hey guys, I got brave and deleted the base gasket. Used motoseal in place of the gasket and checked squish. End result was .020 at the tightest. the squish was .034 before modding. I let the motoseal sit for 30 mins before firing up the saw. Ran quite good for about 30 seconds and now its having idling problems. Wondering if I have an air leak somewhere? I played with the carb adjustments a bit but to no avail. the saw pulled hard in a log for a dozen seconds or so and then started having the idling issues. I'm confident I haven't burned it out from running too lean, the saw barely even got warmed up. Psi to begin with was 115 psi and motor is essentially new. inside was clean and flawless. Ran like a champ before the mod so I know it had good compression, I feel my compression tester doesn't give the full psi. after the mod it was showing a 7 to 10 psi gain. is that normal? saw went start now so I'm wondering what it might be. I will post a video I got right before the saw quit. it was running on full choke only and is showing symptoms of a possible air leak by getting picky about what carb settings it will start with. Choke, no choke, choke with throttle, then no throttle. Last symptom was the saw would fall on its face when I began to throttle up. played with the screws to richen or lean but no problem solved. should I re do the motoseal? what do you think?
372 xtorq Squish and Motoseal Problem?
- Thread starter Artemis
- Start date
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Lightly seat the L&H and back them out 1.5 of a turn and see what happens. The saw is either really lean on the L or the saw has a large air leak. Motoseal doesn't need time to set up, some say 30 seconds to a couple minutes, basically the time it takes to install the cylinder, 30 minutes is much too long, it will get hard and not bond. When Motoseal bonds correctly the cylinder will have quite a tight bond to the case, and will take some force to break the seal. If I had to guess this is the issue, especially if the saw was running fine before you deleted the gasket. 115 psi is much too, low you should have at minim 140psi often more.
I see some scratches on the top of the piston, what is that from? they don't look deep, just odd to see. I also see some what look like defects in the cylinder, that or I'm just seeing some odd reflections. can you get a better pic of the cylinder?
I see some scratches on the top of the piston, what is that from? they don't look deep, just odd to see. I also see some what look like defects in the cylinder, that or I'm just seeing some odd reflections. can you get a better pic of the cylinder?
BuckthornBonnie
ArboristSite Guru
Piston probably had carbon... he removed it and that’s the scratches/brush marks ya see.
Compression seems low but I never trust numbers posted here; wrong tester/valve or other issue could give incorrect comp number.
Good points above about motoseal— worth a quick pressure test to see if there are any bubbles around that gasket surface. Also go through the usuals and make sure everything is torqued correctly.
Compression seems low but I never trust numbers posted here; wrong tester/valve or other issue could give incorrect comp number.
Good points above about motoseal— worth a quick pressure test to see if there are any bubbles around that gasket surface. Also go through the usuals and make sure everything is torqued correctly.
decableguy2000
ArboristSite Guru
I would let the motoseall set up at least 24hrs before running.
spyder62
Addicted to ArboristSite
No expert here but l clean both mating surfaces spotless. Clean again with rubbing alcohol. Apply sealer . Tighten in a criss cross pattern and wait at least over nite
D
Deleted member 117362
Guest
+1, Have used it on many builds without and issue. I applied it to both base and cylinder, lightly, assembled and let sit overnight. Vacuumed checked and finished saw next day. Removing cylinder after using Motoseal can take a little effort, not like removing a cylinder with only gasket used. Use Motoseal and a gasket and it takes a good bump and pull to remove.
Huskitoter
ArboristSite Operative
It's so tempting to try it out instead of waiting overnight. I've only done one - piston change, ported, and gasket. That saw said "Crank me, Crank me..." all evening.
yes the piston had a decent amount of carbon on top and that's what I scratched off. I agree that I don't trust the numbers given by my compression tester. The saw has plenty and you can tell just by pulling on it.
both surfaces were cleaned rigorously with carb cleaner, then wiped off and sprayed with brake clean to remove anything else. I re-did the motoseal last night and I'm letting it sit for a day. torqued the bolts in crisscross pattern while incrementally applying more torque as I went around. I don't have a torque wrench but I did them as tight as I dare. squish is now .018.
