Hey all. So I finally got my bike completed. 2-stroke grubee 66cc slant head. I ran 4 tanks of 24:1 and am now runing 100:1 Opti-2. I have the billeted intake, high performance air filter and SBP expansion chamber on it. The bike runs great except when I hit about 35 the bike starts hesitating, slows down then catches up. It feels like it has plenty of power left. I have not re-adjusted the c-clip since installing the expansion chamber, it is in the 2nd notch from the top (opposite end of the pointed part). Any ideas as to what would be causing this?
Bike bogging out at about 35 mph
- Thread starter jKellym
- Start date
It sounds like it's leaning out. Try moving the clip down 2 notches run the bike hard and check the plug. Take the plug wrench with you, run it hard, hit the kill switch pull the clutch in and coast to a stop. Pull the plug right there and check for color. Many years ago when I raced we had a problem with the gas foaming in the float bowl. This was do to the vibration in the motor. These motors vibrate a **** of a lot more than the motor I was racing. Our fix was a remote float chamber. seperated from the carb and mounted to the frame in a foam rubber jacket. You could also try a float adjustment. I don't know if this helps you or confuses you even more. Good luck
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Check you spark plug for color. Dark, sooty or oily = too rich. Raise the 'C' clip. If the plug is white or very light tan it might be lean. Lower the clip.
Just a word here about Opti-2 and plug color. I've been running Opti for a long time now at 100:1 and my plugs are gray and dry. I've mentioned this before and a couple of other Opti-2 users have said their plugs are brown. I'm not sure why I have gray plugs but all of my 2 strokes run good in spite of the weird plug colors. Two of them are very high milage engines.
Tom
Just a word here about Opti-2 and plug color. I've been running Opti for a long time now at 100:1 and my plugs are gray and dry. I've mentioned this before and a couple of other Opti-2 users have said their plugs are brown. I'm not sure why I have gray plugs but all of my 2 strokes run good in spite of the weird plug colors. Two of them are very high milage engines.
Tom
@ Bob and 2Door, thanks I will check the spark plug color after work.
@ CCC, 35 is actually plenty fast, I usually keep my cruise speed around 33 mph as this just "feels" like the sweet spot. However, when I need to make a light or pass someone, I want to have available to me all the speed I can get.
Cheers
Kelly
@ CCC, 35 is actually plenty fast, I usually keep my cruise speed around 33 mph as this just "feels" like the sweet spot. However, when I need to make a light or pass someone, I want to have available to me all the speed I can get.
Cheers
Kelly
I saw in a thread titled "Stock Carb Mods" suggestions about float height and I followed it. I've been tuning the heck out of my NT and had the symptom you describe(25MPH my top). It would studder just a little. That thread says with the carb upside down, the float should sit about even with the jet. All my adjustments on the float were teeny tiny, but I found the spot. At one point the float sat too low from the jet and this was when it studdered the most. I moved the float higher and it went away. When I say higher, I mean so that rightside up it will float higher in the bowl.
Are you full wide open throttle at that point? It looks like you're running a 44 sprocket- a 36 is surprisingly faster but you'll losea bit of low speed torque- the bike looks a bit heavy- how heavy are you? There's also 41's out there too.
when I went to 36, it really helped- I almost never open the throttle now.
Narrower tires with a smoother tread are much faster too, lighter weight, and stop vibration of beach tires.
Otherwise, I might also guess you might be lean on oil. Better to start with too much and work down- it takes a lot to foul the plug, and you're risking blowing the motor otherwise.
when I went to 36, it really helped- I almost never open the throttle now.
Narrower tires with a smoother tread are much faster too, lighter weight, and stop vibration of beach tires.
Otherwise, I might also guess you might be lean on oil. Better to start with too much and work down- it takes a lot to foul the plug, and you're risking blowing the motor otherwise.
I know this post is quite old, but for anyone googling this or something...
I had the same issue. My tank was not venting at all and fuel was not entering the carb fast enough. See if you can unscrew the cap while riding and if that fixes it, you know that's the problem. I drilled a small hole in the center of my cap, and added a hose to it so it won't collect water or debris.
I had the same issue. My tank was not venting at all and fuel was not entering the carb fast enough. See if you can unscrew the cap while riding and if that fixes it, you know that's the problem. I drilled a small hole in the center of my cap, and added a hose to it so it won't collect water or debris.
