rxs premix (still got problems)

[Carvel]

Im going to run my rxs on premix because it siezed up and I dont fancy ruining another fresh rebore and piston. It was siezed when I bought it so there's obviously something going on.
I was just wondering what ratio to run it on. I ran my fizzy on 20:1 but im not too sure about the rxs.

Help greatly appreciated.

Ollie
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2002 Aprilia RSV1000R, Cbr600Fs, Mk1 B12, Vfr400 NC30...

Matt B: I can deal with crushed nuts to beat Ollie.

[Blau Zedong]

[Carvel]

Im used to it, I used to premix my fizzy. I double checked everything, Bled the pump etc and everything is as it should be. I was thinking it might be something else causing it, like the mixture, but the plugs coming out a good colour and everythings adjusted correctly. The bike itself ran ok, but it rattled like a bastard which got progressively worse before it nipped up. Thing is it used to smoke so it must have been getting two stroke through Bit confused really.
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2002 Aprilia RSV1000R, Cbr600Fs, Mk1 B12, Vfr400 NC30...

Matt B: I can deal with crushed nuts to beat Ollie.

[27cows]

Something must have been seriously wrong. RXS motors are virtually impossible to seize (I once ran my original motor completely dry and it still didn't seize up, though it did make some scary noises ).

If it was smoking, chances are the issue has nothing to do with lubrication. Could be a dodgy rebore, or a dodgy piston. Have you got a picture of the piston?
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The RXS100: vehicle of choice for Chuck Norris

[Carvel]

It wasn't like a locked up and wouldn't turn over siezed, more like ran like shit and made scary noises as you say.

[27cows]

I would say the bore was under done. I've seen it happen on other bikes. Often happens where a barrel is honed instead of actually rebored, meaning people put a bigger piston into too-small bore - leading to the kind of carnage you have.

Having said that, if it was on .75 at a mileage when the original bore should just be nicely bedded in, that would suggest something else. RXS bores/pistons normally go to at least 40K even when relentlessly and mercilessly thrashed.

I'm wondering if there's crap in the oil tank, causing an intermittent blockage. Oil pumps rarely fail, certainly not after such a low mileage.
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The RXS100: vehicle of choice for Chuck Norris

[Kickstart]

Hi

To add an extra thought into the mix, not sure Yamaha sell .75 o/s pistons and a fair chance it is a cheap pattern piston. Some pattern pistons are pretty useless and prone to seizing.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[SnowTigeress]

Tef here (Snowies been at my lappy again!)
Those skirt appatures looked suspiciousely dremmelled to me, so checked e-bay for pics of new pistons.
https://i.ebayimg.com/13/!B))K,IQB2k~$(KGrHqR,!iQEw5yWTwYrBMO5DdEM!!~~_12.JPG
[img]https://i.ebayimg.com/07/!B7Rs(K!!Wk~$(
KGrHqN,!k0Ey+jC1sigBMzvJSioig~~_12.JPG[/img]
I cant be sure but does look like some-one may have tried opening them up. Poss bad DIY porting job?
Quoted oversizes were +50 & +100 too, as Keith said
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[27cows]

You can get .25 for the RXS for sure, pretty sure .75 is also quoted in a parts list I have from Mitsui too.

A poor porting job is certainly a possibility. Why do people do it? It always ends in tears.
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The RXS100: vehicle of choice for Chuck Norris

[Carvel]

This is the piston I bought (crappy pattern one)

https://www.wemoto.com/bikes/Yamaha/RXS_100/83-85/picture/Piston_Kit_0.75_Oversize/

I havn't touched it, thats how it came.

I snapped a ring so had to use an old one but that wouldn't have made any difference.

I checked everything again tonight. The oil tank is squeeky clean. When you take the bleed screw out of the oil pump it flows out fine. Also all the marks on the pulley line up as they should.

That fact that it was smoking before tells me the pump must be alright.

