MZ/MuZ Riders

HI,

Can anyone diagnose or suggest what I should look at for some 'odd' running on my Supa5 250/1?

When riding along with the rev counter showing 3000rpm as I went to accelerate (in top gear) the bike 'hesitated' and seemed like it was going to die. I let the revs drop back to 3000rpm and the bike ambled along as normal. I tried the same thing again and once again it hesitated and 'fluffed' ( if that the right word) as I tried to gather pace...dropping back to steady 3000rpm and all was ok and bike seemed ok at lower revs too. The problem seem to be as the throttle was opened up.

I had filled up with fuel about 5 miles previously and had added Putoline Synthetic (I think) 2T oil using the measure in the cap. Now I may have had a senior moment and added a capful too many (it was definately more than less, ooops ); would this result in such symptoms?

The fuel pipe did have a 'plastic in line filter' and I wondered if that might be to blame...so have swapped that pipe for a new piece of fuel hose (without the filter)...

There was fuel coming out of the fuel pipe when it's its in the 'ON' position but not sure it was 'gushing forth' but then have never looked before so wasnt sure what to expect.

My guess is 'fuel' starvation at a 'more wide open' throttle but wonder if the symptoms I have described are familiar to anyone.

The tank and carb had been cleaned out some time ago (a few weeks) so they seem to be 'rust/clog free' and recently in the last week have done around 250miles on the bike so it seems ok (apart from on one run the exhaust ring nut 'loosening itself' although thats all done up tight now.

Any diagnosis or what to look at as a likely cause; riding around at 3000rpm is all very well but a few more revs might be nice (especially in the rare sunshine we have just had in the UK instead of all this 'wet drought we are having!).

Mark

Have you checked the obvious? (plug/points/condenser?) I had a panic attack after just getting my etz125 on the road and the first journey of reasonable length. I was about 15 miles from home, it was dark and I had left my tools at home. A gentle run through town traffic without incident but once onto dual carriageway decided to open it up and clear the cobwebs. Verry happy as the speed increased nicely, no undue noises, just nudging over 50mph and............ the engine died. No warning, just cut out and refused to restart. So ther I am in the dark on the side of a dual carriageway with me cursing this pece of sh*t I'd bought. Called the (sleeping) wife to bring tools a torch and my RAC membership card and waited. Brain working overtime as to what was wrong. All electrics appeared ok, spark, at plug, fuel in tank (double checked) After checking the fuel tank, tried kicking the engine over again and...... It fired up and ran beautifully. Long story short. the problem was the fuel cap was airtight, breather hole blocked and when on full throttle a vacuum was being created in the tank as air couldn't enter fast enough to counteract fuel leaving tank!!

Had a simular problem with my ETZ251, 49mph ran like a train, got to 50 and started to cut out. Fuel supply was ok, ended up changing the points, and coil before changing the battery cured it.

Does sound like fuel starvation to me. When you cleaned the tank out did you clean the tap? The original has a gauze filter which can get gummed up. Plus I have found the rubber washer inside the tap can disintegrate and block up tap.

i have this happen with my 2002 RT125
it is for me is caused by crud floating in the float bowl
i have to drain the float bowl almost every time i fuel up
its from the stirring of the fuel in the reserve side of the tank ....
water water and more water thanks to the guy that thought ethanol in gas
was a good idea (NOT)
and maybe a tank cap that does not seal very well...
Dave

After reading mirmay's mention of fuel caps that don't breathe my memory was jogged. There is a corrosion problem with the steel and aluminium fuel cap. I knew one guy who kept the fuel level low and rode with the cap only half engaged (if that makes any sense). Others have applied a drill to their caps to ensure that the air can get in.
I have also experienced leaky float problems.
Its always obvious when you're looking back on these things!
Louis