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Author Topic: New honda cb 125e  (Read 14870 times)

Offline grcamna5

  • Posts: 1060
Re: New honda cb 125e
« Reply #50 on: Mar 09, 2016, 08:48:37 »
Where are you located? also you may want to see if getting another carb. would be good for that model.I was also going to suggest if you have any motorcycle salvage yard within driving distance you could look for a similar bike w/ that style carb.(or look at the CBR125 carb..) and see if the needle is a better configuration and then use that other carb.
Do your Best,no one can take that from you.

Offline urastus

  • Posts: 75
Re: New honda cb 125e
« Reply #51 on: Mar 19, 2016, 20:34:00 »
Thanks for the suggestion and sorry for the delay. I haven't been getting emails from this site for some reason.

I've been doing long hours at work so haven't had time to look at the bike. I did check the tracking number for the carby kit (usps) and for some bizarre reason it got turned back by Canadian customs. Ignoring the customs issue, what was it doing in Canada? I'm thinking they got my address wrong or gave me the wrong tracking number.

They are still advertising those kits on Australian ebay for the cb 125e, but I don't think they know what the carb is? The e is an australian only model I believe. So, I can't imagine that they are going to get hold of this bike and test it. I suspect they'll just guess, which I can do. I'll ask for a refund - overall I'm not happy with sigmajet - even if they do supply a correct kit it isn't up to the standard of a dynojet kit (which I've used for a dr 650 and a drz 400e).

I'm going to pull the carb (again) today and try to see what the main and slow jets are (and the model carb). I may have to play with the jets myself.

I'd rather keep the original carb; I just want it to run right with open airbox etc (not lean and hot).

Update: about 3rd april 2016 I received 2 more jets from sigma. Correct type jets but still 120 and a 125 - these are never going to work. I expect to use a 112 or maybe a 115.
« Last Edit: May 01, 2016, 03:27:22 by urastus »

Offline urastus

  • Posts: 75
Re: New honda cb 125e
« Reply #52 on: Mar 20, 2016, 03:06:12 »
OK, I've got the carb off and pulled it apart. I may have found the problem.

The needle sits inside the bottom of the slide. There is a white plastic thing with a spring underneath it. The spring looks as though it is meant to sit on top of the slide (there is a raised part on top of the needle where it looks as though the spring is meant to sit over it). The long spring sits inside the slide.

The problem: there is nothing holding the needle in place. The white plastic thing is a smaller diameter than the large spring. There is nothing to hold the white plastic thing in place (this sits on top of the slide).

I don't remember any other parts when I originally took the carb apart, but I'm guessing there was something else there to hold the needle and the white plastic thing in place.

Can anyone confirm if this is correct?
« Last Edit: Mar 20, 2016, 03:52:07 by urastus »

Offline urastus

  • Posts: 75
Re: New honda cb 125e
« Reply #53 on: Mar 20, 2016, 06:19:38 »
Ha, I've found the solution. After looking everywhere (including the swept up rubbish collected over the last month), I thought I must have lost the part. Then I had another look at the white plastic thing, and thought maybe it does lock in somehow. So, I put it in, pushed it down with a phillips head screwdriver and turned - it locked in! There must be some horizontal slots which I can't see when looking inside the slide - but they're there.

I'm pretty shitty with the shitty generic instructions and poor quality of the sigma kit. Surely these things are aimed at novices like me, so good quality specific instructions would be a great part of the reason for purchase. Dynojet kits are specific and fool proof - I had no problems with their kits on two different bikes.

The easter trip is back on :)

Offline grcamna5

  • Posts: 1060
Re: New honda cb 125e
« Reply #54 on: Mar 20, 2016, 11:09:45 »
Nice  8) How does it run ?
Do your Best,no one can take that from you.

Offline urastus

  • Posts: 75
Re: New honda cb 125e
« Reply #55 on: Mar 21, 2016, 06:49:13 »
So good :) Meaning it is back to what it was. It is good to ride again though. 3 bikes and they were all down.

I don't hold much faith in Sigma, and after all this removing and installing I realise the carb is pretty basic (esp now that I've sussed out that needle).

So, I took some photos of the main jet and the slow jet. The main is a 108s, the slow is a 38s. These are keihin jets and it is a 24mm carb. If I was to take the top off the air box, along with my slightly more open exhaust already fitted, how big a jump do you think I should try? I think the honda dude said 115 is the largest for the main (sigma gave me a 120, but I'm guessing that was for the cbr 125r)? I don't want to run lean, so would like to err a little on the safe side.

