cr125 problem

josheezpapa

josheezpapa

Member
1996 cr125 ran like a beast last night, fuel pickup tube came out of the tank during the 2nd heat, replaced it. We went to the grid, and i THINK it felt like the tans was in gear with "normal" compression. I told him to put in neutral and i would push hum farther up, when we got there, you could barely tell when the car was in gear.felt very simlar to neutral
i messed w clutch cable and stuff, and decided there was a clutch problem and we loaded up. I took it apart today (clutch) and all looked good, but the trans oil was gray ... i think metallic-y, but gray for sure. I then suspected a hole in the piston, i pulled the head off, no hole. i screwed the head back on, didn't torque it, and it seems like we have a little more compression, but still very low. What do i look at next ? the pipe did come loose at the mount by the stinger n the 2nd heat, too, btw
 
The first step would be to determine whether you have good compression or not. Use a gauge or feel it off the crank. If you've got compression, you've got a clutch issue.

The problem you mentioned about the fuel pickup makes me wonder if you starved it and stuck it.
 
we pulled the cylined just now and yes, we stuck it. Cyl and piston both trashed.
I have a spare cyl, Im not sure its heritage, but we may need to try it if we are gonna race friday nite

YIKES pray for rain
 
I'm pretty sure it's a sleeved cylinder, if so get some Muratic acid to put on the bore to eat all the aluminum off of it then lightly hone, install the new piston and go. Be careful not to use much acid , use a Q tip and don't have any running down in the ports, it won't eat the sleeve just the aluminum that got plated on it from the stick. Do it in a well ventilated area and seal the acid bottle up well and store in a secure place, Muratic acid is 10% hydrochloric acid so handle with care. Jon
 
wow. it is a nickasil plated cylinder, will that eat the nickasil ?? sounds like its worth a try. That engine ran really well, Im gonna change cylinders for this weekend, but Id like to have my old one again. Thanks. Any more input on this is welcome for sure. This is our 1st time. we made it all last season on the same piston, and only 3 plugs all year, the thing was as reliable as could be, and fast. then this. what a let down. It really wasnt the engine's fault. My grandson kept telling me (we had only ran it a few practice laps this year, then raced saturday) that the pickup tube was loose. I said it always has been, dont worry about it. WHOOPS
 
I don't know, never tried it on a nicasil plated bore, I have a 99 CR125 cylinder ,don't know if it would fit on a 96 case, it would need a big bore piston , the kid who ended up with the engine put the piston in backwards and hung the ring end in the exhaust port and messed up a good port job and a very fast engine. Kept it for a paperweight.
 
The muratic will clean off the aluminum from the nicasil. The nicasil is very thin and can get damaged from the stick. If you see a spot that keeps bobbling when the acid is applied there is probably a hole in the nicasil coating that is allowing the acid to get under the coating and eating the aluminum cylinder that's under the nicasil. A New stock 99 cylinders are not much more money than it cost to get a cylinder recoated. I think it's from 95-2001 that the cylinder will fit the case. 2000 up has a different head and bolt pattern a long with just one power valve on one side.
 
the cyl i have has apparently some port work done, it has power valve plugs in it (the seem to fit differently against the cyl where the bolt goes in), seems to be a duplicate of my 96 cylinder, maybe i should check the base gasket
 
Definately verify your squish when you change the jug. Muratic acid as mentioned will remove the alum from the nikasil, be careful not to let any spill in the ports of course!
97-99 cylinder and head wiil be easiest way to go because you can re-use your powervalve plugs on those. The '01s make more power on the top end but you cannot transfer the powervalve plugs (must buy new) and they tend to stick easier.
 
You must log in or register to reply here.
Back
Top