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Old 10-02-2019, 10:56 PM
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Help!
BME 100 carburetor kit?

I need a carburetor kit for a BMB 100 twin, the carburetor is stamped with SDC 21-85. Anyone knows where to get them online?
Thanks
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Old 10-04-2019, 11:12 PM
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https://www.ebay.com/p/24015354265?i...xoCQSsQAvD_BwE

....Or .... just take that little number SDC 21-85 and trot on down to your local lawn mower/small engine shop and they'll fix you up for about $10.... and you won't have to fiddle with ordering or waiting.

You probably don't need the metallic parts or the needles in the regular kit, but there's a "gasket only" kit available also.

Just an FYI if you've never done one before. I've found the Walbro carb kits cover several carbs, and have very similar(yet different) parts that aren't necessarily used. in every carb, .... in other words, when you replace parts in your carb, only use the exact new part from the kit. I've heard of people trying to replace everything, just because it was there... it doesn't work like that though.

I would also suggest taking good close up pics as you disassemble it. Getting the gasket and diaphragm order correct is essential to the engine running as it should.

I own 4 BME engines, they're great engines. If you do your carb right, it will run fine.
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Old 10-22-2019, 04:30 PM
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DGrant, thank you for your response. I was able to fix my carburetor with a new rebuilt kit.

After I finally got it running again, because I also had problem with the original ignition. Replace it and got it running but for some crazy reason I cannot get this engine to run cool. I have already back out so much on the Hi and Low needles. On the ground it will get up the 325 degrees without any cowl on. Most of my engines never even see this high of temperature. Don't know what to do.

Vic
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Old 10-22-2019, 04:49 PM
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Do the plugs show a lean condition.
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Old 10-22-2019, 05:22 PM
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yes it does show a bit lean, I back it out and still runs hot cant run it cool whatsoever

I am not sure, but I think I toasted my new Rcexl ignition because of the heat when I had the cowl on. It is now acting like the ignition is bad again.
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Old 10-22-2019, 05:43 PM
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You already did everything to the carb that can be done.I would start looking for a Walbro WJ71 carb or just buy a new carb from DA for a 100. Most of DA carbs run richer than other engines.I ran a BME58 for a long time and I had to watch the temps,it is the only engine that I cook.They are a performance engine with tighter tolerance's.
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Old 10-22-2019, 05:53 PM
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Some of the BME engines had the cooling fins machined down from stock making baffling more important.
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Old 10-22-2019, 06:15 PM
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Hmm... 325 degrees will bake a cake. Although I don't know exactly how hot my BME's run, I'm pretty sure they're not near 325... none of them show signs of overheating.

What's your gas/oil mixed at, and brand of oil?... Prop size? Plug type?.. and any other info you might be able to provide for a possible diagnosis..

I'm still running my original CH ignitions on my early 50cc and 102cc.. with no problems(knock on wood).. the newer version 102 I own has a RCExcel ign if memory serves..

Here's a link where you can download the manual that has the carb settings and other pertinent info...

http://www.bmeengine.com/manual.htm

I'm just pondering what could create a situation that would affect the engine temp to such a degree... How about timing..?.. any issues with the hall-sensor collar slipping or being moved?.. Usually once set they stay put... I've actually never moved mine.. although I'm fully aware of how to adjust it.. they just run.

The initial needle settings are in the manual, and are a starting point to get the engine running(at usually a rich setting)... and you go from there.. If your carb is assembled correctly, you should able to get it set to run correctly, but it does take a little bit of finesse to get them balanced... If this is your first time adjusting one, you might have to play with it a little bit.. but it's not too difficult.

As for the ignition being bad... check the plug that goes from the ignition to the hall-sensor... if that engine got hot there's a slight chance it comprimised that micro plug.. It's just something to check and not take for granted. I had that micro plug connection go south on one of my engines, and it was a real pain in the ass to diagnose, but once I figured it out life returned to normal. So there's a few things for you to ponder..

I'm not sure I would go swapping that carb out for anything other then what is designed for that engine. The stock carbs are fine in my experience, and the engines run like race horses and pull like trains when set up right.

BME is still in biz, and Tom can help you out too. I had some work done on one of mine a while ago and he was great.
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Old 10-22-2019, 06:24 PM
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Quote:
Originally Posted by closetguy View Post
You already did everything to the carb that can be done.I would start looking for a Walbro WJ71 carb or just buy a new carb from DA for a 100. Most of DA carbs run richer than other engines.I ran a BME58 for a long time and I had to watch the temps,it is the only engine that I cook.They are a performance engine with tighter tolerance's.
Funny you said the WJ71, cuz I originally thought it was a carb issue, I did buy a new carb and put it on. The motor still did not run right and I had to use my Miller Pursuader to start it.

