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Mugen MBX6

Old 07-18-2012, 02:59 PM
  #17221  
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Exclamation Mugen MBX6R US Spec fuel tank issue

mr240 and 3dcracer,
I have had similar fuel tank problems with flame-outs in the pits during A-Mains too. I tried different fuel lines, different filters, new Mugen tanks, different engines, and different pipes plus related. HECK, I EVEN Bought a brand new Mugen MBX6R US Spec with all new parts, brand new engine, brand new pipe, new servos, line, etc. ...STILL same issue. This has happened to me many times on different engines, different stuff and is getting super aggravating as I have lost positions because of this issue at big races.
Other racers, who I race with, can agree on here, as they have seen my pit flame-out problem. Other Pro sponsored drivers have tried filling me up with either a fuel gun and bottle in pits during the Mains and they had the same issues.
I have heard from several Mugen drivers and X-Mugen drivers this has become an ongoing issue which started last year. Several drivers have left Mugen buggy because of this issue. It seems as if the new mbx6r tank is somehow different or constructed different then the mbx5 as something has changed since this fuel tank flame-out in the pits on the Mugen MBX6R is pretty well known on the race track. Sad but true.
I even emailed both Japan Mugen and USA Mugen about this and Japan even admitted they knew about the fuel tank issue but thought it might be related to hot weather, but I do not see other manufacture’s cars such as Kyosho, X-Ray, Associated or others having same fuel tank issue. People who are having this issue need to speak up and email Mugen Japan and Mugen USA.
Anybody put a different manufacturer fuel tank on the MBX6R?

Besides the fuel tank problem the buggy runs awesome.
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Old 07-18-2012, 03:02 PM
  #17222  
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Originally Posted by 3DRCRACER
When is it flaming out? Problems with the tank on Mugens are normally related to pit lane and refueling. Cold fuel hits the plastic and it shrinks after closing the lid. Or so I hear anyway. I agree with the above. Clunks are only an advantage if you spend time upside down.
The tanks don't shrink on a re-fuel, unless you are keeping your fuel in an ice chest before you pit your fuel will be the same as the ambient air temperature. The tanks are too rigid to flex enough to cause a problem. Too rich of an idle mixture setting will cause a flameout on a refuel. You can test to see if you will have a problem by getting your motor up to temp with at least a 1/2 to 3/4 full tank and while at an idle pick your buggy up and stand it on the wing. the pressure of the fuel against the pick up in the back of the tank will simulate an overfull tank during a pit, if your motor flames out it means your idle mixture is too rich and could stand to be leaned out some.
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Old 07-18-2012, 03:15 PM
  #17223  
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Concerning flameouts;
During practice and qualifiers it is fine. When I run those long Mains is when I run into the issue. I come into the pits and engine is running great, perfectly snap and idle and excellent top-end plus temps around 240ish depending on track and of course other factors, but never over 260.
Once my pit guy grabs my car and fills me up I then clean it out as normal and then it just flat out dies (flame-out) and have to restart. Even when trying to restart it the engine seems to have richened up dramatically and have to keep it floored to start and then once started I keep blurping throttle till it clears out and I am talking an easy 15+ seconds (which seems super long in an A-Main in the pits). Even if the pit guy uses a bottle, instead of a fuel gun, and does about half tank and rev up a little and then fills it all the way up and then it still dies even if I give it throttle. One time I had him fill it up very slow and I revved it ever so often and then when it was full he lifted up car off pit lane wall and keep trying to rev engine to clear out the rich setting. Anyway again after about 15+ seconds then it seems to clear 'it's throat' per say and then it runs great again. Hopefully this issue, at least from my side, is better understood.
Yes, I do know how to tune engines as it would be odd if 3 other Pro drivers who re-tuned my engines to test issue and it did it to them too. This last weekend I had an issue with my Mugen motor idling weird, but that will be looked at thoroughly this week.

