OzVMX Forum
Marque Remarks => Maico => Topic started by: huskibul on March 22, 2010, 10:13:22 am
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Hey guys, got any tips and baseline jetting specs on converting 490 alpha 1 bing carb to flatslide mikuni (38-40mm?)anything would be much appreciated cheers
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Hi
I have got three Maico's - two with Bing's and one with a Mikuni 38 mm flatside. I am at work currently and I can help you with the jetting on both types of carbs. Personally I would stick to the Bing carb -believe it or not it does work better than the modern Mikuni's. Either way I can help, will follow up tonight. regards Gavin
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that would be great crabman,this is one of a mates bike's which he use's to bring over for a ride but it started getting to hard to start,the slide is worn and iam suspecting the needle and jet as well, does not respond to well to adjustment ,thought the carb would be the best place to start,it has a pvl ignition so i'am ruling out electrical at the moment,do you know if you can get bings resleeved?,i heard somewhere you can buy new bings in uk ?maybe thats the way to go if theres no performance gains in a flatslide cheers
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someone else here (allthings414) has mentioned you can still buy new bings from the us or canada. there is a thread some where on it (over to you Alison)
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maybe thats the way to go if theres no performance gains in a flatslide cheers
There is a massive difference is the performance of a flat to round slide. A Mikuni is a far better carburetor, needle jets don't wear spares readily available etc etc
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Yes lozza,still may be the way to go, ive done couple of mikuni conversions to my bullies,and never looked back ,just like to try and cover all base's especially with someone else's bike cheers. :)
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Yeah. Mikunis on Euro bikes is a better way to go if you're not real good at tuning a carby and don't ride very quick. If you have some nouse though and want your Euro to go like it should, get a Bing. ;)
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Hi all things do you know if you can resleeve bings ,have you had any done and where? i find the euro carbs a breeze to tune when their new but wear fairly quickly once they start and turn into problems, stainless sleeve seems to be the go ? i put alot of seat time on my bikes :)thanks for your opinion
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You can get the Bing re-sleeved, i know someone who had theirs done. I'll try and find out where.
The Bing is the way to go on a 490, myself and a couple of mates have tried Mikuni's on Maico 490's and gone back to the Bing.
Make sure the slide is not worn and use a new needle jet and needle and the Bing is great.. more horsepower over a broader range.
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I've bought new carbies and heaps of bits from this mob over the past few years.
http://www.bingcarburetor.com/aboutbing.html
Always been able to get the bits that I want (as well as a few grouse Bing T-shirts ;))
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Thanks heaps for that johnnyO thats exacty what ive been wanting to hear, first hand info,the slide is badly worn,maybe don newell for a resleeve as well as new slide ;)thanks for the site 414 i'll check it out :)anyone have baseline jetting specs@sealevel for the bing?cheers
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Yeah. Mikunis on Euro bikes is a better way to go if you're not real good at tuning a carby and don't ride very quick. If you have some nouse though and want your Euro to go like it should, get a Bing. ;)
::) ::) The dyno and stopwatch awaits your presence ::)
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Lozza. You seem to confuse horsepower with speed. How much HP do you think a motocross bike really needs? 40, 50, 120 HP? How quick is a rider on a bike that steps its rear end out every time you touch the throttle? I'm talking about a bike performing at it's very best. Not a gain of .5 HP here or 1 HP there at the expense of handling. ::)
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If it was all about HP how come those yanks on their 125's were beating 500's in the GP's in the 1980's?
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A dyno doesn't work for motocross. On a real motocross track you are only at full throttle for a small amount of time each lap.
The dyno only gives a full throttle reading..what about when you're coming out of a slick dry hardpack corner and only using 1/4 to 1/2 throttle on a 490.
Power delivery is more important than numbers and a properly jetted Bing gives good power delivery.
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Sorry don't really care for dyno's and stopwatchs, i'am just after the carb that you can easily dial in, and keeps that beautiful wind-on maico torque ,but the main criteria is easy starting,not a lot of men can ride these things on the edge so i dont think 2 hp means jack .... to the average punter ;) p.s baseline jetting spec's(sealevel)anyone?
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Again I think it is a matter of “horses for courses”. I fitted a 38mm Mikuni to my 250 reed mega2. It starts 2nd kick cold every time. 1st kick the rest of the time, all day long. I jetted it. It blows the performance of the standard Bing to the weeds in every single dept, including it’s journey to peak revs.
BUT, on a 490 Mega it is a much different story, I am yet to be convinced that anything works better than a fresh unworn Bing. If you want a Bing to start 2nd kick cold, I fit it with very soft overflow vent tubes. After you have held the tickler to the fuel flows, grasp your hand around the Bing so that you can pinch both overflow tubes shut, then use your other hand to depress the tickler again for another 6 seconds(as to prime the crap out of it). For MX, my recent experience tells me that the 490 is really suited Bing, for some reason. If it’s a drag race “on dirt” the 490 will win most of those as well.
The beauty about the 490 mega from the day it was born, has always been the way it delivers itself as an MX mount, and I really believe it has quite a bit to do with the Bing.