What else could have caused it?
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2002 Aprilia RSV1000R, Cbr600Fs, Mk1 B12, Vfr400 NC30...

Matt B: I can deal with crushed nuts to beat Ollie.

[Teflon-Mike]

When did it nip up on you?
Cota used to nip up when used on the road... alledgedly... & did so curiousely. Comp-Trial bike, so loads of cooling fins for slow speed running, with little cooling effect.
Run it hard on road, & it would over-cool & nip up. Ritchening the pre-mix weakened the fuel ratio, made things worse, reducing the oil ratio, ritchened the fuel, made it better.
(The err.... underage rider apparently used to slosh half a gallon of neat in the tank to thin it down before heading down the back-lanes to see girlfreind on a Sunday when there were no country busses..... alledgedly!)
If its nipping up when maxed out, could be similar over cooling / weak mixture. Lifting the throttle needle a notch may help.
If its nipping up in traffic, then possibly under-cooling, due to lack of air-flow, may suggest idle mixture too lean.
Whats the ignition timing like? Too much advance / low grade fuel, could be causing knock / hot running.
What about the exhaust? (Is it on the stocker, or it it running a spannie?) pin-hole, leaky joint, lost baffle can make motor run weak, hence hot.
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[27cows]

[Carvel]

[Teflon-Mike]

[Carvel]

[27cows]

Be careful to run in the new bore/piston and you shouldn't have a problem.

Looking at that piston, I'm wondering if the previous owned just jumped on the bike after a rebore and caned it. That is about the only non-oil failure situation that would do that kind of damage to an RXS top end, I think.
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The RXS100: vehicle of choice for Chuck Norris

[Carvel]

Ok I finally got round to fitting the rebored barrel and new piston the other day and have put a few miles on it since. Unfortunatly it's starting to rattle again so im pretty sure it's going to detroy this piston aswell.
Now it runs ok and it smokes as it should so it must be getting oil, but theres a distinct rattle (which is getting worse with use), most noticeable on tickover. And if you keep it at fairly high revs for a little while it gets seriously f*cking hot, like somethings about to melt levels of heat, at which point it runs cack, wont tickover etc, but let it cool down and it's ok again.

I'm at a loss of what to do really.

Any ideas?

Cheers

Ollie
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2002 Aprilia RSV1000R, Cbr600Fs, Mk1 B12, Vfr400 NC30...

Matt B: I can deal with crushed nuts to beat Ollie.

[cb1rocket]

are you running on the correct plug? you say its so hot that the jet is probably wrong. Are you using a new small end bearing, and is there any play in the big end?.

My GP100 was a pig when I got it, and I had to go through a rebore and new piston. The old one shattered itself! At the moment its touch wood so far, and I still have another 300 miles to run in.

[Blau Zedong]

Have you checked the oil pump is pumping, because it sounds like a lubrication issue to me (having destroyed a rare and expensive YR5 top end by ignoring similar symptoms).
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[ms51ves3]

I'd be checking jetting. What mainjet is fitted? Standard is 120.

[Carvel]

[27cows]

I'd be tempted to trash the motor. Rip it apart for spares. Buy another and chuck that in. Having said that, people charge some quite hilarious prices on ebay for RXS engines these days. Bargains do turn up - one with 12,000 on the clock went £30 last year.

One thing it might be worth checking if you're back using the autolube - make sure the oil tank breather pipe isn't blocked.

If possible, post a pic of the plug so we can see the kind of nick it's in.
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The RXS100: vehicle of choice for Chuck Norris

[Carvel]

I never went to premix in the end, i'll give the breather pipe a check.

[Carvel]

Looks about right to me?

https://i979.photobucket.com/albums/ae271/RxsOllie/Plug-1.jpg

Excuse the quality had to use my phone
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2002 Aprilia RSV1000R, Cbr600Fs, Mk1 B12, Vfr400 NC30...

Matt B: I can deal with crushed nuts to beat Ollie.

[cb1rocket]

yeah looks right, how come an RXS is Kawasaki?!