Jug spacer plate.

[Nightbiker07]

ok, heres an oddity.

my stock jug has a spacer plate between it and the bottom end.
i am running a STOCK crank, and a STOCK rod.
if i put the jug on without the spacer, the piston pops out of the top of the jug about 4mm (the thickness of the spacer), causing the piston to crash into the head.

bottom line is that it NEEDS the spacer plate.
spacer plate is NOT purchased, it is homemade, as the craftsmanship is not good quality.

i am asking possibilities of why it needs it. heres what i came up with:
1. Bottom end has been milled, but it still has factory dimples in the surface.
2. bottom of jug has been milled, but again, does not appear to be molested.
3. Top of jug has been milled. not molested, but it doesn't look quite right to me.

i am hoping the cases have not been milled, because then i will have to use this ridiculous plate when i install my 300 kit.

[NINJA]

Nobody would do that unless it had a longrod. Sounds like you have a stroker on your hands.

[SYKO]

Nobody would do that unless it had a longrod. Sounds like you have a stroker on your hands.

I second that, not to many old school air cooled strokers out there, your knock that you described could be becouse of the stroker are you running 2 base gaskets? it may not have enough clearance.

[NINJA]

Good call Syko. I didn't think of that.

[Nightbiker07]

well its not a stroker. i promise.
i put a stock crank in it, from JSWINEHART, and bought a new stock vesrah rod kit.
i could understand if i jad just replaces the rod and the crank was stroked, or if i replaced the crank and the rod was longer, but i replaced both of them.

i know for a fact that the crank is now stock, and getting another rod NEW and it being the wrong part, but the proper size for the homemade spacer are very VERY slim.
stroker crossed my mind when i took it apart for the first time, but after seeing that piston pop out with stock crank and rod ruled that out in my mind.

[Nightbiker07]

and the knock isnt it crashing into the head, it doesnt start knocking until it runs. kicking it without the plug AND dragging it down the road without the plug produce no knock.

[SYKO]

ok what? all stock and dosnt work...... im baffled... you need to show us some detailed pics man something isnt right, do you have another 250 cyl to compare 2 to? im thinking possibly in someones infinate wisdom that the cylinder could be shaved? wtf?

[Nightbiker07]

that, and if it was crashing, the piston and head would show contact signs, which nor show any of.

[Tri-ZNate]

yep need pics

[Nightbiker07]

i dont have the ability to put up pics anytime soon . i do not have another stock jug to compare to either.
but even then, pics would not show a 4mm difference if it was shaved somewhere.

[NINJA]

Yeah, we're gonna need to see some pics now so we can help you out.

[KASEY]

pretty simple solution,,, measure the stroke,,,,,,,,, measure the old rod and the new one.. compare the two cranks,,,,,,,

[NINJA]

eeeerrrrrrrrrrrrrrrrrrrrr not, you posted before me.

[Nightbiker07]

well, that solution is not so simple. with the old crank/rod and the new stock crank, rod it has the same problem. this can only mean that the old balanced crank/rod combo have the same stroke as the stock crank/rod combo.

as i said before, the parts do not look molested, nor show swirls from a milling cutter.

pics wouldnt show such a small discrepancy. the case appears to be fine when i compare it to my other bottom end i aquired off ebay.

FORGOT TO MENTION THIS, but i compared the rod/crank to the one in the bottom end i got on ebay. appear to be exactly the same (yes, measured, same sizes lol)

the jug is 30 minutes away, and i have to borrow a camera to get pics

[Vealmonkey]

Usually strokercranks have shortened rods. You can usually tell a stroker rod by the fact it has been heated in the middle and actually squeezed together to shorten the rod. As far as the piston being taller than the cylinder, you would have to show a picture. A high compression piston will usually have the dome sitting farther up than the cylinder. If the flat sides are not above the cylinder and the dome is, you may have a high or higher compression pitson. On the piston itself, does it look like the piston is contacting the spark plug? Maybe you have the wrong heat range spark plug or the wrong spark plug period. Maybe you have a piston from a different machine. Pictures would definitely help.