300/440/550 Need help with top end rebuild and questions

[kawa js550]

I am thinking about doing a rebuild stated in one of my other posts but have a few more concerns/questions. This is the first thing I will really be taking apart besides carb and pipe. I am 15 and don't have much experience so want to make sure this is what to do. (1990 550sx)

1. Check compression
2. Identify if cylinder needs to be bored or not. (fingernail method?)
3. Get rebuild kit for right size bore
4. Install kit
5. Test/Tune

Do you have to pull out the engine for a top end rebuild? I would imagine, because you need to torch everything to spec but could you get away without pulling it out. Is it hard to realign the motor?

Thanks for everyone who has helped me so far.

 

[Summetyme1]

It takes 5 min to pull that motor. Alignment doesn't need to be done unless you're pulling pump. Do a leak down test first to see if you need crank seals while you're in there. Make sure you do your ring gaps before you drop in the cylinder. Use 1211 on crank to cylinder gasket and crank cases. See if she fires. Buy yourself the clymer shop book. Good reading, educate yourself before you get to far into it.


Sent from my iPhone using Tapatalk

 

[kawa js550]

It takes 5 min to pull that motor. Alignment doesn't need to be done unless you're pulling pump. Do a leak down test first to see if you need crank seals while you're in there. Make sure you do your ring gaps before you drop in the cylinder. Use 1211 on crank to cylinder gasket and crank cases. See if she fires. Buy yourself the clymer shop book. Good reading, educate yourself before you get to far into it.


Sent from my iPhone using Tapatalk

Does the manual have everything I need to know for the rebuild and I heard there are spacers between the motor plate and motor mounts. Do I just put them in the same spot as they were and I should be good.

 

[Summetyme1]

It will, yes. I don't have shims under my motor but I set my pump. The sx bearing housing has some play so they're pretty easy to line up.


Sent from my iPhone using Tapatalk

 

[kawa js550]

It will, yes. I don't have shims under my motor but I set my pump. The sx bearing housing has some play so they're pretty easy to line up.


Sent from my iPhone using Tapatalk

Alright thanks for the help man, just bought a compression tester and when it comes in ill test it to see if I have good compression. If not ill pull the motor and give it a leak down test and if it fails that, rebuild the motor. Completely stock and hasn't been touched, 25 years old, surprised its still running strong

 

[Summetyme1]

You can leak down test in hull. Just plug your exhaust and intake manis. Should hold 8psi. What kind of compression gauge did you buy?


Sent from my iPhone using Tapatalk

 

[kawa js550]

You can leak down test in hull. Just plug your exhaust and intake manis. Should hold 8psi. What kind of compression gauge did you buy?


Sent from my iPhone using Tapatalk

Its a pretty cheap one I got off eBay for like $20. It has the gauge, hose, rubber boots, and a few adapters.

 

[Summetyme1]

It's not going to be accurate.


Sent from my iPhone using Tapatalk