Problems with wind

Hi! I'm new and recently got a VFR750F RC36.

I have a strange issue where the bike will run weak and almost come to a complete halt when it gets gusts of wind from the left. It especially occurs when trying to maintain a steady rpm. Somethings I found out when I got the bike is that the fuelhose had been changed to a smaller one for whatever reason. Got a hold of a new one, changed filter, got the carbs cleansed and it seemed to work better for a while but it's now back to square one. It runs extremely well on idle and on throttle up. But whenever i get gusts of winds from the left and I try to keep a steady rpm (5000 ex) it immidietaly starts hesitating and getting weaker.

Any thoughts appreciated. Oh and it's from 91.

Thanks

 

Stock air box?

 

Yup. Ive also tried running it without airfilter to see if it would make any difference.

 

Never heard of such a thing. Does this happen at all speeds?

 

It is very strange. Yeah, any and all speeds. Applied rearbrake while maintaing steady throttle to see if it had anything to do with the resistance, but no.

 

If it got worse with speed I would have guessed some weird vortice was happening making a vacuum. Hope someone has an Idea for you.

 

Hopefully. Its such an odd problem, never heard of anyone else having dealt with it either. Thanks for the input

 

Are you saying the problem does not occur with wind from the right?

Is the tank and gas clean? I am wondering if the cleaning was what temporarily fixed this issue, and the problem is partial throttle fuel flow.

If the force of the wind is directly impacting a part's geometry, you should be able to press your hand on the same item and detect a leak or problem. Vacuum hoses, or how about the exhaust on the left side? Does physical pressure reveal any cracks there?

Check the charge voltage at 5,000 RPM.

 

All I have is to make sure the vent tube for the float bowls is routed correctly and the wind is not causing an unwanted pressure change in the bowls.

 

It only occurs with winds from the left. Ive had my hands on every part and checked, also checked the charge and everything is fine there. Will however check the exhaust! Thanks for that one

 

Now this is an interesting ans I will check it as I had no idea about the vent tubes! Thanks very much I will keep everyone updated of course.

 

double post

 

huh, are all the carb boots seated and in good condition? none are cracked? Also, all honda carbs from this vintage onward are CV carbs. The tops of the carb (that round cap) need to be secured with a good seal. It's possible you have a diaphragm that isn't seating properly and the wind is forcing it's way between the cap and the carb body mucking things up in that little chamber in the top.

since you say it's wind pressure messing things up, why not borrow an air compressor with a nozzle tip and just start pointing it at random components while the bikes running.

 

The same problem is COMMON on the Honda NT650 Hawk although very rare on VFRs. Toe has it correct: remove or reroute the float bowl vent tubes.

 

Will check the seals and also try the air compressor. Got one at work. Thanks for the nice suggestions

 

also make sure the screws in the intake runner taps where you hook up a manometer for syncing are there and tightened down. I do think a vent tube issue is more likely though.

 

This wasn't the thread I was expecting. On the VFRW home page the topic "Problems with Wind" was sitting right above "How many older guys ride a VFR". I naturally thought they were related somehow...

Ingmarcus I hope you can solve your problem. I think the carb vent tubes would be the most likely cause.

 

Could also be A Monk attack-also a carbon build up on butterflies. take off air filter and spray some cnc in the throttle bodies.:grey:

 

also,

welcome, to make your forum stay more informative and useful I would do the following:

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Under the "My Settings" Heading on the left, scroll down and click "Edit Ignore List"

In the text block where it says "add user to ignore list" type in "sunofwolf" and click okay

If it asks are you sure to add user?, click yes.

 

A theory but entirely unlikely. Air leakage around there wouldn't allow the bike to rev much over midrange.