I have a 13' Pro 800 with 2600 Miles on it, so far problem free. I am going to be rebuilding the top end next week with OEM pistons. I have only done one top end and that was on a YZ125. I am looking for any information pertaining to things to watch out for when taking apart and reassembling. As well as how to keep air bubbles out of the oil line, dealing with draining and refilling the coolant without air in the system. Where can i find specs as far as ring gap, cylinder dimensions, and torque for cylinder and head bolts. What do you guys recommend for break in as soon as its back together? Any information no matter how basic or complex helps! I just want to ensure a successful rebuild so I can stay on the snow this winter.
Tips for a successful Top End Rebuild 13' Pro 800?
- Thread starter bhrider
- Start date
I'm sure some others will chime in here... there are lots of great people with years of experience with these sleds.
Personally, unless you are in a big hurry.... I like to pull the engine from the sled... does't take that much longer.... and allows you to put it on the bench... especially helpful on your first go around.
Sure you can do it in the sled... but lots to work around IMO.
Do it in a warm place with good lighting and a clean work surface.
You will want to check the engine mounts etc and give it a good clean while you have access to the area around the engine.
Make sure you have the right gaskets and sealants on hand... I like to replace all the gaskets and o rings.... Great time to check your reeds for chipping etc too.
I'm slammed for time tonight... but can chime in tomorrow most likely... but will most likely have some others with insight on the specs.
.
Personally, unless you are in a big hurry.... I like to pull the engine from the sled... does't take that much longer.... and allows you to put it on the bench... especially helpful on your first go around.
Sure you can do it in the sled... but lots to work around IMO.
Do it in a warm place with good lighting and a clean work surface.
You will want to check the engine mounts etc and give it a good clean while you have access to the area around the engine.
Make sure you have the right gaskets and sealants on hand... I like to replace all the gaskets and o rings.... Great time to check your reeds for chipping etc too.
I'm slammed for time tonight... but can chime in tomorrow most likely... but will most likely have some others with insight on the specs.
.
Thanks. That is helpful. I look forward to hearing more.
If you are only doing top-end ;its twice the work to pull motor and only real benefit is you get to clean out mess under engine.. top-end is very easy to do ..
Good time to check reeds also. But its a bunch more work also. Mine at 2600 miles were starting to have a couple corners burnt. Went with spx replacements and so far so good but i only have about 500 miles on them.
First I would buy or borrow a shop manual from your Dealer. I would pull the motor out of the chassis. Replace all engine seals and you can get a good look at the crank and rod bearings. I'll bet dollar to donuts your piston pin bearings are blue from excess heat. They will need to be replaced. If you are going to keep this sled for a few more years here is my recommendation.
Look on your mono-block cylinders and see if they are marked A, AB, or B. Each hole can have a different marking. That designation refers to piston fit of that cylinder during manufacture. PI installs the correct piston for the marking. Here is the kicker, PI replacement pistons are an AB fit designation you cannot buy an A or B from PI. I would buy a set of '14 or AXYS pistons and send the mono block to Indy Dan for his hone job. You will be very happy with it, but it's not cheap. Your block may need reniked to get it into spec. Especially if you are on the loose side of the AB designation.
You can do it a lot cheaper, if you prefer, and pray every time you go to the hill����.
Look on your mono-block cylinders and see if they are marked A, AB, or B. Each hole can have a different marking. That designation refers to piston fit of that cylinder during manufacture. PI installs the correct piston for the marking. Here is the kicker, PI replacement pistons are an AB fit designation you cannot buy an A or B from PI. I would buy a set of '14 or AXYS pistons and send the mono block to Indy Dan for his hone job. You will be very happy with it, but it's not cheap. Your block may need reniked to get it into spec. Especially if you are on the loose side of the AB designation.
You can do it a lot cheaper, if you prefer, and pray every time you go to the hill����.
