2002 Yamaha 150 ox66 2 stroke. Ran good at slow RPM. When I give it a lot of gas it would just bog down. I changed plugs and replaced the gas filter even though it looked good and there was no water in the filter. I added seafoam to the gas and then it would run good at a little higher rpm and when I would give it more gas 3/4 throttle, it runs great for about 10 seconds than bogs down to a lower rpm and if I leave it at the same throttle after 5 sec it will bog down to a even lower rpm. However, if before the initial 10 sec is up I pump the throttle it will stay at the higher rpm and I can keep doing this and it runs great at the 3/4 throttle. I mixed 2 to 1 (pints) gas to seafoam and ran it until that was used up and let it sit over night. Than mixed the same and ran it through it the next day. Tried it again, Nothing changed.
Join Date: Oct 2017
Posts: 2
Trader Rating: 0
I checked the 02 sensor and it was very dirty. The Yamaha mechanic said it was the worst he had seen so I replaced. It with a new one. It did not help a thing. Thought that would have been the problem. I can go along at 20k rpm with no problems. When I go over 20k it bogs down unless I pump the throttle. I can keep it going at 40 - 48k rpm if I give the throttle a pump within 5 seconds. If I keep pumping it it runs great. If I do not pump it within the 5 sec. it bogs down and will bog down another two times if I do nothing. If I then put it in neutral I can again take it up to the 40 to 45k rpm and keep it there if I go it the quick pump. Any other suggestions. Thanks
Join Date: Oct 2017
Posts: 2
Trader Rating: 0
I checked the 02 sensor and it was very dirty. The Yamaha mechanic said it was the worst he had seen so I replaced. It with a new one. It did not help a thing. Thought that would have been the problem. I can go along at 20k rpm with no problems. When I go over 20k it bogs down unless I pump the throttle. I can keep it going at 40 - 48k rpm if I give the throttle a pump within 5 seconds. If I keep pumping it it runs great. If I do not pump it within the 5 sec. it bogs down and will bog down another two times if I do nothing. If I then put it in neutral I can again take it up to the 40 to 45k rpm and keep it there if I go it the quick pump. Any other suggestions. Thanks
