|
Post by chanito on Feb 7, 2007 19:43:17 GMT -5
I think its more of a tease to encourage people to buy the remaining big bores. He said has six left. I believe I bought the last one he sold. You are right i only have 6 left but 2 weks ago i used to have nine, i am hoping this will keep up and i will sell all of them, and if i am lucky people will want more and then i will make money
|
|
|
Post by Blackruk on Feb 7, 2007 22:43:57 GMT -5
Well, I'm all for you making money. I'll help any way I can.
|
|
|
Post by chanito on Mar 9, 2007 10:55:20 GMT -5
;DThis is a very helpful explanation of the cv carb [ftp]http://www.hdforums.com/m_68715/tm.htm[/ftp]
|
|
|
Post by Dandy Dan on Mar 9, 2007 13:17:18 GMT -5
That is good...I think when I rejet my next BB engine I'm going to toss in a 38 slow jet just to add a bit of gas across the board because an engine that is 20% bigger has gotta crave more fuel. Then I'll dial in the idle mixture screw until it purrs on the stand and then I'll mess with the main jet to optimize the top end. How does that sound Chanito?
|
|
|
Post by chanito on Apr 1, 2007 20:49:15 GMT -5
I really need to go back and finish this, anyway here are some nice bits of info into our carburetor. Doing research for this thread i found out that the word carburetor was develop from the French carbure, that means mix with carbon, which i think was a great way to create combustible back in the 18 century, anyway later on some miners develop one of the most clever ways to light up an underground mine and that kind of lamp was still used not to long ago as it last way longer than battery operated ones, this lamps used a metering jet to allow water to drip into a container full of carbide pellets, which them released a gas, that was metered again thru a jet and lighted to give a very bright light, they used to called this lamp carburetors so the first carb used on cars adapted that name The carburetor on our scooters is what is called a bleed type CV carburetor, which stands (according to who you ask) for constant vacuum or constant velocity They are called bleed type because they have this small holes on the sides of the jets that allows air to be premix with the gas, a process called emulsification, which makes this carb way smoother than the old style were the jet holders were solid (did not have the holes) these holes get their air supply from two different air jets, the one for the main jet is on the front of the carburetor and gets its air directly from the intake, the slow jet gets its air from an air jet located on the floor of the diaphragm chamber and is very easy to get clogged, and that is the reason i think is a very bad idea to connect the PCV discharge hose to the fresh air hose to the carburetor diaphragm chambers as some aftermarket air filter do Our carburetors have 3 different fuel jets, but we can only change two, they are the main jet and the slow jet, the third jet is the cold start jet, but it is just a hole drilled on the carb, so the only adjustment would be to drill that jet bigger, but, i do not recommend doing it, because if you mess up, the carb is useless One of the things i found during this research, was how misunderstood the slow system is. The main purpose of the slow system is to supply mixture at idle. It will continue to provide fuel during the entire throttle range, but after about 1/8 of the throttle the percentage of fuel supply by this system becomes insignificant, as more and more fuel is supply by the way bigger MAIN SYSTEM. At idle the butterfly valve is covering some very small holes, these are called transition holes and allow some fuel to be suck into the engine at very small throttle openings, so when you adjust the idle speed with that small screw on the side of the carb, you are adjusting the covering or uncovering of these small holes as how more or less air goes pass the butterfly, further back toward the engine there is a bigger hole that allows fuel to be send into the engine, that is controlled by the idle mixture screw, this hole also allows the SE valve to dump extra fuel on cold starts, this SE (Start Enrichment) system gets its fuel from the SE jet and is allow to dump it into the engine until the ECM senses the temp going above 35 degrees Celsius and send a voltage to the SE valve which heats up and closes this circuit, so when an engine is warm all the fuel is supply by the slow jet and the main jet ;D I hope you are still with me so far
|
|
|
Post by Dandy Dan on Apr 2, 2007 8:41:52 GMT -5
I'm with ya I really appreciate this information...it's really good to understand the theory behind rejetting and how all this stuff works because it makes rejetting way more intuitive.
|
|
|
Post by chanito on Apr 2, 2007 18:31:15 GMT -5
I decided to post some pics to illustrate this better, this little jet on the carburetor intake is the main air jet (the one feeding the bleed holes on the jet needle (the one under the main jet) The slow air jet is located under the diaphargm, and here is a pic of it This are the gas jets from top to bottom, main jet, slow jet and SE jet this little holes on the main jet and slow jets are what make this carburetor a bleed type Hope this will clarify my previous post, i still need to get a better quality pic of the transition and idle mixture holes, i will try and do it tomorrow
|
|
|
Post by chanito on Apr 3, 2007 20:52:47 GMT -5
|
|
|
Post by Dandy Dan on Apr 4, 2007 8:57:31 GMT -5
Great pics Chanito! The new pic showing the main jet with that tube with the holes is much easier to understand.
|
|
mrgreg1299
Ruckster
Just call me the OLD GUY !
Posts: 206
|
Post by mrgreg1299 on Apr 5, 2007 18:26:51 GMT -5
Right on Chanito, I printed all this out for my Ruck File. You did a Top Notch job, as we've come to expect from you. Wow, I didn't mean to sound like I was kissing up!! (even if I was, ha!) ;D
|
|
jabba
Junior Ruckster
Posts: 56
|
Post by jabba on Apr 8, 2007 9:44:08 GMT -5
First thing first, i am not a CV carburetor expert, so this is just the way i do it after pestering some pros i know and reading most of the info on this kind of carburetors, so if you disagree please post your way to do it so we can find the easiest The thing most pro agree is that you should do the main jet first before anything else is done. The way i do it, is i do some full throttle runs with the engine cold and then with it warm so i can compare the two, as a rule of thumb if it runs way better warm than cold your jet is too small and if it runs better when cold your jet is too small. I just go full throttle and then release the throttle probably 1/8 down (do not go too far as you want the carb to stay in main jet territory) and go back again to full throttle and just try to feel the bike, remember to be patient and leave a main jet for a couple of days so you are confident on its behavior (unless is way off) Once you are happy with it then is time to move to better things, so ignore the behavior at idle or part throttle until the main jet is settle Second step is the part throttle there is two ways to adjust it, but they do not replace the other, so a combination of both would be perfect but that requires way too much work, they are needle shimming and diaphragm spring clip and the second one is slow jet, just ride it and work the throttle at half way and accelerated steady if the bike react like is on a delay to the throttle input, you are too lean. And if it just ignore the throttle input or just feels super flat you are too rich, sadly this is one of those adjustment that are try and error so you will have to go back and forth until you are satisfy with the scooter Again patience pays And finally the idle mixture adjustment, and on this carbs it affect the whole range so be very careful and only go 1/8 of a turn at a time because if you go too far it will be difficult to start the scooter (i find out the hard way, because i got turn happy with the screw) I made myself a tool out of a radio antenna i got from radio shack for 3 bucks, the second step is the right size and i bent a flat spot with some needle nose pliers, sadly the material is so soft the tool will turn round again after some adjustments, but i just keep flattening the spot as i am a cheap guy and do not want to spent 40+ on a tool i seldom use. Do not even think about doing this without a tach or with an engine not fully warm up, after warming the engine lower the idle to about 1700 rpms and then start turning the mixture screw 1/8 of a turn and blip the throttle stop when you reach the fastest idle, then go back 1/8 of a turn and adjust the idle speed back (the reason you go back is to avoid running rich once you correct the idle speed) in case you mess up the factory setting is 2 and 1/4 turn out after seating the needle (screwing it until it is close, do not tighten it too much as it will damage the needle and the carburetor) that means you tighten the screw and then go back out 2 and 1/4 turn. There you go "my way of adjusting the ruckus carb" Another trick i was taught back in my work at the dealership days, is when it is warmed up, try running with the choke ON especially @ max throttle (pretty much all the time for a ruckus) if it runs Better you are clearly lean. If it doesnt, the first thing to do is raise the needle. This allows the mainjet to come onto full open earlier. Note that its not a dramatic difference, just will manifest itself as slightly snappier throttle response. Given the smogger tuning that most oem 4 stroke motors come with, if you have improved the motor's ability to breathe at all a richer mainjet is almost a given
|
|
|
Post by chanito on Apr 8, 2007 20:16:29 GMT -5
|
|
|
Post by timberwolfmadcat on Apr 9, 2007 22:39:11 GMT -5
So what essentially are the steps.. i seem to read it differently for 06+ models and 05- models..... Do we do the IMS screw first, or set the MJ jet first..... a set of steps with #'s would be awesome!!!
|
|
|
Post by Dandy Dan on May 2, 2007 14:50:20 GMT -5
I'm a bit confused about the relationship between the idle mix screw and the slow jet. Like Turbowagon has bee posting in his BB tuning thread, I find my big bore Ruckus idles best with the IMS screwed all the way in, regardless of what slow jet I'm running (well I've only tried 38/40/42.
With the 40 slow jet I could only get it to hold a reliable idle with the IMS turned all the way in. Then I dropped to a 38 slow jet figuring that this would be the right approximent jet but it still only idles reliably with the IMS turned all the way in. My observations are leading me to believe that only the idle mix screw affects the idle and the slow jet doesn't come into play until you crack the throttle a bit but what I've read tells me that the slow jet is always open and thus should be a factor. Can you explain this relationship for me Chanito so I can get my carb dialed? My Ruckus seems ideal with a 42 slow jet because that makes it haul off the line and then with the IMS screw dialed all the way in it idles too.
|
|
|
Post by chanito on May 2, 2007 18:17:27 GMT -5
The slow jet is always on, but is feeding gas thru the idle mixture discharge hole (the one facing the engine), and the transition holes, some times modifications make the engine produce more vacuum so the signal to this holes is greater, and they discharge more gas than before (that is the reason why in theory, installing a freer flowing exhaust pipe should require a smaller main jet) as more gas is being suck from the slow jet. The trick is just keep correcting your idle speed with any major adjustment of the idle mixture screw, all my numbers indicate that the stock slow jet should flow plenty even for a big bore, but in any case, if you need to adjust your slow jet more than 1 turn out from the factory setting, go to the next bigger size, so yes i think you guys are installing way big slow jets Much better tuning can be done with diaphragm springs of deferent sizes
|
|
|
Post by Dandy Dan on May 3, 2007 9:16:01 GMT -5
Okay when I have a chance to some more Ruckus tuning I'll try the 35 slow jet.
