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BGM 60/110 crankshaft took a dump

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Well, the BGM 60/110 crankshaft in my RT230 engine decided to twist out. My engine started to develop this oddball hiccup that sounded like the electronic ignition missing. I swapped to a new CDI and tested the stator even though it all tested great. Then, over the course of a couple days it got worse and worse and got me stranded a couple miles from home. Last night, while cleaning up/correcting the ports of an RT195 kit, DerekM broke down my RT230 engine. Aft 4,000 miles the RT kit looks stellar!!!

 

25038470934_77e79e4c0e.jpg

BGM RT230 after almost 4,000 miles. by Christopher Ward, on Flickr

 

 

 

However,  problem appears to be that the BGM 60/110 crankshaft had twisted out:

 

25042282653_2be45cb9f4.jpg

I'm guessing twisted crankshaft... by Christopher Ward, on Flickr

 

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I'm guessing twisted crankshaft... by Christopher Ward, on Flickr

 

 

So, after 4,000 I've got a fucked $400 crankshaft and $60 mag flange bearing, and maybe a ruined $270 flywheel. 

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Really? Nice. I kinda just figured because of the miles I put on it, I would be left to my own devices.

 

I'll add: My engine is a FULL BGM-sourced build. Up until last week, it has been a wonderful ride. Every day - rain or shine. Loads of power, great gas mileage, fantastic in nearly every regard from the moment I built it. I have another engine being built in an identical fashion with the same parts sourced from BGM through local and international Lambretta shops. Just look at the inside of that barrel - it looks beautiful for the miles I've put on it with some of those miles being at over 80 mph for extended periods. 

 

BGM 60/110 crankshaft

BGM RT225 (tuned by MrB)

BGM seals

BGM stator

BGM flywheel

 

 

Note:  The BGM 60/110 crankshaft that has twisted was the replacement crankshaft for the BGM 60/110 unit I had previously posted with the over-machined crank arm (where the bearing race would just fall onto the arm). 

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No you didn't get fucked. Send it back to MB they replaced mine. Same thing happened to me. They replaced the crank and flywheel for free.

And the bearings and the seals. 

 

BGM (scooter center), MBD and Jet200 have always taken care of any problems we've had with the BGM line of products. 

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I had Hot Rod Al weld mine up to avoid this issue. I saw a few of them popping up twisted on some Lambretta FB pages. 

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Yeah, but my engine probably only puts out about 24hp - definitely not more. 

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Yeah, but my engine probably only puts out about 24hp - definitely not more. 

right - which you would think it wouldnt twist according to BGM specs. The pin should be super tight in the webs along with the adhesive used. When I saw the twisting pics I was like UGHHH better get that welded 

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Gosh darn it........your piston is practically carbon free compared to mine with 2000 miles on it. I use yamalube r2 at around 2.75 %. Kinda jetted fat but ran frikkin great.

 

Not kidding, your piston looks great. 

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So, I packaged up my new-in-the-box BGM 60/110 crankshaft and am shipping it to Hot Rod Scooters in the morning so it can get welded up. The twisted crankshaft will be returned to SCK with the BGM flywheel for replacement. It sucks that I have to pay shipping, but time is what I need, not money. The Black Sheep ride is coming up on April 30 and I already have my hotel room - and the prospect of riding a stock Jet 200 along with a bunch of other guys with tuned scooters sucks.

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I just had Hot Rod Scooters report back on that new BGM 60/110 crankshaft I sent him for welding.

 

It measured 0.005 at the flywheel-side web and 0.00035 on the drive-side web. After truing and welding it up it is at 0.0015.

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Hell if I know. But at least now I can have my engine running with confidence.

Thanks Hot Rod Scooters!!!

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If you look at a crank as a replacement item, then welding the pin is a good idea. If you plan to rebuild your crank at some time in the future, it's probably best to have it built by someone who is a good engineer. MB was selling his own BGM cranks that he hand built himself.

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I'll be welding up the replacement, as well. I'll likely reach out to Harry Barlow for my next crankshaft. I'd like to buy local and all that jazz, but seeing as I have to BUY the crankshaft first and then get it repaired, I think I'll try to find someone with one already built.

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I'll be welding up the replacement, as well. I'll likely reach out to Harry Barlow for my next crankshaft. I'd like to buy local and all that jazz, but seeing as I have to BUY the crankshaft first and then get it repaired, I think I'll try to find someone with one already built.

 

 

Have you found any with the woodruff key way being under machined? I've had 2 now with narrower than normal keyways. The last one I had was .003" too narrow and had to have the key ground down to match (after welding and installing of course).

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Have you found any with the woodruff key way being under machined? I've had 2 now with narrower than normal keyways. The last one I had was .003" too narrow and had to have the key ground down to match (after welding and installing of course).

 

Yes, I have. I have also found the drive side splines machined wrong so the cush drive shaft will not slide on.

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Yes, I have. I have also found the drive side splines machined wrong so the cush drive shaft will not slide on.

I have not seen that one yet but now that you mention it guess what I'll be checking tonight when I get home?

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Yes, I have. I have also found the drive side splines machined wrong so the cush drive shaft will not slide on.

Yep, have seen that quite a few times. Definitely better to check the sleeve fitment before fitting crank in the engine. I've always managed to dress the splines with a file to aid getting the sleeve on, just takes a while.

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The one I originally had with over-machined bearing collar surface (whatever it is called) had a too skinny key slot. I sanded the woodruff key a littke and it fit.

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Have you found any with the woodruff key way being under machined? I've had 2 now with narrower than normal keyways. The last one I had was .003" too narrow and had to have the key ground down to match (after welding and installing of course).

How on earth did you do this without there being slop where the key goes into the flywheel slot? I seems that if you stepped it, that would be a weak spot, right at the transition.

Yes, I am aware the key doesn't actually hold anything, but man, that would be some funky goings on...

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There is a little "slop" now. About .0015" on each side of the key way on the flywheel. Like you said the key is just for alignment and doesn't actually hold anything.

Ideally a steeped key would be the best fix without fixing the crankshaft.

I'm pretty much fed up with fixing and coming up with work around solutions for new parts.

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