I have a 2004 honda cr125 and.The guy I bought it from hasn't put a new piston in it the whole time he had it(original owner).and I no i've put at least 40 hours on it,but I don't no how someone can recognize a top end needing replaced.It runs fine and dosent foul plugs,or overheat or anything.So do I need to replace it just too be safe.Or is there some way the bike lets u no its time for a top end job?And how much would the shop charge for labor? Because I can buy the wiseco top end for like $120 for the whole kit.I wonder if I can get them to bore it.I heard the newer cr's have some kind of coating that dosent let you bore um too a 144 like the others.Maybe bore it too a 133 or 134cc?Any thoughs.Would I have to get them too rejet the bike for the new piston?And how do you break in a new topend? :coocoo:
How much does the shops charge to do a top end job?
- Thread starter CR_RIDER
- Start date
- Apr 22, 2007
- 84
- 0
Your first port of call should be to get a service manual Top end break in will be covered in here. Also you will be able to judge if you can tackle the piston replacement here. As for overboring , that’s a whole different ball game and is almost certainly beyone the backyard mechanic. Most shops (in my area) are reluctant to do work without supplying the parts also. The only time I got away with this was by saying that I bought the bike with the piston coming as a spare from the original owner. Best of luck though. If the kickstarter is easy to push (very little resistance) it’s a good sign that compression is low. Follow this up with a proper compression test and a leakdown test and you'll be on the right track to knowing if the rings are not sealing anymore. With probably 80 odd hours on the bike though, its practically a certainty it needs changing though…...
2strokerfun
Member
- May 19, 2006
- 1,500
- 1
CR_RIDER said:
The "others" would be pre-1978 CRs with steel-sleeve bores. Yours is nikasil coated unless someone before you sleeved it. You can still have them bored slightly and re-coated, but it does cost some money.
Your a pilot now and the first thing you really need to do is your own top end, jetting and clutch work. When you ride hard the 125 2T may need a new ring in 6-10 hrs and piston/ring @ 20+- so obviously you'll want to do the work yourself.
You need a baseline... so open it up, check and inspect the cylinder bore, insert the new ring, take down the jetting numbers, etc., gotta know what you have to determine where to go thing...
Boring to a 144cc, sent our YZ125 to Eric Gorr came back an EGYZ144 and ran well with the 250F's (mx lites B). Last season went thru 2 pistons and 6 rings.... and the cylinder looks great (round).
Get the manual and you'll be good to go...
You need a baseline... so open it up, check and inspect the cylinder bore, insert the new ring, take down the jetting numbers, etc., gotta know what you have to determine where to go thing...
Boring to a 144cc, sent our YZ125 to Eric Gorr came back an EGYZ144 and ran well with the 250F's (mx lites B). Last season went thru 2 pistons and 6 rings.... and the cylinder looks great (round).
Get the manual and you'll be good to go...
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- Thread starter
- #5
well im only 17 and I always mess up something when it comes too the harder stuff.it just seems to complicated.And I don't no how too do jetting either.And my dad certainly don't no.He would mess it up worse than me.and I can start the bike over with one hard push from the hand!Is that bad?it seems fine.I just wanna be safe from blowing it out.my friends cr blown up.he was in like 4th and it just died and had no compresion.the rings were almost gone and.It scratched the cylinder wall up pretty bad.I just don't want that too happen too mine.He hasn't fixed his in over a year.I always tell him too fix it so we can ride but he isn't worried.He dosent like the sport as much as me I guess.The whole time he had his running he always told me quote "man I wish you still had your 96 yz250" and I was like yeah well the rear shock was toast and would have costed a fortune brand new.(I was 14 at the time) and Didn't no of getting them used anywere.so now that I have a new bike im like quote "Man I wish you would get your bike fixed" isn't that funny? :(
Moparman1539
Member
- Sep 9, 2006
- 804
- 0
Man... labor is free when you do it yourself.. and i find it quite fun...
But like i said in your other post about the sespension its really not that hard... for a top end it take getting about 8 bolts (10 for my bike) out, pulling the top end.. and taking the piston off... which is easy... and getting the cylinder honed which is really cheap.. ($20.00 at my shop, unless you want it bored, which is another $50 + whatever else needs done)
GET A MANUAL!!! It tells yo step by step instructions.. it has the drawing scamatics (sp? right word?) that shows you where everything goes, where all the bolts are, if you need any special tools or not.
And best of all, when you put it all back together and it fires it up.. you feel a great sense of accomplishment...
But like i said in your other post about the sespension its really not that hard... for a top end it take getting about 8 bolts (10 for my bike) out, pulling the top end.. and taking the piston off... which is easy... and getting the cylinder honed which is really cheap.. ($20.00 at my shop, unless you want it bored, which is another $50 + whatever else needs done)
GET A MANUAL!!! It tells yo step by step instructions.. it has the drawing scamatics (sp? right word?) that shows you where everything goes, where all the bolts are, if you need any special tools or not.
And best of all, when you put it all back together and it fires it up.. you feel a great sense of accomplishment...
Mr.Rider,
This is not an all about money thing. If your an on / off rider and keep the bike under 2000-3000rpm and just want to start and go then possibly shop service is the better way. Ride the bike low in the r's (where the powers not) and use the clutch when shifting and don't feather the turns then a shop top end may last 2-4 years and you wouldn't have risked messing something up.
Should your plans include racing MX/AX with the 125 then eventually you'll keep the bike at 9000-10000r's+ feather like hell to stay equal to the 250F's and you'll be doing top ends 2-3-4-6x a season each time 90 minutes or less (pending if your married or have kids). Should you choose to ride at this level you'll actually notice 10-20psi drop in compression, you'll need to know when to lean things out, etc., bottom line to race the 125 it must be a fine tuned machine just like the rider and even if you choose not to do the work you've got to understand the whole mechanical thing so you can relate to the shop what you want done.
We all learned at one time or another and while I respect your not wishing to exceed your mechanical abilities sometimes you've got to start somewhere. Best might be for you to find a fellow rider who does his own work and offer to pay him to do your top while you watch.
If your plans include coming thru Louisville KY anytime soon stop by, I'll plug in the turbo heater and we'll dive in...
Later... good luck
This is not an all about money thing. If your an on / off rider and keep the bike under 2000-3000rpm and just want to start and go then possibly shop service is the better way. Ride the bike low in the r's (where the powers not) and use the clutch when shifting and don't feather the turns then a shop top end may last 2-4 years and you wouldn't have risked messing something up.
Should your plans include racing MX/AX with the 125 then eventually you'll keep the bike at 9000-10000r's+ feather like hell to stay equal to the 250F's and you'll be doing top ends 2-3-4-6x a season each time 90 minutes or less (pending if your married or have kids). Should you choose to ride at this level you'll actually notice 10-20psi drop in compression, you'll need to know when to lean things out, etc., bottom line to race the 125 it must be a fine tuned machine just like the rider and even if you choose not to do the work you've got to understand the whole mechanical thing so you can relate to the shop what you want done.
We all learned at one time or another and while I respect your not wishing to exceed your mechanical abilities sometimes you've got to start somewhere. Best might be for you to find a fellow rider who does his own work and offer to pay him to do your top while you watch.
If your plans include coming thru Louisville KY anytime soon stop by, I'll plug in the turbo heater and we'll dive in...
Later... good luck
You're "only 17"??? Man-hood is a year away, dude. Get a manual and learn to do it. I was tearing down my own 125's at age 15 with no dad, no mentor, nothing but a manual and a small set of wrenches. The day I got my first torque wrench was a red-letter day. I'm confident that you can do it and if you can't, you need to learn how.CR_RIDER said: