kinetic crank bearings

Steamboat Aka J. R. Stevens /

My TFR(USA) parts manual say the crank has ball bearings. I have not seen this before, is this good or bad? comments please. jim

Re: kinetic crank bearings

hey

if i am not mistaken isnt a TFR a vespa knockoff.

if so the engine has 2 main ball bearings...one for each side of the crank

they are easily replaced. my vespa moped takes size 6202

bearings, about 8 dollars apiece.

you know theyre going out if your ped has a low rumble at idle or crawls across the garage floor slowly when its on

its centerstand idling

leo

Re: kinetic crank bearings

I would think this is good. Puch engines use them.

kinetic crank bearings

What other kind of bearing would you expect? Ball bearings are the standard for mopeds...do they use a different type in other vehicles?

Re: kinetic crank bearings

Steamboat Aka J. R. Stevens /

I expected to see brass inserts. What type of rod bearings do mopeds use?jim

Re: kinetic crank bearings

John Joedicke /

Hopefully needle bearing

Re: kinetic crank bearings

Yes, from the service manuals that I have read so far, they use needle bearing on the big and small end of the rod. The ball bearings are on each side of the crank next to the seals.

Re: kinetic crank bearings

Steamboat Aka J. R. Stevens /

My kinetic uses bronze on the small end I think the crank, rod and rod bearing must come as a package. comments please. jim

Re: kinetic crank bearings

Richard Wisniewski /

dude take the bearing into a bearing manufacture and they will have what you need talk to a old guy. These moped bearings are all normal sizes.

Re: kinetic crank bearings

Steamboat Aka J. R. Stevens /

Hey dude, I was asking a technical question, not where I could get them.jim

Re: kinetic crank bearings

Well, if that is what the engineers design there I do not think you would be able to replace it with a ball bearing. Most bronze bushing are smaller in total diameter and only have a 1/8 inch wall thickness. Bearings have a larger OD, (Outside Dia.) for the same corresponding ID, (Inside Dia.) size. The casing boss probably does not have enough material to be able to machine it out for the bigger diameter roller bearing. You may be able to replace it with a needle bearing, depending on where you are placing it.

Re: kinetic crank bearings

Steamboat Aka J. R. Stevens /

Thanks Pepied, I have lots of experience with 4-stroke auto engines but I have never been inside a 2-troke.I have not seen an auto engine with ball or needle bearings, always brass inserts.It seems strange that Kinetic would use ball bearings on the crank ends and brass inserts on the small end of the rod. Comments please.jim

Re: kinetic crank bearings

hey man

they use ball bearings in 2 stroke engines because the oil you mix with the gas lubes the bearings. in a 4 stroke the crankcase is closed off from the combustion chamber and so can run in its own oil bath which is clean and separate

not so with a 2 stroke. bearings are always exposed to the fuel mixture because of the design. instead of valves like a 4 stroke the piston is the valve in a 2 stroke.

the bearing in the small end can be either roller or bronze bushing, either way it works

Re: kinetic crank bearings

Larry Picarello /

considering the price , I'm suprised it has bearings at all

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