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General => Technical | How To => Topic started by: Shaka on July 16, 2009, 03:27:53 PM
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Does anybody have any experience tuning an Arreche 19mm carb? I just got one for my zx50. Along with a Technigas pipe and Airsal 70cc big bore kit. I got it running and idling. I just cant get the main jet tuned right. When I give it more than about 3/4 throttle there isn't really anymore acceleration. The motor seems to make a clicking noise. I can't really tell if it's internal, or just something rattling. I'm running an 85 jet right now. I had the 90 in it, but seemed to do the same, however I have it running better overall since I had the 90 in it. The needle is in the middle clip position. I'm about to do some plug chops, but it seems that it may be quite a bit off. Just wanted to get some opinions before I throw a bunch of plugs at it.
Thanks, Shaka
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try raising the needle 2 notches. this will give you a direction to go w/ jetting. Also check your burn pattern on the plug. dark is bad, white is worse. I also run 1 0z. of synthetic 2 stroke in every tank to help w/ the larger cylinder, and higher temp. If raising the needle makes it worse go down on the jet, and visa versa. By raising first you are at least not leaning out the mix , and taking a chance of burning the piston.
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Zombie- Thanks. I will first start with raising the needle. I only have one notch to raise or lower it too. I'm also running premix, so the oil should be good. Unfortunately, yesterday the auto choke wires fell down onto my exhaust and melted together, which fried it! I need to wait for a new choke to get it going again. Hopefully that is the only reason it died! It really sucked too, I had to push it home a mile! I'm hoping to get it going again this weekend. I will keep you posted.
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Yeah man Iv'e pushed a few myself! good thing they are light. your posts will help all who are in the same spot. seems most posts have to do w/ carb/ fuel trouble.
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I got the choke replaced. She's running again! I'm going to in grab some spark plugs and mess with it tomorrow. Will post results/questions.
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I've done a few plug chops now. It looks like my 90 jet is too small, even with the needle raised all the way. I'm off to try and find some jets locally. I read that the mikuni jets will fit. Guess i'll find out shortly.
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To fit jets in a mako 490 i once owned I bought a set of pin drills. They are rated in thousandths. I kept going up till I locked in what I needed.
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My local dealer didn't have the right jets. I ended ordering some. I know i could have drilled them out. At this point i have been messing with this thing so long that i want to eliminate any other variables or errors on my part.
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I hear that!!!
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I got the new jets in and did a couple more plug chops. The largest one I got is a 110 and I think it is still too small! The knocking sound at WOT is still there, but has gotten much better, and the plugs are still white on the tip, but maybe a little more tannish colored further down. For the most part they all look about the same from 85 - 110. The only thing that has really changed is the very loud knocking has quieted down. I'm gonna have to order more jets, they make them up to a 140 so hopefully that will be big enough! I am curious what size jets others are running on their 70cc's. Any imput would be greatly appreciated!
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I have an italian carb (forgot the name) their jets are metric , but a 95 thousandths bit fits perfect. my needle is the stock one from the carb ,and i raised that 2 notches I have a malossi 70cc jug w/ technigas pipe. i also went down 1 step on the plug (colder) Every add on on your scoot will have an effect on jet size right down to tire preasure. it sounds like your on the right track though. The sound you are getting could also be your pipe. try removing the glass packing ,and see if that stops it. tan is good! I also loosley wraped bi/weave fiberglass cloth in my silencer. It let me use the colder plug w/out fouling
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Thanks Zombie! That gives me some comparison. I don't know why I'm having to jet so much larger than your? I guess it's just a little different setup. I have gone to a cooler plug I'm running a B9HS. The needle height shouldn't affect the WOT. From my research it should be fully lifted out of the jet at that point. It is supposed to control between 1/4 and 3/4 throttle. I did move it for a few test runs and it didn't make a difference. It just ran much richer at about 1/2" throttle, so I moved it back to the middle position. As for the knocking, I'm almost positive it is detonation at WOT, not good! I'll look into the exhaust as a possible culprit though.
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Dude it might sound silly, but are you running Premium gas. It makes a HUGE difference. I didn't post ,Opening your silencer will make for a LEANER mix, thus increasing your problem. You know I Use whatever works NO-MATTER what the book says.If you are up to 140 jet MAYBE your carb is too large! 2 much cfm?
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I am running premium gas, premixed with full synthetic oil. I got a good ride on it today, it definately seems to be running lean. The noise sounds very bad at WOT, and definately seems to be coming from the engine! Correction, they only do jets to 130. I'm going to order the rest of them to finish off my set! :) It seems to be running pretty good, maybe a little rich up to 3/4 throttle. Not being able to fully open her is frustrating though! She seems to want more fuel badly! If anything if the 130 is still too small, it seems as though I would need a bigger carb, maybe 21mm. Am I wrong?
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I got the 130 installed and it definately seems to run better. However, it is not running as fast as it was. It seems like it hits about 42-44mph and it just doesn't have anymore. The plugs chops at WOT are looking pretty good. It seemed it was bogging at 1/2 - 3/4 throttle so I dropped the needle all the way down. Seems to be smooter through the throttle, but still lacking in top speed. And the bad sound I was hearing before at WOT was the piston slightly hitting the head at the top of the stroke. I put in another, total 2, head gaskets. I was already 2 gaskets between the the cylinder and the crankcase. Seems to have taken care of the clearance issue.
