I'm having an issue with my 95 VFR 750 being hard to start. Here's some history and symptoms. This bike sat for about 2 years without being started; before I got ahold of it. It was garage kept, so it's actually in surprisingly good condition. Aside from a few minor dings, it looks almost brand new. It's sad that the bike sat so long, because cosmetically it's been really well kept. This bike is all stock components, there haven't been any aftermarket modifications. I have spent some time working on it already and have it running really well now, once it warms up. However, I'm still having issues getting it to start when cold. I have replaced jets and some gaskets on the carbs, since they were pretty shot when I got the bike. In fact, I spent almost a month just getting the carbs and fuel systems working right again; this included getting the rusted tank professionally cleaned. At this point I know I'm not having fuel issues, after testing and retesting the fuel systems. I'm also getting good spark from brand new plugs, good charging circuits, etc. I have tested both fuel and electrical multiple times now. I do have a service manual and have been using this as I go, to make sure I'm not missing anything obvious. Once the bike does start and has had time to warm up, it runs great and pulls strong. The symptoms I'm seeing seem to indicate that it's a choke/air issue; but I've also cleaned out all these passages, etc. several times now. When cold, the bike will turn over fine and catch; but then it doesn't idle up correctly, even when the choke is fully open. In fact, the choke doesn't seem to make the bike idle higher correctly even after things have warmed up. Usually I can start the bike by turning the idle up manually, so that it's just idling higher in general. I then turn the idle back down after it warms up; and the bike then runs great. If I play with the choke after the bike is running, at most it will idle up for just a few seconds when I first engage the choke; but then it will go back to normal idle after a few seconds, even though the choke is still fully engaged. Shouldn't the bike always idle higher with the choke fully engaged? My thinking right now is that something is either clogged in the choke, or a bad gasket is leaking air somewhere it shouldn't. Does anyone have any suggestions I could try before I go and replace all the choke valves and gaskets? I have inspected all of the choke mechanisms and gaskets, and there's nothing obviously broken or worn out. I have also make sure that none of the passages are obviously blocked. Has anyone else seen problems like this before? Any suggestions would be greatly appreciated. Thanks, Kelly Shutt
Your enrichener should nearly kill the bike when it's fully warmed up. If working perfectly, it should fast idle when it's cold started. All of the air/fuel circuitry for the enrichener is fixed in the carb body, except the plungers...and if they go up and down they're basically OK. There's no mechanical "fast idle" as in older vintage carbs. Cloggage in the carb body can be really stubborn to remove. The best luck I've had is complete disassembly and long term soaking in appropriate solvent, followed by compressed air and aerosol cleaner. Are you sure the fixed enrichener jets in the float bowl are open? How did you verify this?
I agree with what dizzy said. If opening the choke when fully warmed up doesn't kill the bike, then the choke passages are not clean. Did you soak the carbs in cleaner and blow the passages out with compressed air?
Ditto...the enrichener circuit is actually pretty complicated. There's the fuel supply inside the float bowl, the plungers themselves, an air inlet in the air cleaner side of the carb, an air bleed for the fuel supply underneath the slide diaphragm, an outlet in the throat of the carb by the butterfly valve. In addition...there's three small 'bypass' holes near the butterfly that 'borrow' air from the main jet air bleed...that's what actually allows for a non mechanical fast idle. All that air ciruitry usually isn't a problem, as no fuel is in there to varnish. But when they do get obstructed...it can be tricky, as all the angles make it difficult to determine if any cloggage exists. I've found the best way to do this (verify) is to get a good full can of carb cleaner with plenty of pressure...in turn spray each part of the ciruitry with carb cleaner...while plugging other parts with your fingers shoot a quick burst of compressed air into the ciruitry in question and watch that it comes out where it's supposed to. You can get an idea by comparing all four carbs for consisitency, as it's unlikely all four are clogged. Hope that makes sense and if you try it wear eye protection or you may get an eyeful of carb cleaner.
