welsh beta Posted December 22, 2013 Report Share Posted December 22, 2013 Hello,im strugling with my beta evo 250,2010.i find the throttle not very smooth,i have allready change to the slow response throttle.would changing the reeds help this or not.i ride the white route.thanks. Quote Link to comment Share on other sites More sharing options...
zerorev3rev4 Posted December 23, 2013 Report Share Posted December 23, 2013 fitting a flywheel weight would help if not fitted or retarding the timing if possible Quote Link to comment Share on other sites More sharing options...
dan williams Posted December 23, 2013 Report Share Posted December 23, 2013 I put VForce carbon reeds on all my bikes to smooth them out.. Boyesens would probably have the same effect of increasing crank pressure at low RPM and therefore increasing torque. Proper carb jetting is essential to get a smooth transition between the different circuits in the carb. I also drop one tooth on the countershaft sprocket which I find better matches the power and of the engine to my meager skills. You may want to disassemble and clean the carb with compressed air as the pilot circuit on the Keihin is notorious for getting blocked with dirt or even water. That will make the throttle response seem abrupt as the bike comes off the malfunctioning pilot onto another jet circuit and suddenly wakes up. Can make a bike very hard to ride. Quote Link to comment Share on other sites More sharing options...
welsh beta Posted December 23, 2013 Author Report Share Posted December 23, 2013 Many,many thanks to the both of you for taking time to answear my question.Dan,do you mean the sprocket on the rear wheel ?Regarding the timing issue,i remember retarding the timing on my 290 sherco ,2004 and this did help then so this is another route to look into.the beta can be a devil sometimes but lot of this can be my riding.once again thant you and a happy christmas to you all. Quote Link to comment Share on other sites More sharing options...
peterh Posted December 24, 2013 Report Share Posted December 24, 2013 Agree with Dan - do the simple things first as far as cleaning the jets particularly the pilot. Has the bike always run the way you describe or is this recent. If it is a recent change, then likely to be something has changed and thus could be dirt/water blocking jets - if it is carby related. I have installed Boyesen dual stage reeds to 2009 Beta Evo 125 and 2012 Evo 200 and on both bikes the greatest benefit is low down torque and also responsiveness throughout the range - all assisted by good needle and jet settings. In fitting my sets of Boyesen reeds, I have followed the instructions on this link, written for Miknui and Keihin carbs (on Lambretta scooters) and found this process easy to work with rather than doing the plug chop method in my suburban street!! http://www.smellofdeath.com/lloydy/jetting.htm Note that the guide starts with the needle clip in the middle position and changes are then made around that starting position. So getting the pilot and needle correct without any influence from the main jet (or making me understand when the main jet circuit was coming into play) worked well for me. Having then set it up on the stand, then take it to your favourite practice ground and you can then test it on sections you are familiar with plus/minus doing plug chops through the various ranges. This helps refine the jet settings for the load and type of riding you do, but doing it first on the stand gets you a very good baseline to work with. I have also used an excel spreadsheet software that allows you to graph the effect of different jet sizes and needles have on the various ranges of throttle and the transitions. But that is my obsessive compulsive stuff coming in to play there. Good luck Quote Link to comment Share on other sites More sharing options...
dan williams Posted December 24, 2013 Report Share Posted December 24, 2013 I drop to a ten tooth engine sprocket. As far as being obsessive for jetting it really is necessary. Jetting is all about test, tweak, test, tweak. It takes patience but the reward is a bike that pulls like a steam engine yet jumps like a scalded cat when you twist the grip. Quote Link to comment Share on other sites More sharing options...
welsh beta Posted December 24, 2013 Author Report Share Posted December 24, 2013 Peter,i would say it been like this since i,ve owned the bike roughly 6 months.i thought that it must have been my fault,to aggresive but i just cant "slow " it down any more and seems to be taking me for a ride.i will start with a carb clean,it wont do it any harm anyway.i didn,t thought about a carb clean purley it allways a good starter.regarding the reeds how far "out " to the instructions did you have to change the jets ? Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted December 25, 2013 Report Share Posted December 25, 2013 I drop to a ten tooth engine sprocket. As far as being obsessive for jetting it really is necessary. Jetting is all about test, tweak, test, tweak. It takes patience but the reward is a bike that pulls like a steam engine yet jumps like a scalded cat when you twist the grip. Dan Jetting in the uk isn't much of a problem to be honest, occasionally pilot jets are wrong but the fuel we use is very consistent tbh. Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted December 25, 2013 Report Share Posted December 25, 2013 (edited) welsh beta what is the tickover set at? Edited December 25, 2013 by nigel dabster Quote Link to comment Share on other sites More sharing options...
