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General Category >> Rubber Side Down! >> Checking BS 40 carb for the first time
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Message started by Fabricio Bino on 05/07/20 at 12:53:29

Title: Checking BS 40 carb for the first time
Post by Fabricio Bino on 05/07/20 at 12:53:29

Hello!
As I now run a mikuni vm38 in my savage, i decided to disassemble my bs 40 to learn something form it and maybe make it run better, as it was very bad, not getting over 90km/h even when the throttle wide open.

I opened up and the first thing i noticed is how hard it was to remove the slide, it was somehow stucked by dirt:

http://https://hebhpq.dm.files.1drv.com/y4mEFdEOJq2oGRtISqs1nMoeP2Quj7d1nOOUvI3MTzUddI32Z5Nyt3kEX0JTo2u0Yht-HL0Fc6LqcpqrHJ20QTZyd0HlFth0-cQhjrcmmEzLQ-PbPFan3V_kwy-dwZJmdGRzVayB_GWxMs-bswApVzJIrF-cWC-gwJixmIykI4z2T-EcJt5JRBxcOGDjRhqcbt7Xa4wtBn746lVUVSIdvq12Q?width=1024&height=768&cropmode=none

I cleaned it up with some kerosene and now it slides smoothly inside. But is all this wear and scratches normal? should I brush it with something like steel wool to make it better?

Also is this gap between the throttle plate and the carb's "walls" normal?

http://https://hubgpq.dm.files.1drv.com/y4mlbDZPuGSE0WRY0R1VjuLNGonH3kgWMMaRJs1k9kwgsmhKWjLDBoWjWs0MXJNAdzfzfIXsQNgpL9dj0JCTM5DmMXHz7bH_VqU8xqgJPjy2cftBpF3Y3infoOAa1oC9pZB7l8UnwfwhrLSG8dhSf19hE7Yzwh-W7FGlavs1X-Ih083xMYYgY54DUUpCf3q8WsR-oqavNThvEynnwlXK2rrWw?width=768&height=1024&cropmode=none

Title: Re: Checking BS 40 carb for the first time
Post by batman on 05/07/20 at 13:08:54

The black coating on the slide comes that way and you should not remove it! If the slide moves freely your good to go, don't even touch it when replacing it. The gap you see in the throttle plate is from the Idle adjustment screw holding it open (normal).

Title: Re: Checking BS 40 carb for the first time
Post by IslandRoad on 05/08/20 at 01:52:24

90 km/hr is terrible (as you know). You should be able to hit 140 without a problem! I would do a general service ... air filter, oil filter, check the jets and fuel line etc. If all good there, I would check the exhaust port for carbonation (are you running a stock muffler or open pipe?) If still good, then maybe a compression test.

Oh, and the stock fuel tap can produce some weird symptoms.

Title: Re: Checking BS 40 carb for the first time
Post by DragBikeMike on 05/08/20 at 14:27:25

Fabricio, your carburetor is extremely corroded. I don't think I have ever seen a throttle shaft and throttle plate with corrosion like that. The cover for the diaphragm is also severely corroded. That's an area that is supposed to be dry (air only). Was this thing stored at the bottom of a pond?

All the special coating is worn off the slide, and it is scored badly. I suspect it will continue to stick. The sticking slide would certainly explain why it couldn't exceed 90 kph.

Just my opinion but I think your BS40 is ready for the training aid shelf. It is no longer serviceable.

Title: Re: Checking BS 40 carb for the first time
Post by IslandRoad on 05/08/20 at 21:53:42

Forget what I said ... and listen to Mike!

I didn't appreciate (at first glance) what condition your carb was in.

Title: Re: Checking BS 40 carb for the first time
Post by batman on 05/09/20 at 07:34:42

I think the point was missed that he has already installed a VM38 on his bike, I don't think he's looking to use the stock carb for anything but a training aide.

Title: Re: Checking BS 40 carb for the first time
Post by Fabricio Bino on 05/09/20 at 15:14:44

I appreciate all the thoughts!!
Indeed, as I have no experience with carbs I decided to inspect it and understand it better. It runs, poorly, but it runs, but yeah the vm38 right now is the one I'm using

Title: Re: Checking BS 40 carb for the first time
Post by justin_o_guy2 on 05/10/20 at 22:53:03

How many miles on the bike when you swapped carbs?
That slide looks like the bike swallowed a lotta dirt or someone "cleaned" it with a brillo pad ..

Title: Re: Checking BS 40 carb for the first time
Post by Fabricio Bino on 05/13/20 at 08:44:30

I can't say for sure the mileage on it, because i bought it used, it's a '95 savage in 2020 and the speedo tells me it ran only 30k kilometers. I reaaally doubt that.

Also there are other issues in the carb that i didn't show, such as throttle cable assembly was somehow swaped.

