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.
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.
Edited April 8, 2016 by Knight
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.
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?
squirrelman
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. :cheerleader:
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.
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?
squirrelman
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. :cheerleader:
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
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.
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.