smaller on the mainjet too. A new pilot as well if I remember correctly.

Jets are cheap, and I bet they solve the problem.

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