Carb problem leading to strange gloopy fuel situation

steven_191 · Nearly there... Joined: 31 May 2009 Karma :

so after a bit of messing around on the bike i had a running problem.

its a cagiva mito 125cc with dellorto PHBH28RD carb

it seemed to be ok at low throttle throughout the rev range and at high revs in the powerband at full throttle. any amount of throttle inbetween and it bogged down. but then after a bit it wouldnt work right and i would need to switch the fuel tap to prime to force fuel into the carb and then back to ON and it would go back to how i just mentioned.

anyway i think it may be the carb as it engine is running ok at idle and full whack and it seems to be throttle position making everything run funny.

so heres the weird bit.
i just stripped my carb down and poured the fuel into a pot. gave it a check over and checked the ports and such but when i picked up the main jet from the fuel i poured out it had turned into a gloopy glue like crap. which i peeled off the jet. when i poured it out it seemed ok.

so is my fuel contaminated? because surely this doesnt happen as the temperature of the fuel warms up. otherwise we'd all be fucked.

kestrel · Nearly there... Joined: 04 Sep 2006 Karma :

Has the tank been lined with a resin tank sealer? If so, the ethanol added to modern fuel dissolves the resin in most sealants and causes the 'gloopy' fuel in the carbs as you describe. Might not be the problem but worth a look.

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

Fuel does go snotty on it's own but takes a very long time - my guess would be that there was something in yer pot already (dried paint?) which the fuel dissolved.

If it's running ok with the tap at "prime" (there's no reason why you can't ride about with it like that) then you've got a problem with the tap itself or the vaccum tube which operates it.

f.

steven_191 · Nearly there... Joined: 31 May 2009 Karma :

I did try a rust removing fluid but that mostly leaked out and it ran for nearly a year with no trouble. It was only after a stripped it and tried playing around with things that it stopped. I'll try flushing the tank just in case though.

G and J recovery · Two Stroke Sniffer Joined: 03 Oct 2010 Karma :

take the fuel tap of and clean the filter ,
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glen

steven_191 · Nearly there... Joined: 31 May 2009 Karma :

I've worked out the fuel problem. The pot I poured it into had actually melted and that's what made it glue like. As for my carb problem. I found some fuel in one of the floats. Might all be sorting now.