'86 cr125r will not idle????

MROLP84 · Feb 17, 2008

Im a small engine mechanic (chain saw,mowers) but new to bike motors. the cr125 will start right up and has very good throttle response but will not idle. i cleaned out the carb. set the screw back to where i started, replaced and gapped the plug, new fuel but still wont idle. the center needle is on the third groove. now the exhaust leaks right where it meets the engine but im not sure that would effect the idle. any help will be great. thanks oh and the mix is 32:1 :bang:

CRazy250 · Feb 17, 2008

you could have bad reeds or cracked carb boot.

MROLP84 · Feb 17, 2008

i will take a look at the boot and reed but my main concern was with that exhaust leak. other than spraying gunk everywhere would that be effecting the idle.

MROLP84 · Feb 17, 2008

checked the boot and found no cracks. i pulled the reeds out and from what i can tell they look to be ok but as this is the first set that i have seen up close i am not to sure. they are all intact and there are no gaps between the layers and they seem to be a yellowish color but i think that might just be from the mixed gas. i did find that the choke pull seems to also be an idle adjustment, is this true? it is a keihin carb. thanks again for any info i just cant see myself buying a manual since this bike is not mine just looking at it for a friend.

WPGRider · Feb 17, 2008

don't all 2 strokes "not idle"?

sixds · Feb 17, 2008

They aren't supposed to idle.

yz80nbeast · Feb 17, 2008

actyally 2 strokes do idle just a very wierd idle, not like on a four stroke were the things just sits there, and goes doop,dopp,doop,doop etc(you get my point), my kx125 sits there and after you rev it sounds, good then it semmers, down to a fast click,click,click,click etc(u get what i mean) as if you are kicking it from a cold start with the choke up, but all in all they idle just not as like a four stroke, but your always moving so theres really no reason to let it idle, unless im betting my friend on his crf150r, that i can wheelie past the little ****

2strokerfun · Feb 18, 2008

Every 2 stroke I've ever had would idle. If the carb needle is worn, they won't idle well. If your float level is off they might not idle well. If your pilot jet is too big --or clogged, they won't idle well. If your choke plunger is worn they won't idle well. A worn slide can stop them from idling. And, yes, I know some MX bikes were never made to idle, but the 86 CR125 should idle, if set up properly. I've seen people cheat and just adjust the throttle cable a little short for idle when dealing with a worn carb.
A small exhaust leak at the cylinder shouldn't stop it from idleing.

MROLP84 · Feb 18, 2008

im working on this bike for a friend and i was just trying to guage off of my kx125 which will sit and idle. its not like a lope like in a four stroke i know this but it should stay running when sitting still. i mean when i stop and it comes off revs it just dies. my kx will atleast stay running. i was just concerned with the exhaust leak

jason33 · Feb 19, 2008

sixds said:
They aren't supposed to idle.

YES THEY ARE

exhaust leak or not you can still set the idle - if there is a set screw on the carb--- it will be on the side of it :cool:
and yes the loss of back pressure will let the air out of the head , and it would need set again, try to fix it- or it will warp the cylinder,and cases eventually -

slowgsxr97 · Feb 19, 2008

pilot jet clogged? It controls from 0-1/4 throttle. It will still start and run good with a clogged pilot jet just not below 1/4 throttle.

All my 2 strokes idled fine.

MROLP84 · Feb 19, 2008

so after scratching head, cursing , scratching head i found it. the choke knob is the idle adjustment as well on this style carb. it took awhile but while i was cleaning the carb for the second time, there it was molded into the side of the carb. i started the bike and turned the knob till i got the best rpm's and called it a day. now all ive got to do is fix the exhaust leak... thanks for all the help

IndyMX · Feb 19, 2008

I found that the OEM seal for my CR125 pipe sucked.

So, I took the pipe off and ran a bead of high temp silicone around the manifold, let it cure for a couple of days and put the pipe back on. Works great!

I do have to redo the silicone if I pull the pipe off, but that's really not a problem. Plus it's a nice looking red!!

2strokerfun · Feb 19, 2008

High temp RTV is all I've used for the past two years. I finally found a stash of o-rings that will fit, but I'll probably still use a little RTV.
I generally just put some around the manifold, wait about 10 minutes and fit the pipe in the manifold. I wait a couple of hours before starting the bike. It has always worked excellent.

MROLP84 · Mar 1, 2008

well after cleaning the whole exhaust system i found that all the o-rings were missing and that the pipes themselves were all a poor fit, plus the guy had all the springs replaced with wire, my guess it was a quick fix. anyways i put a good solid bead of high temp RTV at all the connections and replaced the wire with new springs and now there are no leaks. the bike runs great and even sounds better. thanks for all the help. -matt

'86 cr125r will not idle????

MROLP84

CRazy250

MROLP84

MROLP84

WPGRider

sixds

yz80nbeast

2strokerfun

MROLP84

jason33

slowgsxr97

MROLP84

IndyMX

Crash Test Dummy

2strokerfun

MROLP84

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'86 cr125r will not idle????

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