Since the Sworks buggy is like the Mugen, I wonder if its tank or somebody else’s tank would fit.
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Old 07-18-2012, 03:20 PM
  #17224  
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Originally Posted by JohnT
Concerning flameouts;
During practice and qualifiers it is fine. When I run those long Mains is when I run into the issue. I come into the pits and engine is running great, perfectly snap and idle and excellent top-end plus temps around 240ish depending on track and of course other factors, but never over 260.
Once my pit guy granbs my car and fills me me up I then clean it out as normal and then it just flat out dies (flame-out) and have to restart. Even when trying to restart it the engine seems to have richened up dramatically and have to keep it floored to start and then ocne started I keep blurping throttle till it clears out and I am talking an easy 15+ seconds (which seems super long in an A-Main in the pits). Even if the pit guy uses a bottle, instead of a fuel gun, and doe sabout half tank and rev up a little and then fills it all the way up adn then it still dies even if I give it throttle. One time I ahd him fill it up very slow and I revved it ever so oftenb and then when it was full he lifted up car off pit lane wall and kep trying to rev engine to clear out the rich setting. Anyway again afater about 15+ seconds then it seems to clear 'it's throat' per say and then it runs great again. Hopefully this issue, at least from my side, is better understaood.
Yes, I do know how to tune engines as it would be odd if 3 other Pro drivers who re-tuned my engines to test issue and it did it to them too.
John, what motor/pipe/glow plug do you run and how much compression does your motor have? What brand fuel do you run?
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Old 07-18-2012, 03:53 PM
  #17225  
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Originally Posted by JohnT
Concerning flameouts;
During practice and qualifiers it is fine. When I run those long Mains is when I run into the issue. I come into the pits and engine is running great, perfectly snap and idle and excellent top-end plus temps around 240ish depending on track and of course other factors, but never over 260.
Once my pit guy grabs my car and fills me up I then clean it out as normal and then it just flat out dies (flame-out) and have to restart. Even when trying to restart it the engine seems to have richened up dramatically and have to keep it floored to start and then once started I keep blurping throttle till it clears out and I am talking an easy 15+ seconds (which seems super long in an A-Main in the pits). Even if the pit guy uses a bottle, instead of a fuel gun, and does about half tank and rev up a little and then fills it all the way up and then it still dies even if I give it throttle. One time I had him fill it up very slow and I revved it ever so often and then when it was full he lifted up car off pit lane wall and keep trying to rev engine to clear out the rich setting. Anyway again after about 15+ seconds then it seems to clear 'it's throat' per say and then it runs great again. Hopefully this issue, at least from my side, is better understood.
Yes, I do know how to tune engines as it would be odd if 3 other Pro drivers who re-tuned my engines to test issue and it did it to them too. This last weekend I had an issue with my Mugen motor idling weird, but that will be looked at thoroughly this week.

Since the Sworks buggy is like the Mugen, I wonder if its tank or somebody else’s tank would fit.

Never had any flameouts with my MBX6 or MBX6r EU with RB/OS/Alpha/Bulllitt.
I always use a fuel gun for refilling during mains and if its an important meeting, i'll put a new plug in for the final. I'd look at your fuel and plugs to be honest and maybe how rich the bottom end is on your motor.
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Old 07-18-2012, 04:05 PM
  #17226  
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The SWorkz tank looks to be shorter and taller compared to the mbx6. I am not sure if it would fit but it may be too short giving more room between the bell and tank.
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Old 07-18-2012, 04:34 PM
  #17227  
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Originally Posted by Slider30250
The tanks don't shrink on a re-fuel, unless you are keeping your fuel in an ice chest before you pit your fuel will be the same as the ambient air temperature. The tanks are too rigid to flex enough to cause a problem. Too rich of an idle mixture setting will cause a flameout on a refuel. You can test to see if you will have a problem by getting your motor up to temp with at least a 1/2 to 3/4 full tank and while at an idle pick your buggy up and stand it on the wing. the pressure of the fuel against the pick up in the back of the tank will simulate an overfull tank during a pit, if your motor flames out it means your idle mixture is too rich and could stand to be leaned out some.
Actually they do the heat from engine causes fuel tank temps to be a lot hoter then in the bottle and the tank swells in car once fuel from bottle hits it has to clear out.

Originally Posted by JohnT
Concerning flameouts;
During practice and qualifiers it is fine. When I run those long Mains is when I run into the issue. I come into the pits and engine is running great, perfectly snap and idle and excellent top-end plus temps around 240ish depending on track and of course other factors, but never over 260.
Once my pit guy grabs my car and fills me up I then clean it out as normal and then it just flat out dies (flame-out) and have to restart. Even when trying to restart it the engine seems to have richened up dramatically and have to keep it floored to start and then once started I keep blurping throttle till it clears out and I am talking an easy 15+ seconds (which seems super long in an A-Main in the pits). Even if the pit guy uses a bottle, instead of a fuel gun, and does about half tank and rev up a little and then fills it all the way up and then it still dies even if I give it throttle. One time I had him fill it up very slow and I revved it ever so often and then when it was full he lifted up car off pit lane wall and keep trying to rev engine to clear out the rich setting. Anyway again after about 15+ seconds then it seems to clear 'it's throat' per say and then it runs great again. Hopefully this issue, at least from my side, is better understood.
Yes, I do know how to tune engines as it would be odd if 3 other Pro drivers who re-tuned my engines to test issue and it did it to them too. This last weekend I had an issue with my Mugen motor idling weird, but that will be looked at thoroughly this week.

