I have seen a couple other threads related to this problem..seems to come up from time to time on the Yamaha trikes.
Done recall the suggestions to fix..try a search in the Trikesylvania section!
As a new member you can't post there yet, but you can access and read.
Current toys..
1986 Honda 350X..trail bomb!
1985 Honda 250SX..my main mudder
1985 Honda 250ES..Back in Black Trike
Current non-trike toys:
1990 Honda TRX300FW
1995 Seadoo GTX
1998 Polaris Indy Lite 340(Nearly new looking)
1998 Polaris Touring 500
1998 Club Car (electric)