CR125 problem solved!

[morg_nz]

For a while now - i.e. since i bought the bike - i've been wondering why it had had no bottom end. I've been told 125 2T's have no bottom end etc., but it wasnt until i rode a mates KX125 that i realised my CR125 had something seriously wrong. After returning the bike to stock jetting, checking float height and needle condition, rebuilding the gearbox etc I have just pulled the head off and apart. The pistion and cylinder look in great condition (except for the carbon on he piston cause it is running crap. So looking at the powervalve is about the only thing i can think of. What I found odd looking up from the exhaust port was that I could see above the powervalve when it was in the static position (i.e. closed). As it turns out I cant actually see a way to adjust the CR125's powervalve, so it seemed particuarlly odd to have such a gap above the powervalve (as this would let the petrol air explosiion decompress too early off idle.

So after much head scratching I pulled out the box that contains the 'spare' engine that I got with the bike - which was the one that had a big end bearing blown. I started looking at the head, and noticed that the edges of the exhaust port looked much sharper, and almost a different shape. I sat it next to the head that i have just pulled off the bike and it looks like whoever "rebuilt" the engine has taken a dremel or the likes to the exhaust port, and bored it out so the powervalve does not actually fit any more (hence the gap above it). Furthermore, i notived that the powervalve flaps in the current head also have holes drilled in them (bout 1mm dia. in each flap) for god knows what reason. I dont think this is a standard feature!

So quite interesting really, whoever 'rebuilt' that engine is a bloody butcher, and the guy i bought it off trademe obviously either did it himself or figured that out and offloaded it!

So my question is therefore who reconditions motorcycle heads in the manawatu region, and what does that cost? the old head that i was comparing the current one to looks ok, except it seems to have a few vertical marks (not scratches though) in it, and a couple of patches where it has some build-up on the surface. everything else looks great though, so im hoping i can get that one reconditioned (properly) and then the bike should be a great runner!

Im acutally quite happy i figured out what was wrong as its the first bike i';ve really pulled to bits and only paying 2k for it, i dont want to be paying a shop to fix the thing cause its so easy. and it will be good when its running properly too as the rest of the bike is in mint condition!

[morg_nz]

so looking at both cylinders again this morning, the piston obviously fits in the cylinder i just took off the bike, but it is too big for the old cylinder. i presume therefore that the current cylinder has been bored and a bigger piston bought - and i presume that i will have to have this done when i get the other cylinder reconditioned. any ideas how i would specify size for the rebore/piston?

[barty5]

it sounds like the second barrel has had a sleeve fitted to it as the 01 has a nikasil bore standard if the piston is still in the second motor it will have a number or letter stamped on the top of it which will tell you what over size it is

[morg_nz]

it sounds like the second barrel has had a sleeve fitted to it as the 01 has a nikasil bore standard if the piston is still in the second motor it will have a number or letter stamped on the top of it which will tell you what over size it is

na no piston with second motor unfortunately

[barty5]

na no piston with second motor unfortunately

you will need to get someone to measure it unless you have a Vernier to do it you should be able to tell from the bottom if it has been sleeved easy to work out what size piston is needed once measured

[morg_nz]

you will need to get someone to measure it unless you have a Vernier to do it you should be able to tell from the bottom if it has been sleeved easy to work out what size piston is needed once measured

interestingly enough, the current cylinder has had a sleeve fitted, and the second one does not look like it has had anything done to it (that i can see anyway)

[honda_power]

post up a pic of what you think is wrong with it, ill compare it to my 02 in bits atm... pretty sure they are the same

[barty5]

post up a pic of what you think is wrong with it, ill compare it to my 02 in bits atm... pretty sure they are the same

good idea our 01 has the top end off at the mo as well

[morg_nz]

took the cylinders to honda yesterday to get a price for a resleeve - they rang back saying that they could get a brand new cylinder from honda nz for $369 as they are having a bit of a sale on their older parts (it was going to cost aobut $450 for the resleeve) so i should have a brand new cylinder arriving today, should be excellend :-)

[D dub]

took the cylinders to honda yesterday to get a price for a resleeve - they rang back saying that they could get a brand new cylinder from honda nz for $369 as they are having a bit of a sale on their older parts (it was going to cost aobut $450 for the resleeve) so i should have a brand new cylinder arriving today, should be excellend :-)

You will need a new piston to match the cylinder as well!

[morg_nz]

You will need a new piston to match the cylinder as well!

yep, ordered one of those too! although the bloody cylinder arrived today, but not the piston! grrr, was hoping to rebuild tonight so i can ride at the weekend, but now i'll be out of town till then!