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Must agree with Roscoe, ie 414, tried the wizbang 38mm bored out mikuni from the states on my 81 490, went back to the bing carburetor, of course you have to make sure that the carby is in good condition. The bing carby would be the easiest to jet, you can even sit at the startline & take off the bowl with riding gloves on, its true, I had to do it one day, somehow I got water in the fuel & the thing was blubbering, I reached down, turned off the fuel, took the bowl off, held the floats up with 1 hand, tipped the water out of the bowl, put it back & holeshotted into last place ;D ;D but the bike ran beautiful. There were guys on modern bikes watching me do this & could not believe it. In my opinion, the bing is the best carby for Maico's. I pushed my 490 into Keith Stackers workshop one day, Keith is the man when it comes to Maico's & all he said was, get that thing off, it wont work on a Maico, I guess he would know. 81 490 jet specs, running 278 needle jet, 185 Main, 55 pilot, 8 G2 needle or 6L2 needle, air screw 1 1/2 turns out, this is the jetting my son used in Tasmania in the Aussies to win Evo & Pre 85. Hope it might help you.
Ken Baker
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Yeah thanks for that mick de and ken, sounds a lot clearer now and i have a baseline,do you think it's worth muckin with the carb resleeve or go for new? cheers huski
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I've tried 'em all on my Maicos, Mikuni, Amal, Dell'Orto and even a moment of madness when I tried a Lectron on my squarie and absolutely none of them work as well as a Bing on a piston port Maico. I had some minor success with a 38mm Mikuni on my reed valve '84 Maico SC500 but the difference wasn't worth the hassle of buying a new air filter adapter.
Keith Stacker once told me a story about when Neil Hudson bought his '75/76 250 GP works Maico to Ausrtralia and left it at Stackers while he did the tourist sights of Melbourne. While Hudson was out they started his Maico and found it to be the usual blubbery, leaking mess so, seeing that Stacker had had some success using Mikunis on their own Maicos, decided to help Neil out by fitting his bike with one of their well jetted Mikunis. The bike started easier, was as crisp as a Jatz cracker and the bike felt like it was ooozing horsepower. Upon their return Hudson and his mechanics weren't very impressed by what happened but not wanting to insult their hosts decided to give them the benefit of the doubt and see how the bike performed during the upcoming practice session.
At the track the bike started first kick, sounded crisp and took off like a scalded cat. Neil put in some very fast lap times and it looked as if Stacker had done a good thing until Hudson came into the pits complaining that although the bike was crisper, it felt much slower. They quickly refitted the original Bing and the bike instantly picked up four seconds a lap. The Bing stayed on the bike and it wasn't long before Stackers Maicos went back to Bings as well. Lesson learned.
With big budgets and ample dyno and track testing at their disposal, don't you think that the works Maico, Husky and even the Montesa and Bultaco teams would have replaced their Bings with Mikunis if they had proved to be better?
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With big budgets and ample dyno and track testing at their disposal, don't you think that the works Maico, Husky and even the Montesa and Bultaco teams would have replaced their Bings with Mikunis if they had proved to be better?
My thoughts are that they may have been stuck in their old ways and had brand loyalty towards the Bing. I could have never imagined they would of fitted a 'Japanese' Mikuni even if they were miles better than a Bing
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Bings were cheaper in 76' ;D
$90 for a new slide is nut's.
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My thoughts are that they may have been stuck in their old ways and had brand loyalty towards the Bing. I could have never imagined they would of fitted a 'Japanese' Mikuni even if they were miles better than a Bing
You've gotta be kidding Leith. This is the works team where winning races is everything. Even the uuber trick Wheelsmith bikes in California had Bings. Trust me when I tell you that these blokes rooted around with everything imaginable to improve on the Maico and they left the Bing on unless the customer pecified a Mikuni. When I was researching my article on Wheelsmith for VMX I spoke at length with Wayne Meridjian who was the shop foreman and he told me flat out that fitting a Mikuni to a 490 Maico was a backward step.
I could understand the production department being locked into contractual and traditional reasons for sticking with Bings but the race teams had ample opportunity to experiment with carburetion and everything else in a bid to get an edge. Husqvarna did eventually go with Mikuni so not using a Mikuni because it was Japanese doesn't hold water.
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I could understand the production department being locked into contractual and traditional reasons for sticking with Bings
yes this is what i was referring to/trying to explain. Guess i just didnt make it clear that is what i ment. I was indeed refering to the factory.
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I have often heard over the years that Bings are the go for Maico’s, but I have always been intrigued as to what the difference is, as in a mechanical sense?
The carby just mixes fuel and air in the right proportions as it is sucked into the motor.
Theoretically any carby that is set up properly should be able to do this, but apparently not in practice.
So why is it that the fuel / air molecules can recognize when they are being sucked into a European cast barrel?
I have just heard a new urban myth about YZ 490’s being a copy of the Maico barrel. So would YZ 490 owners be better off fitting a Bing
The fuel / air molecules wouldn’t realize the deception until they are spat out the exhaust and they see Yamaha across the back of the seat. ;D
So what is the actual working difference between the carbys?