I
inspector01
Well-known member
Just wrapping up the rebuild on mine, so here are my additional recommendations:
- clutch balanced
-injectors cleaned
-new fuel filter
-replace the recoil cord if you take the engine out
-motor mounts- check/replace if needed
Not related to motor, but check all of your bushings in suspension as well, I've replaced basically all of them at least once
This should help:
http://www.snowest.com/forum/attachment.php?attachmentid=179040&d=1346187544
- clutch balanced
-injectors cleaned
-new fuel filter
-replace the recoil cord if you take the engine out
-motor mounts- check/replace if needed
Not related to motor, but check all of your bushings in suspension as well, I've replaced basically all of them at least once
This should help:
http://www.snowest.com/forum/attachment.php?attachmentid=179040&d=1346187544
D
Drewd
Well-known member
I just tore an engine down today. It was a 3 beer job and took me about 3 hours to do it and that was taking my time and digging thru my unorganized tool chest to find tools. I did not remove the head studs because I was lazy. Instead, I drilled holes in my 40 year old wooden work table that aligned with the studs and made it a little easier to work on splitting the case.
I found that a small impact wrench really helped removing stuff and make things so much easier.
Overall, it was pretty damn easy. This was my first sled engine rebuild but i did rebuild a Yamaha 2 stroke golf cart engine about 15 years ago.
I found that a small impact wrench really helped removing stuff and make things so much easier.
Overall, it was pretty damn easy. This was my first sled engine rebuild but i did rebuild a Yamaha 2 stroke golf cart engine about 15 years ago.
Thanks for the info/advice. Is there anywhere to find a service manual online? Still wondering about ring gap, oil system and torque specs
Your injector o-rings will likely rip when you pull the injectors out.
might as well replace the reeds while your in there.
might as well replace the reeds while your in there.
I
inspector01
Well-known member
Pulled it appart last night. Looked like brand new in there. Had 105psi on the mag side and 110 on the pto side. When I took the head boots off there was a gray silicone looking substance under the bolt heads. Does anyone know what that is and if I should reapply it? Also I haven't found the tourque specs for the cylinder or head bolts. Anybody know?
I
inspector01
Well-known member
Do i need to post the same link a 3rd time? It has torque specs and most info for engine rebuild.
I don't know how I missed that... Thanks, exactly what I needed!
D
Drewd
Well-known member
Couple things I've picked up working on my 700 CFI. All I need to do now is put oil pump, fuel rail, and pull start and she is ready to go back into the sled.
a. Buy a couple of spare circlips if you don't want to re-use one. I had one shoot out into orbit on me.
b. Don't attempt figuring out which side of the piston ring is up without good lighting, eye glasses on, or a magnifying lens. The lettering on top of a piston ring is tiny!
c. Check FSM for thermostat orientation. I didn't know that it has to be aligned a certain way until I ran across it in the FSM.
d. Use a good torque wrench. A 3/8 inch wrench sitting in my toolchest for years let me down meaning it was not accurate. A sled engine is not the place to test an unproven wrench.
e. Yamabond 4 works great on engine cases and was available at my local cycle/ATV shop.
f. If you use a chemical cleaner, make sure none of it oversprays any o-rings. I used a little brake cleaner to clean off shavings from extracting a broken head stud and a little overspray caused my head o-rings to swell.
g. Make sure your gasket kit is complete. Mine was missing a water pump gasket.
h. I installed the new piston with new rings into the cylinder bore first and them lowered it slowly onto engine to attach the connecting rod. It was easier this way for me. Gudgeon pin in freezer for a bit helps it go in easier with a finger push. I put a little grease on the roller bearing to keep it in place using this method. I'm not 100% sure that the grease is a good idea but I've done it before on smaller 2 strokes.
i. Stuff a paper or cloth towel into case to prevent circlip from falling into it when trying to install them.
j. You will find missing hardware, nuts and bolts, after you purchase replacements at the hardware store.
k. Double or triple the time you thought it would take to rebuild your engine and/or top end because life and work seems to like to get in the way of projects like this one.
l. DON'T PROCRASTINATE AND WAIT TILL WINTER TO DO AN ENGINE PROJECT or your time to ride will be hindered. I always seem to think I'll get stuff started and finished between mid-Fall and Winter, NOT!