I can post the others photos of the carb if you guys are interested to see

Title: Re: Checking BS 40 carb for the first time
Post by justin_o_guy2 on 05/13/20 at 12:01:07

Kind of a moot point, Innit? Its swapped out and youre running and from what I see,, it needed parts or a dfferent carb.. Job Done! Way to go,,

Title: Re: Checking BS 40 carb for the first time
Post by DragBikeMike on 05/13/20 at 16:26:17

Sure Fabricio, post the pics. There's always something new to learn. As I previously mentioned, the corrosion on your BS40 is extensive. Never seen anything like it. Let's see all the gory details. What's it look like inside?

Title: Re: Checking BS 40 carb for the first time
Post by Fabricio Bino on 05/14/20 at 08:02:25

These are the other pics of the carb
http://https://euaqpq.dm.files.1drv.com/y4mBaqAp2DeleUk1SskCoOo9MPavL7tHdwiM6MdW4Y1jjdAixLCuOykHnWtWQm9CKMtuwOt67Kt_4pRSIOl3N-kA8BZXxZWqsj7pzBv6Y0J1blMTlsT2PQzAnuyhMYxrSKECYl9gyPqyGLc2Qpw7kHuR9LQzQhscmdixCqvEH-POf3LhkJ2r_hk-p7hCriyMDKmFXeZRe946q180vCI6-Gcjg?width=768&height=1024&cropmode=none

http://https://hea6pq.dm.files.1drv.com/y4mxtrV0CY5SZsWNOewaIhFsrKari3tZrfrQ37k0Wt4G_Wiy_iujHvQRhW9iR97nyIUr9ILHw6JY9EH1mrlv1n0ULARiCX70B0Ppw37MYnWPSpvAtF31IYoRS4tK8tmOXA6s-SluizLHstBTY_PaxE0WFXcHU9uAM2uGLIsDY7-2FACForL5CLyhxXRqJsLeVeQnfrc0DHJiPWc881Kr8RexQ?width=1024&height=768&cropmode=none

http://https://hea7pq.dm.files.1drv.com/y4mErU1SYvY-irOmq47CLl3jYQDVF8sNEBDzQo1nlHY0I3kJyQzYP4tMF1m1inUQTMQjKRX-w3aDjNnMc887pIxJaGL9G_OS2klgjmCi39IMaowKS8_S_UQiD5UxhxCVJEscEAizLcTJvXRxOb_ONU05Dy42czio_PnaO72hNnHadQH-qGXAMRrBo2OHliMSqhxEJ__YVhQIrc3cQilItpo4A?width=768&height=1024&cropmode=none

http://https://hea9pq.dm.files.1drv.com/y4m02Bv_6IShj9Y0EAV0zEkyI73jL2AarTDeeU-AJMTGRkx4v7n0YBCWQAfnF4JZtW8--WOlZ0GXHrDtg0rAMGU1CiBFLe_edwZfA61TZ5qs6kvGZVzcfFHWFqxvcfcD449EhNqP5XhuQhkJdVOQTxUYbCehhuIsKgWRUYM6PXDMDDmOCTV6M3Z68Z7XPRTmJD0EiLhxYoa1DHFwHPuOgRu9A?width=768&height=1024&cropmode=none

http://https://heaqpq.dm.files.1drv.com/y4m9kKfkkZ5mluBaFNzcN7mTfn-cQsrT6uy9pxD0BNirGge6sCXv-6MIr8LKRoZpNS9_cXrnz1JdKuEUWWVdFxkqSEgu7nhyjEjBpI8L6o5kVKwlWo-WgTTOpPz9ZOzlJRG5HawL67qWcTZzp5CwHmQYiaK0h_Ry8y09JaEYbFzO3S0VXTJBfxVkNGm3xlTJ9IK3QGzNVy_iedUqWtovAfLNg?width=768&height=1024&cropmode=none

http://https://g0a8pq.dm.files.1drv.com/y4mvcxo8F0k-MXCUayMMAONwTov9NymPNf_-QelMA1kjC0jLyGgUHiYrsVFDO694p5inVmvNEC4r4RpT8gOsF5hSj-RUqRd8US0kdK7K_K8dd0pf-lpz9kA6KwmWjdwkO-egQf86So7IhVtlsxvqY76HqBvdPJu8El1J8Uqk9XZrjYLgBoy8KvWvu7Rz6FzfGd6go7mJ1yYbUrh0HhgSqD2yg?width=1024&height=768&cropmode=none

http://https://g0a7pq.dm.files.1drv.com/y4m3dGw1XtIw_TGQkfimatCfrmJkDSsCufF4yF0nMEuvdV4bJOHBHGZyea_IX4XkVeG90Vj484_DVac81Jr05hLrUyCmwU65_TQ2rAPw94W30KnV56nLF0lbNb6qNy5kLktaX-qGgfPaMBzDGrYZyBqfPEa5H2ioYEChWt3asvrxdLDNrYwsa48R3U3FsL2cfOYq-AjKauX92nO41kQOHhZWw?width=1024&height=768&cropmode=none

