Connecting Rod Issue - Help Needed

[UK Ben]

Hi all. Just rebuilt my 1991 CR 500 with genuine Honda connecting rod kit. Pressed pin level with flywheel however side play was excessive.

Pin and Rod are the same size, I must therefore assume the thrust washers are thinner (can't measure now crank is together). Or these 500’s run with lots of side play.

Decided to press to 0.0018, needless to say pin would then hit main bearing and therefore forced to remove excess from pin. Put back together and all looks great, however now the bike will not rev out. Sounds like motor is retarded i.e flat, getting hot quickly, not revving. Swapped entire electronics with spare bike, same issue.

I noticed the ignition pickup (the small one at the top) is now slightly offset with the magnet on the generator. Caused by now narrower flywheel assembly which is pulled towards main gear.

My questions are:-
Has anyone come across any of this before with genuine Honda parts?
What side float is recommend on the connecting rod?
Does the ignition sensor impact timing advance at higher RPM?

[Roostius_Maximus]

Has anyone come across any of this before with genuine Honda parts?
NO

What side float is recommend on the connecting rod?
It can be lots, i've run them double oe spec on side clearence without trouble

Does the ignition sensor impact timing advance at higher RPM?
deffinately

[UK Ben]

Thanks. I will try to replicate the fault on my spare bike by packing the sensor out with a thin washer. If this turn out to be problem I can then modify the stator plate or strip the engine and increase the side clearance.

[dannygraves]

side play isn't an issue, axial play is.

[UK Ben]

Update. Swapped all the electrics and carb from spare bike however still flat and poor starting. Shaved stator plate to bring ignition pickup inline, no joy there either. Friend has spare crank, will give this a try this evening. I can only assume the flywheel assembly being 0.050 narrow is impacting the power source some how. All very strange. If this doesn't work not sure where to go next.

[bodger]

Do you still have a note of the connecting rod part number, if so post it up?

The reason for asking is that you say you used honda parts but as far as I know honda never supplied the conrod kit for the 1990’s engines, they only offered the full crank assembly. (maybe someone can correct me)

However they did supply for 1984 to 1986 engines with the short rod, so are you sure the piston came up far enough in the cylinder.



bodger




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