clarkp Posted November 15, 2004 Report Share Posted November 15, 2004 Just a note to let everyone know that if you DO connect the two carb overflows with a loop of tubing (connect them together) you may experience difficulty starting your bike. No more dribbling carb, but it won't start unless you kick the #$!% out of it. The remedy is to cut a 'V' shaped slot (or drill a couple of holes) in the tubing at the top of the loop to vent to atmosphere. Starting problems gone, dribbling carb - gone. Quote Link to comment Share on other sites More sharing options...
billyt Posted November 15, 2004 Report Share Posted November 15, 2004 (edited) Note to all: You can, quite successfully connect the two hose without cutting them with one VERY IMPORTANT POINT. If you choose to connect the tubes ..then.. The connected tubes must go over the top of the carb and not down below it as many have done and created anomolies in running and starting. . Putting them below the carb creates a potential to trap gas and thus preventing atmospheric equilization. Some thing like a "P" trap on a toilet bowl.. BillyT Edited November 15, 2004 by BillyT Quote Link to comment Share on other sites More sharing options...
clarkp Posted November 16, 2004 Author Report Share Posted November 16, 2004 Billy, thanks for clarifying that the looped tube shouldn't go under the carb, but over the top - good point! I feel like clarifying a point of my own, however. My bike was running great, 32.5 pilot jet, 145 main... everything was spot on... except for the fuel drool. So, I connected the two vent pipes with a loop of tubing (yes, over the top of the carb...). With that being the only thing changed, my Rev3 250 became VERY reluctant to start. So, I vented the loop by cutting a "V" shaped section out of the top of the loop. Once again, my bikes starts on the second kick every time. Given the scenario, my only conclusion is that the venting of the tube must have made a difference. I guess every owner willing to try the 'loop-of-tubing' fix should, at least, know of my experience. Try it for yourself, if it starts reliably without the vented tube loop, great. If it becomes hard to start, try the vent procedure. Quote Link to comment Share on other sites More sharing options...
billyt Posted November 16, 2004 Report Share Posted November 16, 2004 Clark The VERY original looping that I peformed was with a small "T" . Both ends of the hoses went into a "T" over the carb. The actual outlet was the third part of the "T" that had a small hose attached to it and then vented down ways to prevent water and dirt etc from getting into the carb. The picture you show make me very concernd that water or crap can and will get in to the carb tubes through the cut you made in the tube.. Go to Home Depot or somewhere and find some very small plumbing fixtures that afford a "T" like connection from the two hoses and then turn the third hose down and away from outside crap. This way no water can get in and the dirt is kept out. The joining of the tubes must be in the above the carb method with the thrid tube going down. Cut the thrid tube at a very steep angle to increase its surface area. This will alleviate mud collecting on its surface and blocking the tube opening and also it will break any shiponing affect. Back to being stealth BillyT Quote Link to comment Share on other sites More sharing options...
clarkp Posted November 16, 2004 Author Report Share Posted November 16, 2004 Excellent idea, Billy... I'll make the mods and post the pics for everyone's benefit. Thanks for the update! Quote Link to comment Share on other sites More sharing options...
craig10 Posted November 16, 2004 Report Share Posted November 16, 2004 Clark, am I right in saying that you are connecting the 2 atmospheric vents at the either side on the top part of the carb together, or one atmos. vent to the overflow outlet on the bottom of the float bowl?. Not too clear from the picture. I had my carb modded by Beta UK which moves the internal overflow height up. It doesn't dribble from anywhere now, but if you park it facing downhill it floods if the petrol is not shut off. In other words, instead of leaking from the overflow, which is now higher, it dribbles into the crankcase. I tried Billys float level mods but felt it made the bike a bit gutless (it's a 200cc). One for Billy T: Could you explain the theory behind this carb mod on the BVM web site?. All I can see is that it increases the volume of the float bowl, but its not going to increase the amount of fuel available to the main jet, unless the jet itself is lowered. Unless the original plug is so close to the MJ that it restricts the fuel, but I doubt it. They say it helps on hill climbs. Carb Float Bowl Mod. As used by Team GP Beta. To fit Beta Rev 3. Sustains constant supply of fuel to main jet. PRICE JUST Quote Link to comment Share on other sites More sharing options...
clarkp Posted November 16, 2004 Author Report Share Posted November 16, 2004 Craig - yes the loop of tubing connects to the same locations your clear tubing is now. Just pull off the clear and connect those two ports with a loop (with the new venting "T" mod - pictures soon...). Quote Link to comment Share on other sites More sharing options...
billyt Posted November 17, 2004 Report Share Posted November 17, 2004 (edited) Craig My honest opinion on the protrusion from the float bowl! Spend your money on a new rear tire or something. Some history: Float bowl modifications have been around for years on carb Edited November 17, 2004 by BillyT Quote Link to comment Share on other sites More sharing options...
craig10 Posted November 17, 2004 Report Share Posted November 17, 2004 Thanks for that Billy, I believe the mod may have been to help when doing big splatters as well as hill climbs, so option 1 seems realistic. As to my own bike feeling sluggish after lowering the float as per your mod, would this not make the mixture leaner due to the lower level of fuel in the bowl than previously ?. Are you saying the mixture would be richer because of the increased vacuum required to lift the fuel, the higher vacuum being brought about by a smaller throttle opening, therefore less air for the same amount of fuel?. Craig Quote Link to comment Share on other sites More sharing options...
billyt Posted November 17, 2004 Report Share Posted November 17, 2004 Craig Some question about your bike. What oil gas ratio do you run? Are you using the bowl extender? What is the jetting in your bike? What were the symptoms when you say sluggish? What was the weather characteristics? What kind of Beta? Have you changed the timing spec? Was the bike sluggish before you made the mods & did it clear up after you made some other mod? BillyT Stealth Is Best Quote Link to comment Share on other sites More sharing options...
craig10 Posted November 18, 2004 Report Share Posted November 18, 2004 1.5% synthetic 2T, no bowl extender, standard jetting for 200cc '02 Rev-3 (don't have the figures to hand as I'm at work for next 10 days), after lowering float level the low down power from the engine was worse, struggling in 2nd on hills once the revs dropped, weather normal for Scotland. Was definately worse with the lower float level mod. I reset the float and got the carb modded by Beta UK (they redrill the overflow to a higher position in the carb). That stopped the dribbling. The bike has never been great at pulling from low revs. I recently reset the ignition timing (not touched since new) using data from the factory book by marking the flywheel at TDC, and setting the timing at tickover to 1.6mm BTDC, checking with a strobe light. This has definately improved the low down pull. It was too far retarded. Bike still knocks a bit on closing the throttle. Need to check the carb inlet rubber again. Using super unleaded, 98 octane. Knocks really bad with normal 95RON fuel. Craig Quote Link to comment Share on other sites More sharing options...
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