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Bike has lumpy acceleration pulling away


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Hi,

I've recently seen the light and have bought a 92 vfr 750f

It has a couple of niggles I'd like to resolve and I'm sure the knowledge on this forum will be able to help. 

 

Ok so when cold bike runs fine, smells a little rich coming from an injected Ducati 

However once warm it struggles to pull away from a stand still and requires a lot of revs plus sometime when warm it struggles to accelerate past 4k - I experimented by adding choke and it began to run well again.

 

The bike is stock apart from a full FUEL exhaust system and an R1 reg-rec . Additionally, I get the odd backfire pop through the air box. 

 

Please help as I really want to put some miles on this bike.

 

Thanks in advance. 

 

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Sound like carb problems. Quick fix try some seafoam and see if it gets better. Any history on the bike ie sitting for a long time, Old gas, This is a 27 year old bike.  I just rebuilt my carbs last  week. What a difference. And my bike ran well before. VFR's do not  like extras choke..If you can not sort it soon do not keep riding it or you may do damage.

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inspect air filter, and inspect sparkplugs to see if colors look good and are all the same. consider replacing plugs with new. could be partly-clogged idle jets or something else in carbs.

 

good luck.

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Get a picture up!

 

Your fault almost certainly lies in the fuel system.

 

You can try adding fuel treatments like Seafoam or Wynn’s , but In my experience it’ll do very little good. 

 

Your tank probably needs emptied and flushed out. The carbs need stripped and cleaned, and a new fuel filter added. While the tank is off it’s probably best to check / fit new plugs and air filter. Get the carbs balanced too. 

 

Ive got a 93 FP that exhibited similar problems to yours. I’m no expert but found stripping the carbs fairly straightforward and transformed the running of the bike

 

 

0225996E-9755-4AFA-8888-936AD83158DC.jpeg

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Hi all and thanks for all the advice. Sounds like I'll have to bite the bullet and give the carbs a strip down and clean, once that's done I'll change the consumables .

I'll keep you posted of my progress. 

Thanks again. 

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Update. Hi all.

Ok, so I flushed the tank and removed the pet-cock to inspect the filter-all ok. Next was remove

 The carbs...however..when I went to loosen the straps/bands around the carbs where they meet the motor, the straps/bands on the two carbs nearest the radiator were loose-really loose. So I tightened it all back up (also noticed the sub air filter was knackered so have replaced) and took it for a ride.

 

And you can imagine my happiness when it ran almost perfect.

Still a light hesitation on pulling away but no backfires or loss of power anywhere else. So I'll balance the carbs,new plugs and air filter and hopefully...

 

Thanks all for your support and knowledge. 

 

20190512_115207.jpg

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Additionally I changed the air filter and spark plugs. I opted for the Champion 9698's instead of the NGK's and the bike runs perfectly. 

 

Thanks to everyone for their constructive support .

 

My next project is an alternative to the stone age suspension and replacement to the rusty radiator.

Thanks  again for your advice and suggestions. 

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