Since the Sworks buggy is like the Mugen, I wonder if its tank or somebody else’s tank would fit.
This is a issue with few. It seems like a issue happening with the average guys. Never use fuel gun, keep Ron up in pit and tell ur put guy to let you clear out a Lil before getting dropped out. Also tune can cause this, it's. Not only mugens.

Originally Posted by JohnT
mr240 and 3dcracer,
I have had similar fuel tank problems with flame-outs in the pits during A-Mains too. I tried different fuel lines, different filters, new Mugen tanks, different engines, and different pipes plus related. HECK, I EVEN Bought a brand new Mugen MBX6R US Spec with all new parts, brand new engine, brand new pipe, new servos, line, etc. ...STILL same issue. This has happened to me many times on different engines, different stuff and is getting super aggravating as I have lost positions because of this issue at big races.
Other racers, who I race with, can agree on here, as they have seen my pit flame-out problem. Other Pro sponsored drivers have tried filling me up with either a fuel gun and bottle in pits during the Mains and they had the same issues.
I have heard from several Mugen drivers and X-Mugen drivers this has become an ongoing issue which started last year. Several drivers have left Mugen buggy because of this issue. It seems as if the new mbx6r tank is somehow different or constructed different then the mbx5 as something has changed since this fuel tank flame-out in the pits on the Mugen MBX6R is pretty well known on the race track. Sad but true.
I even emailed both Japan Mugen and USA Mugen about this and Japan even admitted they knew about the fuel tank issue but thought it might be related to hot weather, but I do not see other manufacture’s cars such as Kyosho, X-Ray, Associated or others having same fuel tank issue. People who are having this issue need to speak up and email Mugen Japan and Mugen USA.
Anybody put a different manufacturer fuel tank on the MBX6R?

Besides the fuel tank problem the buggy runs awesome.
Originally Posted by Keith Lewis
The SWorkz tank looks to be shorter and taller compared to the mbx6. I am not sure if it would fit but it may be too short giving more room between the bell and tank.
No I heard sworkz tanks are worse.
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Old 07-18-2012, 04:46 PM
  #17228  
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Well just to be clear, I took one of the engines and pipe (O.S. V-spec with JP3) that had the fuel tank problem off the MBX6R and put in the Durango DNX408v2 and no fuel tank flame out problem.
I have swapped many things, but to start off, as far as engines, I tried my, O.S. V-spec, O.S. Speed, Werks B6 Pro, and Mugen Ninja BX21B02 plus 2 of these were brand new, but all did the same thing. BTW, All 4 engines still have great compression and run great, but all had the weird fuel tank flame-out issue during mains. This is an odd coincidence.

I am no newbie in tuning engines as I have been tuning engines for about 10 years. These same engines run great in two other brand vehicles with no issues and other racers have used my same tuned engines in their buggies too (Kyosho and Losi). It is strange how I received two private messages about this same fuel tank issue. Not to be rude as I agree with their frustration, but honestly people need to email Mugen, not me as then hopefully Mugen will realize this has been an ongoing issue to seriously look into to fix this fuel tank issue. Sorry, but I have been quiet too long and this has costed me too many main positions to stay quiet any longer about it anymore.

I would hate to trade to another brand like other racers have already, because of this problem, as the Mugen MBX6R buggy is rock solid and drives great.

Last edited by Fast1rc; 07-18-2012 at 05:52 PM.
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Old 07-18-2012, 06:14 PM
  #17229  
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I own racemugen.com, and have for several years.
We have Team drivers, a support forum, I race and we have a nice sized client base.

Other than a few instances I have read about on here, I am not aware of any tank/flameout issue. The tanks are the same as they have been since the MBX6 was introduced.

If you were in Georgia I would be happy to look at it on a track with you and troubleshoot it.
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Old 07-18-2012, 06:19 PM
  #17230  
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Since eveything else has been changed, I would consider trying dramatically different fuel line routings. Just to see if it makes any difference. Again, "dramatically different" is the key here. Even if it isn't practical. Heck, put 18" of hose on it just to see if it corrects the problem.
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Old 07-18-2012, 06:47 PM
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Originally Posted by MadRussian
I own racemugen.com, and have for several years.
We have Team drivers, a support forum, I race and we have a nice sized client base.

Other than a few instances I have read about on here, I am not aware of any tank/flameout issue. The tanks are the same as they have been since the MBX6 was introduced.

