Need help and Advice on pulling an SX motor out of its frame.

[Tri-ZNate]

The last time I did this my neighbor did most of the work and we pulled the drive shaft out of the engine causing all the gears to fall out of place so what I need to know is...

1. how many mounting brakets hold the engine in?
2. where should the drive shaft be separated at?
3. how many bolts hold the head on?
4. is there any electrical, mechanical, ect... that i need to unhook before I take it out? I already know to unhook the carb boot and oil cooler.

[Dirtcrasher]

The last time I did this my neighbor did most of the work and we pulled the drive shaft out of the engine causing all the gears to fall out of place so what I need to know is...

1. how many mounting brakets hold the engine in?

There are front brackets, top brackets and frame mounts.

2. where should the drive shaft be separated at?

Slide back boot and pry off splines


3. how many bolts hold the head on?

A bunch of 8MM head bolts


4. is there any electrical, mechanical, ect... that i need to unhook before I take it out? I already know to unhook the carb boot and oil cooler.

There is no oil cooler. Starter positive and ground are connected along with a plug from the ignition side. A reverse and nuetral plug.

Reverse cable and foot pegs too.

That engine is HEAVY and a tight fit too. Rolls out the right side, good luck!

[MTS]

Are you sure your timing chain just didnt pop off befor you pull the whole motor?

[Tri-ZNate]

Are you sure your timing chain just didnt pop off befor you pull the whole motor?


I have no compression

[MTS]

I have no compression
yes and a timing chain would cause that if one or more valves stuck open.

[Tri-ZNate]

There is no oil cooler.

what is the line running up to the right side of the head? It starts on the right top of the engine and runs up there.



Rolls out the right side

so I have to take the exaust pipe off to?

[Tri-ZNate]

yes and a timing chain would cause that if one or more valves stuck open.

All I want to do is look at the piston which means the head had to come off, which means I could look at the chain, but there isnt enough room to get all the head bolts off because of the lack of room. So i have to take the engine out.

[MTS]

yes and a timing chain would cause that if one or more valves stuck open.
I say this becuse motors just dont all of a sudden have no compression from a 2 second ride if it was fine the day before(normally lol) what im thinkin is your mom was usin the elcltricstart and it startted and she kept on the electric start button and it coulda back fire'd n sent the timin chang flyin (if it was loose)...just my 0.2 cents...could save you time to check it! :beer, you can just pop the pulse rotor cover off and see if the chain is still on and tight, takes like 5 mins..

[Tri-ZNate]

I say this becuse motors just dont all of a sudden have no compression from a 2 second ride if it was fine the day before(normally lol) what im thinkin is your mom was usin the elcltricstart and it startted and she kept on the electric start button and it coulda back fire'd n sent the timin chang flyin (if it was loose)...just my 0.2 cents...could save you time to check it! :beer, you can just pop the pulse rotor cover off and see if the chain is still on and tight, takes like 5 mins..


oh so i dont need to take the head off?

[MTS]

oh so i dont need to take the head off?
...you dont have to take the head off, just the rocker cover, hell to make it really easy yto see whats goin on just take the valve adjustment caps off and crank it over see if your valves move, if they dont you know its a cam chain.

[Tri-ZNate]

are the caps on the head? and I just got done reading the 350X ticking thread and mine was ticking for a while and it still was up till yesterday. I see one of the replys is a loose timing chain. So I hope its just that simple.

[MTS]

yes they should be on the head. up there someware..lol

[BIGCRIP28]

that line running from the crankcase to the head is not for a oil cooler it is just to get more oil up to the head instead of going through like the 200 engines.

[Dirtcrasher]

There are quite a few possible reasons for no compression - snapped connecting rod, broken crank, broken cam, sheared timing chain sprocket key or bolts in the upper sprocket and so on. Simply remove the 2 - 8mm bolts holding the cam chain tensioner in place and if it pops out 1/4 of an inch then the chain isn't snapped. Generally the head gets pretty noisy if the chain is on the way out. I too would remove the valve cap cover and check out the cam etc (there is no pulse generator cover with t chain access) The book says that the rocker arm cover comes off in the frame but I had difficulty in removing mine. I had a dowel pin stuck in the head which prevented it from slipping off so I just yanked the motor.

[Tri-ZNate]

i took the valve covers off and the valves are moving just fine. SO i dunno whats wrong.

[bigredhead]

When you say " No compression " .. have you put a pressure gauge on it yet ?

The kickers on the 85's are prone to failure from what i've read..... does the electric start still turn ? if it does.. open the side cover ( with engien IN frame ) and check the starter gears before you take the time to remove the motor.

I bet the head pipe bolts break when you try to remove them !!!!! don't need that " Head " ache !! lol....

if you put it in gear.. to bump start it... does it lock the rear wheels until you get to 3rd or 4th ? or just rolllll in 1st ? if it rols in first.. you got probs.. if it don't i think you have compression !!..

just some things to think about i guess.

good luck man ! ;)

[Tri-ZNate]

When you say " No compression " .. have you put a pressure gauge on it yet ?

The kickers on the 85's are prone to failure from what i've read..... does the electric start still turn ? if it does.. open the side cover ( with engien IN frame ) and check the starter gears before you take the time to remove the motor.

if you put it in gear.. to bump start it... does it lock the rear wheels until you get to 3rd or 4th ? or just rolllll in 1st ? if it rols in first.. you got probs.. if it don't i think you have compression !!



I dont have a comp tester big enough for th hole. The one I borrowed is just a staight tube with a meter on the end.
I havent messed with it in a couple days due to how murdering my job is and how tired I am. If I remember correctly if it is in gear it wont roll.
But as for the starter gears, I think they are fine. I took the valve cover off hit the electric start and the valves move so I dont think the starter gears are broke.

