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xs650 > > Motorcycle Systems > > Fuel > > Won't rev or accelerate under full throttle.


Won't rev or accelerate under full throttle.
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Jamesl
New Member
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Joined: Apr 08, 2006
Posts: 2
Location: Texas

PostPosted: April 8, 2006, 6:45 pm    Post subject: Won't rev or accelerate under full throttle.

Hello All,
I have a 1983 Heritage Special with 15k miles. It's stock. I've owned it for 4 years and in that time have put less than 3k miles on it.

The entire time I've owned it, it has run fine, idled fine, everything except go under full throttle unless it's really under-revved when I crack it open. If I take off fast, say like needing 3/4 throttle or more, it just blubbers. If I'm going 50 in third and crack it open, it just blubbers and loses rpm. I even tried free-revving it and if the throttle's wide open, it just blubbers and pops.

I've cleaned the carbs, sync-ed them, tried them without filters, tightened everything,...no change. The tank is spotless, the filter on the petcock looks like new, and the plugs are fine...no rich or lean indications.

Other than that, it's been perfect. It starts fine, pulls fine until the point where one would expect it to go on the main jet, then it's all over.

Last year, I ordered 2 size larger jets from MikesXS and installed them...to no avail. There was no difference.

Don't know what to try next. Any suggestions would be much appreciated.
Thanks in advance,
Jamesl in Austin
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650rider
WebMaster
WebMaster


Joined: Feb 09, 2005
Posts: 431

PostPosted: April 10, 2006, 12:11 am    Post subject: Re: Won't rev or accelerate under full throttle.

Hold on someone will offer some good help I'm sure
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veetors
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Joined: Feb 10, 2006
Posts: 14

PostPosted: April 18, 2006, 9:52 am    Post subject: Re: Won't rev or accelerate under full throttle.

from what it sounds like, the bike is too lean, but you say that you put in some bigger jets, did you adjust the needle at all? have you adjusted the idle mixture screw?
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turk64
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Joined: Aug 09, 2005
Posts: 41
Location: Harrisburg PA

PostPosted: April 18, 2006, 1:41 pm    Post subject: Re: Won't rev or accelerate under full throttle.

I had the same problem with my 83. It changed when i replaced the spark plug caps. Check the resistance. Ya might want to double check your carb clean up for blockage. Good luck.
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veetors
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Joined: Feb 10, 2006
Posts: 14

PostPosted: April 18, 2006, 1:46 pm    Post subject: Re: Won't rev or accelerate under full throttle.

"Ya might want to double check your carb clean up for blockage."

I kinda thinking the same thing. the holes are fairly small.
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650rider
WebMaster
WebMaster


Joined: Feb 09, 2005
Posts: 431

PostPosted: April 18, 2006, 2:35 pm    Post subject: Re: Won't rev or accelerate under full throttle.

Thanks for responding to this members question, Thanks!
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Jamesl
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Joined: Apr 08, 2006
Posts: 2
Location: Texas

PostPosted: April 29, 2006, 10:33 am    Post subject: Re: Won't rev or accelerate under full throttle.

Thanks for the suggestions guys.
For the record: 1. Everything is clean inside the tank, filter, carbs 2. I don't think I can adjust the needles on these carbs.3. I'll try the spark plug caps, that couldn't hurt under any circumstances.4. I checked the tank vent and it's clear.
Thank all of you for the help. I'll keep you posted as to the outcome. I haven't been riding much lately, but will do more soon.
Jamesl
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oldschool
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Joined: Jun 07, 2006
Posts: 1
Location: Des Moines, IA

PostPosted: June 7, 2006, 12:31 am    Post subject: Re: Won't rev or accelerate under full throttle.

Hi,

New user as of today. I can't help but think that you should check the workings of your timing advance. It's really easy to check and fix if needed. These things tend to corrode fairly easily and will exhibit the kind of problems that you are having (experienced with the problem.)

Please note that I am a novice, but my XS650C, 1976, was fixed by cleaning and lubing the shaft and parts. Of course, if you have electronic ignition, please ignore my post.

Roy
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jimdi
650Rider Supporter
650Rider Supporter


Joined: Oct 27, 2005
Posts: 512

PostPosted: July 14, 2006, 8:26 am    Post subject: Re: Won't rev or accelerate under full throttle.

It sounds like you have a less severe problem similar to mine -

To me, it definately sounds like a mixture probem. To adjust the mixture screws you must carefully drill out the plugs - you sound a little lean to me - but keep in mind - that too rich also gives you the same symptoms.

use your spark plugs as a guide - to rich or lean - run your bike and inspect them - dark grey/ black too rich
White - too lean.

here are links to the "hidden plugs"
www.mikesxs.com/tech_tips.html
650rider.com/News/arti...id=19.html
There is a good one right here on this site under News -
Where are those hiddlen air jets (idle mixture screws)

Let me know what you discover.
jim
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