280 Offshores service experience?

[DSIDan]

I have been told alot of things about my motors, Im worried about rebuild intervals, sportmaster service intervals, and mix/fuel grade. Im looking for actual data: Please respond to this post with your personal experiences. Thanks, Im trying to keep them alive awhile. :cool:

[MONEYFURNOTHIN]

If you havnt all ready get vent kits intalled on your sportmasters. I would do this asap, these lowers are famous for heating up and blowing seals which will lead to water in the lower and then KA BOOM 3500.00 please (each). I have an annual service done on my 300x at the begining of season. Probly not necsasary but makes me a little more comfortible when i take off down river. Boatmaster on here is a pro, im sure he'll be here soon to anwser your questions. Good luck

[stoker2001]

Dan,stick with Mercs recommended Oil/fuel ratio of 32to1.I like the 100% synthetic oils like Alyson pro,Klotz or Pennzoil.If merky has 100% syn,i am sure it would be ok too.I know it is a pain,but if you want to run them hard i would run 10 to 20 percent 100low lead AV gas or race gas as this is cheap insurance.Have your fuel injectors Dynamicaly tested/flowed every 100 hours,I reccomend Kinsler in Ohio as they are the best in biz.These Bosch injectors even brand new have been found to have more then 8% flow varience.I reccomend removing the injector inlet filter screens,if Merky hasnt done so already.Change out your fuel filters as per mercs intervals if not sooner.In my opinion,you should get at least 200-300 hours between rebuilds depending on how hard they are run

[gearcase]

stoker2001 have you seen an octane booster called tk-7? or tried it. im thinking i might try it. im running av gas now.

[JMC]

I have seen early 2.5 260's and the carb version (245) with over 500 hours on them and still pull mid 120's on compression with stock heads. The newer 280's usually can live 300 hrs even though 250 is the norm. I would go with Klotz on the oil even though there are several very good oils out there. Too many drag engines turning over 10k all season long to consider anything else. I know of a couple of guys running the Alisyn oil and they seem to like it. I have never had a problem with the Lower units even going back to the early 90's with the CLE cases. Like Moneyfornothing said, the seals can head south on you. I have seen one CLE case run all weekend with no oil but filled with water. After I saw that it was clear to me how tough these LU's are but we were running 500 - 600 lb. hulls. Stoker also brings up a good point. The injectors are VERY sloppy right out the door....some worse than others.

[stoker2001]

stoker2001 have you seen an octane booster called tk-7? or tried it. im thinking i might try it. im running av gas now.Never heard of tk-7,i have seen octane boosters (VP race gas brand)chemically melt the inlit screens of fuel injectors so iam a little weary.I have ran AV gas for years with good results,how much cranking compression are you running?