02 m/c 800 efi engine

[diggler]

so i blew a piston this winter on my 02 and i got rebuild the whole works, just wondering how much bigger pistons, and if i can give it a mild port job, without it leaning out to much. luckily i think i shut it down soon enough that the cylinders are still good. any help would be greatly appreciated.

 

[76FOMOCO]

I think you can put a 900 (03-06)top end on it easily and unplug the ethanol wire to make up the need for extra fuel. but i would check on here to see on the efi if anybody had done it without problems. There is a bunch of after market BB from 975-1160 stuff but you would need a fuel controller and other stuff just how much do you wont to spend!
what caused the motor to go down?

I might have a whole 900 top end to sale...

 

[89sandman]

don't think the 800 to 900 swap is as easy as it sounds. checked into when i had my 02 800, ecm, stator, seems it would have been cheaper just to buy the 900. someone on here had done thiers when i was looking to do mine, just wasn't cost effective.

 

[diggler]

well not sure what caused it but the skirt on one of the pistons broke sending all kinds of cast presents down to the bottom end. have a friend that said he will take it apart and rebuild the bottom end, but while it was apart just wanted to give it a little mild port job. not looking at going with a big bore, and as sandman said i have heard its not as easy as it sounds to put a 900 top end on it.

 

[diggler]

ttt

 

[diggerdown]

I wish I had know you were still playing with that sled, I could have got you a 2004 King for $2200 and you could have sold that one for that much this fall. Steve could have brought it up to you. Be carefull on who you let port that thing. A lot of guys own a die grinder and think they can port, but you could end up with junk. Make sure you get some good feedback from customers on whom ever you choose. I would check with Keslsey at RKT first. Recut the heads for a 13/1 comp ratio and run primium.

 

[diggler]

yeah i just got done putting a new track on it and bearings, took it out and she blew. thats a steal on the king cat. im got a machinist thats a yamaha cert. mechanic thats gunna do it for me or i will just leave it. i just didnt know if giving it a mild port would lean it out to much being an efi.

 

[diggerdown]

The efi runs a little on the rich side anyway, so I don't think a mild port job would cause any lean problem as long as you're not running twins on it.

 

[diggler]

no, no twins for me. unless its women your talking about

 

[twistedtunnel]

Don't be such a tight *** Diggler get yourself one of them used 1150 motors.

 

[ZRrrr]

Cat 800 and 900 twins do reeeeaaaally well with porting. I own a die grinder and thought I could port my own engine....so I did! Works amazingly well and I am no where lean, even with my other mods.

 

[diggler]

so i got the motor back, decided not to do any porting on it. went with wiseco pistons and new crank bearings basically a new motor. just wondering if theres anything i need to look for before putting it back in, like the oil pump anyway to test it? I know to run premix thru the first tank. i also noticed ,not sure this would cause it to burn down, that one of my throttle body boots has a slight tear in it, would silicone hold together this i know that silicone and gas dont mix. but if i were to silicone it on the outside woultd that work. Just wondering what i need to look for and or do after and during putting the new motor back in, cuz it would suck for this thing to burn down again, thanks guys

 

[kidrman]

That ripped boot will definitely let too much air in and cause a lean condition.

Can someone tell me why a 800 to 900 isn't a bolt on for an EFI?

 

[Sledbrain2]

That is a common problem with the boot next to the steering post. I used weathersriping adheasive to fill the gap. I works pretty well, yes you will have a lean cylinder and it will also bog as soon as you have snow come over the hood. There is a lean mid to that 800 from the timing curve.

 

[Arcticatdan]

The stator, stator plate and fly wheel are the same from 02 to 06 on all EFI 800/900.
The only difference is the ECU. The throttle body is the same also.

 

[diggler]

so i got the motor back in and ran it for about 1.5 mins. two questions, theres a hose on the throttle bodys on the clutch side, where does this hose go to? also what is the best way to bleed the air out of the coolant system? thansk

 

[Twostroke]

what I do is top the cooling system off like normal, then pull the thermostat out(on the cyl. head) and fill it up there also, if not you can get a airpocket there and the thermostat will not open, don't ask me how I know this!!

 

[diggler]

still curious about this hose that comes off the throttle bodies, its about 6-8 inches long apears it should go to the head, what i did was hooked one end of the drain up to that maybe i hooked the drain hose up in the wrong spot? the other end of the drain hose i hooked up on the water pump, help guys

 

[Twostroke]

The hose that comes off the throttle bodys should run under the motor and attact to a t-fitting under the starter recoil. I just had to replace that line, it got rubbed through from my steering post.

 

[diggler]

so it gets hooked into the antifreeze line, kinda like a heated carb setup?