I am one of several owners on this site of 90's yamaha 600 twin motors that are/were getting poor mileage. It was frustrating to me because when new the sled got 12 mpg. Tried a lot of fixes over the years but none had any affect on mpg. Finally heard of something new(to me) and it sounded like what I needed. It was the main nozzles mentioned by 74Nitro. I'm back to 11 mpg and a happy camper. They are scarce so hurry if you'll need them. Thanks to 74Nitro- now the needle on the fuel gauge doesn't move as fast as the one on the speedo.
JohnnyG383
Member
SR540 do you have any pictures of the main nozzles? where do they go on the carb?
JohnnyG383: If you saw my previous reply, please disregard. Go down about 6 threads from mine to: "1997 v-max 500 mid range rough, using lots of gas". Go to page 4, then down 4/5 threads. You will see 2 from 74Nitro. They should contain answers to your questions. Good luck.
ironman_gq
New member
Where did you happen to find nozzles?
For owners of these sleds with the 5/600 twin engines, it is also important to inspect the oil pump drive shaft every few thousand kms. It is the flat 'male' bar attached to the pump that inserts into the female slot in the end of the pulley shaft. Make sure it is not worn too much and put grease on it, or some choose to clean everything up and put some RTV silicone on it and let it dry.
NorthofSixty
Member
What happens if the oil pump drive shaft is not lubricated?
Dirtyredvmax
New member
I think I am having the same problem with my 600 twin. Where did you happen to find the nozzles? I haven't been able to find any, looks like they are discontinued.
I've seen the male portion wear right off and then the oil pump doesn't drive anymore resulting in an expensive engine failure.
NorthofSixty
Member
I have the opposite problem. The thing drinks two stroke oil. Different pump failure I guess
I happen to call a yamaha dealer in Baxter.mn who had no nozzles, but had a list of dealers who did have them. He steered me to a dealer in South Dakota and one in Toronto.