650/X-2 a few 650sx rebuild questions.

C

CJ's 650

Location
NY
so late august my 650sx suddenly shut off while riding, it did start back up but from then on starting progressively got harder until a few weeks later it did not start at all, only cranked (did have a spark). did a compression test and got 30psi front, 70psi back. pulled my head and cylinder block and noticed a few things.

first off the sleeves were scored and cracked, and there was actually a chip out of one that seems to have chewed up the piston head and dome. the bottom end looks really clean but that chip out of the sleeve seems to be missing, could it have fallen down there?

my head domes and a little chewed up but is the head still usable? (see pics). i wouldn't mind buying an OEM head but i like the fact that this one is a high comp. westcoast.

when i first started to have the problem, after the was running it would get really hot. like so hot you couldn't even touch the spark plug boots. what might have caused this?

lastly, i'm not sure what to call it, but the pin that holds in my piston heads seems to be missing (not sure if you can see it in the pic), is this little pin something that comes in the average top end rebuild kit?

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i plan on buying a new cylinder block and top end kit from sbt for around $300. i don't think its worth buying a whole new engine but that may be an option since its only $200 more and if something ever went wrong a new bottom end is over $300.

any help would be great!
 
Fatman

Fatman

Location
West Michigan
What size domes and compression numbers before melt down? Was your cooling system working? I'd pull that bottom end apart and look for pieces. 650 motors can be had for under 300, especially a short block.
 
C

CJ's 650

Location
NY
not sure of compression and dome size, i'd need to pm another forum member who i bought the ski from to find out. cooling system was working i believe, was shooting water out the side pissers and exhaust port like usual.

is the bottom end hard to take apart? never opened one up but i'm a fairly mechanical guy so i think i'll be able to do it. anything i should inspect while its opened up?
 
eastcoastjumper

eastcoastjumper

James
Site Supporter
Location
Long Island
looks like you had a lot of detonation going on. the piston edges are all pitted and those domes are shot. you can hit them out with the plug in them. put in on a flat surface and just tap the plug with a rubber hammer. they should have the cc size somewhere on them. I'm pretty sure i have 33 or 35cc domes in my westcoast head. about 185 psi compression.

Where you located on LI? I have a few 650's also.

bottom end is easy to take apart. Id check the crank bearings and rod bearings. you definitely have all kinds of metal shavings and whatnot in your bottom end. If you are going to spend any money on cylinders and a top end you should replace the crank seals and reseal the case.
 
C

CJ's 650

Location
NY
actually in CT for now, forgot to change the location.

when you say hit them out, you mean i can tap out the domes and replace them? never knew that, where do i buy new domes?

i guess i'll open up the bottom end and have a look but i probably will end up selling the ski in the spring so i don't want to through to much money into it.
need to save the $, working on modding my gp1300.
 
eastcoastjumper

eastcoastjumper

James
Site Supporter
Location
Long Island
i found my west coast domes on eBay. you can pop them back in by hand once you clean up the head. there are orings in there too so pay attention when dissembling and order them too.

if you are going to sell it id just put a stock motor in there. Its hard to find the westcoast parts and they are expensive.
 
Myself

Myself

manic mechanic
Location
Twin Lakes AR
Yes, it will cause little hot spots all over the head which could cause detonation. Replace the domes, have a machine shop recut the domes, or find another head.
 
C

CJ's 650

Location
NY
when i put the new cylinder block and pistons/rings on is there any kind of lubrication i should be putting on anything while putting everything together? is there any kind of break in oil i should run the engine with? if so, for how long?
 
C

CJ's 650

Location
NY
just ordered an sbt top end a few days ago. what ratio oil should i run with at first? i usually do 50:1 but some people say 40:1. I assume just run a whole tank of gas with the extra oil
 
C

CJ's 650

Location
NY
Got the whole ski back together and ran it on the hose for a few minutes. Started up at the touch of the button with barely giving it any throttle. sounded great, ran strong but I noticed 2 gaskets leaking. The head gasket and the manifold to pipe gasket. I assume I'll just be tightening more, I torqued the head bolts to 22lbs like the manual said but I guess I'll just have to go tighter. should I have used any gasket sealant for this?
 
Yami-Rider

Yami-Rider

TigerCraft FV-PRO
Location
Texoma
Did you clean/resurface the gasket areas before re-installing new gaskets? You should not tighten any tighter then torque specs. You could also have corroded/damage gasket surfaces.
 
grezzmky

grezzmky

Suckin paint fumes
Location
Saint Louis MO
soooo you didn't do anything to the bottom end? Goodluck... the gas actualy enters the crankcase first and lubes the crank befor getting pusd to the top end. when the crank bearings go bad the metal shavings eat up the head and the piston like that. Lets hope that wasn't the cause of your problem. but if it was ur need a new top end every two rides till you fix that crank. Should have bought a uset motor imho....
 
C

CJ's 650

Location
NY
The gasket was brand new and so was the cylinder block. I sanded the head surface to get off all corrosion. any ideas?

@grezzmky I tested crank seals with a leak down test and I turned the engine on its side and flushed out everything inthe bbottom end with gas.
 
grezzmky

grezzmky

Suckin paint fumes
Location
Saint Louis MO
CJ's 650 said:
The gasket was brand new and so was the cylinder block. I sanded the head surface to get off all corrosion. any ideas?

@grezzmky I tested crank seals with a leak down test and I turned the engine on its side and flushed out everything inthe bbottom end with gas.
Click to expand...


Was there stuff in the bottom end??? There shouldn't be. Once the bearings start go this will keep happening no matter how much you rinse it out.
 
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