intek engine ring gap

jimmyw

Hi,the diameter of the above 17.5 hp lawnmower engine is 3.5 inch diameter,what should the new piston ring end gaps be?

I am getting a measurement of 0.018 inches??

gctest50

is it a Vtwin ? manual for one of them attached

jimmyw

No,its a single cylinder engine. I may have measured it wrong as I am getting now between 0.010-14 roughly.

gctest50

might find a few useful bits in this :

http://web.missouri.edu/~schumacherl/276781SingleCylinderOHV.pdf

jimmyw

gctest50 wrote: »

might find a few useful bits in this :

http://web.missouri.edu/~schumacherl/276781SingleCylinderOHV.pdf

Wow, alot of info there, cheers.

jimmyw

This intek engine is back together again.Only issue so far is with the compression in the engine is too high.The motor wont turn it over.There is an automatic compression release on this engine that was working (springing back and forth) when the cam was removed, but is there a way of checking if its working?

I set the valves correctly I believe by setting the piston on TDC, and then moving the piston back down the cylinder by 6mm, and then setting the clearances.

Could it be the motor is not turning it fast enough? I can turn the flywheel with the plug in with a ratchet using one hand including on the compression cycles.

https://www.youtube.com/watch?v=gZkCy53mE1U

https://www.youtube.com/watch?v=oshpuqrn2GA

fox0512

Hi

Did you hone or bore cylinder and increase ring size?...if not orig size is fine....the 17.5 intek engines are prone to cam lobe premature wear and valve guide movement and both can effect compression release depending on model...the compression release can be seen in slight movement at the valve om compression stroke...

fox0512

Forgot to add...test your battery under load (Multimeter)...if your batt is bad under load it may appear that you may have to much compression...any reading under 9v when you turn key is a fail..

jimmyw

fox0512 wrote: »

Hi

Did you hone or bore cylinder and increase ring size?...if not orig size is fine....the 17.5 intek engines are prone to cam lobe premature wear and valve guide movement and both can effect compression release depending on model...the compression release can be seen in slight movement at the valve om compression stroke...

No,I didnt bore out the cylinder as it looked totally unworn with no damage
The lobes looked Ok too,so apart from honing and new piston and rings,nothing else was done. Am I right in thinking that the release device works on the lower valve with the aluminium rod which is the inlet valve?

The spring loaded device rides on the cam follower slightly ahead of the cam lobe to operate the release mechanism?

jimmyw

fox0512 wrote: »

Forgot to add...test your battery under load (Multimeter)...if your batt is bad under load it may appear that you may have to much compression...any reading under 9v when you turn key is a fail..

I never thought of checking the battery under load,forgot about it.

By the way, the old piston rings on the old piston were jammed in deep in the grooves solidly. There was no way they were going to move,but she still had compression?:-(.

fox0512

Reckon your compression release is just fine...once it springs back when you checked it.....if you dont have a multimeter just jump from car...just connect neg to you car first and then to the oil drain bolt etc...then you red lead to car batt and directly to the starter...if she fires up, you have your answer...let me know how it goes...other than that it just sounds like valve adjustment issues..

fox0512

jimmyw wrote: »

No,I didnt bore out the cylinder as it looked totally unworn with no damage
The lobes looked Ok too,so apart from honing and new piston and rings,nothing else was done. Am I right in thinking that the release device works on the lower valve with the aluminium rod which is the inlet valve?

The spring loaded device rides on the cam follower slightly ahead of the cam lobe to operate the release mechanism?

Yes thats correct...i never had an issue with one to date... once its checked and it springs back by its own accord its fine...

fox0512

....lol, again for got to add!!... now that you have fresh rings in there you will have bags of compression and this might be to much to handle on a batt that has some work hours on it...batt will work ok on engine with lower compression if you follow..

fox0512

jimmyw wrote: »

I never thought of checking the battery under load,forgot about it.

By the way, the old piston rings on the old piston were jammed in deep in the grooves solidly. There was no way they were going to move,but she still had compression?:-(.

I am curious tho why those rings were jammed in that old piston..possible overheat?...no oil slinger issues in sump?....

