Doesn't want to accelerate past ~6Krpm Need help please

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Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby squirrelman » Sun Jul 07, 2013 1:44 pm

IMO, NEVER spray starting fluid into a running engine !!!!!! :o :o

It strips normal lube off pistons, rings, and cylinders, causes extreme wear in seconds, and can cause piston siezure !!!! :oops:

Your carbs need attention (cleaning/adjusting), but first inspect the interior of the fuel tank for any signs of rust, cuz with shedding rust particles, you're carb problems will continue. :evil:
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Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby YoshiHNS » Sun Jul 07, 2013 8:51 pm

squirrelman wrote:IMO, NEVER spray starting fluid into a running engine !!!!!! :o :o


It wouldn't be starting fluid if the engine was already running. It would be running fluid. ;) or as we call it in the common world, petrol.

I agree with cleaning out the carbs after sitting for a year, especially if you did not drain the carb bowls. If the bowls were drained, you should be fine, as my 96 VFR fired right up and ran fine after sitting for a year with the fuel drained out of the carbs. Even after a few weeks of sitting you might have issues with the carbs.

You could also try putting some seafoam in the tank and seeing if that helps clear anything out. I wouldn't hold my breathe on that working, but it's a quick thing to try if you're going for a ride.
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Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby Bronco638 » Mon Jul 08, 2013 8:23 am

I had a similar issue. The main jets were clogged. The only way to really address the issue is to remove the carbs and have a look inside the float bowls. You're going to discover that the carbs on the VTR can be quite "particular" with respect to cleanliness and adjustments. If the bike is going to sit for an extended period of time, stabilize the fuel and/or drain the float bowls. Since you're going to remove the carbs, now is the time to replace those (likely) hardened carb-to-engine boots. They're still available from Honda (~$16 each, IIRC). You can also switch the 4 boot clamp fasteners from J.I.S. screws to Allen Head cap screws (stainless steel, if you want to be hard core :D ).
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Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby Kasper » Wed Jul 10, 2013 2:27 am

Thanks for the replies everyone. I will try to take a look at it tomorrow and let you know what I find out. Oh, also if I just keep accelerating past 6k it struggles and bogs for a little bit until it eventually pushes past and then accelerates normally from around 10k+
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Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby cawalther » Wed Jul 10, 2013 4:42 am

awesome info. glad to see it is just fuel related.
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Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby Bronco638 » Thu Jul 11, 2013 10:35 am

Still sounds like a fuel/carb issue as walth stated.
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Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby Kasper » Wed Jul 24, 2013 8:17 pm

I looked over my bike today. I inspected the slides, and they are not locked up. I sprayed carb cleaner in the carbs. It didn't really do much. On my test ride I noticed that if the clutch is pulled it will accelerate just fine, but if I am in gear there is this hesitation where the engine goes from sounding normal to kinda flattening out?? It will still accelerate but it is slower, and then the rpms will get to about 7.5 and it will start to act normal again.
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Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby Bronco638 » Thu Jul 25, 2013 7:25 am

I still think you have jet issues within the carb(s).

Also, be very careful with shooting carb cleaner in/around those carbs. If any of the cleaner comes in contact with the slide diaphragms, the diaphragms will dissolve (and you've just turned a carb cleaning into a gigantic carb rebuild project). I would remove the carbs, dis-assemble them and give them a good cleaning. Keep the slides and the slide diaphragms far away from the carb cleaner.
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Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby cawalther » Thu Jul 25, 2013 8:58 am

It is also good to be cautious messing with the slides, right? Since the needles are thin and sensitive and may get bent. Just a thought.

Did a search on google for (without quotes" "): venturi carburetor dead spot jet

This is a really good read!! >> http://www.dansmc.com/carbs2.htm

It also has some additional links / manuals at the bottom for Mikuni and Keihin.
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Re: Doesn't want to accelerate past ~6Krpm Need help please

Postby Bronco638 » Fri Jul 26, 2013 7:36 am

cawalther wrote:It is also good to be cautious messing with the slides, right? Since the needles are thin and sensitive and may get bent. Just a thought.

Yeah, I treat them with care when they're out of the carb bodies. That said, I don't think the needles will bend just removing them from the slides but it wouldn't take much to nick them. That will cause air flow/mixture issues that may or may not be felt. The quarter turn needle retainers can be a little finicky. Take care when removing/reinstalling those.
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