701 sm

[cg_ops]

So glad I don't have to deal with my 701 after revisiting this thread

The 890 has been such an awesome step up in hooliganess, nimbleness, and enjoyable...ness.

I do miss the 701's propensity to raise its front end like a preying mantis every time something spooks it. The 890 may be a lot more powerful but the geometry of a sumo is MUCH more conducive to whoolies

[JesasaurusRex]

Originally Posted by cg_ops

So glad I don't have to deal with my 701 after revisiting this thread

The 890 has been such an awesome step up in hooliganess, nimbleness, and enjoyable...ness.

I do miss the 701's propensity to raise its front end like a preying mantis every time something spooks it. The 890 may be a lot more powerful but the geometry of a sumo is MUCH more conducive to whoolies

haha glad you like the new bike

i've flogged this thing for 10k miles so i'm really not too upset if it's a head gasket. Also bang it off the limiter more than i should lol . Finally stiched up the oil leak on the tx300i so I still have something to ride


So i got my new pressure tester and was able to complete a pressure test with the snapon adapter and without the faulty test cap and it holds pressure fine. Maybe dropped .025 bar in 30 mins time, i think that's probably acceptable?
Unfortunately i still don't know a good way to test the OEM cap. You can't go through the cap obviously because it would just vent back into the pump, so one would have to either splice the radiator hose or go through the sensor port on the radiator. Both of which would take a little bit of fab that i'm not interested in. So i'm going to throw the new cap i purchased on the bike and ride it around and see what happens. If it's fixed, great. If not i'll pull the head.

Keep you guys posted

[RichieRich]

Good information, I need one of these in my life!

[JesasaurusRex]

Originally Posted by RichieRich

Good information, I need one of these in my life!

sell you one

[JesasaurusRex]

Well got started, time to order parts i suppose

[paul cbr]

Originally Posted by JesasaurusRex

Well got started, time to order parts i suppose

So it wasn’t the cap?

[JesasaurusRex]

Originally Posted by paul cbr

So it wasn’t the cap?

Not unless the new one was bad too. Doubt it, but still haven't found a good way to test it unfortunately.

So far not really that much of a chore, hope it stays that way.

[JesasaurusRex]

So it's been about a month since I pulled the motor, holidays, work, family and other hobbies/bikes has consumed my free time. Got around to pulling the head today so about half way done. The really odd thing is I did a leak down test before pulling the head and I had 10% leak. After staring at the gauge for what must have been 30 seconds I decided i wanted a picture so i started searching for my phone and somehow in that time frame the thing sealed up and I was at 2% leak. Pretty positive the engine didn't rotate any and all the valves were closed. I took the air off and pulled the cam before retesting to be absolutely sure, but I was unable to recreate what had happened and it read 2% steady the entire time. Once again, positive the valves were closed. There may be some weird thing going on with these motors and head gaskets, which would explain the pushing water under load but not at idle thing. Very odd, but saw it with my own eyes. Anyways, here's a few pictures, maybe someone that knows what they're looking at better than me can shed some light if they see anything odd. Nothing jumped out at me really, piston seems a bit dark but the lighting isn't the best in my garage? 10k miles so i donno how it's supposed to look. Unfortunately I don't have a machinists straight edge to see how straight the block/head decks are. Rule of thumb as taught to me has always been .001" per cylinder on a bank, but it only being 1 cylinder I don't even think i have a .001 feeler guage. Gonna clean up the decks tomorrow and probably slap it back together and see what happens. Fingers crossed.

Top of piston/block deck



Head side of gasket


Block side of gasket


Bottom of cylinder head


Leak down

[JesasaurusRex]

Ordered a straight edge, gonna make sure the head and block decks aren't warped before reassembly. What's a few more days at this point?

[JesasaurusRex]

So nice surprise, my straight edge arrived today and I ordered it yesterday. Woowoo

So the head deck is straight as an arrow, checked it multiple places, still haven't on the block but unless I report back different it's also straight.
Putting the head on my bench with a little better light I did notice the top right exhaust valve in the photo is a bit discolored towards the outside of the combustion chamber. I have no known oil consumption issues, is it possible by the looks of it that this is the side my coolant is leaking into the combustion chamber? Someone with more knowledge than me please Also looks like the side with the most carbon buildup. Picture with the straight edge is after I cleaned it up, first picture is before any cleaning.

[Woody146]

Dude! Props for tearing it down and looking for a culprit!

If I have learned anything from this thread, it is that the 701 sm kicks ass, but it’s not the bike to try to squeeze hp out of.

Open the air box, get a slip on, maybe a fueling dongle and just rip it!

3 people have tried to buy mine in the past 3 months. It’s not going anywhere!

[JesasaurusRex]

Originally Posted by Woody146

Dude! Props for tearing it down and looking for a culprit!

If I have learned anything from this thread, it is that the 701 sm kicks ass, but it’s not the bike to try to squeeze hp out of.

Open the air box, get a slip on, maybe a fueling dongle and just rip it!

3 people have tried to buy mine in the past 3 months. It’s not going anywhere!

Send those 3 my way

[JesasaurusRex]

K got some PT stuff coming. Starting to think this is all a bit overkill lol, but there has to be a reason this is happening to these motors. Probably peel the mls gasket apart too, wonder if they can fail mid layer.

[JesasaurusRex]

So got around to PTing the head deck and the cylinder sleeve/engine deck.
TLDR didn't find any relevant indications

What should have probably been an hour job turned into a few, as I wound up PTing the engine side 3 times and the head twice. Why so many times? Well the engine block I still had the piston at TDC trying to save some time on the reassembly and that penetrant just sits between the top ring and the top of the deck. Put that developer down and it just pulls too much penetrant back out. Don't think it would have kept me from finding any significant defects as I was watching the entire time, but I was already here and my hands dirty (kidding i wear gloves) so decided to do it until I was happy with the test. Put the piston down in the hole a bit and test again. Those machined edges really hold that penetrant too and quickly saturate the developer as well, which bothered me with the second test, so 3rd times the charm.

Anyways, didn't find anything relevant and I think I tested it enough times to be sure of myself. I want to say this is a good thing because it means my parts aren't cracked, but it's also bad because that pretty much means i still have no clue as to why my bike was pushing coolant. Still haven't pulled the head gasket apart which I plan on doing and i still haven't checked the cylinder sleeve/engine deck for flatness so there's still those possibilities but i'm not thinking i'll find anything. Obviously will report back if I do.

105mm is the bore which works out to 4.13" or so. Pretty dang big for 4 head bolts imo. Not sure if that's the actual issue but if my head gasket investigation doesn't turn anything up I have no other idea what it could be.

Two developed pictures of head are initial application of developer and 10 mins after
Cylinder/engine block is initial application, forgot to take picture 10 mins after

[JesasaurusRex]

Peeled apart the MLS gasket , it is 3 pieces in total but I am only showing 2. The white portion in the photo is the middle of the gasket and the black portion is the cylinder (bottom) portion of the gasket. The sides you are seeing were touching one another. If you take a look at the black gasket you'll see a section of coating removed that looks like it got torched a bit. Don't know if that's the culprit but it's all I found that raised an eyebrow. Engine is mostly back together, I really didn't find anything that jumped out at me, my next update will be if the issue has been resolved. Hopefully it's my last update.