If you were in Georgia I would be happy to look at it on a track with you and troubleshoot it.
+1!IMO dramatic line routing is bad aswell. I have never had a issue, running tank BONE STOCK minus the fuel limiter in tank(which is common unless you tech above legal fuel limit). Lines are ran from tank around filter to fuel filter then around to carb and pipe is from tank to pipe. Very simple routing. I was told running about 8/10 inch pressure line reduces flame outs but i have never needed to try it. Its a confusing issue to help solve but im 98% sure the fuel tank isnt the MAIN issue. I had a issue once it was a leak in fuel filter causing flame outs all day even i think causing a engine to fail way before it was suppost to. Lesson learned, i ran spacers on the clip for lid to help it close better but i learned when a tank is 5 gallons old the rings grow old lol.
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Old 07-18-2012, 07:35 PM
  #17232  
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Originally Posted by NitroXray80809
+1!IMO dramatic line routing is bad aswell. I have never had a issue, running tank BONE STOCK minus the fuel limiter in tank(which is common unless you tech above legal fuel limit). Lines are ran from tank around filter to fuel filter then around to carb and pipe is from tank to pipe. Very simple routing. I was told running about 8/10 inch pressure line reduces flame outs but i have never needed to try it. Its a confusing issue to help solve but im 98% sure the fuel tank isnt the MAIN issue. I had a issue once it was a leak in fuel filter causing flame outs all day even i think causing a engine to fail way before it was suppost to. Lesson learned, i ran spacers on the clip for lid to help it close better but i learned when a tank is 5 gallons old the rings grow old lol.
I think you're missing my point. If I read correctly, he changed the whole car. So what's in common here? The only thing left is how it's being built. Well, the only thing that would effect this when the car is built would be fuel line related. So, to eliminate that, go to an extreme to eliminate that as a possibility. Can't hurt.
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Old 07-18-2012, 08:08 PM
  #17233  
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yes totally different car, fuel line, engine, routing, tank, filters/no filter as I have tried everything, as I could lsit everythingf I tried, but it would serioulsy be a long list since I ahve dealt with this issue for over 3 months and about 8 races.
The ONLY thing that was the same was the fuel, which I thought could be a possiblity. A good friend of mine, who is sponsored with VP Pro, gave me some bottles of VP Pro fuel at the race to try out and see if the problem persists. Thanks bud!! Hey, who knows, as sometimes you can get bad fuel, even though this has been through 4 different gallon bottles. It is worth a shot as that was the only thing the same.
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Old 07-18-2012, 08:43 PM
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Originally Posted by JohnT
yes totally different car, fuel line, engine, routing, tank, filters/no filter as I have tried everything, as I could lsit everythingf I tried, but it would serioulsy be a long list since I ahve dealt with this issue for over 3 months and about 8 races.
The ONLY thing that was the same was the fuel, which I thought could be a possiblity. A good friend of mine, who is sponsored with VP Pro, gave me some bottles of VP Pro fuel at the race to try out and see if the problem persists. Thanks bud!! Hey, who knows, as sometimes you can get bad fuel, even though this has been through 4 different gallon bottles. It is worth a shot as that was the only thing the same.
I don't want to get a war going, nor make anyone think that I don't love my Mugens... but honestly, this has been an ongoing issue with mine also. I replaced the tank about 3 gallons ago...and now with 3 different engines. Ever since the orginal tank, it has caused me nothing but problems, both with flameouts during mains, and now tuning issues. During heats, no problem, but pits during the mains, or even after an extra long warm-up = flameout... During my last race at the JBRL in Hesperia, CA, I watched at least 6 other mugen drivers in different classes have the same issues.

The tuning issues I had with my RC8B when I had it, was finally cured with a different brand fuel tank (the handling issues weren't, so enter the mugen). I am going to try the Tamiya tank, as I read somewhere in here that it works with very little modification and see if that helps...

I'm not sure if they changed the materials since the M-Spec, but it seems like I am hearing, reading and seeing more of this problem.

Again... Im glad some people aren't having issues, but it's like the RC8B tank issues, some people swore nothing was wrong, others swore there was something wrong... even a team driver told me there was so... I went through 5 tanks trying to find one what worked, and even then after a couple runs it sustained a micro crack somewhere... so D8 tank it was... (nothing like someone telling you that its your tuning when you can watch bubbles traveling into the carb (like watching a beer glass amount of bubbles).

So my plan ... replace the lines, fuel tank, glow plug, set motor to base setting, get rid of filter to test, test different lengths, test engine for possible air leaks, and test different brand tank... I will get back on here with my findings when I can...

Additionally this had not been as an extreme problem in the MBX6T, but it has done it also...

I know... Im all over the place... but maybe like the RC8Bs the tanks are getting micro cracks from hard landings...

Last edited by Stirex; 07-18-2012 at 09:04 PM.
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Old 07-19-2012, 12:11 AM
  #17235  
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hi guys, does anybody know if any other brand - hopeful a bit more durable - than the mugen damper bushings fit the mugen damper caps/standoffs? the mugen ones are a bit finicky compared to ones I've used on other cars...and once the little lip comes of its stuffed lol

thanks
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