joolstacho Posted August 17, 2014 Report Share Posted August 17, 2014 Help me solve this little mystery. I bought a new Carb Reco kit from IOCON LTD UK (it's a Cotton branded part No. 251353805147) -advertised (ebay) as correct for a: TL125E (England) '73-75.On receiving it I've foundthat it's for a different carb to my (Oz) '74 TL125E K1 model, for example the throttle needle length on my carb is approx 43mm long, but the one in the Cotton kit is approx 58mm long. My carb is the original, -correct for the year and Oz delivery. I think the later 'S' Model may have had a different carb, certainly different jetting. I'm wondering if UK models had different carbs to Oz models in '74. My throttle needle and needle jet are worn, so I need replacements but need to sort out this mystery so I can ID the correct replacements.Anyone shed any light on this?Jools Quote Link to comment Share on other sites More sharing options...
mcman56 Posted August 17, 2014 Report Share Posted August 17, 2014 From my understanding, US TL125s all use the same basic 22 mm Keihin carb. I have one of an unknown year and a Reflex carb and they are also the same. The big difference is that the Reflex came with a non adjustable needle. To get an adjustable needle, I purchased one of the NOS Keyster carb kits from ebay for an SL125 and the needle fit. (Kester quality does not look as good as Keihin quality.) I see different kits listed for different 125 models but suspect the difference is the jet sizes. This same carb was sold in a 24 mm version. It uses the same casting but the oval bore is taller and therefore symmetric when looking at the engine side of the carb. I don't know what models these came on. Is your carb marked with 22 on top by the cable entrance? Quote Link to comment Share on other sites More sharing options...
joolstacho Posted August 18, 2014 Author Report Share Posted August 18, 2014 No, mine has '20' cast (not stamped) in the top plate near the throttle cable entrance. I wouldn't have thought this would have any relation to the choke size though would you? If as you say they all use the same basic 22mm Keihin, the Cotton reco kit must be wrong because the Cotton slide needle is 15mm longer than the original one. I'm sure Honda would have used the same carb for other bike models, perhaps with different jetting, maybe that's another line of enquiry - as you say you've used a needle off an SL125. Quote Link to comment Share on other sites More sharing options...
mcman56 Posted August 18, 2014 Report Share Posted August 18, 2014 I have seen a 22 and a 24 and it definitely related to choke size on the ones I saw. The oval bore on the 24 was taller. You can modify the bore of a 22 to match the 24 but also have to take a cut off the top of the slide to get it fully open. The difference in slide height could explain why they cast the numbers on the top plate. I did not get to measure the 24 top plate so maybe they used a shorter stop on the top plate rather than a shorter slide. Could your model have come with a 20 mm carb? (I'm not sure how they get just a diameter for an oval shape.) Quote Link to comment Share on other sites More sharing options...
dalfetta Posted August 21, 2014 Report Share Posted August 21, 2014 The TL125S year 76-78 have a 18mm carb ( Keihin PC18 ) Earlier models, have the same one than the 125 SL : a keihin 22mm Quote Link to comment Share on other sites More sharing options...
joolstacho Posted August 22, 2014 Author Report Share Posted August 22, 2014 Right, so... what I need to find out now is if the needle out of an SL125 Is 43mm long or 58mm long. Anyone got a carb handy they could measure the needle length? Quote Link to comment Share on other sites More sharing options...
tlrider Posted August 22, 2014 Report Share Posted August 22, 2014 To the best of my knowledge and my experience with the TL125's I have owned and worked on the US market 'K' bikes have a 20 mm carb. The US 76 'S' model also has a 20 mm carb but it is a more robust body, i.e. the casting is thicker and reinforced to reduce the barrel from collapsing when tightening the flange mount. Visually the two carbs are easy to tell apart , the 'K' carbs have a spring clip on the float bowl and on the 'S' carb the float bowl is screwed on. I have been using an 'S' carb on my 'K' bike for a number of years now and combined with the carb insulator I make with an o-ring on the head side I seem to have eliminated the air leak and sticking throttle issue common on the 'K' bikes. Before I got the 'S' carb I ordered a 22mm carb listed as fitting the TL125, physically it was too large to fit the bike. I hope this is helpful rather than prolonging the mystery! Quote Link to comment Share on other sites More sharing options...
joolstacho Posted August 23, 2014 Author Report Share Posted August 23, 2014 Thanks guys. Interesting tlrider "I ordered a 22mm carb listed as fitting the TL125, physically it was too large to fit the bike" -Have to assume that you got wrong info from the seller telling you it was for the TL125. Yup, the type with the Springclip floatbowl is correct for a 'K' as you say, and until someone says they know different I'm going to say that this carb has a needle that is approx 43mm long. Does anyone have an 'S' carb handy that they could measure the length of the needle? (If it's 58mm then that pretty well solves the problem). Key to it is identifying what carb the Cotton kit (with the 58mm long needle) is for. (Helpful YEP tlrider, but not solved yet!) Quote Link to comment Share on other sites More sharing options...
joolstacho Posted August 23, 2014 Author Report Share Posted August 23, 2014 Here's pics of the Re-co kit from the UK (that has the longer 58mm needle). Quote Link to comment Share on other sites More sharing options...
tlrider Posted August 27, 2014 Report Share Posted August 27, 2014 (edited) I have both carbs and will measure the needle lengths. I presume you are measuring the overall length? The 22mm carb was listed as fitting SL,XL,CL,CB,TL 125's. I think it was a case where the seller assumed all of the 125's use the same carb. I've seen numerous parts listed that way on ebay. NOS, used and aftermarket parts listed as fitting all models of a specific size. Buyer know your stuff. edit)I didn't understand Honda's part numbering system at the time and the importance of the three digit product code. Back to you in a few days... Edited August 27, 2014 by tlrider Quote Link to comment Share on other sites More sharing options...
tlrider Posted September 3, 2014 Report Share Posted September 3, 2014 (edited) Jools, I have two 'S' carbs and four 'K' carbs from the US market and all have 20 cast in the cap. I have a NOS needle in an unopened package part number xxxxx-355-xxx (sorry I didn't write down the number) and a Keyster TL125/S carb rebuild kit. All of my needles measure 43mm. The TL125/S was the only street legal TL125 sold in the US and has the two piece head vs. the one piece head of the K model. I guess it's possible the England market bikes had a larger carb. I realize this still does not solve the mystery but I suggest that you should be using the 43mm needle. Look for a carb kit labeled TL125/S. I got my Keyster kit from Sirius Consolidated. edit: Gave you the link to the S carb in the unedited post, now have both links. They appear to be the same kit with the exception of the jets. Main: K=95, S=92 Slow: K=38, S=35 (K carb) http://www.siriusconinc.com/pro-detail.php?pid=&product_id=464 (S carb) http://www.siriusconinc.com/pro-detail.php?pid=&product_id=463 Edited September 3, 2014 by tlrider Quote Link to comment Share on other sites More sharing options...
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