billyt

Sorry. I just copied one of the links i.e. www.youtube.com/watch?v=a2FHl-KJwp8 and then pasted it in on the front page of You Tube and it opened just fine? Copy a link and then paste in You Tube. Maybe there is a better way of posting it? BillyT

Hey guys. I did it, I went over to the Four Stroke dark side. I played around with the carb and re-jetted, re-sprung the CV carb slide. The four stroke is messing with my timing & mind for sure. I am now back at square one learning all over again. I posted some You Tube (3) videos of me playing around on this BEAST . www.youtube.com/watch?v=a2FHl-KJwp8 www.youtube.com/watch?v=2gJXGjB6eC4 www.youtube.com/watch?v=OqpPFM5qYvw Not good riding skills but fun non the less. Cheers BillyT

Sam What is the latest with the 125cc project? How is the bike running now since the changes? Hopefully you are a satisfied lad? LOL..... BillyT

Hey Cope You have a new friend with crossed hoses. I did not know you where gay! LOl.............. Maybe you can syphon his hose for him in Oka. See you in Munester in June hose man. BillyT

Ralph Thanks mate. I will no doubt tear into the CV carb when the bike gets here. Mostly to satisfy my curiosity and will call my mate over at Mikuni to get the low down on the CV carb. Stay tuned as need more help adjusting to a four stroke! Cheers BillyT

Steve Where did you send the message to? I sent you one a couple of weeks ago, did you get it? My e-mail address is williamtraynor@hotmail.com Cheers

Hi Cope Yes a new 2010 Beta Evo 300cc is on its way from American Beta. Apparently the bike has changed much since 2009. My mate is the VP of Mikuni in Northridge CA. known him for about twenty odd years now. He will be getting a call from me on Monday with me asking for every bit of technical info on that carb and any secrets that the lay man does not have. I will no doubt share it with my bros here. I have spoke with the new importer at American Beta and he is an old trials rider so he should be very helpful to all who buy a new Beta.

Oh but there is! Much to learn. I have access to much at Mikuni and will exercise that. You may not have a need, there may not be a need but a desire for education on a new type (at least to trials bikes) of carb. To each their own. Respectfully BillyT

Hey BE4T guys. I have went over to the dark side and ordered a 2010 Beta 4T 300cc. Getting excited now and looking forward to feeling what all the buzz is about. I called my mate at Mikuni and asked for all of the Mikuni carb specs and an education on same. Look for future posts seeking help with this new to me 4T beast. Cheers BillyT

Hey BE4T guys. I have went over to the dark side and ordered a 2010 Beta 4T 300cc. Getting excited now and looking forward to feeling what all the buzz is about. I called my mate at Mikuni and asked for all of the Mikuni carb specs and an education on same. Look for future posts seeking help with this new to me 4T beast. Cheers BillyT

Sam It has two base gaskets for a reason! That reason is taking one out to tune the engine. Of course it changes the squish BUT so does swapping for a modified higher compression cylinder head and people do that! If it were me! I would do the following in the order as I write. Take the cylinder/jug off Remove ONE BASE gasket Put the jug back on! THIS NEXT STEP VERY IMPORTANT! When putting the cylinder head back on and after torquing down cylinder head and jug/cylinder REMOVE SPARK PLUG AND TURN/PUSH START LEVER SLOWLY. This will verify that the piston is not hitting the lowered ( lower due to removing a base gasket) cylinder head! If it does NOT hit then proceed with re-assembly and then start bike as usual. You may have to increase the octane of the petrol If this first step works let us know and we can walk you through the next steps. Good luck! BillyT

yzeefoureight Firstly, I am not familiar with Gas Gas engines. BUT these principles work for all trials bikes. Okay Jay I will start. You pitch in at any time, or in fact anyone pitch in. If I wanted to increase a 125 cc trials bike for more bottom end, depending on the riders level of riding here is what I would do. An advanced rider: On a 125cc trials bike the bike is more than likely ridden with high RPM's most of the time. The bike in stock form is pretty close for high RPM riding. Leave the stock 26mm carb alone. I will explain why in the following changes to a 125cc if I was a average club rider. Change the head for a higher compression. Race fuel/ higher octane will be necessary now due to increased compression. Change timing. Open up the exhaust port to let the bike breath better. If I was average club rider and was NOT the greatest at revving the **** out of the bike to get up objects, hills rocks etc Here is what I would do to get more bottom end and snap with some torque. Change out the carb for a smaller one. Trials bikes usually come with a 26mm I would go with a 24mm. Why? The movement of the piston piston creates the vacuum on the carb. It will be the same level of vacuum regardless of what carb is on the bike. The smaller carb performs better on a smaller displacement bike for the following reasons. If the vacumm is the same regardless of carb size then a larger orifice carb such as a 28 mm will see higher air flow BUT lower velocity. This lower velocity (due to a larger throat on a 28 mm carb) will not aerate/atomize fuel at the venture as efficient as a 24 mm carb with a lower flow but higher velocity. The step from a 26 mm to 28 mm will gain flow but there was enough flow already with the 26 mm what we are looking for is mixing velocity at the needles/jets venture. A 24 mm carb has enough flow for an average club rider. In fact I always when possible switch out a the 26 mm for a 24 mm carb. This is carb basics. For the same amount of vacuum (air & fuel) to go through go though a smaller opening it has to speed up (velocity) making a better venture effect. The lower velocity from a 28 mm carb will feel funky at low rpm's and give the impression that one has lost bottom end due to running poorly/boggy lost snap due to funky fuel mixture. Granted the bigger carb will run better at higher RPM, and if you are a top flight rider on a 125cc you may want that? But I disgress, this segment is about an average club rider on a 125cc. I would also take off the jug/cylinder and either machine the base of the cylinder to lower the ports. Or if the jug has two gaskets remove one. Putting a thiner gasket is the cheapest and non destructive way of doing this. BUT not all manufacturers offer thinner base gaskets. If you do machine some of the base and you do not like the results or are now a top flight rider that needs to rev to the heavens then you can always put an extra base gasket back under the jug to take you back to where you started from. Lowering the ports by this method will also increase compresion and give some mid range power also. Obviously if money was no object then buy a spare jug and have the transfer ports lowered in the jug itself leaving the exhaust and intake ports alone. And for Jay. Wenn ich mich erh

