ETZ 125 carbs

[otb123]

Hello, new here...

I have acquired an ETZ125 which doesn't run particularly well (spluttered to a halt and made me push it up a hill!), fuel tank was rusted up and blocking the petcock badly (but seemed to run ok after cleaning this out), so I assumed it was this it... Anyway, have had the tank off and given it a really good clean removing the vast majority of the rust, also installed an inline filter... Ran about a pint of fuel through the petcock and didn't collect anything in the filter so am happy the fuel supply is now good...

Removed the carb and open it up, all the installed jets were as the Haynes manual with the exception of the main jet, the book specifies a 100, I have 115 fitted. The needle was badly worn/corroded, however with nothing to hand to replace anything I gave it a little clean and refitted...

Also to note, I went to inspect the air cleaner to see if it was fouled, only to find it missing! will get one ordered... And on a 5 min look the timing appears to be a little advanced (~3.5mm BTDC, the Haynes says 2.5mm). Also, pending the level in the oil tank going to down to make sure the pump works, there is a gallon of 50:1 in the tank not strait petrol.

Does anybody have any suggestion with what to target first? I have been looking to see if I can pick up an after market carb, however only see the 24N2 (presumably larger for the 150) carbs at reasonable prices (the one fitted to the bike is 22N2), however looks like I can get the jets specified in the haynes book for mine... Does any body have axperience of runing the 24N2 carb on the 125? or advice on how to jet it?

Any help suggestions etc greatly appreciated!

Kev

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[otb123]

When going well it sounds good, tends to bog down when wide open so will revert back down to the specified main (with air filter, so prob should anyway), I'm pretty sure that the wear (although it looks more like a a chemical thing (corrosion), could equally be abrasion from particles in the rusty tank) on the needle has been leading to random fueling... I've ordered an air filter, new needle, the specified 100 main jet and a new set of points as when I timed it up the existing were pretty pitted...

I wasn't stuck on a new carb, more that for the ~£30, if all the jetting was going to be pretty much there, it may have been easier / quicker, although now I'll wait until I have an air filter back in and new points before trying to set the fuel up...

How much arching is generally accepted as normal? I'm getting what look like pretty low energy sparks that seem to originate from the cam side contact and appear to move out away from the engine rather that higher energy arching across the contacts.

K

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[otb123]

Luckily I have ordered a new condenser as well, but am seriously considering going electronic... Either way I need to wait for the new air filter and needle before setting anything up so am stuck waiting for the postman

I'll report back with how I get on...

[otb123]

So, air filer now fitted and carb restored the book settings (100 main and new needle)... Running is much better!

I will do some plug chops at some and see what you guys think...

I currently have the needle clip at 3 from top which the book says is for running in but want to see how overly rich this actually is, also I have 50:1 in the tank and the autolub still all connected so more oil than normal, which would lean out the petrol some?

In light of the above, during an hours run last night I am only getting 50ish out of it, does this sound normal for the 125? Once I get the oil pump off and on just premix at least I'll know the oil ratio is correct...

[otb123]

Attached is a pic of the plug after some general running about i.e. a mix of all throttle positions... the plug was not new and the insulator was covered in black prior to this from how the bike was running prior to carb clean, re-jet and timing being set right...

Does anyone see anything wrong here? I'll do some controlled runs at some point with new plugs...

[otb123]

Well, I had a go at some plug chops, however pretty sure the results are no good due the run not being long enough...

Attached is picture of the plugs, the one on the left is at ~50% throttle and the one on the right wide open, however the bike did idle during the run down (the lights were on and I just clicked the key once, to the ignition still on position! )...

As I say I don't think the runs were long enough and were likely less than 60 seconds, need another go I think, I'd be very surprised if the 50% was as lean as it looks as the needle is already one position higher than the book says.

Plugs are B8HS.

What do you guys think..?

Cheers

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[otb123]

I have also taken a look a the crown with endoscope, there is carbon deposit all over to edge, so I've raised the needle by one and only had a short run but seems maybe a little better acceleration, certainly no worse...

Regarding smoke, while flat out I'm not seeing massive amounts which I had expected to (oil pump and premix together)? The oil in the premix is a low smoke semi-synth (no idea what's in the oil tank other than its red) so maybe that's why, I have been monitoring the level in the autolub tank and it is going down so its doing something... Either way I'll be removing the pump, need to make a blanking plate up over the next few days then see how I go when I actually know* what oil ratio I'm burning.

I now have the lower needle clip 4 notches from the top and the plug is a nice chocolate brown colour...

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