Hitchcocks Forum

Hello all,
I am wondering if there is a way to judge if a conrod and/or crank is not true without splittling the cases?
I've got a '04 kick only Bullet that recently blew a gudgeon pin circlip and the gudgeon walked out and scored the bore. The damage wasn't too bad but a rebore and oversize piston are on order.
When I watch the conrod move when I roll the motor, it stays in line with the case seams and the big end is fine. The crank was rebuilt and balanced with a steel conrod and roller bearing 2 years and 13000 klm ago. A friend in the Enfield club here is telling me the crank is out of true because the gudgeon pin looks to have punched through the piston circlip, which indicates a sideways force. As I said, all my inspections seem to show the crank/conrod being fine but I don't want to disregard this gentleman's opinion.

Thanks

I am wondering how a conrod little end can grab a gudgeion pin and punch it sideways? Surely a little end grabbing the pin is a seizure? What is most likely is that the circlip was not fully seated at the rebuild and finally made a successful bid for freedom. As you say the rod is runnung true by observation, my opinion for what it is worth is that the bottom end is fine. Just make sure the circlips are seated before refitting barrel!

Thanks for your help. I was thinking the same, in fact, I had re-used the circlip when I decarbonized the piston and head several months ago. I have since learned it is not best practice to re-use circlips.
However, it is good to check these things just in case.

As per Beeza, If its a forged piston are you sure the right circlips fitted? Note Mr H says do not fit eyed or tanged clips on forged Omega pistons as an example..

I wouldn't know why and i wouldn't wish to find out so i do as he says..

Hi matey--------Sorry to hear about this but Cardinal Rule No.1 = Never re-use old gudgeon pin circlips ...Now you know why, eh ?.............How many miles does "several months ago" translate into ??..........Just out of interest, why did you remove the piston to do a de-coke ??...........When you get the opportunity put the old piston in a vice and try knocking the circlip out with a hammer and drift.......Those steel con-rods are "Tuff as old boot" but had that been an Aluminium one things might have been different..............Have a nice day !!

Hi Joe,
you are not telling all here, I have seen a pic of the piston, takes a lot of sideways force to bust the circlip area out of an Accralite piston as I have said, not the pistons fault, not the circlips fault so what else is left and I have seen a number do that and about 15,000ks seems about when they go, think Electras with bad cranks

Thank you all for the replies. However, as I asked.... without taking apart the whole engine just to check, is there a way to check the conrod/crank for straightness?

Nope

I would use a carpenter`s set square; yes, it is a rough and ready way
of checking. Then measure the distance to the connecting rod from each side of the crankcase to check if it is not offset to one side more than the other. Maybe there is a spacer or something missing or in the wrong place to have moved the crankshaft over to one side?

Here are some links to some photos and videos of the situation.

http://www.aussieenfields.com/aebb/Foru ... G_0299.JPG
http://www.aussieenfields.com/aebb/Foru ... G_0308.JPG
http://www.aussieenfields.com/aebb/Foru ... G_0329.JPG
https://www.youtube.com/watch?v=aS1HjToh4VI

Thank you all again for your time and advice.