[R1slowflyer]

I have a 2003 and i get no compression when trying to kick it over.

literally you can take one finger and push the kick down. The piston and rings have been replaced multiple times, not by me. most recently though the piston and rings were replaced with stock? and i think it may have been bored out a bit due to the condition of the cylinder.

so my questions.

would it be better to just replace the cylinder, piston and rings at once just to know that its all stock and brand new?

should i find out the bore and get the piston and rings accordingly if in fact it was bored out, or resleaved?

could it just be a possible wrong or poorly installed gasket?

[OreoGitorio]

Before we get too freaked out, are you sure it's turning the engine over? If the only resistance is the kick lever return mechanism then it's probably not engaging with the crank.

put the bike in gear, roll it forwards & backwards a few times to turn the engine a little bit then try it again.

[R1slowflyer]

no its turning the piston......

i wouldnt have asked if that was the problem.

[SSearchVT]

Dumb question - the spark plug is tight? Have you had it running recently?

It could be stuck rings - remove the plug, pour a teaspoon or tablespoon of motor oil in, kick it over very slowly one or two times, let it sit for an hour, put the plug back in and see if the compression increases. If not you have to pull the top end off to see whats going on.

Check to see if the cylinder can be bored (you didn't mention if it was a high tech race bike, or low tech trail bike, or 2 stroke vs. 4 stroke). A badly blown head gasket (or loose head bolts) can cause a total loss of compression.

[R1slowflyer]

my bad 2 stroke cr125

i am gonna try the oil trick.

the last time it was running it had to be jump started, for lack of compression then also!

[gregp]

My guess is that you have pinched the ring in the groove. I just repaired one with the same problem....same symptoms. Do not try to save it. The top end kit for that bike cost about $80. When you disassemble the top end, you will probably find a small galled up area on the piston, that matches up with the exhaust port bridge. The ring will probably be pinched there.
You can have that top end apart in 20 minutes, so I wouldn't even bother farting around.
BTW- That bike has a long kick start lever compared to the older steel framed CR 125's, so the lever length makes those motors *feel* like they have very little compression to begin with, but if you have to jump start the bike to get it going, you definately have a problem there. If the piston has been replaced several times, you might want to measure the bore to make sure that it is in spec. You can order an A or a B piston, so make sure that you get the right one! Your cylinder will have an A or a B stamped on the rear, facing the carb, IIRC. I see mostly B's.

[R1slowflyer]

how would i go about measuring bore????

sorry i havent done this in years!

[SSearchVT]

Originally Posted by R1slowflyer

how would i go about measuring bore????

sorry i havent done this in years!

Take it to the shop with you when you go to buy the new top end kit. Ask them to measure it - may cost a few bucks.

[The Crashing Tomato]

Especially if you *haven't done it* in years ... save time and don't get frustrated or discouraged ...bring it to a shop (sure someone here can reccomend one close to you).

Depending on how badly the cylinder is marred up ... if at all ... will help with over bore or sleeving it and piston decision.

I've got 4 different bikes in the last year that needed this same type of attention *piston and cylinder massage*(1 each for the step kids, my hill climber, and an old beater 125 that friends use)

[R1slowflyer]

Originally Posted by TESTINGurTOMATO

Especially if you *haven't done it* in years ... save time and don't get frustrated or discouraged ...bring it to a shop (sure someone here can reccomend one close to you).

Depending on how badly the cylinder is marred up ... if at all ... will help with over bore or sleeving it and piston decision.

I've got 4 different bikes in the last year that needed this same type of attention *piston and cylinder massage*(1 each for the step kids, my hill climber, and an old beater 125 that friends use)

Are you saying that you took it to a shop, or that i shouldnt attempt to measure it myself????

edit: ill take it too a shop. recommendations? Seacoast? (it is a honda) DAS?

shops i will not go to

3A cycles
plaistow powersports
hudson cycle!!!!! (never again)

[R1slowflyer]

Ok so today was the initial teardown.

what i have found.....

this bike needs quite a bit of care

*disclaimer*

if you keep a bike outside and dont cover it you are screwing yourself over in the long run and possibly whoever you sell the bike to in the future.

so after tearing it down almost comepletely (which i may do at this point)

I have found a few things.

first - i have never in my life seen a chain this tight. it was at the ends of the tensioner.

second - for a bike i have ridden many times i had no idea it was in this bad of shape (not really bad, just not what i expected)

third - Alicia hates me because i bought a bike that runs and hers needs quite a bit of work.

so without further ado.

heres some pictures, not great but i need some help from some people with technical experience.

