It was perfect when I last used it but after standing for 12 months the bike is releasing boiling water from the radiator overflow and surges and dies when the throttle is opened up.

I've cleaned the carb and jets, the reed valve is fine, new correct spark plug, the fan kicks in and off and the exhaust is good. It starts very easily and ticks over perfect but when I use the bike it surges and dies but will tick over fine. After testing it three times twice it emitted coolant and once it did not but still died when opening the throttle when it got warm.

Any help is much appreciated!

It was perfect when I last used it but after standing for 12 months the bike is releasing boiling water from the radiator overflow and surges and dies when the throttle is opened up.

I've cleaned the carb and jets, the reed valve is fine, new correct spark plug, the fan kicks in and off and the exhaust is good. It starts very easily and ticks over perfect but when I use the bike it surges and dies but will tick over fine. After testing it three times twice it emitted coolant and once it did not but still died when opening the throttle when it got warm.

Any help is much appreciated!

Did you put absolutely fresh premix (no old premix whatsoever) in a flushed-out tank? Some mineral-based premix oils will cause carbon buildup in the exhaust headpipe, you might want to check. Exhaust restriction will cause overheating.

Jon

Edited November 1, 201312 yr by jse

Thanks Jon good point, I did suspect this as I may have put in some dodgy chainsaw oil/fuel by mistake as is was blowing a bit blue. I did attempt to take off the exhaust pipe but as usual the bolts were solid, being as you also suspect this I will have to get them out and inspect the head.

Cheers..

If you have the Ducati regulator/rectifier, check the back for burn marks. I've had 3 go bad on my 2007.

http://www.flickr.co...05/10612379923/

This last time the fan began running slowly and overheated. Compare your fan speed with a new bike. Mine ran about half speed. Another time the rectifier for the spark plug burned up. The top one is for the spark plug and below it is for the fan. I dug away the epoxy, pulled a good circuit and attached it to another unit.

http://www.flickr.co...05/10612106504/

I think the soldering damaged the circuit because it burned up right after the fan kicked on. I identified the circuit and it is a Taiwan Semiconductor S3M. I can by 20 of them online for $7. I want to find an alternative that I can clip on and not have to solder. Heat damages the rectifiers and I think the mounting position over the radiator causes it to overheat and fail. I'm going to move it to behind the numberplate. If I can't fix it I will have to spend another $200 on a new one for a failed circuit that costs pennies.

Have you checked the water pump is circulating the coolant, if not this can cause rapid overheating and lead quickly to the piston seizing in the barrel.

Overheating - Sediment / corrosion in coolant. Fan running slow - internal corrosion or corrosion on wiring contacts.

Surging - fuel or fuel supply issue, just possibly leaking crankshaft seal.

One of the worst things you can do with any vehicle is not use it. Far better to start and thoroughly warm it up every 3 months or less.

Great advice, many thanks. It looks like I'm going to have to strip the bike and check all the possibilities that have been mentioned. It has to be one of them, or more!

Hi all, an update. There was no carbon around the the head, I changed the coolant and all looked clean inside and the pump is working fine. All electrical contacts appear clean and tidy and the plug rectifier looks mint. The only discrepancy was on the the two yellow wires for the fan rectifier, about 3/4 of an inch away from the rectifier on both yellow wires was a small burn mark where they may have been in contact with other wires. The rectifier itself is a Leonelli and it is clean.

I went through the fuel system again thoroughly.

I started on the second kick and while it was still cold it flew up the street perfectly. Unfortunately the fan did not start but I may have cured the surging.

I tested the thermostat in a pan and it opened and closed perfectly.

Does anyone have any suggestions before I do the refit?

I also tested the fan with a battery and it worked ok.

It sounds like the wires may have burned inside the insulation. This can happen if they get pinched and there is power applied to them. I suggest you cut both wires back past the burn and splice on new wires to reach to the rectifier. I suggest soldering them rather but some of the good inline crimps can work OK. Be sure to wrap them with good electrical insulation tape or heat shrink tubing.

With the engine running, connect the thermoswitch wires together, the fan should come on. If not, fan or wiring is faulty. That's assuming you have power.

TLTEL

Success!! The fan did come on TLTEL so I renewed the wiring as thats a five suggested. I also went round all the connections tightening them up and cleaned the earth.

I can't be certain what was wrong as I went over everything again, but this time thanks to all the suggestions it ran like a sewing machine, it was pumping coolant and the fan kicked in and out. Fingers crossed for the field test!

Thanks to everyone.