Here is what I have tied.

1st time - Carb spills a bunch of fuel when starting, started but started with a Miller starter. I replaced the diaphram as it was hard. Ran over 325 degrees, ran erratic, needle at default 1.5 H and 1.5 low.

2nd time - new diaphram, less fuel spill but still would not start by hand use a Miiller starter, still ran hot and erratic.

3rd time - replaced the carburetor with a brand new WJ71, no change still the same, hot and erratic.

4th time - replace iginition, 3 flips and it started yay! It ran really smooth and powerful, I thought my problem was solved however it still ran hot.

5th time - thought it was my timing, tried 30, 28 and 26, and it still ran hot. But now I think I just cooked my ignition when I put my cowl back on. It is now miss firing like it was 1st - 3rd time.

My friend thinks I have an air leak somewhere. I am lost, I may have to take the entire engine apart.

Does anyone know how to check an overheated Rcexl ignition? The ignitions I have seems to work fine with my ignition tester.
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Old 10-22-2019, 06:34 PM
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Wow vic... I got nothin. You've tried several things and more that I and probably everyone in your thread would have tried.

The initial default needle settings always have these running on the rich side in my experience... and it should be no different with your settings... but maybe turning them out a fuzz more could help?.. just something to ponder there.

Curious if this engine was parked for quite a while and then resurrected.. or if the initial problem just came up out of the blue in a regular days running.

Again sorry I got nothin, but I'll ponder it for a bit though.
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Old 10-22-2019, 06:50 PM
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You mentioned default needle settings. Does the engine richen up normally when you adjust the needles out from those settings? Other than hot, does the engine seem to be running normally?
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Old 10-22-2019, 06:52 PM
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Wow vic... I got nothin. You've tried several things and more that I and probably everyone in your thread would have tried.

The initial default needle settings always have these running on the rich side in my experience... and it should be no different with your settings... but maybe turning them out a fuzz more could help?.. just something to ponder there.

Curious if this engine was parked for quite a while and then resurrected.. or if the initial problem just came up out of the blue in a regular days running.

Again sorry I got nothin, but I'll ponder it for a bit though.
DGrant thanks for the thinking, I am out of ideas at the moment.

Yes this motor was given to me 4 years ago and I have no history on it. The pistons look great and clean, compression is amazingly strong.
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Old 10-22-2019, 06:56 PM
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You mentioned default needle settings. Does the engine richen up normally when you adjust the needles out from those settings? Other than hot, does the engine seem to be running normally?
Yes it does richen up but it runs very sluggish, however the temp is still too high at above 300 degrees. Never had an engine do this ever.

When I take it apart, I am going to take some pictures.
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Old 10-22-2019, 07:29 PM
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Please do take pics when you get a chance. Not saying we'll see anything out of the ordinary, but you never know.

Does the crank spin very freely without the plugs in?.. with no resistance other then normal.. I'm wondering a little if there's an internal problem, IE crank or rod bearing that's not being detected, that's creating heat. I had one of my 102's into Tom at BME over the summer because a rod bearing went out, and it created alot of heat, although still had ample compression, and would run, but had a terrible knock. He replaced the whole crank and rod system along with main bearings. They did a great job and it runs like new now... but it did heat up when there was a problem. It was very clear when I got the defective crank/rod assembly back and there's excessive play in one rod, as well as bluing from the heat on that rod end(big end).. which was exactly where it went south.

I'm curious what your rod-ends and crank look like, and if there's any scarring or bluing from a previous overheating situation... since you don't have any history on it, there is that possibility. I can tell you BME still works on them, and has parts, and again they did a great job.. but I am curious and a little suspicious of your bottom end in that bad boy now.
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Old 10-23-2019, 11:24 AM
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Well nothing looks out of ordinary other than a small chip on one of the reed valve leaf. Bearings all feel and looks good. It certainly heated a bit but no damage to the liner or piston as they are shiny smooth. I did not take the crank out as I do not have the tools that can manage it nor the expertise to do so. I assembled the engine back using the anaerobic gasket on all metal surface to make sure there is no leak. Notice the WJ71 carb has onely 1 breather hole compare to the BME carb, I am not sure if this makes any difference.

Without knowing the history on this motor, I did changed out from 14mm plug to a 10mm CM6 plug, which I do often on all my engines. All my Zenoahs have them. Maybe the spark plug compatibility with this engine? I am not sure.
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