neta160 Posted June 20, 2008 Report Share Posted June 20, 2008 Has anyone replaced the stock Mikuni on an 07 270 Rev3 with a 28mm Keihin? I haven't researched the idea, by hunch is that I might need: 1) a throttle cable from a 2008 Beta (uses a 28 mm Keihin) 2) a 2008 intake and filter tube (rubber tube between airbox and the carburetor mouth) to accomodate the larger carburetor Does anyone know for sure what is required and if there are any issues with this setup? Tim Quote Link to comment Share on other sites More sharing options...
dortwilder Posted June 23, 2008 Report Share Posted June 23, 2008 (edited) Contact this guy - he sells complete changeover kits for the rev3 and other bikes. I have converted my early model Beta rev3 & I am very happy with the results. (btw he is in Australia) trialtech@optusnet.com.au DW Edited June 24, 2008 by dortwilder Quote Link to comment Share on other sites More sharing options...
neta160 Posted June 24, 2008 Author Report Share Posted June 24, 2008 Will do. Thank you. Tim Quote Link to comment Share on other sites More sharing options...
worldtrialchamp Posted July 6, 2008 Report Share Posted July 6, 2008 dortwilder, I heard he sells 2 types of kits (for the Rev3). Which one did you use? Did it run straight out of the box? Quote Link to comment Share on other sites More sharing options...
neta160 Posted July 6, 2008 Author Report Share Posted July 6, 2008 Hi, Yes he sells two kits. I didn't buy either. The "base kit" for $175-$200-ish that includes an OKO flat slide carburetor, thottle cable and a special guide, jets/needle and clamps...but he said additional parts are needed for it to work. Unfortunately I don't know what else is needed. He also sells a "complete kit" that I believe upgrades the carburetion to be just like the 08. This kit costs a lot more though, $600-ish. $600 is too much money for me. $200 is reasonable to me but it isn't a complete solution. Tim Quote Link to comment Share on other sites More sharing options...
dortwilder Posted July 7, 2008 Report Share Posted July 7, 2008 Hi Worldtrialchamp, I upgraded with the complete kit. For $200(AUS) the base kit with all those trials specific extras is good value, particularly given you just can't get it anywhere else. I had priced other carbies namely the Keihin (which has identical specifications) and it was $325 and needed $100 of further Keihin parts before one could even consider installing it onto a Rev3 (jets, special guide). Add to that a throttle cable, clamps, jets, the fact that the idle and mixture screws would be on the wrong side and you start to see the value of the complete kit that includes everything to match a 2008 model. Its easy to overlook the fact that you are not just paying for parts, but also the time someone has invested to make sure this thing works and fits well. I am not particulary technically savvy - yet it was reasonably easy for me to fit and when I had an issue (my fault) they guy was able to help. I guess it depends on whether you are happy to spend many hours & effort trying to make something work or just want to buy something allready sorted with all the bits you need and all the hard work done. Hope this helps DW Quote Link to comment Share on other sites More sharing options...
neta160 Posted July 7, 2008 Author Report Share Posted July 7, 2008 Given my limited time for tinkering, I don't want the base kit even though it is still a good value. The "complete kit" is the way to go for me, since it is a complete package with support. I just can't justify the expense. Tim Quote Link to comment Share on other sites More sharing options...
ptradam Posted July 8, 2008 Report Share Posted July 8, 2008 So what are the results of this kit? I know that the 08 rev 3 runs much better than my 05 and even the 07's I have ridden. I'd be interested in trying this if it makes the bike run like an 08 does. Quote Link to comment Share on other sites More sharing options...
steve Posted July 8, 2008 Report Share Posted July 8, 2008 Just out of interest, what are the 'issues' you guys are having with the Mikuni? Years ago I seem to remember people taking delorto's off and putting mikuni's on!! Quote Link to comment Share on other sites More sharing options...
neta160 Posted July 8, 2008 Author Report Share Posted July 8, 2008 My Mikuni is working fine after making the recommended changes (bowl extendor, drilling internal vents, rerouting tubes, etc.). However, I am looking for more low-end snap and was hoping to address it with a larger 28 mm carburetor. Quote Link to comment Share on other sites More sharing options...
