I need to split the flywheels on my Royal Enfield WD/CO. Does anyone have any advice on how to do it. I will also need to press them back together again. I don’t have a press, but may buy one to do the job if it’s needed. I’m sure it will come in handy for other jobs, but what size would people recommend?
Tom I have split them with metal wedges, but much better with a press. (my small press is 10.000 psi). You need to support the upper wheel between heavy angle iron. After assembly the wheels and shafts have to run true to within a thou or two. So I entrust that to my engineer who has the proper equipment.
I think I will be stripping my CO engine again some time for scrutiny, as it still vibrates more than I'm happy with. It's already been statically balanced. Something needs re-checking though. :thinking_face: Ron
Hi Ron, I’ll give the wedges a try. If I struggle with that I’ll have to invest in a press. I’ve found a place that will dynamically balance the cranks, but they have to be supplied with the con rod removed and flywheels true to within 0.5 thousandth of an inch. The high compression pistons we have are only 7:1, which I didn’t think was that high? The G3WO is 6.3:1 as standard. My 6 cylinder TR6 engine was increased to 12:1 and I didn’t have any issues with vibration on that. But perhaps it’s not that simple?
I had my standard 6:1 WD/CO engine dynamically balanced and it was very smooth from what I can remember.
Tom I don't think it's the higher compression that throws out the balance, it's the higher weight of the new piston. From memory mine was over 3 onz heavier. My Engineer balanced the whole assembly statically. But it still vibrates too much for my liking, so I might have to start again.
I fitted one of those 7.1 pistons to my WD/G with no balancing and that bike is a joy to ride. So I'm wondering if there is something else out of true with my CO.
You will still have to assemble your crank absolutely true. I'll be interested to hear the outcome. Ron
You can split a crankshaft by using 5 or 6 pairs of short fine thread bolts with nuts.
The bolts need to be as long (pretty short!) as the gap between the cheeks.
Place the crank assembly horizontal (with shafts vertical) and insert the short bolts + nuts in between the cheeks.
criss cross unscrew the nuts and the flywheels will be pushed apart.
Thanks Vincent, I would never have thought to try something like that. Hopefully I’ll have some bolts help the right size to fit between the flywheels. I’m hoping to get the engine out and apart this weekend, I’ll let you all know how I get on.
Hello Tom, Ron,
I need to add that this method works very well with a tapered big end.
They come undone quickly once the initial contact of the tapers is broken.
If the crankpin is straight (like in a Ariel VH)you need two sets of bolts + nuts (short ones and a bit longer ones) to reach the whole distance.
Succes.
It already exsist : https://www.holmatro.com/de/industriell/spreizer-isu-20-st
I think you need at least two of them, that might be a bit costly ?
:smiley:
No problem Ron, I’ll keep you posted. The last WD/CO Crank I had dynamically balanced before was very smooth. But the first crank I gave them wasn’t suitable, as the crank halves that came out of the engine weren’t a pair and wouldn’t true properly. Perhaps one of your crank halves is out of tolerance? Watch this space...
