1sherco1 Posted March 18, 2009 Report Share Posted March 18, 2009 i was just wondering if one had put a kiehn on a 125 sherco and does it make a difference Quote Link to comment Share on other sites More sharing options...
copemech Posted March 19, 2009 Report Share Posted March 19, 2009 i was just wondering if one had put a kiehn on a 125 sherco and does it make a difference Yes, it has been done. But for a number of reasons they are a pain in the butt! Add Overkill! Far as I know, Paxau still does not run or recommend them. Spend your money on some V-force reeds or something. Put a new set of rings in to keep it fresh if you run it hard. Better off! Quote Link to comment Share on other sites More sharing options...
neo Posted March 19, 2009 Report Share Posted March 19, 2009 (edited) Hi Have an OKO 24mm (Keihin copy) on my sons 06 125 and it's awesome. Better low end power. Revs up cleaner, never drips and since fitting it 6 months ago it's NEVER missed a beat or needed adjusting. This in total contrast the Keihin 28mm, then OKO 30mm (then back to the Keihin 28mm) I fitted to my own 06 250. I've only recently been able to get it running next to perfect....but it's taken me a year of on-&-off tinkering to get it that way. My recommendation is the OKO 24mm for the 125. Sorry I don't mean to contradict Cope....as he really knows his stuff. Best of balance. Neo Edited March 19, 2009 by Neo Quote Link to comment Share on other sites More sharing options...
axulsuv Posted March 19, 2009 Report Share Posted March 19, 2009 A 26 OKO would most likley be the best bet , A 28 kehin will help top end if your a pro class rider , but at the sacrafice of a loss of bottom end and very poor throttle response . As copey said , Just overkill ... Bigger is not always better , if lose your intake velocity performance will suffer Drastically . V-force and a 26mm Okowould be sweet ... Glenn Check OKO .uk (classic trials ) , He's probly already done it and/or will have the jetting down already ... Quote Link to comment Share on other sites More sharing options...
1sherco1 Posted March 19, 2009 Author Report Share Posted March 19, 2009 defintly not a pro its just at the tops of long hill it starts to die abit thanksi might just get a pipe cheers josh Quote Link to comment Share on other sites More sharing options...
copemech Posted March 20, 2009 Report Share Posted March 20, 2009 No, actually I think Neo may be on to something that I just never had a chance to do with the OKO 24 on the 125's, would probably run well for average rider. To me, the primary issue with the Kiehin on the 125 is the physical size, as the inlet is closer to the case than a 2.5/2.9 and seems to at least require(i have heard) a beveled intake spacer to get enough angle for clearance of the bowl. On the OKO(copy) this may or may not be exactly the same. The second issue seems to be simple overkillin that the 125 cannot ingest all that the 28mm carb is able to supply. Even on the 2.9, the bowl wants to set and rub on the case, even with a bit of grinding for clearance. Although it will work, I just do not like it. Add the fact that I just do not really need better throttle response or more power on the 2.9, the Kiehin has been shelved for some time now. Things being what they are, I would not be surprized if the 24mm OKO did not work well on the 2.5/2.9 as an actual power limiting device! Yet still delivering smooth power off the bottom? Bottom line, if they were not such a pain to fit, tune and test, I may have done a lot more with them, but the time proven Dellorto well tuned has sufficed, and I still think may be less aggressive off the bottom, mind you, a far fetch from what may be desired on the 125 that this discussion was about. As a side note, I did run the 2.5/2.9 header on the 125 I had several years ago. Larger pipe at the inlet, but still really could not tell much difference, just replaced the dented one! Some said they produced more top end, but? Quote Link to comment Share on other sites More sharing options...
tony27 Posted March 20, 2009 Report Share Posted March 20, 2009 From what I've seen on the OKO oz site there would be absolutely no issues with being fiddly to fit as they do a complete kit comprising carb(not sure if spacered), manifold, airbox connector & cable for around $400 AUS, pretty much same price as keihen carb only. Thinking could be interesting to try with the v-force I've been using Quote Link to comment Share on other sites More sharing options...
