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900 oil delete/ pulling motor/ premix thread

oldschooldoo

New member
Nov 30, 2007
111
2
18
Oil delete for the 900

ALWAYS MARK POSITONS OF PARTS (rebuild takes half the time)
also if i was to do it agian i think i would drill 1/4" high up on the case...

I wasn’t 100% sure on doing the oil delete like they do on the newer lay down motors, I heard yes from some and no from others. So I went with the already used version where you drill a 45* hole into the top of your water pump gear cavity.

First off I chose to pull my motor (doing a big bore) I’m sure you could leave it in the sled if you feel comfortable enough. If pulling the motor, you will probably want to pull your hood off just to be safe, followed by your belt, and your exhaust pipe. The carburetors need to be pulled away from the reed boots (or just pull them out along with the air box), also the oil pump cable will have to be removed, the APV cables need to be taken off the solenoid, and all electrical plugs going to the engine need to be disconnected including spark plug wires, once again this is up to you, you can pull the primary or leave it on if you leave it on, take care not to leave the weight of the engine on it as it is lower then the engine base. Next its time to drain the coolant, as for me I have never found an easy way to do this I use a shopvac and pull the bottom engine hose. And lastly pull the four engine mount bolts and the motor will lift out Care should be taken and it should come out very smooth with no resistance, there is a grounding wire that is hard to see that’s right under the recoil starter.

Now that the engine is out and a bench its time to pull the top end off the motor you can do this two way first way if your doing a top end anyways pull the heads, APV valves and finally the cylinders (you can pull the y pipe if you want I always leave it I like to keep my cylinders and heads on the same side after I do a rebuild. If you don’t want to do a top end you and just pull the eight cylinder base bolts and you can pull the complete top end section off the motor with CARE!

This is what you will be looking at(attachment two), now see the holes going down theres four of them, those are there to provide your bottom end bearings with the proper amount of oil. We will be drilling by a center hole; it doesn’t mater what side you drill,

Alright now come the time you start getting the nervous feeling, you honestly don’t have to worry it doesn’t matter where you drill into the water pump gear cavity at, it could be on the side or top just as long as you hit it, get your drill bit out I used a 5/32 and put and good amount of grease on it, I practiced holding my drill at a 45* angle first before I drilled just to be more comfortable. Now its time to drill go nice and slow and take care that the aluminum shards are being collected by the grease you will have to stop a couple times to clean it off and apply new grease, I also used the shopvac to be on the safe side, once through make sure the hole looks clean, now grab a15/64 size drill bit cover the tip in grease and barely start it so just the radius of the drill bit gets drilled in the case, this forms a cup so oil can gather easily. . I filled the cavity ½ way with 2 stroke oil. next step is to pull the oil pump off, there are only two Allen bolts holding it on (don’t forget to disconnect the line going to the bottom of the case) I used a 6mmx1.0pitch that was 3/8 long with lock tight and a fiber oil pan gasket to plug the hole where the banjo fitting was in the bottom of the case, the pump will pull off very easily, no there is a collared piece that stays in the motor this supports the other end of the shaft, next either make a plate to cover this up or buy one cutlers still makes them for our sleds (I bought one cutlers is very very nice to deal with and always has info to help your install go smoothly.. now just put everything back in reverse order with new gaskets, and remember you must torque everything don’t go off feel!!! Fill it with coolant and its good to go!!!!

Now if you decide to keep your motor in your sled, remove your exhaust pipe, your spark plug wires, and you wires that go to your coolant for your head temp, next drain your coolant and remove your top end via the eight cylinder base bolts take care when pulling up as you can easily tweak something, once its pulled off zip tie it out of the way taking care not to leave tension on the APV cables, Alright now come the time you start getting the nervous feeling, you honestly don’t have to worry it doesn’t matter where you drill into the water pump gear cavity at, it could be on the side or top just as long as you hit it, get your drill bit out I used a 5/32 and put and good amount of grease on it, I practiced holding my drill at a 45* angle first before I drilled just to be more comfortable. Now its time to drill go nice and slow and take care that the aluminum shards are being collected by the grease you will have to stop a couple times to clean it off and apply new grease, I also used the shopvac to be on the safe side, once through make sure the hole looks clean, now grab a 15/64 size drill bit cover the tip in grease and barely start it so just the radius of the drill bit gets drilled in the case, this forms a cup so oil can gather easily. I filled the cavity ½ way with 2 stroke oil. next step is to pull the oil pump off pull off the cable, there are only two Allen bolts holding it on (don’t forget to disconnect the line going to the bottom of the case) this might be a bi@#h and you might have two pull the bottom belly pan, I used a 6mmx1.0pitch that was 3/8 long with lock tight and a fiber oil pan gasket to plug the hole where the banjo fitting was in the bottom of the case, the pump will pull off very easily there is a collared piece that stays in the motor this supports the other end of the shaft, next either make a plate to cover this up or buy one cutlers still makes them for our sleds (I bought one cutlers is very very nice to deal with and always has info to help your install go smoothly.. now just put everything back in reverse order with new gaskets, and remember you must torque everything don’t go off feel!!! Fill it with coolant and its good to go!!!!

Now if you tore the bottom end apart like I did please take care when putting everything back together and I always put 2oz of two stroke oil in each side case bottom to help with start up, also I premix 32:1 and if I’m doing a engine break in i start the sled for 5 to 10 min at idle(watching my egts) and the let it cool I do this about 3 times then my first trip out after I unload it I kind take it easy for about a mile then I ride it like I normally do, break in is a huge debate and I’m not trying to knock on anyone just giving my input on it

As for oil mixture like I said I run 32:1 that’s just me I’m sure some people use 50:1 on some race gas machines, keep this in mind the high premix number the (richer) the sled will run because it will get more fuel, and the lower the premix number the (leaner) the sled will run however with the lower premix number I.E 25:1 the cooler your egts will be due to lack of fuel burning, so in other words play with your engine mix and jetting a little bit then once you find a good mixture stay with that oil brand and ratio, also fuel has a lot to due with it, the higher the octane level the cooler you engine will run do to the fuel combusts better and more uniform and also cleaner, that leads to cooler and more dense air which leads to more power.. I better stop here

If you guys want any other info let me know.

and if im wrong about anything please inform me
 

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Last edited:

Idcatman1

Well-known member
Lifetime Membership
Nov 26, 2007
898
124
43
Ashton, Idaho
I wouldn't drill from both sides. You would get a small amount of pumping pressure loss from the pulse going back and forth between the cylinders. I hope that makes sense, it would be like having a leak in the center seal on the crank.
 

oldschooldoo

New member
Nov 30, 2007
111
2
18
it looks like im spliting my cases agian so i will post pics asap on what the hole looks like from inside the water pump gear cavity!!!! also i have my sled torn down to just the bulk head, so if anyone wants any info on a how to let me know think i will start a "build" thread im putting a m series suspension and a fabcraft front end with fox floats, wildchild post, vanamburg boondocker bumper kit, polishing all aluminum(will post that) digatron guages, and som umm well you know:gossip:! but like i said any info let me know! the only thing that is actually on the sled still is the first half of the tunnel is rivited to the bulkhead along with front cooler!!!!:peace:
 

coug66

Well-known member
Oct 31, 2010
518
167
43
NW near Greenwater
newbie question

How does this help, what is the benefit to doing this?

I like doing mods to help improve things but just don't what this does.

Thanks

Ian
 

hellcat66

New member
Dec 5, 2010
31
3
8
WASATCH MTNS
nice write up bro! very informative and i agree with your break in procedure... a few heat cycles and no constant throttle... thanks for the info..throw up more pics of your build
 

akmodshop

Well-known member
Dec 4, 2010
153
47
28
Anchorage, AK
How does this help, what is the benefit to doing this?

I like doing mods to help improve things but just don't what this does.

Thanks

Ian
Pre-mix is way more reliable the injections and drops 10#'s or so of the wet weight of your sled, and runs way cleaner, less smoke. All my sleds are pre-mix.

The block off plate with a grease zerk work just fine also, and is way less work, have done this to lots of motors. I also have lots of these plates on hand, if any one needs them, they are $15.