steve Posted July 8, 2008 Report Share Posted July 8, 2008 So what are the results of this kit? I know that the 08 rev 3 runs much better than my 05 and even the 07's I have ridden. I'd be interested in trying this if it makes the bike run like an 08 does. If you have friends with an 07 or 08 could you perhaps swap carbs over for a test? I would have thought there were many small things that make the difference between the 2 bikes, the carb being just one of them. Of course there is also the fact that your bike has 3 years more use. Change the piston rings, repack the silencer, de-coke the front pipe and repack / renew the middle box for starters. The middle box is often overlooked as it's not an easy job, yet it can have a big impact on the bikes performance. Works teams will change the middle box every trial. Quote Link to comment Share on other sites More sharing options...
ptradam Posted July 8, 2008 Report Share Posted July 8, 2008 Steve, my bike runs fine. Just as good as any other 05. I rode an 07 when it was pretty much just out of the crate. I wasn't impressed enough to want a new bike. It ran just like my 05 270. I rode an 08 that just came out of the crate this year and WOW! This was a whole new animal. Quote Link to comment Share on other sites More sharing options...
putrid_fruit Posted July 9, 2008 Report Share Posted July 9, 2008 Hi, Just for reference I have an 07 270 with the stock carb fairly well sorted (float and jets) (think I want a 2.5 slide but these seem hard to get), also the timing is advanced up a fair bit, no other work. I rode an 08 270 early in the year, which was one of the top guys bikes but stock, and the '08 it was a bit better, but no tmassively in the way that has been suggested here. I would recommend sorting the carb and timing before dismissing the mikuni outright. Also for a harder bottom end I have the thin base gasket but haven't installed it yet. // 's all thanks! Cheers, Chris. Quote Link to comment Share on other sites More sharing options...
neta160 Posted July 9, 2008 Author Report Share Posted July 9, 2008 Chris, Good info. My objective is to get a snappier response starting from low rpms to help with zaps and other techniques. I was hoping that installing a larger carburetor would be a quick and inexpensive fix, but apparently not. That said, I am open to your suggestions. For those reading this thread, please don't misinterpret my desire to tweak my Beta as a sign that I don't like my bike or that it is inferior in some way. To be honest, I have been into Trials for 12 years and have purchased 12 new Trials bikes. My 07 270 Rev3 was my first Beta. I love it, especially the plush suspension and durability, and I plan to buy another one. Also, the carb kits that are available appear to be a well thought out solution with good technical support, in case that is the route any of you want to take. In any event, if you don't mind a few more questions Chris.... What fuel are you using and what is your jetting? When you changed the slide did you have to change anything else to make it run right? (I am running a 27.5 pilot, stock needle in middle position, stock slide, 35 main. Fuel is a mixture of 80% pump gas (93 octane) plus 20% VP Racing C12 (112 octane) and oil at 80:1 ratio. Everyone around here runs some amount of racing fuel to eliminate pinging, except in the 08s.) I have never dabbled with advancing the timing. Is there anything else you can tell me so I can basically duplicate your change? Or, if it is advisable, I will call my local dealer. Quote Link to comment Share on other sites More sharing options...
putrid_fruit Posted July 10, 2008 Report Share Posted July 10, 2008 (edited) Hi Tim, Happy to help, first thing though is that I haven't changed the slide, as ones for the right hand "choke" are too hard for me to find. so that's stock. Other things relating to the carb are the bowl extension, float level as per the diagrams in this forum, the pilot is the 27.5 and the main is one leaner than stock (130?). The fuel I run is 98 RON pump fuel. at 75-80:1 oil. The timing makes a big difference, with your fuel you should be able to run a fair bit of advance. In this image: http://www.betatrialuk.com/content/view/70/51/ I decreased that measurement by about 3 mm (from whatever it was on a stock 07) I'd guess the measurement on that diagram would be about 4mm on mine now (but i'm not checking for you). A nice clean, correctly gapped plug (.5-.6 mm) ensures you can run max advance without the knock, and is something that I see often overlooked, so worth checking. Also I have boyesen reed valves, I'm not sure (forget) how much effect these had. Good luck, Chris. Edited July 10, 2008 by bad fruit Quote Link to comment Share on other sites More sharing options...
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