The first time I applied the motoseal I mated both the surfaces but didn't torque them down until 20 mins later. I have since re-done the motoseal and torqued the bolts as soon as I got both surfaces together. now I'm letting it sit for about 20 hours
Andre is right - you shouldn't need to let Motoseal sit more than 20-30 seconds before mating the cylinder to the crankcase and you can start the engine within a few minutes.
Check your intake boot - I have seen a few of those with small tears.
Check your intake boot - I have seen a few of those with small tears.
SteveSr
Addicted to ArboristSite
I gave up on Motoseal on Stihl clamshell engines and switched to Dirko HT. Motoseal is not rated for gap filling and being non-hardening will eventually suck through any gaps leaving you with a big air leak. Luckily I found this out with a vac/pressure test so that no engine was damaged.
1. Clean that saw!
2. Don't put that stuff on like you are putting makeup on Tammy Fay. Very thin is best.
3 Clean out the pulse hole. It may have motoseal in it.
4. How about new carburetor innards?
5. Like JJ said check your boot.
2. Don't put that stuff on like you are putting makeup on Tammy Fay. Very thin is best.
3 Clean out the pulse hole. It may have motoseal in it.
4. How about new carburetor innards?
5. Like JJ said check your boot.
Motoseal is every bit as good as Dirko, IMHO, it's pretty much the same stuff. Motoseal does dry just like Dirko. I've actually seen Dirko leak a few times from the factory. Surface prep is the most important thing in getting the sealant to bond properly.
I figured it was do to carbon, I alway use something soft and wide so I don't scratch anything, not that what you did caused any harm. [emoji111]
No pulse hole on the mating surfaces, instead its located in the crankcase and runs a tube to the carb. I think I let the motoseal sit too long the first time before torquing. it takes about 2 mins to put all the motoseal on each piece nice and clean but I torqued the cylinder down as soon as I got it together. I'll fire it up soon and see what's changed
Chainsaw Jim
CJ Saws, LLC
I know this will rub a few the wrong way, but....
Motoseal is not anaerobic and despite what the directions may say, it requires curing time before mating the pieces together. It is a gasket maker, not a cylinder adhesive. Once it cures for at least a half hour you should be able to touch it without it sticking to your fingers. Are oem gaskets sticky? No.
Clean excess goop around the inside edges before mating the pieces or it can squeeze out and make contact with the piston at bdc. I can assure you that even after curing for a full 24 hours apart that it will still bond to the cylinder after the pieces are torqued. Don't ask me how many times I've had to scrape that **** off both the case and cylinder base and then finish with carb cleaner after this method of application, lol.
I have had air leaks more than 50% of the time when I stick them together wet, and I've pulled jugs after being torqued down longer than a week to find wet uncured material.
Motoseal is not anaerobic and despite what the directions may say, it requires curing time before mating the pieces together. It is a gasket maker, not a cylinder adhesive. Once it cures for at least a half hour you should be able to touch it without it sticking to your fingers. Are oem gaskets sticky? No.
Clean excess goop around the inside edges before mating the pieces or it can squeeze out and make contact with the piston at bdc. I can assure you that even after curing for a full 24 hours apart that it will still bond to the cylinder after the pieces are torqued. Don't ask me how many times I've had to scrape that **** off both the case and cylinder base and then finish with carb cleaner after this method of application, lol.
I have had air leaks more than 50% of the time when I stick them together wet, and I've pulled jugs after being torqued down longer than a week to find wet uncured material.
thanks for your help guys! I believe the problem has been solved. After redoing the motoseal and letting it sit for 18 hours I fired up my saw and she is running great! It's way louder too! the throttle response is intense and she pulls hard in the cut. I set the H and L both to 1.5 turns out and it's almost bang on perfect. It 4 strokes hard at WOT (limited coil) and burps nicely in the cut. I can feel the increase in torque, as well as the rpms sitting a little higher and being maintained better throughout the cut. I guess that's what an increase in compression gets you. once again thanks guys and we will see if any air leaks develope.
spyder62
Addicted to ArboristSite
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