rear wheel lockup at 70mph (engine seizure)

[spitfire123]

hi all,

i rebuilt my cagiva mito 450 miles ago...now for all of that i have gently been running it in....


now....everything was going perfectly but i was a on the A10 yesterday (with my mate on his nsr follow behind me) and at 70mph at about 6.5k rpm the rear wheel totaly locked up and the back swung right round...i managed to pull the clutch is and turn in the the skid JUST in time before it threw me off.

Now when i coasted up to the next junction my mate noticed that the temp was at 110 degrees

and i had checked the temp litraly 2 miles before and she was running perfectly at 70 degrees and yet 2 miles down the road a totaly lockup? i mean WTF!!?

ive taken the head of and part of the sparkplug has melted about 2mm of the bit that hangs ove rthe electrode. and the pistion has a dip on top of the dome abouyt the size of your thumb and the cilinder has some metal stuck to the bore and some scuff marks

now the pistion/rings/bearings/bottom and top end are 450miles old and the bore 550 miles old.

also i have been running injector ASWELL as 2st oil in the fuel so it was litraly PLOOMING blue smoke.


now...we let the bike cool down for 20 mins or so and we managed to bump start it and i got it home (9 miles) but at full throttle it was only reving to 8k (very stiff and boggy) but it ddent overheat or anything?

i 1st though the waterpump had gone BUT 9 miles on the way home and it got me back being at normal temp?

so im baffled? does anyone know what the hell went wong and that was extreamly dangerous AND im seriosly out of pocket now


cheers
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You won't be able to eat my dust......As it'll settle before you get there.

[Blau Zedong]

Ran lean, got hot.

Possibly as a result of running the oil pump and premix. Either that or ignition timing (if that is adjustable).
____________________
18:54:48 Rob Fzs: jews don't give away stuff for free

18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth

[Kickstart]

Hi

Above could well be correct.

However that it appears to have started to burn through the piston suggests the ignition timing might have been too advanced (timing needs to be set accuratly). A lean mixture will make this worse.

All the best

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

[Burnzy1989]

All of the above , have you checked your thermostat and made sure your impeller has not dropped off. but to me it also sounds very mutch like your ignition timing is way to advanced.

Have you got a timing light to check your ignition timing and is your ignition timing able to be adjusted because the CDI does all of this and i cant see it having a timing plate or can you move and adjust the pic up coil that sits up above the magneto (Fly wheel).

Have you had the carb apart or played around with the mixture screw?

[spitfire123]

[Burnzy1989]

Why did you adjust it before?

[spitfire123]

[_sketch_]

[spitfire123]

[Kickstart]

Hi

That is a fair amount of oil (probably twice what is meant to be going through the oil pump alone), so quite likely it leaned the mixture off noticeably.

All the best

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

[chillpill]

[Burnzy1989]

I used to run my Kawa kx 125 on 32:1 and that was ruffly 158mls oil to 5 liters petty. so were you putting in ruffly 210mls of oil to 5ltr of petty this is just a ruf estimate of 25:1 and premixing it at 5ltr

[spitfire123]

[spitfire123]

[Kickstart]

Hi

Mixing the oil with the petrol means that you are getting that much less petrol in, hence running lean by that much. Added to which there might be a slight change in the viscosity of the petrol making it slightly harder to draw though the jets.

All the best

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

[stevo as b4]

IMO if any you should have been running the oil pump once correctly bled and adjusted, and maybe 100:1 in the tank for the first tank full. If you ran with the autolube and 25:1 in the tank, you will have dangerously leaned out the mixture. You'd need some serious re-jetting for the carburation to be correct at 25:1.

I bet with the pumped lubrication that it never gets more than the equivalent of about 40-50:1 anyway, so 25:1 was never a good idea, and is not needed on modern engines with modern fully synth oils. I've never run my trials and motocross engines at less than 40:1, and never had a problem.

Your idea to keep everything really oiled and lubricated with that extremely oil rich fuel mixture has cost you dearly sorry!

[tshort2007]

https://www.smellofdeath.com/lloydy/piston_diag_guide.htm

[spitfire123]

[Kickstart]

Hi

Still think timing is the most likely main issue, although running lean will make this more likely to cause a problem.

All the best

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

[_sketch_]

Yours if you want it.
____________________
A sucker for 2 strokes
Cagiva Supermoto project

[spitfire123]

[spitfire123]

[Kickstart]

Hi

RS piston can't be used. The RS uses a smaller bore.

All the best

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

[spitfire123]

[Blau Zedong]

Will you admit -

A) You messed up pre mixing.

B) You did not bother to set the timing with a dial gauge or TDC tool.

Because your making it sound alot like it's the bike's fault rather than you being mechanically inexperienced.
____________________
18:54:48 Rob Fzs: jews don't give away stuff for free

18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth