Forum

[Cranky]

You got to be kidding me. I took off the head and this huge piston was looking at me. It wobbled side to side like a sausage in a shirt sleeve. I mean its only done 5,100KM.

2017 500 UCE EFI (used to be)

Its been clancking for a while with a clonking when pulling hard up the drive. I always thought piston slap went away when hot--well this dont , it gets worse. It was embarrassing at the lights but did not smoke,--clank clank.

Plus a wirring bearing kinda noise from the case.

Im gonna pull out the whole lot and start again.

Theres a great shop in Siricha that does pistons --probably an Isuzu diesel --what ever matches the Gudgeon pin to the crown ,-- Ille bore it to fit .

Hey maybe have a UCE 550 next week.

The crank pin allignment is critical, if its not then the con rod tends to slap the the end of its travel on the crank pin .

The crank pin is just pushed in and allignment is some times not taken too much interest in the heat of the Chennai day.

Be a while but ille be back.

[Adrian]

Standard bore on these is 84mm, the CGT 535 is 87mm (90 mm stroke in both cases), piston skirt to bore clearance fore and aft is, I believe, somewhere in the order of 4.5 to 5 thou (metric =?) for a cast alloy piston this size, though some of our hosts' forged alloy pistons need a little more. The very similar Electra-X piston weighs about 400g complete. Gudgeon pin diameter 20mm.

Assuming you haven't got a cooked big-end you could also check for a loose crankshaft or gearbox drive sprocket.

A.

[Rattlebattle]

It seems to me, Cranky, that you have a C5 citrus, as do I. I think you’ll find that the piston itself isn’t the issue; it’s the crankshaft. You may also find that the timing side main bearing is in fact ok. Mine was, though I replaced it. Although my crankshaft was deemed to be ok by an engineer friend, I have reached the conclusion that, in fact, the side play was caused by failure at the factory to fit the crankpin absolutely squarely. My engine was fine for about 3,500 miles, when it suddenly became rough. I now believe that this was caused by the misaligned crankpin causing sideways wear on the big end. This in turn caused wear in the piston/ rings, detectable by less compression, oily residue in the air box and and audible click at each end of the stroke when slowly kicking it over. The whirring that my engine also had was, I believe, caused by the generator windings touching the rotor. I found an odd bit of material when doing an oil change; it was a piece of insulating material off the windings.
Having put it all back together with new bearings I am now faced with the prospect of having to do it all again to replace the big end or crankshaft. The whirring has returned and the vibration is terrible. I’m currently considering my options: flog it as in need of repair, dig a hole and bury it after riding it until it blows up or do the crank and risk even more money being wasted on what is without doubt the worst new bike I’ve ever owned. It seems to me that, certainly back in 2015, they just threw the bikes together. Maybe as mine was a limited edition not available on the home market despite demand, the workers thought sod it and took their revenge...Good luck. Do report back. BTW I believe Harald is also a member of the C5 citrus owner’s club.

[Cranky]

Oh dear --Well I now have mine totally apart washed and cleaned. The piston is a terrible fit and yet shows no wear. The skirt seems ok but the land( the top of the piston where the rings are) is about 0.45mm slop in the bore, I think its just badly machined, if I hold it up to the light I can see daylight past the piston, without rings of course.

Ring gap is about 1mm.

Big end seems ok, not much side play or side movement -im going to leave it.

Im impressed with the machining of the engine cases though and is nicely cast. The clutch spring tool which I don't have is a pain in the arse though, shall have to make something from a G clamp.

Crank chain sprocket was tight, I had that off a month ago and I lock tighted it. Shall be assembling very carefully taking care with side play.

It took me a while to investigate where the cast spacer went that tinckled to the bottom of the case when I was easing them apart. This silly thing is shamfered to fit in the case of the layshaft bearing. What a stupid Idea is that. If its not held in place by grease on re assembly in its correct position the cases wont be able to meet. Oh and that silly starter gear shaft that you cant assemble till the two cases are together

The timing side crank bearing is a needle 30x45x20 im going to replace that , it seems a bit swishy and its made in Chekoslovakia as is all of them I suppose and this is where RE lets themselves down, a poor product that could be better with just a bit of care.

Like you Rattlebattle this is its last chance. If its no quietened down its going on the internet

[Rattlebattle]

Not sure what you mean about the clutch, unless you mean you don’t have a puller. The plates can easily be removed by taking out two of the four bolts and replacing them with the longer primary chaincase bolts to relieve the pressure exerted by the springs.
Czech bearings are good. Mine was swishy but so is the replacement. It’s the cheap Indian sourced fakes that RE seemed to use at times - my gearbox output bearing was toast. Still, it had done 6500 miles...The piston is surprisingly short-skirted for such a pedestrian engine. The motor really is an unusual design altogether.
Yes, there is a lot that is good in these engines but they can be let down by poor assembly and/ or sub-standard bearings.
I won’t decide what to do with mine until later in the year as I need to have garage space to have a new door fitted and I don’t want the RE in bits when the work is carried out.
Good luck.

[Haggis]

Yòu don't need to open up the clutch pack.
Unless your wanting to replace the plates, just undo the centre nut and the whole clutch pack lifts out.
No pullers required.
There was a similar story with a bike, think it was in Colombia.
Piston to bore clearance was huge, just like yours, with no sign off any actual wear.

[Rattlebattle]

Yes, that’s right. My mistake, puller needed for rotor. I had a look at my plates while I was in there. They were fine. My piston was ok really, just a slight scuff on the rear face. I feel that the short skirt allows the piston to rock more at tdc and bdc than would one with a longer skirt as is usually found out in engines of this type.

[Cranky]

Im having difficulty locating a Piston. As I passed the Royal Enfeild place I went in for a laugh and they knew what it was, he just looked at it and said C5?. He said he would have to order one. I also went to a local big bike shop and he laughed out laud when he saw the slop.

This piston is a mess, like I say no wear but the sides are not flat, its more like a barrel and yet the bore is like new with cross hatching clearly visible Im sure that I am on the right track.

I can get a piston out of a AN 400 or Skywave 400, or a DL 650 all seem to use a 83.5 mm with 20mm pin but only 15mm land (area from pin to crown). My piston on the crown is 83.29mm and the skirt is 83.8

These are available on Lazada internet market like your Ebay. The crown is flat with valve notches. Im thinking the 5mm loss of land will be compensated by their flat top piston. A risk Im not prepared to take.

Yes the swishy bearing is silent when lubed,--it has gone back in. Ille have to travel North closer to the mighty Bangkok where engineer shops are out of this world. I will be able to get one if I can find it.

[Cranky]

Well looks like I cant get a piston. I could order another Indian crap piston but then im back to square 1.

I can get a flat top which is 5mm less from Gudgeon pin to crown. The stock piston is dished by 1.2mm.

If the swept volume is more with the piston being being smaller in height and therefore the intake volume is higher but will this result in a usable compression ratio

[Rattlebattle]

Hitchcocks do a nice forged one as a straight swap for the original, not cheap though. I just bought another standard one from same source - seems ok.
Worn or odd-shaped pistons don’t cause a whirring noise. If it’s not the t/s main bearing, what is it that’s causing the noise. I’d take the generator stator off and have a look to see if there’s evidence of it touching the rotor.