Member Contributer thor294 Posted April 8, 2016 Member Contributer Share Posted April 8, 2016 How can I tell if the jets in my bike are too big? I purchased this bike and it was already modded, but I was wondering if the jets on it are way too big. It pops a lot on decel, and the MPG is horrid (30-32ish?). It does have smaller sprocket on front and possibly bigger on back too so that doesn't help. Not sure if all bikes pop on decel because we have no emissions stuff (like no kitty kats like cars do), or if I am running too big of jets. Here's the dyno video for refence.. and the dyno sheet Thanks all! I just want to make sure my VFR is running as good as it should :) Link to comment Share on other sites More sharing options...
Knight Posted April 8, 2016 Share Posted April 8, 2016 With the context that i cannot read the dyno due to my firewall... Any engine, particularly tuned for high performance, may pop. Barring problems (such as listed below) the pop can be ignored. You should think about how the bike is performing throughout the RPM range. You can also examine the spark plugs to help answer that. * (Only if it does not show it on the dyno) You should post your setup here, aka the exhaust and the various jet sizes. Others with a similar setup may be able to provide their comparable setup. Double check, does the dyno record reflect the jets that are currently on the bike? * A lean condition can cause excessive pop. Other pop may be normal. * Check all vacuum ports and hoses for leaks or loose fit. * How are the exhaust seals particularly at the header? If this bike is pre-PAIR valve then a leak here can introduce fresh air, and act the same, igniting excess fuel. Regarding mileage: What percentage stop and go vs freeway do you ride? To cancel out the effect of the gearing change, take a freeway trip, keep it at what you may think is an efficient speed based on the rpm, be easy on the throttle the entire time. Fill it up then check the mileage. That really is your hardware sanity check, as you have an extreme gear change and that is going to kill the mileage under city riding. A problem with the cooling system, particularly the thermostat, brakes that are binding, and underinflated tires can bring your mileage down. Ideally this all checks out and you are experiencing mileage that matches your habits and the hardware setup, and the pop is normal. Link to comment Share on other sites More sharing options...
VFRBert Posted April 8, 2016 Share Posted April 8, 2016 Is the horsepower output as measured on the rear wheel, or is it corrected to crank horsepower. It should be more for a fine tuned rc24 Link to comment Share on other sites More sharing options...
squirrelman Posted April 8, 2016 Share Posted April 8, 2016 With some intuition and careful tuning it might be possible to minimize the dip in the curve in the first 1/3 section. There's a loud clattering sound that might be loose valves, and if that guy is pushing the engine hard like that, there should be a bigass fan in front to cool the radiator. Might be good to know what jets are in your carbs now, but that would require alot of work and agro. Your power numbers seem excellent. Link to comment Share on other sites More sharing options...
Member Contributer thor294 Posted April 12, 2016 Author Member Contributer Share Posted April 12, 2016 Is the horsepower output as measured on the rear wheel, or is it corrected to crank horsepower. It should be more for a fine tuned rc24 I'm guessing RWHP? With some intuition and careful tuning it might be possible to minimize the dip in the curve in the first 1/3 section. There's a loud clattering sound that might be loose valves, and if that guy is pushing the engine hard like that, there should be a bigass fan in front to cool the radiator. Might be good to know what jets are in your carbs now, but that would require alot of work and agro. Your power numbers seem excellent. The bike has always had that valve noise... I just thought it was a honduh thing LOL. previous owner said its done it forever. I might actually investigate it this season, though. I know its jetted but not sure what jets, and the exhaust is a full hindle stealth 4into1. Might fix valve noise and do plugs and redyno it. Link to comment Share on other sites More sharing options...
VFRBert Posted April 12, 2016 Share Posted April 12, 2016 I think it is missing some power, but i am used to european bikes'. http://www.vfroc.nl/forumVFR/index.php?showtopic=15842 Showing the graph from a 89 rc24 Is the horsepower output as measured on the rear wheel, or is it corrected to crank horsepower. It should be more for a fine tuned rc24 I'm guessing RWHP?With some intuition and careful tuning it might be possible to minimize the dip in the curve in the first 1/3 section. There's a loud clattering sound that might be loose valves, and if that guy is pushing the engine hard like that, there should be a bigass fan in front to cool the radiator.Might be good to know what jets are in your carbs now, but that would require alot of work and agro.Your power numbers seem excellent. The bike has always had that valve noise... I just thought it was a honduh thing LOL. previous owner said its done it forever. I might actually investigate it this season, though. I know its jetted but not sure what jets, and the exhaust is a full hindle stealth 4into1. Might fix valve noise and do plugs and redyno it. Noisy valves means to much clearance. mening less valve lift, mening les air/fuel mixture, mening less bang in the engine Link to comment Share on other sites More sharing options...
Member Contributer thor294 Posted April 12, 2016 Author Member Contributer Share Posted April 12, 2016 Noisy valves means to much clearance. mening less valve lift, mening les air/fuel mixture, mening less bang in the engineMakes sense 100%. Valve inspection time! OEM plugs... Any other parts I should have handy? Also what about brake parts? Where do you guys shop Link to comment Share on other sites More sharing options...
VFRBert Posted April 13, 2016 Share Posted April 13, 2016 I watched the video, the clattering sound is the chain, having to much slack, you see it dancing at decelleration. Revving up, i hear a misfire now and then. And some noise when the rev limmitter kicks in. Most VFR's imported from the US i inspected had their valve's to tight. Wich of course costs some hp and made the bike's start difficult. 2 VFR's had al 16 valve's to tight. Difficult to start. After adjusting valve clearance, they started stone cold with one push on the button. A new air cleaner might help and carb synching also. If maintenance was a while ago, replace fork fluid, brake fluid and coolant. And of course engine oil. Link to comment Share on other sites More sharing options...
Member Contributer thor294 Posted April 14, 2016 Author Member Contributer Share Posted April 14, 2016 Alright so im chasing chain noise? not valve noise? I'll inspect all but just want to make sure :P Link to comment Share on other sites More sharing options...
VFRBert Posted April 14, 2016 Share Posted April 14, 2016 As far as i am able to see on the video it's chain noise. Valves make a different kind of noise. Link to comment Share on other sites More sharing options...
Member Contributer thor294 Posted April 17, 2016 Author Member Contributer Share Posted April 17, 2016 I'm gear driven though... I thought I didn't have a chain? Link to comment Share on other sites More sharing options...
Knight Posted April 17, 2016 Share Posted April 17, 2016 Since he saw it in the video then he must be referring to the drive chain. Link to comment Share on other sites More sharing options...
Member Contributer thor294 Posted April 17, 2016 Author Member Contributer Share Posted April 17, 2016 The noise is from the engine not from the chain for sure. I noticed he said dancing on decel. Lol derp on my end. I've adjusted it before and the noise doesn't change. All that noise is from the engine. Link to comment Share on other sites More sharing options...
VFRBert Posted April 17, 2016 Share Posted April 17, 2016 Well you have a very loud exhaust and maybe the snorkel removed from the airbox. This might give some resonance, but a worn front sprocket might also give noise at deceleration. Valves give a tapping sound. Link to comment Share on other sites More sharing options...
Member Contributer thor294 Posted April 17, 2016 Author Member Contributer Share Posted April 17, 2016 I'll have to record it with the bike idling. Maybe its just a valve noise. Link to comment Share on other sites More sharing options...
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