[bogan]

sounds like a pretty good deal! you got new powervalves for it too? or try with the old ones

[morg_nz]

sounds like a pretty good deal! you got new powervalves for it too? or try with the old ones

na, i'll tidy up the old powervalves from the second cylinder (which look pretty good) - the powervalves that came out of the cylinder i was using had holes drilled in them!

really looking forward to riding the bike like it was meant to!

haha i was just about to order some v-force 3 reeds as well, but the bloody engine check light came on in our murano and it wants $1k worth of catalytic convertor so guess further performance upgrades for the bike are on hold for a while (note to anyone reading this - nissans are very reliable, but bloody expensive to fix!)

[bogan]

na, i'll tidy up the old powervalves from the second cylinder (which look pretty good) - the powervalves that came out of the cylinder i was using had holes drilled in them!

really looking forward to riding the bike like it was meant to!

haha i was just about to order some v-force 3 reeds as well, but the bloody engine check light came on in our murano and it wants $1k worth of catalytic convertor so guess further performance upgrades for the bike are on hold for a while (note to anyone reading this - nissans are very reliable, but bloody expensive to fix!)

yeh, she'll be a completely different animal ofter those upgrades I reckon. Personally i see no reason to mod any furthur, the bike certainly isn't the one inhibiting my lap times, and it's a bucketload of fun with the power its got now!

You ride trail or tracks?

[morg_nz]

yeh, she'll be a completely different animal ofter those upgrades I reckon. Personally i see no reason to mod any furthur, the bike certainly isn't the one inhibiting my lap times, and it's a bucketload of fun with the power its got now!

You ride trail or tracks?

trail mostly, but joined the club earlier in the year - really enjoyed riding the tracks but the bike couldnt get out of its way in a corner. once fixed thought i think i'll get back into it cause its a great way to build skills i reckon. im more interested in riding enduro long term but need to work on riding skills/physical fitness first!

[barty5]

na, i'll tidy up the old powervalves from the second cylinder (which look pretty good) - the powervalves that came out of the cylinder i was using had holes drilled in them!

really looking forward to riding the bike like it was meant to!

haha i was just about to order some v-force 3 reeds as well, but the bloody engine check light came on in our murano and it wants $1k worth of catalytic convertor so guess further performance upgrades for the bike are on hold for a while (note to anyone reading this - nissans are very reliable, but bloody expensive to fix!)

cut the cat out or bash out the inside it will just be blocked

[bogan]

trail mostly, but joined the club earlier in the year - really enjoyed riding the tracks but the bike couldnt get out of its way in a corner. once fixed thought i think i'll get back into it cause its a great way to build skills i reckon. im more interested in riding enduro long term but need to work on riding skills/physical fitness first!

yeh, I always prefered track over trail, two strokes seem to be a lot more suited to track as well I reckon. And you can take a break every few laps!

seem to be lucky to get out every second month atm though, so my riding endurance is shot, technique seems to be improving though :D If you're ever in need of a riding bud for the track gimme a holla :yes:

[morg_nz]

cut the cat out or bash out the inside it will just be blocked

yeah i would if i coudl get to it, but i'd need a hoist, and even then i think it would still trip the engine light cause of the bloody oxygen sensor! if there is no change between the upstreem and downstream it will register a fault too i think. all the technology in new cars is just rubbish!

[morg_nz]

yeh, I always prefered track over trail, two strokes seem to be a lot more suited to track as well I reckon. And you can take a break every few laps!

seem to be lucky to get out every second month atm though, so my riding endurance is shot, technique seems to be improving though :D If you're ever in need of a riding bud for the track gimme a holla :yes:

will do, what tracks do you ride?

[bogan]

will do, what tracks do you ride?

whatever ones my army mate gets us access to, seems its all about who you know round here

[tommorth]

drilling holes in the power valves wtf were they thinking , good score on the new cyl it's sure to run a heap better with all its bits working properly.

[morg_nz]

drilling holes in the power valves wtf were they thinking , good score on the new cyl it's sure to run a heap better with all its bits working properly.

bloody annoying though - got the cylidner this evening, and realised that i either need new stud bolts or need to get someone to remove the old ones from one of the cylinders cause i dont have the tools to, and ditto for the powervavle bearing! bugger, i was looking forward to doing it tonight!

[bogan]

bloody annoying though - got the cylidner this evening, and realised that i either need new stud bolts or need to get someone to remove the old ones from one of the cylinders cause i dont have the tools to, and ditto for the powervavle bearing! bugger, i was looking forward to doing it tonight!

you tried putting doing up two nuts on a stud to get it out?

[morg_nz]

you tried putting doing up two nuts on a stud to get it out?

yeah and with no luck!

[bogan]

yeah and with no luck!

huh, must be in there well good then, cos i always figured two nuts is the proper tools!