http://https://g0aqpq.dm.files.1drv.com/y4m1Dje8FfFyNnJYuhb-RpvTik3Vs4JlNEwiGWVoqlnFR3vAtMpjtDFeeEo54yyxCTuC-VHQMAIGmkKkLgiDhqChsam5SQT3rOMMSj3WRa4bdmTHxIZ97Z7X0yxQL8YPi8oHdsTHPt9MPkMyR-9a2vwgKbrrrPsDDZbeFV-sLx6bgOLF9Ud37dttmjBN5ZWf8BHhEV_K5jEf-PSVZ2RJKZsKA?width=1024&height=768&cropmode=none

http://https://hka7pq.dm.files.1drv.com/y4mfHBUeT_O7q4XT4L7d4OWBDLF-o_05Bex5M0BHjGFFLpyz_h2jQS1DYrd_XsdmhWFKB_Wfpe6uqkzuIYsbAIeCW0ZhPep8ctJPGADv7tTkw4lDZxSRz1Yrw41AED4VnJUXpc_hoPdS1s-8zA87p8fcmniFlTAVjIg0HprM0Ni6KmKqxbiJxL_l6rxkBmCCQyeM5lvXM5DfiKkM-h6AuJ_Mw?width=768&height=1024&cropmode=none

http://https://hka8pq.dm.files.1drv.com/y4mm9rO7cFNS0wSEhxNXH8u5p1Lfh5njEJLL5GmIT0Id0Aa5_Vb7LAR8u5v0Qo29lQbmQDNy-ilcE4YVRQUu5zqj0EiVkdDyobBYRPQe0L4L0wRjgFVzW8G62_NkWoVTJLH32zRQyulu-GRooSHVXUb-zMp8OoEgNZX8mR5EGUbRnEVovoWPhLk61F8tu6LbHHCM_eqq74zopL4YcVYH5RDig?width=1024&height=768&cropmode=none

http://https://hkappq.dm.files.1drv.com/y4m7g5DuW7AALm-3UIQxGU3rCpLjk5AyrJSftaMjXWwMsCliuLJ6XocV6fZR53VMamgUWaVDsQtcFWIrwq5FlVfgGrCrauC88wTyFBDs38x29_AYfYh8i1_E5OA2HZqa7CwElUnZhqNHjgXHqFutYXTGCxlWBfdtz4hmnlAzxH3pcS2iB3zkFVvbwklwO6YHOWu08rxP2800HbYmm-Z2rttEQ?width=1024&height=768&cropmode=none

Title: Re: Checking BS 40 carb for the first time
Post by DragBikeMike on 05/14/20 at 15:09:51

Wow! Thanks Fabricio. What an education. I don't think I have ever seen one corroded quite this bad. It actually ran like that?

I can't get over the corroded throttle shaft. Do you have any idea where this thing was stored? Was it simply left out in the weather? How many years?

One thing I find really interesting is it's corroded, but it's not gummed up. You can see the base metal. Its badly pitted but it doesn't have a quarter-inch layer of gummy residue like typically seen in a carb that has been sitting for an extended period.

Is there any way you can share some history on this thing? Maybe the prior owner could fill you in. I believe you are in Brazil, do I have that correct. Do you folks in Brazil have straight gasoline or do your service stations dispense gasohol (ethanol & gasoline blend)?

Title: Re: Checking BS 40 carb for the first time
Post by Fabricio Bino on 05/14/20 at 15:18:01

that is correct, our "gas" is made up by 27% ethanol and the rest is actually gasoline.

I belive the previous owner replaced this shaft with something else, as the "disk" where the throttle cable is attached has signs that it was soldered. Ill take a picture of it tomorrow.

It ran, i could get to 100km/h and made 20km per liter of fuel, but what really annoyed me was that with this carb, the bike has not idle speed, the engine ran pretty fastwith the idle adjuster all the way out. It was so high that i could easily move from parked position by just releasing the clutch.

Title: Re: Checking BS 40 carb for the first time
Post by ohiomoto on 05/14/20 at 19:10:38

Looks like it was in the ocean!

Title: Re: Checking BS 40 carb for the first time
Post by batman on 05/18/20 at 21:47:30

Dragbikemike , you should buy that carb , then you wouldn't have to complain about the CV carb not having a center drain plug in the bowl to make it easy to change main jets, (my 95 has that feature as well) :)

Title: Re: Checking BS 40 carb for the first time
Post by DragBikeMike on 05/19/20 at 12:45:53

Nice to know that the earlier models have a drain plug. I didn't notice it. Cool.

Can you actually change a main jet through that little hole?

Title: Re: Checking BS 40 carb for the first time
Post by LANCER on 05/19/20 at 16:04:02

54525D21232420100 wrote:

Nice to know that the earlier models have a drain plug. I didn't notice it. Cool.

Can you actually change a main jet through that little hole?

Nope, the drain screw lies horizontally on the bottom of the bowl and on the end of it.

Title: Re: Checking BS 40 carb for the first time
Post by batman on 05/19/20 at 18:03:23

1995-#29-plug ,drain 13247-44080
1996 #28- screw, drain 13247-02340
To be honest I've only used the plug to drain the carb for winter, and don't know if the main jet will pass through it. I don't know why it couldn't be made larger.