(i can get clearer pictures tomorrow, for some reason only a few came out really clear, but you can still make out the problem areas.)

In this picture you can make out in the top center of the piston abnormal wear, i forget who posted it, but the ring was frozen in the piston it had no freeplay to it


In this one you can make out the gouge in the piston right next to the pin


This one was supposed to show the chip thats missing in the top of the piston


another gouge in the back side also the coloration is strange..... it looks like its burnt.


on the outer ring of the combustion chamber the metal is all chipped away.


so with just these i have come to the conclusion that head, cylinder, and piston and rings need to be replaced. i am weighing the options as far as boring it out a little more and upsizing the piston and rings, but what to do about the cylinder head?

also if anyone knows a good reputable shop i am all ears.........

[R1slowflyer]

heres some pictures of the cylinder.

again they didnt come out so well, but at least with the cylinder i know there are options. it doesnt necessarily have to be replaced.

in this picture here, you can clearly see the wear on the top of the cylinder. the same chipping shows on the head. WTF???? any ideas?




heres some pictures of the bike as it sits right now. I am wrestling with the idea of just tearing it down to frame and rebuilding it at this point, but i may save that for the winter.

pics.







a small list of things i need

front brake lever (broken)
handle bar clamp (bent)
chain (seized in spots)
front and rear brake pads
air filter
?rear wheel bearings? (not sure about this one yet as the axle was frozen in the wheel and took a good amount of hammering to get it out, never a good thing!)

[Paul_E_D]

Add to that list:

Cylinder, head, and piston kit. I'd also check the rod for freeplay... May need a bottom end too.

[R1slowflyer]

Originally Posted by Paul_E_D

Add to that list:

Cylinder, head, and piston kit. I'd also check the rod for freeplay... May need a bottom end too.

yeah the cylinder, piston, and head were a given. I gave it a second look today and its just gonna be replaced.

as for the bottom end.

are there specs to check in the service manual, or is it a job for a shop?

if it is a job for a pro, any recommendations on a "good" shop.

I have had bad experiences with most of the shops around here as far as dirtbikes go. they all apparently know whats wrong until they have to fix it.

[Paul_E_D]

There is a spec, but it's relatively little play, so a "grab the rod and shake it back and forth" technique can tell you a lot. If it feels tight, you're OK to run it a bit longer. If it moves side to side, just have it done.

[R1slowflyer]

alright. i checked it out last night, seems to be ok.......

if it moved at all the total amount was very very little. mm worth of movement.

tonight, ordering parts

[Pigman]

Ive got an extra fuel tank for that if you want it free......I have no use for it

[R1slowflyer]

well if you just have it laying around. Ill take it, but i dont really have a use for it unless the tank i have is bad and i dont know it yet.

[DBConz]

Keith, those pictures are way too small. can you make them at least 1600x1200 and put pictures of a midget's garage in there?

[R1slowflyer]

Originally Posted by DBConz

Keith, those pictures are way too small. can you make them at least 1600x1200 and put pictures of a midget's garage in there?

you could fit 5 midget garages in my one garage

too bad its not finished and full of stuff.

[R1slowflyer]

OK so this question pertains to my 250

It bogs at WOT..... WTF

I would assume dirty plugs, but it only bogs at WOT. maybe the carbs need to be cleaned or improper jetting? its got a new pipe and silencer.

[1/2pint]

the jetting is either wrong or the main jet is getting stuck

[R1slowflyer]

more work

no i keed! i love ripping these little two strokes apart.

first things first finish her bike then ill tear mine apart. that way i still have a bike to ride. Brap Brap Brap BBRAAAAAAAAAHHHHHHHHHHHH BRAAAAAHHHHHHHHHHH

[Paul_E_D]

fuel starvation of some sort. Gas cap breather? Or maybe air restriction? Clogged air filter? Exhaust packing coming loose?

or jetting. Main jet just so big it fouls the plug?

[R1slowflyer]

Its not normal fouling, it revs fine in the lower rpm range and will still idle (somewhat)

its just WOT.

I think its the jetting, either clogged or too small.

also you think a dirty air filter or even gas cap breather would effect it this much?