|
|
|
Post by chanito on May 3, 2007 20:58:49 GMT -5
It is a good idea to set the idle mixture screw first, then go buy 2 carb springs (they are cheap) and cut 1 coil of one and 1 and a 1/2 of the other, and then go for a road test and see which one give you the better part throttle response, and accel the cleanest, with any luck that should take care of part throttle even after setting the main jet, but there is a chance you will have to readjust the spring after the main jet tuning
|
|
|
Post by Dandy Dan on May 4, 2007 9:32:49 GMT -5
Okay so here's what I'm thinking:
1) Set carb to a 35/85 setup and from there play around until I get the right main jet 2) Try different slow jets to see if they work better at part throttle/off the line 3) With the MJ and SJ set, dial the IMS. 4) Experiment with different springs
Is this the best order to do all this?
|
|
|
Post by chanito on May 6, 2007 11:01:17 GMT -5
Okay so here's what I'm thinking: 1) Set carb to a 35/85 setup and from there play around until I get the right main jet 2) Try different slow jets to see if they work better at part throttle/off the line 3) With the MJ and SJ set, dial the IMS. 4) Experiment with different springs Is this the best order to do all this? OK this is my revised version, due to your input, and i like it so far, i do not like the spark plug method of main jet adjustment, because it can get very expensive, but it is the very best , so i will instruct you guys on how to do it properly, and then put my cheap method (which is the one i use) 1.- leave the idle or slow jet stock (that is 35) and set the idle mixture, if it takes more than 1 full turn out to adjust it right then go to the next size up, if not, LEAVE IT ALONE 2.-Use the Chanito method to set the main jet. You will need something to mark your throttle grip (i use whiteout) Then with the engine off, open the throttle all the way, and using the partition between the two halves of the controls make a mark on the grip, something like this Ride your scooter for at least 15 minutes, that, will ensure the engine is fully warm, then look for a straight that will allow you to get your fastest speed. Making sure no one will get on the way take your scooter to the beginning of that straight and Just go all out until you feel the scooter is at full speed, now let the throttle roll back until your mark on the grip aligns with the beginning of the relief at the side of the control, i had a hard time explaining so i took this photo to illustrate Now using all your riding skill and butt senses feel what happen, if the scooter pick up speed and feels stronger, you are LEAN; but if it seems to have a hard time for a little bit and then it recovers, you are RICH; but if it does not make any difference then you are in the right jet (or very close) The proper method is to get a set of NEW plugs (the engine have to be very rich or very lean to change the color of a used plug). Change the plug for a new one, start the engine and immediately accelerate to full speed, once at full blast, kill the engine with the kill switch and coast to a stop, your plug reading will be significant now, a white plug LEAN, a black one RICH and a tan or light brown PERFECT, of course we are talking about the porcelain of the plug when we talk about plug colors. 3.-Order 2 carburetor diaphragm springs, and cut 1 coil of one and 1 and a 1/2 of the other, then just install one and go for a ride, then swap it for the other and go for a ride, install in the scooter the one which gave you the best performance all around, and you should be done
|
|
|
Post by Dandy Dan on May 7, 2007 9:01:20 GMT -5
Thanks for the info Chanito....your methods are very clever. I really appreciate you sharing your expertise. I finished rejetting my Ruckus Saturday with very favourable results. Following your suggestion, I dropped my slow jet to a 35 and I was able to set the idle much easier with this slow jet. Instead of setting it with the idle mix screw all the way it, the ideal idle mix was somewhere in the middle which was nice.
For the main jet, I ended up with an 88 which is giving me a nice tan plug....and great performance results. My 0-50km/hr (30 mph) times are down a bit because I've got the 45T Metro final drive gear so it's taking me about 7.3 seconds on average but my top speed is smoking. I recorded consistant 50km/hr to 70km/hr (30mph to 43 mph) times of 10 seconds and I was redlining at 78km/hr (48.4mph) easily just 22 seconds into my run. Without the redline I'm definately capable of over 50mph speeds....I'd say in a tuck on a long flat, wind free straight I could get to 53/54mph. I run into the redline pretty solidly. I guess I'll know for sure when I get that CDI installed today or tomorrow.
My actual cruising speed (i.e. the speed I reach when I'm not tucking and in a reasonable about of time (ie. 20 seconds)) is about 43mph right now but I'm thinking that removing the Metro 45T final drive gear will raise this a bit because my taller gearing is great when I'm tucking but for real world conditions the lower gearing and higher RPMs should enable me to hold a higher top speed. I'm going to get that Posh CDI installed and do some before and after graphs with that setup and then remove the Met gear and again compare Veypor results.
|
|