dan williams Posted December 25, 2013 Report Share Posted December 25, 2013 Consistent fuel is great but there's often an advantage to tweaking the jets just a bit. On the mikuni equipped Betas I've owned dropping the pilot to a 27.5 was pretty standard around here for the '08 Stock jetting was fine with a needle adjustment. The '13 was a bit of a surprise. It felt a bit boggy off the bottom so I dropped the pilot to a 45 and it got worse. Going up to a 50 from the stock 48 cleaned it right up. Easy starting is not always the sign of perfect jetting. For example if the bike starts easy without choke on a cold day the pilot is probably a bit too large. 1 Quote Link to comment Share on other sites More sharing options...
welsh beta Posted December 27, 2013 Author Report Share Posted December 27, 2013 Nigel,tick over is ok,never have any problems.i like it a touch faster.Dan,regarding the good start,i allways have to use the chocke (only when cold.) Thanks boys. Quote Link to comment Share on other sites More sharing options...
peterh Posted December 29, 2013 Report Share Posted December 29, 2013 Peter,i would say it been like this since i,ve owned the bike roughly 6 months.i thought that it must have been my fault,to aggresive but i just cant "slow " it down any more and seems to be taking me for a ride.i will start with a carb clean,it wont do it any harm anyway.i didn,t thought about a carb clean purley it allways a good starter.regarding the reeds how far "out " to the instructions did you have to change the jets ? Hi - sorry about delay getting back - plum pudding got in the way! The original settings for my 2012 Evo 200 (2012 model now comes with the Keihin PWK28 carb) were Pilot Jet 48, Main Jet 125, Needle size jjh and set on the 4th clip from the top. (this I also see is the standard jetting for the 2009 Evo 250) as delivered by the factory. After Boyesen Reeds and working through the various throttle ranges and transitions and also use of a spreadsheet from James Dean Jetting - (JDJetting) and then riding in the usual terrain the following are my current settings. Pilot Jet 45, Main Jet 122, Needle size jjj and set on the 3rd clip from the top (ie the middle). Air screw is 1.5 turns out from seated. I ride mainly close to sea level (not more than 400m above sea level) and use mixture of 80:1 Belray MC1. I also use an NGK BR7E-IX iridium which to me seems to help give a very nice consistent idle - but may be I just want to find something worth the expense . However, this is what suits my motor/carby combination and each bike may be different. Good luck and keep those feet up. Quote Link to comment Share on other sites More sharing options...
dan williams Posted December 31, 2013 Report Share Posted December 31, 2013 peterh, That's interesting that you went the other way jetting with the Boyesens. I can't find MC1 anywhere around here. All I see is the H1R Bel-Ray which I run at 100-1 with VP C12 race gas. Quote Link to comment Share on other sites More sharing options...
peterh Posted January 1, 2014 Report Share Posted January 1, 2014 peterh, That's interesting that you went the other way jetting with the Boyesens. I can't find MC1 anywhere around here. All I see is the H1R Bel-Ray which I run at 100-1 with VP C12 race gas. I think I remember my first set of Boyesen Reeds instructions said that they made the main rich and pilot lean. But that didn't seem to work for me at the time and I went back to basics to optimise jets and then my next set of reeds with instructions say that they make engines run rich with main jet most affected, and found with setting needle and jets as per the process I had found, have ended up with all settings leaner. I also fitted the Boyesen X-Power Wing which may (hopefully) made a difference too. Bel-Ray MC-1 is listed on the Bel-Ray site http://www.belray.com/powersports/products/2-stroke-oils used with 98 Octane Unleaded. Quote Link to comment Share on other sites More sharing options...
0007 Posted January 1, 2014 Report Share Posted January 1, 2014 Low speed jetting, (pilot and needle) are all related to signal strength, basically suction at the Venturi If a pilot needs to be richened after reed install that means the reed is opened further and the amount of vacuum is decreased, so larger pilot is required to get the same amount of fuel through it The reverse is true, greater vacuum requires smaller pilot It's the same if a large bore carb is fitted, larger jets are required as vacuum is reduced The angle on the slide also changes vacuum at the Venturi Quote Link to comment Share on other sites More sharing options...
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