Twice a year and at the start of cutting season I advise folks to remove engine cover and clean grass or mouse nest away from engine fins...if clogged up will cause overheating..

jimmyw

fox0512 wrote: »

Reckon your compression release is just fine...once it springs back when you checked it.....if you dont have a multimeter just jump from car...just connect neg to you car first and then to the oil drain bolt etc...then you red lead to car batt and directly to the starter...if she fires up, you have your answer...let me know how it goes...other than that it just sounds like valve adjustment issues..

Thanks,yes I have a multimeter I will check it later after I have charged up my power pack. I may have to use a jump from a car too if need be,but need to check the volts first.

jimmyw

I put the car battery on it with the jump leads,and it's taking 6-7 volts with the spark plugs removed,and about 3-5 with them in so that's not right.I wonder if the motor is at fault possibly?

jimmyw

fox0512 wrote: »

I am curious tho why those rings were jammed in that old piston..possible overheat?...no oil slinger issues in sump?....

Twice a year and at the start of cutting season I advise folks to remove engine cover and clean grass or mouse nest away from engine fins...if clogged up will cause overheating..

The reason the engine had to be stripped was that the engine started blowing out oil through the breather,and it would only run at full revs. The reason for the high speed?.......the screws loosened from the throttle plate and fell into the engine and pot marked the piston and head but as I said previously,no damage to the bores

I am not using the mower battery,but a power pack and a car battery. I have the motor apart and I will give it a clean up and lub a little. The brushes don't look all that worn. I have cleaned up the mounting bracket of it already.

When I took off the motor and put it on the batt,my meter read about 10volts.

fox0512

Did you put your positive lead straight to starter???...if your car batt is in good condition and starter is receiving 12v then its a compression/timing issue....

fox0512

When I have this issue I check mower batt first under load...if batt dips low when u crank over I go straight to starter...I will check that the batt Im jumping off (if disconnected from car) is also not dipping low under load....if this batt is ok and it wont turn over then I know for def its a weak starter motor or timing issues...apologies if im repeating myself

When I jump I will come straight from Car when running... ya not supposed to do this i know lol...

fox0512

Any batt giving a reading of 4 5 6 7v will not be strong enough to run starter

jimmyw

These are the voltages, the motor is drawing 10 volts with no load at all, 6-7 when turning the engine with the plug out, and 3-5 with the plug in.

fox0512

ok...batt/s are wrecked...

jimmyw

fox0512 wrote: »

ok...batt/s are wrecked...

.......................or leads? Car engine was running on one test too.

fox0512

hmmmm.. possible if they damage somewhere or bad ground... if there is compression or starter issues your healthy batt should still read 10v ish under load with plug in etc....if you jump from car i would first check the car batt underload and if its given you 10+V and you do a live jump then u know 100% its timing or starter issues...personally I dont rely on booster starter packs etc....i come straight from a live batt in car and that cures any doubt...saying that my car is not a fancy nancy with a million circuits and fuses stuck to the battery like a fiat stilo ...so I can live jump as much as I like!!.... but FACT, you give that starter 12v and it doesnt crank an engine with no timing or other issues,the starter is fried...and if you can turn her over with both hands flat on flywheel cover (clockwise) passed TDC on compression stroke you can be confident there is no compression issue...

jimmyw

I had the car engine running at 14 volts, jumped onto the starter terminal, earth the other jump to a bolt on the mower engine along with my meter,and 3-5 volts I got with the plug in


So its breaking down either at the leads, or motor.

fox0512

Right.... Sorry wasnt 100% if you had full V and direct to starter... well, at this point what I would do given you have 14v at car batt is to check what V you have at other end of positive lead on its own (not connected to starter) and then connected to + terminal on another batt ...if you have a V drop the lead is the problem...hope u get it sorted....scratching my head here!!! they could be problems in starter motor creating v drop so thats why I would check lead free first..

jimmyw

Well I actually tested the 14 volts at the starter end of the cable.

I took apart the motor and I will clean it up lightly and maybe put some grease on the shaft, but it looks ok generally.I would have thought that the magnets would have been the electromagnetic type instead of the permanent type though.

fox0512

Best of luck... let me know when results are in!! ....now the start of chainsaw season top end to do on a husky...nice change from wrestling with ride ons all summer!

jimmyw

thank you

fox0512

no worries but I prob added to the confusion!

jimmyw

Ah no, very helpful.I have a suspicion my jump leads are not great, they only cost 10 quid a few years ago.:D;)