Quote:
Originally Posted by Skyliner70cc  I installed my boost bottle this morning and took it for a ride.
Here are my findings to date:
1. Engine is harder to start-there are no airleaks in the intake system. Everything is sealed properly.
2. Low to midrange throttle operation is POOR. Idle is erratic and engine stumbles when increasing from idle to higher rpms.
3. At high rpms, full throttle, the engine runs good (same as before). Top speed from same starting point at bottom of hill with speed checked at a point 1 mile past starting point is improved by 0.2 mph. I suspect the 0.2 mph improvement is mainly due to fact that it is 47 deg F outside and the cooler crisp denser air is the reason behind that 0.2mph increase.
4. Next steps:
a. fiddle with needle clip height and see if mixture changes at high speed help.
b. Measure volume of entire setup. |
Ok folks, I fiddled some more with it. I got some extra tubing and began trimming it down and checking response on engine. After about 15 1/4-1/2 inch cuts, I found a sweet spot that gave me the following results:
1. NO change in top speed.
2. My low and mid range acceleration is better than stock. It seemed to lean out the overly rich idle and mid-range. I was very surprised by how much acceleration improved over stock. Mind you I am at over 7,000 foot altitude with stock jets that are too rich at my altitude and thinner air.
3. I knew I was tuned to the appropriate total boost bottle volume with appropriate tube length when my idle speed increased significantly and my exhaust note got that buzzy sound of a tuned pipe-its weird I know but it did happen. I had to turn the idle screw a bunch to get the idle back down to normal.
4. NEW OVERALL IMPRESSION: While it did not improve top speed, it greatly improved my low to mid-range carburetor and engine performance. I highly recommend a boost bottle if you are at high altitude with stock jetting. I no longer have low-mid range stumbling and uneven acceleration. I cannot recommend this for someone at sea level as of yet. I am moving in 1 month to sea level and will let you know if it makes a difference at seal level with or without boost bottle. I would have liked more top speed which is the reason I bought it but I'm happy with the results I've gotten.