Good advice. But not everyone who needs a re-ring needs a bore and hone and wrist pin bearing either. Some folks re-ring as a preventative maintenance program (I get your point, obviously not this guy) just to freshen things up and unless there is evidence of a problem with the wrist pin bearing, there's no need to crack the wrist pin circlips for it. The only way to know for sure is to measure and inspect.
Low Compression???
- Thread starter lukewozniak2000
- Start date
Good advice. But not everyone who needs a re-ring needs a bore and hone and wrist pin bearing either. Some folks re-ring as a preventative maintenance program (I get your point, obviously not this guy) just to freshen things up and unless there is evidence of a problem with the wrist pin bearing, there's no need to crack the wrist pin circlips for it. The only way to know for sure is to measure and inspect.
It comes from 20 years of engine building PROPERLY
its simple math really.
you dont find the actuall recommended compression specs in most manuals because there are so many things that can affect the base compression numbers.
The Blaster's Base UCCR 9.84:1 = 135 psi
thats on paper in real life you lookin at 125-130.
did you ever stop and thingk..gee why do so many people have broken and exploding pistons in the blaster engine? because they think 110 psi is ok to run.
I tell everyone test the compression during break in... thats where it will be the highest and 125+ is normal up to 135 in some cases depending on gaskets and pistons used etc.
If you build an engine with tight specs... .002" clearance and .008" ring end gap you will have a much higher compression engine then one with a .003" clearance and .016" ring end gap. Thats pure FACT.
Most quality engine builders will machine the cylinder then hone in the crosshatch to the .002" for the best performance. less quality shops will bore it to .002 then hone the cylinder.
each ti thier own but if people would stop running their engines at such low compression we would see a LOT LESS busted pistons
its simple math really.
you dont find the actuall recommended compression specs in most manuals because there are so many things that can affect the base compression numbers.
The Blaster's Base UCCR 9.84:1 = 135 psi
thats on paper in real life you lookin at 125-130.
did you ever stop and thingk..gee why do so many people have broken and exploding pistons in the blaster engine? because they think 110 psi is ok to run.
I tell everyone test the compression during break in... thats where it will be the highest and 125+ is normal up to 135 in some cases depending on gaskets and pistons used etc.
If you build an engine with tight specs... .002" clearance and .008" ring end gap you will have a much higher compression engine then one with a .003" clearance and .016" ring end gap. Thats pure FACT.
Most quality engine builders will machine the cylinder then hone in the crosshatch to the .002" for the best performance. less quality shops will bore it to .002 then hone the cylinder.
each ti thier own but if people would stop running their engines at such low compression we would see a LOT LESS busted pistons
I agree.
Im not sayin they have to change it, but they do have to inspect it. personally I dont do any top end work writhout replacing the top end bearing.
My point to everyone is I dont believe in halfazzed repairs... as a mechanic I cant afford to gamble with customers engines like that. It can give you a really bad reputation really quick.
clips, pins and breaings are dirt cheap. (Aprox $25-$30)
There is no point taking the cylinder off and replacing or even inspecting 1/2 of the suspected worn parts.
Do it all.
Thats why most piston kits come with new bearing and pin.
95% of the time if the rings are worn from high use or poor oil etc the bearing and pin are worn to. If not at least you know.
The rod is a stronger steel, but a quick check will let you know. People dont realize the stress on that tiny bearing.., they always think the piston does all the work, but they dont realize all the force from the combustion to put that power to the wheels is up to that one tiny bearing.
Ive watched several videos on this site... the rattling and knocking of some of these engines makes me cringe... they sound aweful. Sure all blasters are loud lil engines but WOW... people dont even realize when they have crank, rod and CB issues until its too late.
Whenever I re-ring I get my mirror out and look for any discoloration around the small end of the rod and pull on the piston while holding the rod to see if there is any movement. I also use a small screwdriver to push on the wrist pin and make sure it's can slide from end to end inside the wrist pin bearing (not gummed up or starting to sieze). If it passes that check, it's good for another go 'round.
Of course this isn't a customer's engine either. If it were a customer's engine I would replace the wrist pin bearing too but for most of the blaster owners out there a thorough check-out is all that's needed, not necessarily replacement every time.
Of course this isn't a customer's engine either. If it were a customer's engine I would replace the wrist pin bearing too but for most of the blaster owners out there a thorough check-out is all that's needed, not necessarily replacement every time.
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