REBUILDING 1981 440E SRX MOTOR

[messina1974]

Hello guys I am getting ready to pull the motor and tear it down to rebuild it. I think the seals are shot, the sled has not run right for the last couple yrs. I believe I have it narrowed to the seals and surely hope this makes her run again. Well just wondering if there is anything to be particularly aware of. I bought a service manual and have the owners manual and will be relying on them for help. Bought a new set of pistons that I am planning on using also. Well thanks again for any help or relevant information, I have never rebuilt a 2 stroke, but am fairly good with a wrench, and have bulit numerous SBC motors. Thanks FOR YOUR HELP GUYS!!!

[tyler440]

if its not too late you could do a compression test to see what kind of compression it has... it might not even need rebuilt, could be clutching or something completely differnet

[chrisrider63]

Where did you get pistons for the 81 SRX 440?? I need some..

[tyler440]

i believe dennis kirk sell aftermarket ones still im sure others do too... for OEM your probably just going to have to look around untill you find someone with them for sale

[chrisrider63]

A pair sold for $40 totall last winter on ebay i just missed it lol. The yami piston kits are $110 each not including tax.

[messina1974]

Compression test revealed 120 and 110 poundsfigured thats probably enought to run

[Vmax540]

A leak down test is the best for checking C.C. seals.

[opsled]

A leak down test is the best for checking C.C. seals.

OR,

A little trick I use to test crank seals and bearings when the jugs are off is what I call a "fuel test". I fill one crank cavity with fuel to a level that is higher than the top of the seals. Then rotate the crank by hand and let it sit for 10 minutes or so. If you don't get any fuel leaking into the next cylinder or out an end seal those two seals are doing their job. If all is good I empty that crank cavity of fuel and blow it out so it is dry then move on to the next cylinder and repeat untill they all have been done. If they all check out good I then rotate the crank with the now clean dry bearings to feel for any hitches and listen for clicking noises that are a sign that a bearing cage has come apart. If all is good I then squirt new 2 stroke oil down the passages that feed the mains until I get some puddling in the bottom of the case. Lube up the rod bearings in the same fashion and you're good to go.

I also use this test when I am going to replace seals regardless of their condition just to help pinpoint any possible bottom end issues that need to be addressed before I take it apart. Testing end and center seals is not possible after it's apart and I always like to know where I'm going before I get there.

I would start with the center on a tripple but it doesn't really matter as long as you do them one at a time. To remove the fuel from the case (if the engine hasn't been removed) I use an electric fuel pump setup with hoses on both ends (this setup doubles as my summerizing pump to empty the fuel tank). This is also a good way to clean a bottom end that has had a cylinder go down.

Good Luck, opsled

[messina1974]

Thanks guys, thats a good idea and will check the seals that way as well as identifying any other issues I may have. Again I appreciate the help. will let ya all know what I have come up with

[MAPEX]

I'm also in the process of doing the same, are there any tricks of getting the water pump housing off the case and then the case apart? Thanks

Mike

[chrisrider63]

YOu have the pull the housing off with a puller, then you just split the bottom end apart and clean it up and get new seals for it.

[messina1974]

THANKS FOR THE HELP GUYS,
Motor is apart and cleaned and ready for reassembly, I was going to put a light coat of rtv on the crank seals before I reassembled it and wondering what you guys thought of that. Also was goign to put a light coat of rtv on the halves also.

[chrisrider63]

Put grey goop on the halves for reference I put the water pump gear on the fire stove in the shop and it slipped right onto the shaft. But firstly you gotta put grey goop (gasket maker) on the halves but you have to hurry up to put them together before the goop dries. It did a practice run before i put the goop on and also put the top of the cases down and put the crank through and then the bottom half.

[messina1974]

again thanks so much for the input/help. After inspection of the crankshaft i notice that several of the bearings just dont spin as freely as the others. I have pb blastered the bearings in hopes that would help. was wondering if this is something that I should have fixed or let it ride. The 2 bearings do not appear bad by looking at them, no real rough spots or binding just not moving as freely as some of the other (better) bearings. any thoughts? This is something that I think I will send out if needed, any thoughts on where would be a good place to send it? Or if this is something reccomended (sending out) to simply have it trued and gone through, or have an expert inspect before rebuild. I know its hard to say not being able to see the crank just hoping for a little insight! thanks again all...... MIKE

[Vmax540]

How freely they spin (as in how long after letting go) is not always a good measure. Depending on position on crank, style/type of bearing they will not all spin the same. I'd be looking for one that like you say have rough spots, binding, excessive play and/or noise ?