neo Posted March 20, 2009 Report Share Posted March 20, 2009 To me, the primary issue with the Kiehin on the 125 is the physical size, as the inlet is closer to the case than a 2.5/2.9 and seems to at least require(i have heard) a bevelled intake spacer to get enough angle for clearance of the bowl. On the OKO(copy) this may or may not be exactly the same. Hi Cope, The 24mm is exactly the same physical size as the 26mm, 28mm. 30mm and the PWK. The bowls and even the slides are OKO interchange able (but the slides don't fit in the Kiehin). I know the bevelled intake spacer you mean as I've seen these on the GasGas's. So without it all the carb bowls rub on the gearbox case, even with the Sherco 5mm manifold spacer. Although I think it is a fairly light rub. I use and 5 cent piece wedged between the carb bowl and the case. It doesn't move so the case is not damaged in any way. Also I have a clear plastic bowl on this carb so if there was a lot pressure it would have cracked or leaked by now. Best of balance. Neo Quote Link to comment Share on other sites More sharing options...
copemech Posted March 21, 2009 Report Share Posted March 21, 2009 Neo, These things OKO are intresting, I have always thought of these things in TWO ways, firstly, the Jap style carbs are better mixing devices, secondly, the Dellorto is the best $15 carb that ever came out of europe! It just works! And a good one properly set can work very well. Then there is that flat slide vs round issue? well? I have an idea that the 5mm spacer for the Sherco can be put on a belt sander to achieve a proper bevell, yet the holes for the screws may require some angle put to them. If you could get the thing off the case it would be better allround installation. You know, this whole thins is just not something I would normally recommend for your average kid to do! Just cram the friggin 28 in there, it will be fine! NOT! I have a dandy of a coupling hose from carb to airbox that worked well on the 2.9. It is a reinforced intake hose for small aircraft that fits perfectly and is soo tight on the carb inlet requires no clamp really, once you get it on the thing. They are inexpensive and far better than some muck of radiator hose. As purely an experiment, I would be interisted to find your results of testing the 24mm OKO on your 2.5? I sort of think it would run just fine, with less agression than the others. Good for many, specially the 2.9 riders that like things a bit more toned down. Quote Link to comment Share on other sites More sharing options...
copemech Posted March 26, 2009 Report Share Posted March 26, 2009 Well, Neo? Quote Link to comment Share on other sites More sharing options...
neo Posted March 26, 2009 Report Share Posted March 26, 2009 Sorry Cope, I'm currently on a business trip. Might not be able to try the 24mm for a couple of weeks or so. What jets should I start with....same ones as the 28mm? Best of balance. Neo Quote Link to comment Share on other sites More sharing options...
trialsnutterman Posted March 26, 2009 Report Share Posted March 26, 2009 It would be a all right starting point but you will probably have to lean them off. As your using a smaller diameter carb, the air will flow at a higher velocity causing more suction on the jets so it will probably run rich. Oh and could you edit the spelling of title to Keihin so people can search for this thread easier in the future. Quote Link to comment Share on other sites More sharing options...
neo Posted March 27, 2009 Report Share Posted March 27, 2009 (edited) Oh and could you edit the spelling of title to Keihin so people can search for this thread easier in the future. I think you might need to put that question to 1shercohe1..... But either way I think "Keihin" has been mentioned enough times in this thread to come up in a search. Thanks for the tips on the jetting. From what I've seen on the OKO oz site there would be absolutely no issues with being fiddly to fit as they do a complete kit comprising carb(not sure if spacered), manifold, airbox connector & cable for around $400 AUS, pretty much same price as keihen carb only. Oh and the Oz kit will not stop it being fiddly...The ports (Intake and Airbox) are too poorly aligned to stop that. Best of balance. Neo Edited March 27, 2009 by Neo Quote Link to comment Share on other sites More sharing options...
neo Posted March 27, 2009 Report Share Posted March 27, 2009 You don't want the bowl to rest on the engine case as it will often cause frothing of the fuel in the bowl and that will affect the air/fuel mixture ratio and performance. I just noticed this on the GasGas forum.....This is interesting but do you reckon it's plausible? Best of balance. Neo Quote Link to comment Share on other sites More sharing options...
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