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So would YZ 490 owners be better off fitting a Bing
Probably. I'm gunna. ;)
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Good point gmc i have the odd bing kicking around maybe i should try one on my 430 husky as well ,(someone said their not that much better on reed motors ?)come's to the point why did husky go to mikuni in the early 80's , maybe a cost saving exercise ?
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My 1984 SC500 came with a 40mm (from memory) Keihin which was supplied by Tony Hatton. My wife grew up with his daughter and they live close by so jets and parts were easily obtained from him. After speaking to him it seems the prevous owner went from the Bing to Keihin because the bike seized up. It turns out that he was running it at 50:1. I'm not a fan of this but that's another can of worms altogether.
There was issues with the carby boot not matching up. I fitted a set of Boysen reeds which are apparently listed the same as a 1981 CR450, and downsized the pilot jet and found the bike never gave any problems.
I have the original Bing and have never compared the two carbs, so I really can't comment from that perspective. as which had the best effect on the bike. I now have a FMF pipe on the bike but am yet to run it to see what it goes like now.
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A dyno doesn't work for motocross. On a real motocross track you are only at full throttle for a small amount of time each lap.
The dyno only gives a full throttle reading..what about when you're coming out of a slick dry hardpack corner and only using 1/4 to 1/2 throttle on a 490.
Power delivery is more important than numbers and a properly jetted Bing gives good power delivery.
On a dyno, you pick the best gear and roll it on. You don't just hold it wide open. Rolling it on gives you the torque curve. Peak HP is interesting, but not super important if the motor is ballpark. If you can get good torque where you want it in the rev range, then you're headed in the right direction. Pretty valuable on a motocross bike if you ask me. Running a higher gear in corners, anyone?
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A dyno doesn't work for motocross. On a real motocross track you are only at full throttle for a small amount of time each lap.
The dyno only gives a full throttle reading..what about when you're coming out of a slick dry hardpack corner and only using 1/4 to 1/2 throttle on a 490.
Power delivery is more important than numbers and a properly jetted Bing gives good power delivery.
On a dyno, you pick the best gear and roll it on. You don't just hold it wide open. Rolling it on gives you the torque curve. Peak HP is interesting, but not super important if the motor is ballpark. If you can get good torque where you want it in the rev range, then you're headed in the right direction. Pretty valuable on a motocross bike if you ask me. Running a higher gear in corners, anyone?
EXACTLY a dyno is just a tool unless you have to know what your doing and looking at.Novices get caught up in peak numbers. Shape and area under the curve are the important things. More area under the curve the faster the bike is around the track, regardless of the peak number.
If the Bing can decrease laptimes in such a significant way the dyno will easily pick that up.
As Geoff says what is the differnce between the carbs? I reckon there is a really simple answer........................
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Different carbs would have different flow characteristic's maybe the flow of the bing just suits the 490? or velocity, could be something as simple as that,need a carb wind tunnel for that one (maybe that's why there not such a difference in the reed model :-\
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On a dyno, you pick the best gear and roll it on. You don't just hold it wide open. Rolling it on gives you the torque curve. Peak HP is interesting, but not super important if the motor is ballpark. If you can get good torque where you want it in the rev range, then you're headed in the right direction. Pretty valuable on a motocross bike if you ask me. Running a higher gear in corners, anyone?
Every dyno run i've witnessed the bike was always put into top gear then the throttle wound onto to full.
The TC450 Husky's we had dyno'd for the Husqvarna race team that showed the strongest curve were usually harder to ride and more aggressive on a motocross track and we ended up using an engine closer to standard.
There is nothing like track testing and rider feedback rather than the best graph on a dyno.
I think a dyno is better suited for road racing with good traction on bitumen.
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Husky HOONS
The jetting as promised.
Mikuni 38 mm ( NOT A GREAT IDEA)
Pilot 40
Main jet 380/ 400.
Airdcrew 2,5 turns out
Bing 54 (SEA LEVEL) Only way to go- absolutely spot
Mainjet 190 ( thick sand 200)
Piolt Jet 60 (thick sand 65)
Needle top last notch
Neddle 6h2
Needle jet 280
Best plug NGK B8EIX
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In my Bing i run
190 main jet
50 pilot jet
278 needle jet
8G2 needle (have tried both 6L2 and 8G2)
needle on the 3rd groove
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Thanks for your spec's guy's, with all this info i'll be soon sayin that maico HOONS !!!!!!!! :o
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Hey guys does anybody know the difference in taper and diameter of those two needles ,or where i can find a table for bing needles ?seems the 8G2 is out of mc 400 and the 6L2 is out of the 490,(is it alphabetical with L being richer/thinner?) if so there's a fair gap between L and G , like to start on the side of caution :)cheers
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The 8G2 needle is leaner off the bottom and richer in the mid than the 6L2. It cleaned up the bottom end blubbering and mid range pinging on my 490.
It is also the standard needle in the 1980 440.