Hey Paul It is not hanging anymore. I spilt some race fuel on it and it is driving me mad with power. It wants to go out and clean something. LOL How are things with you? So Jay. Lets try and help this guy as tag team to get more bottom end on his 125 si si senior! Okay? Please, no more silly magical horse power increase suggestion from puerly adding fuel. DEAL? Danka mein her.

Jay......... This is getting nuts. You must be a female as you will not admit that you are WRONG! LOL.... Lets do this.............. yzeefoureight go mix up some high octane race gas, put in the bike. do nothing else to the bike. And if you are still alive after all of that power increase let us know how marvelous the power increase was! LOl..... Over to you amigo! Das es das liebien. BillyT

Jay This is right from VP Fuels web site. Not one mention about extra power purely that race gas affords one the abilty to fine tune the engine heads, exhuast, carb etc without pre-detonation due to the charactistics of the fuel. It also affords a more consistant source of fuel affording leaner jetting etc. That is why you may see a slight cleaner (adding race fuel only) running of the bike due to fuel consistance and leaner jetting but more power hell no!. What does octane really measure and how important is it? One of the most frequently asked technical questions we get at VP involves the difference between Motor, Research and R+M/2 Octane Numbers. The next most frequently asked question is why some fuel companies represent their fuels with Motor Octane Numbers, while other companies use Research or R+M/2 Octane Numbers. 

Realize first that octane is a measurement of a fuel

Sherco Jay So we are both engineers (mine Mechanical & Electrical). So, one simple question one simple answer. If one does nothing to their bike (porting, exhaust, high comp head, timing etc) but add a higher race fuel will one see a noticeble higher output in power across all the power band on a trials bike? If so, tell me where this extra surface area of piston came from, how the stroke changed, how the timing changed, how the porting of the engine changed, all by mearly by adding a fuel source that had a higher flash point? Where did this HP come from? Over to you mon ami! BillyT

"Fifth gear did a test on the fuels about a year ago, yes I know its own cars and the engines aren

"Running higher octane does NOT give you more power!" "But it will up the overall bhp of the bike" Please tell me how it will possible do that? Purely adding a higher octane by itself will do nothing but burn more cleanly! When you add a higher comperession head you will need the higher octane to stop/prevent pre-ignition due to a higher compression and squish band. The flame or burn pattern will be more controlled with a higher octane, but adding a higher octane fuel to a stock bike thinking it adds more power is a placebo at best. In fact many studies have shown that you could in theory get less power by adding a higher octane to a factory stock bike. If you have or know something different please educate us! Respectfully BillyT

Hi Guys If I may offer my humble opinion on this subject. It is not mearly a question of bumping up power on a 125 cc but where you want the extra power in the power band? The suggestions offered so far will do the following: A larger carb, 26mm > 28mm will loose bottom end and gain top end. A higher compression head will boost power mainly in the mid range causing the bike to bind up in the higher RPM range. Running higher octane does NOT give you more power! I can go into details for each line if you wish? yzeefoureight Please tell us where you want the extra power? Cheers BillyT

Hey Dan I must commend you for your well written technical article. While I agree with what you wrote and the changes made there is MUCH more going on in the clutch that the lay person misses, and much more that can be done to smooth out the clutch and its pull, and releasing. We should talk as it is nice to have conversation with another tech head such as your self. If only I had the time, patience, and computer skills needed to post my thoughts. Cheers Dan. BillyT

Scotty Adjust the idle screw down (in) low to afford/allow slow idle speed AFTER CHAINGING TO A LARGER PILOT JET. The pilot jet should be a standard as a #30 I change mine to a number #35. Check the number stamped onto the side of the pilot jet and tell us what it is. Also disconnect the throttel cable from the throttle tube and see what this does? Cheers BillyT

Scotty If there is an air leak in the rubber boot the bike would be running lean/crazy at all RPM's not just coming down from idle. When you snap the throttle shut the pilot jet is the only jet supplying fuel at that point. If the bike was on a high rev before you shut it down the cylinder is looking for lots of fuel and air as it winds down and sucking air like crazy. It is not the mixture screw but rather the pilot jet it self. The idle air screw maybe out to far also. Been there down that........ BillyT

Hi Guys Pilot jet to lean.................... Simple. Cheers BillyT

Thanks for the help. I signed up and posted the picture. BillyT

I have the pictures ready to go on my Apple desktop. I posted a reply on the Honda forum and wanted to include a picture from my Apple desktop. BUT........... I do not see an area or button that says "upload picture" etc. I can find now were on the site that tells/gives instruction to uploading a picture or is it JUST silly old me? LOL..