how much pinch at TDC does your engine have
 

guys at what point is a piston & sleeve classed as worn out...with the (glow plug out) i know when turning the flywheel over with your finger at TDC there should be some resistance, like a notchy feel at TDC....or is a sleeve & piston still classed as good when there is no resistance at TDC.i know this is a buggy forum and will be buying one during the year.i recently purchase a new a traxxas jato and was using 20% AT Racing premixed fuel distributed by VP Racing.i almost used a gallon of this fuel and with glow plug out the engine had very good pinch (notchy) at TDC.i then decided to make my own home brew:eek:....using fresh nitro and methanol from my hobby shop i made a litre...my mix was 650ml methanol...200ml nitro.....150ml of maxima 927.i know maxima 927 is ment for motocross bikes but with it being well known as a quality oil i thought i give it a go.after going through two tanks i took the glow plug out and the pinch had gone.[&o].ive kept using the home brew and there has been no more loss of compression...and the engine still performs excellent.though i wont be using home brew when i get my new buggy.

also on average how much fuel can you go through until you lose that pinch at TDC with (glow plug out)

RE: how much pinch at TDC does your engine have
 

check the pinch while the glow plug is in the engine not when its out the engine

RE: how much pinch at TDC does your engine have
 

thanks jextel for your reply,

there is still good compression in the engine with the glow plug in,but before i started using home brew there was alot more compression and it was very hard to turn over the flywheel with my index finger.i would still like to hear from anyone who has 1-2 gallons or more of fuel through there engine and still have pinch at TDC with the (glow plug out)

RE: how much pinch at TDC does your engine have
 

Here is a good method for checking compression.
With the engine removed, glow plug and flywheel installed,put a few drops of ARO in the exhaust port and turn the engine over a few times. Then spin the flywheel till you feel the beginning of the compression stroke, hold the engine by the flywheel with the cooling head 90 degrees (perpendicular) to the ground, time how long it takes for the weight of the engine to turn through the compression stroke and the cooling head is pointing at the ground.
Anything less than 10 seconds for this to occur means your engine is on its way out.

This is a much more comprehensive method of checking the overall compression than checking the engines pinch at TDC...some engines have a taper pinch while others use a straight pinch, engines with a straight pinch will feel like the pinch is gone while they still have good compression.

RE: how much pinch at TDC does your engine have
 

thanks scrapheep for the tip,

i will try it next time my engines out.i am not familar with ARO oil,who makes it.
i am sure my sleeve is tapered.

can someone give feedback on there engine using the finger test on there flywheel (glow plug out)

thanks.

RE: how much pinch at TDC does your engine have
 

ARO = After Run Oil

ARO is a must after weekly used.
if you didn't use any ARO to your engine, and about to ran 1 gallon or more then you're in way out.

compare it with other engine compresion.
if you think it still perform great and why you ask about compresion. that thing will kill you. just enjoy it and take care of your engine

RE: how much pinch at TDC does your engine have
 

that is the stupidest thing ive ever heard...so what what your saying is your engines compression is directly proportional to its weight.....lol.....

id say the best method is to use a compression guage

RE: how much pinch at TDC does your engine have
 

again "stupid" what about those of us that use sidewinder fuel...it says right on the bottle to not use afterrun oil after your done running

RE: how much pinch at TDC does your engine have
 

just outta curiosity, whats tdc?

RE: how much pinch at TDC does your engine have
 

top dead center

RE: how much pinch at TDC does your engine have
 

LOL Motopro...you dont have room to go around calling other people stupid.
As a matter of fact YES your engines compression is directly proportional to its weight and the specific amount of time it takes for the engines weight (ALWAYS CONSISTENT) to cycle through the compression stroke.
Hell the old finger on the flywheel trick is more accurate than your compression gauge...but I can verify the accuracy of my stopwatch.

RE: how much pinch at TDC does your engine have
 

lol stupid is as stupid does lol

RE: how much pinch at TDC does your engine have
 

Compression gauge should read 4 to 6 PSI at TDC and hold the compression, if you notice the PSI reading slip down then you have a problem. the engine will still run but not without flame out..

The engine weight method is crude but very effective and is widely used. as stated by Scrapheep

The other method is to just run the engine till it dont wanna run no more that the best way unless you are racing and need a reliable motor..

RE: how much pinch at TDC does your engine have
 

it seems that you enjoy to call other ppl stupid [:@] [:@]

i wasn't talking about other ppl that use sidewinder. but i was talking about this man and this man need to be helped (not to be called stupid ????)

THX any way
it seems that this forum isn't really usefull again.

RE: how much pinch at TDC does your engine have
 

nobody realises that Motopro's aviatar is an actual likeness ..

RE: how much pinch at TDC does your engine have
 

A motor is perfect when there is compression with the glow plug in, and should basically feel no resistance at TDC with the glow plug out. Generally this will occur around the 1 gallon mark (on Novarossi motors). When the motor will not hold a tune, or stalls when it heats up, that's when it is time to get a new motor.

RE: how much pinch at TDC does your engine have
 

ya know motopro, I never saw the posts you make that everyone gets on your ass about but those 2 above just go to show your ignorance......
please bless us w/ some jems of wisdom or STFU!!!!
CHAZZZ if this is the stock 2.5 mill you may have done it in.....don't try to rebuild it just run it into the ground.....they make really unique lookin paperweights.....but just suck as an engine....

RE: how much pinch at TDC does your engine have
 

atleast i can spell you have 2 mis spellings in your post and one in your signature....lol.......i never called anyone stupid i called the other guys method of checking compression stupid.....HUGE DIFFERENCE...... as far as myself being stupid well i do do stupid things from time to time and i certainly say a few stupid things but rest assured when it comes to nitro motors im no idiot.....

RE: how much pinch at TDC does your engine have
 

actually i bet you dont even realize(realise) who my avitar(aviatar) is....dont sweat it its a mid 70's american thing probably hsaent caught up down under just yet

RE: how much pinch at TDC does your engine have
 

I always thought when there is no pinch with glow plug out it is properly brok in and ready to race. I personnaly think u are fine. the 2.5 is hard to tune but once u get used to it, it works fine. I had mine repinched and it came back with way more power than what it went in with. same rod, carb and everything. the only thing I did was have it repinched. costs 15 bucks great deal. when the motor does give out give it a try. save 100 bucks from getting a whole new engine. 2.5 has power just hard to tune.

RE: how much pinch at TDC does your engine have
 

yeah we dont read Mad down here we are still trying to catch up with the 50's o ris it the 40's

RE: how much pinch at TDC does your engine have
 

thanks everybody for your help & replys

i think netmaster hit the nail on the head with his reply..and i also think i have been a bit to fussy about the pinch...even a friend pointed that out...and xrichs philosophy sums it all up...(that thing will kill you)