1990 Vfr 750 , Hard Start And No Power.

HELP PLEASE! I HAVE A 1990 VFR750 AND WHEN COLD I CAN ONLY GET IT STARTED WITH STARTING FLUID. I INSTALLED A NEW CHOKE CABLE AND ADJUSTED IT AND ALSO PUT NEW PLUGS AND AIR FILTER IN HER, BUT THE SAME PROBLEM. I HAD A FRIEND REMOVE THE CARBS AND CLEAN , BUT THE SAME PROBLEM REMAINED. IM LOST, I HAVE CLEANED THE TANK AND FILTER AND I EVEN RUN HIGH TEST GAS ALL THE TIME. IT IS ALSO VERY WEEK OUT OF THE HOLE AND DOESNT START TO PULL TILL AROUND 7500 TO 8500 RPM. I TRIED USEING CARB CLEANER AROUND THE ENGINE WHILE RUNNING TO SEE IF I HAD A LEAK AROUND THE CARB BOOTS ALSO. AND WE DID A COMPRESSION TEST AND EVERYTHING CHECKED OUT WITH THE HONDA SERVICE MANUAL. PLEASE HELP , I DONT KNOW WHAT TO TRY NEXT.

 

fuel pump?

 

carbs out of sync? Valves need adjusting?

 

Exhaust clogged maybe?

 

Well Im Not Sure About The Carbs Being Out It Runs Smooth , But It Free Revs Slow, Is There Any Way To Test The Vacuum Pumps, And If I Dont Use Starting Fluid In The Mornings It Will Just Crank And Flood Out. It Does Not Backfire When Running And I Dont Hear Any Valve Noise. Could A Fuel Pump Cause The Revving Slow Problems??

 

just before i bought my bike the owner was having similar problems, tried a few things before replacing the pump, with no success, it was the pump.

 

Whew, hard telling with out me being there, I'd be looking for a vacuum leak of sorts way many little hose and plugs that can crack fall off etc. Then head to the fuel system. Just my 2cents. Mine did some familiar, thing was it was working just fine one minute, lousy the next. she was due for a 32k service anyway so in she went. Guess what they found wrong? a rubber plug that lets them hook up their gear was missing, causing a huge vacuum leak.

 

I agree with Whitestar. I had an '86 VFR750 that had a similar problem.
It was a clogged fuel filter. Not a bad idea to carry a spare :biggrin:

 

i've got a similar problem with my 1990 viffer...here's the deal.... with new battery, fuel filter, and OEM Honda regulator rectifier installed October 2006, after approximately 140 mile ride (approx 2 hours) engine begins to die, and stops running at freeway speed (75 – 80mph). After disconnecting headlight, engine restarts, for approximate 10 mile trip home (headlight remains disconnected for 10 mile trip home)...took her to dealer for some routine maintenance, and to have the charging system checked...dealer says charging system fine, however, i do have an exhaust leak in one of my cylinders...cost is about 4 bills to get in, and replace bad gasket, so, its gotta wait until next month to resolve...could the exhaust leak be the problem?

 

fuelfilter?

 

engine cuts out after about 125mi...

...then needs to have choke fully enaged to restart, and get the last few miles home...

...changed fuel filter already...has to be either: 1) carbs need cleaning, 2) exhaust leak in one cylinder, 3) vacuum leak somewhere...

...is there anything else i haven't looked into?

 

If the bike is flooding out, the needle valves and seats for the floats might either be sticking or not closing fully.

If these are not working, the fuel never really stops flowing, even when it doesn't need to be flowing.

This would explain why you have lots of top end power (when fuel is needed the most), but it has no low end power because the engine is getting too mch fuel, or fuel that is not atomized completely.

Did your friend that cleaned the carbs replace anything or just take them apart, clean what he could see, and then re-assemble? I bet anything that one or more of your float needles are sticking open or not seating fully (allowing the fuel to flow).

I'm afraid the carbs are going to have to come off the bike again...:unsure:

 

carb cleaning...

...thanks for the info...when it was at the dealer last year, they only recommended that they be cleaned...consequently, thats my next potential solution...

...i have a funny feeling you're right since everything else has checked out OK...