Hey all, How you doin? I just found this site, and for the past week, I've been using your search feature like crazy! lots of great info you guys have out there!

I've got a 2000 Scrambler 400 that I just bought this past tuesday, I bought it in a non-running condition [img]i/expressions/face-icon-small-smile.gif[/img] as a fixer upper from a co-worker. if you look at my sig, you can see the mods that it has.

the problem is that it is eating pistons, and my fear is that with these mods the oil injection system cannot keep up with the airflow and fuel coming into the engine causing problems with piston scoring and broken rings.

to test this, would it be ok to just plug the oil injection inlet and oulet lines so that no oil is injected and use premix? Just like it Ran out of oil? I understand I'll prolly need to jet rich, but I was planning on switching to Amsoil 100:1 so jetting would be negligble at most.

this is my first oil injection atv, so your help is appreciated

Thanks

Ken

 

actually I might have found a probable cause to my problem...

the main jet is a 310, shouldn stock be 230, and with my mods be using a 250 jet? possibly did the previous owner have this jet in to compensate for premix?

 

With a jet that big you shouldn't be burning up pistons. You may have a oil injector problem. The oil injectors don't have any problems with the mods you have. You can buy a block off kit from HPD for around 20 bucks or so then premix the Amsoil. You should probably be running a 260 main jet or so.

 

I would check for an air leak at the carb boot, base gasket, clutch side of the crank or at the magneto side. That jet is HUGE! It was probably put in to compensate for an air leak that made it lean.

 

thanks guys....I've read about checking for leaks on the magneto side and the clutch side by using baby powder? is this a viable means to determine a seal leak? does the engine need to be running to check those items?

 

oh, and I've seen the block off plates, it is just that the cylinder and piston should be here and done by tuesday, and I don't think I'll have enough time to wait to receive the block off plate for the oil injection.

Is it ok to still have it there, but with no oil in it? will it burn out?

 

Best way is with a leakdown tester-- It's more involved than a 4-stroke leakdown, (due to all the plugs you need to install in every opening) and, not many people will have one unless they wrench for a living. But baby powder will quickly show oil seeping past. Should work good.

Here's what I'd do: Spray both crank seals (one at a time) with carb cleaner, while idling. If there is any change in RPM, then there's the culprit. If nothing happens, spray the intake boot (one side at a time and one end at a time-- left, right, then carb side, cylinder side), then the base gasket, then head gasket (basically, anywhere air could possibly enter the engine--check everything) Carb cleaner will make the RPM's rise in the presence of an air leak. Quick & easy test.

Good luck!

 

Almost forgot........

I'm not sure how Polaris does their oil injection, so double check-- but, on jap machines, it's just the engine vacuum that feeds it. If you run without it (obviously, DON'T FORGET PREMIX!!) you'll have to seal those openings (for the little hoses) real good, or you'll create another air leak----which may be the one that ends the life of your motor!

I'd check and fix any air leaks first before condemning the oil injection.

 

thanks smitty

I'll do as you advise with the carb cleaner

but the block off kit is on the way so I'll just do away with it [img]i/expressions/face-icon-small-smile.gif[/img]

I also found out I have a 14 to 1 head and the guy that I bought the bike from was just using pump gas, no wonder it died. lol

you wouldn't happen to know the volume of a 14 to 1 head would you?

thanks!

Ken

 

I do know with a 14:1 compression you had better be running strait race fuel(110).......I have 12.5:1 and run 75% race 25% premium(93)