Additions added 1/27/17
m. Clean and dry all bolt holes on head with Qtips. If you don't, any residual coolant will cause head bolt to shear since fluid is not compressible.
n. Some folks recommend you torque head first then torque cylinders into monoblock. Not sure why but it is a common thing to do.
o. Put sealant on all headbolt flanges or you will get leaks like I did when I added coolant. I used case sealant and it did the trick.
p. Grease new fuel injector washers. Be extra careful as I had two of mine fall off and didn't realize it until later. Glad I caught it.
q. I bled the air in oil pump before engine install. Had someone hold the oil reservoir like an IV bag while it bled air out. Much easier than after engine is installed.
r. I used plumbers grease to hold the head o-ring gaskets. It does not swell or soften rubber o-rings.
s. Gasket tack keeps the cylinder bottom gaskets where they need to be and I think it strengthens the gasket material too.
t. I screwed up and used a file and a dremel bit to file and polish piston ring ends when setting ring end gap. Has worked for me on other engines in past but realize there is a special tool/stone used to file piston ring ends.
a. Buy a couple of spare circlips if you don't want to re-use one. I had one shoot out into orbit on me.
b. Don't attempt figuring out which side of the piston ring is up without good lighting, eye glasses on, or a magnifying lens. The lettering on top of a piston ring is tiny!
c. Check FSM for thermostat orientation. I didn't know that it has to be aligned a certain way until I ran across it in the FSM.
d. Use a good torque wrench. A 3/8 inch wrench sitting in my toolchest for years let me down meaning it was not accurate. A sled engine is not the place to test an unproven wrench.
e. Yamabond 4 works great on engine cases and was available at my local cycle/ATV shop.
f. If you use a chemical cleaner, make sure none of it oversprays any o-rings. I used a little brake cleaner to clean off shavings from extracting a broken head stud and a little overspray caused my head o-rings to swell.
g. Make sure your gasket kit is complete. Mine was missing a water pump gasket.
h. I installed the new piston with new rings into the cylinder bore first and them lowered it slowly onto engine to attach the connecting rod. It was easier this way for me. Gudgeon pin in freezer for a bit helps it go in easier with a finger push. I put a little grease on the roller bearing to keep it in place using this method. I'm not 100% sure that the grease is a good idea but I've done it before on smaller 2 strokes.
i. Stuff a paper or cloth towel into case to prevent circlip from falling into it when trying to install them.
j. You will find missing hardware, nuts and bolts, after you purchase replacements at the hardware store.
k. Double or triple the time you thought it would take to rebuild your engine and/or top end because life and work seems to like to get in the way of projects like this one.
l. DON'T PROCRASTINATE AND WAIT TILL WINTER TO DO AN ENGINE PROJECT or your time to ride will be hindered. I always seem to think I'll get stuff started and finished between mid-Fall and Winter, NOT!
Additions added 1/27/17
m. Clean and dry all bolt holes on head with Qtips. If you don't, any residual coolant will cause head bolt to shear since fluid is not compressible.
n. Some folks recommend you torque head first then torque cylinders into monoblock. Not sure why but it is a common thing to do.
o. Put sealant on all headbolt flanges or you will get leaks like I did when I added coolant. I used case sealant and it did the trick.
p. Grease new fuel injector washers. Be extra careful as I had two of mine fall off and didn't realize it until later. Glad I caught it.
q. I bled the air in oil pump before engine install. Had someone hold the oil reservoir like an IV bag while it bled air out. Much easier than after engine is installed.
r. I used plumbers grease to hold the head o-ring gaskets. It does not swell or soften rubber o-rings.
s. Gasket tack keeps the cylinder bottom gaskets where they need to be and I think it strengthens the gasket material too.
t. I screwed up and used a file and a dremel bit to file and polish piston ring ends when setting ring end gap. Has worked for me on other engines in past but realize there is a special tool/stone used to file piston ring ends.
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Thanks for all the advice. I defiantly procrastinated way to long to do this, but I got it done and got50 miles of break in before I went out west and now have 300 on it. Runs great and feel the power like it was new. All the specifics scared me but when it comes down to it it's just a 2 stroke motor and it's really not that bad of a job but if you read to much on here you can definitely intimidate yourself before you dive into it. This forum is a great source of knowledge, and I'm glad to have it as we drove 1,200 miles one way to Idaho and it ran great