[Dirtcrasher]

Valves can move but the piston won't if the connecting rod broke. This will be the 1st con rod I ever heard of snapping in an SX. There was a service bulletin about 1985 cranks snapping until Honda installed a new coil, affects certain part numbers. If you don't have time to yank the engine, first of all is there any compression at all - does it even remotely blow off your finger?? Second, put the flywheel on "T" and if you reach into the plug hole with something skinny you should feel the piston head up at Top Dead Center. Then rotate the crank 180 degrees (not 360) and you will be at Bottom Dead Center and whatever you put in there should now go in a couple inches deeper. That will tell you if Mr con rod and crank "seem" ok. But, even a slightly bent valve will prevent any compression from happening but the rockers will still move. That could have easily happened a few different ways.

[Tri-ZNate]

I have decided that I have too many SXs and need funding for a 350x so I'm gonna sell it.

[short4stuff]

I have decided that I have too many SXs and need funding for a 350x so I'm gonna sell it.

lol your giving up and havent even began? ...
A running SX will get you alot more than one that has a "blown" engine...

[Tri-ZNate]

I can get $600 outta it easily.

[bigredhead]

you can more out of it " easily " if the engine runs too !!!! a good shape SX gets minimum 1000 around here.

[phreakboy]

So Anyway, I got the 250sx off of 250sxwheeliepop, Right now I do not have a compression gauge, but I have popped the cover off and the valves are moving, piston is moving, So I am either thinking bent valves or rings. There appears to be no compression when you put you finger over the sparkplug hole. So I guess next step will be pulling the motor, is there anything special I should know about before I do? I really want to get this trike going asap so any help would be appreciated, and yea if it is in gear it will not roll.
phreakboy@comcast.net

[slothminx]

So Anyway, I got the 250sx off of 250sxwheeliepop, Right now I do not have a compression gauge, but I have popped the cover off and the valves are moving, piston is moving, So I am either thinking bent valves or rings. There appears to be no compression when you put you finger over the sparkplug hole. So I guess next step will be pulling the motor, is there anything special I should know about before I do? I really want to get this trike going asap so any help would be appreciated, and yea if it is in gear it will not roll.
phreakboy@comcast.net

i would take the head off straight away and check out the piston if you cant feel any air coming from the plug hole i woould say a holed piston from a valve hitting it (maybe overrevved) or the rings have broken and its losing compression there. im very interested to know what has happened to this engine

will

[bigredhead]

when and if you remove the engine from the frame.. do NOT remove the angled part that hooks into the drive shaft on the motor side ( pumkin gear ? ) the shaft has washers that will fall into the tranny if you pull that puppy out.

other than that.. i highly suggest a manual.. it's an expense, but highly worth it !

[phreakboy]

ok now after messing with it more, when I have the sparkplug in and I crank it over, I have major air pressure coming out of the exhaust so I am assuming that something happened to the exhaust valve. ANYONE? Also is it possible to remove the head while the engine is in frame? I know that I can get to all of the bolts So I am hoping that it can be done without pulling the motor. If the valve is screwed up where is a good place to get new ones and any idea on price?

[Tri-ZNate]

If you can get to all the bolts I'd take the head off and leave the engine in. I didnt think you could get to all the bolts though.

[Tri-ZNate]

Were you able to make any progress?

[phreakboy]

THe only thing I got done so far was to get the top part of the head off to where I can see the cam, but I guess I have to take the side cover off to get the timing chain off so hopefully tomorrow I will do that.

[Dirtcrasher]

THe only thing I got done so far was to get the top part of the head off to where I can see the cam, but I guess I have to take the side cover off to get the timing chain off so hopefully tomorrow I will do that.


Take the 2 10mm bolts out of the cam and then the 2 8MM bolts out of the cam chain tensioner bolted on the front of the cylinder itself. It's tricky but the cam can come out then. Tie a wire around the chain or it falls in the case and then you WILL have to pull the cover. The cylinder and head do come off in the frame but the dowel pins must be slid down from where the sit or they won't allow the head to come off.

Valves are like 30$ a pop, I buy OEM but hear Vesrah is just as good.

If you aren't reading and following a manual then your asking for more trouble.....

[phreakboy]

Well thanks for the help there, Unfortunatly I do not have a manual yet, so I am kinda wingin it and reading everything that I can possibly find on it(not much luck there). You have answered a few questions though so I thank you for that.

[phreakboy]

Well I finally got a chance to tear on it some more, I got the head off, exhaust was a pain in the butt!!!!!!!! Pipe would not cooperate. Two bent valve, so my next question is, how did they both get bent, Intake is stuck open about a 1/4 inch and ehaust is open about 1/2 inch. Is there anywhere online that I can order these or is there any chance that the local dealer might have them? Is there anything else I should do while I am in here? I am assuming that I shouldnt reuse the head gasket?

[bigredhead]

Timing chain.... chain prokets.. valve seals.. have the cam checked for spec.

all that.

[Tri-ZNate]

wow how did I **** up 2 valves? I didnt think I ran it that hard.

[phreakboy]

my thoughts are either (A)It jumped timing or (B) It got revved extremly high and floated the valves. There is markes of the piston from where it hit the valves.

[Tri-ZNate]

The exaust and intake shouldnt be open at the same time should they?

[phreakboy]

no they wouldnt be, but it is still possible to float them if it was way over revved.

[Tri-ZNate]

That is so weird though because it ran fine till I shut it off. If it was over revved it would have shut off durring operation right?

[Dirtcrasher]

I hold my SX wide open for long periods of time, I'll bet you just jumped time.