Recently my LT1200 (1999, has been running for 7000 miles), got a problem on the handle bar.
When i ride it at the speed of 65km/h (or 43 miles/h) and i put my hands off from the handle bar (only for testing that the bike will run straightly), then the handle bar will get wiggled/ trembling. For the first (maybe) 2 seconds it just tremble lightly, then will get heavily and i got to hold the handle bar back to avoid the bike become uncontrolable. This problem will not happen for the speed above and below 43miles/h.
My bike got a new tyre in front, Bridgestone BT 014 and has been got balanced with the balancing machine, and i am still using the old tire of BT 020 (year 2006), i also have just replaced the seal and the cup of the telescopic fork (only on one side, as the other side is still OK) as there was the leakage, and change the oil of the fork.
The Ball Joint of the fork (31427681040) has been checked too, and it looks fine.
Then i see no reason, why this problem could happen.
Is it possible from the using of the front tyre BT 014, that mostly used in the sports bike?
Or did i still miss to check any other items?
Another problem i have on the engine.
I usually set the idle rev at 1000 rpm. When i just start the engine, then i throttle up (until maybe 3000-4000 rpm) the gas handle on the right handle bar and release it, the engine's rev will never drop below 1000 when it back to the idle position, but when the engine has been running for several minutes and the engine got warmer (simulating that the bike has been probably running), then the response of the engine will quite slow when return to the idle position (after throttling up on the gas handle again).
The rev will drop to 500-600 rev, when i release the gas throttle, and the engine's sound will be heard so rough, before coming to the normal sound at the idle of 1000 rpm.
I feel that the engine will have slow response when it get hot, and can recognised this by seeing the needle of the RPM meter, that will drop to below the idle position (1000rpm).
In the running bike condition, this will cause the engine off after accelerating and release the gas throttle, without bringing up the gas again while pulling the clutch lever.
I have replaced all the sparkplugs, cleaning the fuel system (gasoline tank and the pump) ,change the fuel filter, cleaning the injector nossle, and check the ignition wire (still in good condition), but this problem still happen.
How to make the engine never drop below 1000 rpm after throttling up, when the engine is hot?
I know that we can do this by set the idle at 1500 rpm, so when it drops, it will drop to 1000rpm and the engine will never shut off, but it is not the right solution to solve this, as the idle of 1500 rpm will be too high for the engine.
Is there some thing wrong with the engine and what should i do?
I will appreciate all the response and help.
Thank you very much.