Crank

[sporty982000]

If some of you have been following my blaster pic and post.

I got the flywheel off today, and got the cases split.

I had previously, mentioned, its a hot rod crank. and might be a stroker.

Here our some pictures, the lower rod bearings are toast. but one thrust washer is still there and not saying its any good.

But it led me to look at the cases when I took them apart. I noticed groove in case, from the crank.

I put the crank back in and seen that the thrust washers were touching the bottom of the case. thats what caused the groove.

Which leads me to think this is a stroker ????

And they did not adjust or remove material for clearances ..

So let me know, if you think I am correct in my assumption.

here is pictures

One of the bearings is still on the rod . Do you think I should try heating it to get it off ? Best tip on removing the bearing from the crank ?

Sporty

 

[JonS]

damn! that's definitely a 4mil. doesn't appear that they trenched it before hand, but it's hard to tell from my crappy computer screen. yikes!

 

[frankin blaster]

congrats on the nice find for a paintball gun and with getting a 4mil crank with it...sucks they didnt do it correct the first time but hey not everyone reads up on things thats why people sell more parts lol that blasty would have been a perfect parts bike for me since i need new a-arms and i already have the 03+ spindles i could have bolted them right up

 

[sporty982000]

Thanks,

Yes, what to do, so you think its a stroker.

I have had a offer of to swap it as is, for a working stock and rod and crankshaft.

But not sure what to do. or what it would cost to get the hot rod fixed.

Sporty

 

[OConnor Racing]

That’s a +4 stroker crankshaft. All you need to do to repair it is have a new rod, pin, bearing and washers installed. Pro-X, Vesera or OEM rods are all good choices. You’ll need to have the cases properly trenched if you decide to run that crankshaft. Trenching should be done with a mill and not a die grinder. We remove 3mm from the inside of the case with a Bridgeport. You’ll also want to check the squish and have it set to .055. Compression should be no higher than 180 PSI when you’re finished. You can remove that bearing with a press and a clamshell puller. Another option is to heat a piece of pipe and place it on the inner race of the bearing, then use a chisel to tap it off. The crank is going to need to be rebuilt no matter what and the removal of that main bearing should be part of the job.

 

[frankin blaster]

i would say from the trench from the crank sheering away at the case its for sure a stroker... to rebuild it all you have to do is look for a bottom rod bearing and remove to c clips and should slide right out... now since it show's sighns of over heating due to rubbing against the case it may be a little harder to get it to slide out im sure your going to but not positive of this but since you have it open i would do new everything bearing and seal wise that is if you have the funds to do so

 

[Awk08]

not sure what "clips" are mentioned above, but there are none on a 2 stroke crank, a press is required,

not a blaster crank, but similar principle and procedure.........

edit: found kens blaster crank rebuild vid on here........

http://www.blasterforum.com/engine-13/crank-rebuild-vid-28898/

 

[joeak47]

i would say from the trench from the crank sheering away at the case its for sure a stroker... to rebuild it all you have to do is look for a bottom rod bearing and remove to c clips and should slide right out... now since it show's sighns of over heating due to rubbing against the case it may be a little harder to get it to slide out im sure your going to but not positive of this but since you have it open i would do new everything bearing and seal wise that is if you have the funds to do so

Thats not signs of over heating either. Thats the heat treatment.

 

[frankin blaster]

not sure what "clips" are mentioned above, but there are none on a 2 stroke crank, a press is required,

not a blaster crank, but similar principle and procedure.........

edit: found kens blaster crank rebuild vid on here........

my bad i thought i had removed two c clips like the one that hold your wrist pin in on my crank on my rm125 but went back and looked at my pics and was wrong

 

[Blaaster]

Thats not signs of over heating either. Thats the heat treatment.

I beg to differ, that is sure signs of a toasted crank pin, and rod, and not heat treatment.

The crank pin bearing has picked up schrapnel and it has caused failure.

Without actually measuring the rod is hard to say if it is a + size that has caused the problem.

This is a classic example, that this problem may have been caused by a previous piston which has dropped its skirt and the cases have not been split to remove all the debris.

The pic of the crank pin assembly shows no roller bearings, this could have caused the overheating.

With no disrepect to Ken, but I would shy away from reusing the crankshaft.

 

[OConnor Racing]

A stroker crankshaft and a stock stroke both have the same center to center rod length. The rods are identical with the exception of the Vito’s rod. The Vito’s rod has a smaller big end diameter. This is why you don’t have to trench cases for the +3 crank they sell. The longer stroke is from the pin being 2mm farther away from the centerline of the shaft. If you look at the pin in the picture, you can see how it’s moved farther into the outside of the web. The crankshaft is definitely a +4. The heat marks on the webs are nothing to worry about. This is done at the factory to aid in assembly. We see it all the time.

 

[Blaaster]

Thanks Ken, I was more concerned about the heating of the rod, I would have tossed the crank out as well..

A stroker crankshaft and a stock stroke both have the same center to center rod length. .

And stuff me I knew that, I did not put my brain into gear before my finger hit the keyboard.

Nearly 70 and still learning.

 

[little3mil]

some good info in this thread! thanks Ken!

 

[sporty982000]

A stroker crankshaft and a stock stroke both have the same center to center rod length. The rods are identical with the exception of the Vito’s rod. The Vito’s rod has a smaller big end diameter. This is why you don’t have to trench cases for the +3 crank they sell. The longer stroke is from the pin being 2mm farther away from the centerline of the shaft. If you look at the pin in the picture, you can see how it’s moved farther into the outside of the web. The crankshaft is definitely a +4. The heat marks on the webs are nothing to worry about. This is done at the factory to aid in assembly. We see it all the time.

Thanks ken for the reply and info and help.

Thank you,

Sporty

 

[Triplecrown421]

Thats not signs of over heating either. Thats the heat treatment.

I beg to differ, that is sure signs of a toasted crank pin, and rod, and not heat treatment.

The heat marks on the webs are nothing to worry about. This is done at the factory to aid in assembly. We see it all the time.

lol i have like 4 spare used cranks all with these heat signs on them just as bad as the pics above....... i planned to re-use them if needed