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Showing results for tags 'loss of power'.
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Greeting to all here, I'm a newbie to the Venture scene but I have ridden for about 40 years and I'm a life-long Yamaha fan (FJ1200, 550 Vision, FJR1300, FJ09, among others) and I do most of my own work. I have been working on this new project bike I just picked up, a pretty clean 83 Venture with a VMax (!) motor of unknown vintage, transplanted by the father of the previous owner, that doesn't seem to want to make power at large throttle openings. I'm suspecting the carbs but I haven't gotten into them yet. The bike came to me without an airbox cover so I got off of Ebay and it anything, adding the cover made it worse. It runs OK at part throttle but when you open it up over 4000 RPM and expect that VMAX thing to start happening it just doesn't, and it starts to misfire like it's lean. It wont pull hard or really at all at large throttle openings. I think the carbs are from the Venture but I cannot be sure. I don't know if the bike was rejetted after the transplant, and I'm not sure if the engine has Vmax or Venture cams in it. I did get a big box of valve shims and lifter tools with the bike. Also I just refilled the tank for the first time and I got 100 miles out of 4 gallons of gas. Not great but I'm unsure if this points to something or not. So if I gather from all the searching I have done in the forum, spanning a couple decades, that the CV diaphragms tend to go bad and that fits the lean misfire thing if they are leaking and aren't letting the needle rise out of the jet making it lean. My forum search is not yet complete but if anyone has the link to where the latest/best source for the best carb kits and diaphragms I would be grateful. I will be pulling the airbox tomorrow to try to assess the state of the slides and diaphragms before tearing the carbs off. I'm also open to this being an ignition problem but it sure does feel like carburation. If there is something I've missed that happens to these bikes that causes this problem I could sure use that news too. After I get this resolved it will be time to do something about those linked brakes. Wow what a bad idea, at least as it is now on this bike. I already have all the parts (forks, R1 brakes, etc) for that except the lines. But I have to make this thing GO better before I worry about making it STOP.