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RPM's don't drop

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RPM's don't drop

PostAuthor: SBG71 » Mon Jun 15, 2020 3:33 pm

82 750, having an issue when shifting, the rpm's don't drop. Also when coming to a stop, I pull the clutch lever in and the rpms stay up and then to idle in about 3-4 seconds. Pretty certain I do not have any kind of leak. I was thinking if the needle is sticking can it cause this issue. Maybe inside float issue but I did remove the carbs and made sure everything is clean. Run's fine on street and freeway and seems to idle fine with some slight pop at exhaust. Any input is appreciated.

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Re: RPM's don't drop

PostAuthor: Jake » Mon Jun 15, 2020 4:04 pm

SBG71 wrote: Pretty certain I do not have any kind of leak.


That’s the 1st thing everyone says. A vacuum leak is the first suspect. 2nd suspect would be a dry throttle cable needing lubed.
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Re: RPM's don't drop

PostAuthor: SBG71 » Mon Jun 15, 2020 4:15 pm

Cable snaps back firmly when I test it so don't think it's that. I have new gas lines, new boots, gaskets from carbs to jugs are ok and I replaced exhaust gaskets about 3 months ago. What if anything to do with carbs would cause this issue if not leak or cable?

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Re: RPM's don't drop

PostAuthor: faffi » Mon Jun 15, 2020 5:09 pm

Carbs out of sync and an overly lean mixture can in my experience cause these issues.
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Re: RPM's don't drop

PostAuthor: Flyingdog » Tue Jun 16, 2020 3:59 am

:yup:

Assuming you're "absolutely" sure there is "no" vacuum leak (don't take much as Jake mentioned..even a tiny hose crack around a manifold nipple can wreak havoc), best way to understand what's going on: ever been round a chainsaw or lawnmower when it runs outta gas? RPMs always go up. Same principle on yer bike. Pilot still iffy, raise the needle with a thin washer (meaning: need to rich'n that fine area between pilot / needle setting), check the pilots' 0ring condition, sync'n carbs are a few items to look at.
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Re: RPM's don't drop

PostAuthor: faffi » Tue Jun 16, 2020 4:39 am

Actual float level should also be set by the use of clear fuel hoses attached to the floats - low fuel level can cause lean running also.
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Re: RPM's don't drop

PostAuthor: Flyingdog » Tue Jun 16, 2020 11:54 am

faffi wrote:clear fuel hoses attached to the floats


I'm sure you meant: attached to float bowl. SBG would probly figure it out, but someone might be trying to figure out: "How the Hell you do That"! :bg:
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Re: RPM's don't drop

PostAuthor: SBG71 » Mon Jun 29, 2020 3:18 pm

Friggin air leak!!! As one mentioned, one nipple to vacuum line had come loose down by boot, didn't think that small of a leak would cause that problem. All good now.

Thanks.

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Re: RPM's don't drop

PostAuthor: Jake » Mon Jun 29, 2020 4:08 pm

Told ya so !
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Re: RPM's don't drop

PostAuthor: SBG71 » Mon Jun 29, 2020 4:44 pm

Jake wrote:Told ya so !


Yes you did. Made me take a second look, worked out.

Thanks,

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