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Hey man. Sorry it's been a while. What kind of bore kit did you use? Did you contact the manuf? Seems to me there has to be a wrong part mixed up in there somewhere! Not trying to panic you but you should not have an interference issue w/ a new kit. Also I didn't notice if you worked on the variator/ clutch. They will give you the 50- 55 mph mark. I'd double check the jug kit just to sleep well. Just another thought, If you raise the jug, you are also raising the ports w/ it. That will have a small amount of difference in performance. Most likely not enough to feel, but when you are squeezing tiny amounts of HP at a time It all counts. Keep posting because this has turned into basicly, a full system build overview. Good luck Bro.
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Zombie- I got the kit from moped hospital. It is an Airsal 46mm jug. Everything I have come across points to that being the correct kit. The manufacturer number matches with what I have run across from other suppliers as the correct kit. When I got it Steve at moped hospital told me to use two bottom gaskets. He said the Honda Dio uses one, but the zx50 uses two. He actually forgot to send me two to begin with and I had to call him because the piston was hitting pretty badly after initial installation! This is when he told me I needed two gaskets, and he sent me another. When I put the other gasket in it seemed to be better, until I got it spinning fast enough. Then apparently is was just barely touching. There doesn't appear to be any damage. The piston just had a small silver ring around it where there was no carbon build up. It sounded way worse than it was! I thought about the port timing. I guess that is another question I need to address. It is such an insignifigant amount that the jug is raised, maybe 2mm at the most. Could be enough to make a difference though. As for the variator and clutch. I am still running the stock ones, but have installed 6.5g rollers, down from 8.5g, and stiffer clutch springs (green). These came with the kit. I am also running a Malossi kevlar belt. Could this be what is holding back my top speed? I also got a chance to mess with it a bit today. I tried the needle in the middle and fully raised position. It bogged out pretty badly. It wouldn't even idle with it raised all the way. I put the needle back in the lowest position and it ran alright. I played with the mixture screw and still couldn't get the top speed any higher that about 42mph. It accelerates way faster than it used too, but I had a higher top speed before I did any of this work. Something is just not right!
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Hey shaka, Do you still have the stock belt? I am running all malossi prod. in mine, and the variator is a different diameter than the stock unit. your malossi belt may be too small to get topped out. also there is another post (I think in the zx/50 forum) about removing a spacer washer behind the stock variator. IF the malossi belt is too short this may give you some extra room. I thought these things were supposed to be FUN! Oh well.
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It is fun when I'm riding it, not working on it! As for the belt, I still have the stock one, but it is very worn! I do recall the malossi one being a little bit shorter. I replaced the belt right before I did the rest of the kit and it went about 44mph on the flat and 48mph downhill with the stock motor. This leads me to believe that the belt, variator, and clutch are not the culprit. When I bought it used the dealer removed the washer in the variator, so it's not that. I think it is the carb. I rode it to work and home today and it just seems to be possibly bogging out. I'm going to try swapping the jet out for a smaller one. I haven't tried anything but the 130 since I put the 130 jet in. Now that the clearance issue is remedied it might run better with a smaller jet, hopefully! The other thing I was thinking is that the combustion chamber is slightly larger now with the extra head gasket. This may be the reason why I need to almost start over on tuning it. I need to get some more spark plugs to do some more chops. And more free time to mess with it! At this point I have about a dozen spark plugs I used for previous chops. Can I reuse these for another run? They are all very clean looking still as it was running lean before, and I only used them for about 1/2mile each.
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Yeah Bro, Reusing the plugs is fine, Just give it a few miles to take a new reading. It all makes sense. You were chasing a pre ignition problem w/ jets, only to find it was a clearence problem. You prob are too rich on the jet now. Funny thing, I took off my cyl. head after posting , and getting back in the mood to trouble shoot mine somemore. I put on the new regulator, still had good spark, still was getting fuel, still no start! pulled the head , and found a pin hole in the piston. you cant get a sewing needle through it but turned upside down fuel just runs through. No matter how many times you think you got it down and don't need to look there/ there it is. I also lost my key, go figure. Thanks for ALL the help along the way. When I get this thing put back together I'll post a few Pict's.
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Zombie- That sucks! I guess it is a good thing that you found the problem though! Hopefully, that is the only thing wrong! Good luck!
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I got some time this afternoon to do a little more tweaking. It has been bogging all week with the 130 jet installed. I also noticed that there was a "sweet spot" in the throttle between 1/8 and 1/4 throttle. If I just held it there it would run at a faster top speed than anywhere else, kinda weird, but makes sense with the jet too big. It was a little scary a few times while decelerating I would run back down past this point and it would take off on me again! Anyways, I down jetted today and ended up with a 115 installed currently. That took care of my WOT bogging at smoothed out the entire range of the throttle. Now I'm getting a top speed on the flat of about 47mph. Still seems a bit slow for my setup, I'm going to check the belt and variator next time I get a chance and make sure it is operating correctly. I'm gonna run this 115 jet for a few days and see how it goes. Will post updates, any input would be appreciated. Anyone else running a similar setup? What kind of a top speed are you getting?