Right now the plug looks OK - but I've been putting a bit of valve saver in the tank after fitting the exhaust.

Offline cxman

  • DTT SUPPORTER
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  • Posts: 2498
Re: New honda cb 125e
« Reply #56 on: Mar 21, 2016, 09:07:59 »
i have never seen copper colored kehin jets

or slow jets with with burrs on the distribution holes

or screwed up threads
1978 CX650 Super Deluxe
1979 XS1100 Special
1974 xl350
1983 cx650 Custom
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1974 kawasaki 350 bighorn
1983 GL1100 aspy full dress
1983 GL1100 Nekid
and a bunch of others

Offline teazer

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  • DTT BOTM WINNER
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  • Posts: 8615
Re: New honda cb 125e
« Reply #57 on: Mar 21, 2016, 10:01:46 »
The first thing to know about Keihin jets is that they are not flow rated like Mikuni.  Keihin jets are size calibrated, so a 100 is 1.00mm and a 120 is 1.2mm, so 20% larger yes?  NO. Flow through a 120 is related to the area of the jet as well as other variables which don't change.

So the area is 1.20 x 1.20 x 3.1412/4 compared to 1.00 x 1.00 x 3.1412/4  or 144% of the flow of a 100 jet.  And that is way too much.

I would start with a 110 or 112 and see how that works.  You may find that stock jets are OK but always better to start safe (rich) and work down.

Offline grcamna5

  • Posts: 1060
Re: New honda cb 125e
« Reply #58 on: Mar 21, 2016, 10:27:16 »
Please show some pics of the spark plug presently and after you change main jets,try to take pics showing the porcelain center electrode down inside w/ good light.
Do your Best,no one can take that from you.

Offline urastus

  • Posts: 75
Re: New honda cb 125e
« Reply #59 on: Mar 22, 2016, 04:40:57 »
The first thing to know about Keihin jets is that they are not flow rated like Mikuni.  Keihin jets are size calibrated, so a 100 is 1.00mm and a 120 is 1.2mm, so 20% larger yes?  NO. Flow through a 120 is related to the area of the jet as well as other variables which don't change.

So the area is 1.20 x 1.20 x 3.1412/4 compared to 1.00 x 1.00 x 3.1412/4  or 144% of the flow of a 100 jet.  And that is way too much.

I would start with a 110 or 112 and see how that works.  You may find that stock jets are OK but always better to start safe (rich) and work down.

Huh, the knowledge of some people :) I think the jets are original keihin judging by the symbol, but there are after market jets for keihin carbs (I've looked) so maybe the symbol is for a common after market brand. They are probably more yellow than the pictures - it could be my camera's ability to judge white balance.

I was thinking 112, just because it was close to midway (not based on any knowledge). If you think there is a chance stock is OK, I might try 110 then.

What about the slow jet? Any ideas?

Thanks for the offer of checking out the spark plug. I'll get a "before" picture over easter.

An aside note: all those rough roads took their toll on that poor quality exhaust. The exhaust has a rubber bumper on a bracket for the centre stand to rest against when it is up. I heard an unusual rattle on some rough track and found that the bracket (very mild steel) had buckled, and the centre stand was resting against the chain (there's a groove in the centre stand now). I made an emergency fix with the wood saw on my swiss army pocket knife, a branch, and some nylon ties. I'm tempted to put a bumper under the swing arm near where it pivots on the frame, and use a little occy strap to give extra support holding it up. That should do for the easter trip anyway.

I knew the wood saw would come in handy - one of the justifications of putting a swiss army pocket knife in the toolkit. Also the file/hacksaw and scissors, fine pliers, tweezers etc. After researching I got the handyman if that helps anyone.

Oh, I also disconnected the safety switch from the clutch lever. Now if I choose to I can start the bike in gear with the clutch out :) I tested it the same way as the side stand switch; disconnected the wires from near the clutch handle, tried to start the bike while in gear with clutch out - no go. Then did the same again but with the two wires connected - it started (on centre stand with rear wheel in air). So I soldered the wires together and used some shrink wrap again. Another potential bike stopper gone.
« Last Edit: Mar 22, 2016, 04:55:15 by urastus »