scifi Posted November 23, 2017 Report Share Posted November 23, 2017 Hi Guys, our club trial has a section that is around a tree then down a steep bank, then a tight turn at the bottom and over a tree log. This gets me nearly ever time on my TY175. The engine takes in too much fuel from the Mikuni on the downhill, and stalls at the bottom of the bank. I have ridden that section by keeping the engine revving going downhill, but there must be a cure for the Carb. I think the float chamber has a breather hole at the top, which with the bike pointing downwards, pours neat fuel into the engine. the fact that the carb is already angled 20 degrees down does not help. . Quote Link to comment Share on other sites More sharing options...
pschrauber Posted November 23, 2017 Report Share Posted November 23, 2017 You might check out when the valve will close the gas supply to your carb. As the carb is already in an angled position the standard routine of the valve should close the gas supply when the float are parallel leveled to the contact area of the bowl can't be applied. (I hope I wrote it down correct ...) Quote Link to comment Share on other sites More sharing options...
mink_man Posted November 23, 2017 Report Share Posted November 23, 2017 53 minutes ago, pschrauber said: You might check out when the valve will close the gas supply to your carb. As the carb is already in an angled position the standard routine of the valve should close the gas supply when the float are parallel leveled to the contact area of the bowl can't be applied. (I hope I wrote it down correct ...) i agree, check your fuel float valve it could be sticking or worse the seat or actual plunger itslef may be damaged, its a cheap fix though. All the mikuni carb kits come with the brass valve and plunger. Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted November 23, 2017 Report Share Posted November 23, 2017 I had the same problem with an aftermarket mikuni conversion on my old Ossa mar. Never did cure it. Spoke to Allens where i got it from and they said it was because it was already 20deg angle with the bike on the flat. In the end i fitted a Dellorto and solved the problem at a stroke. Mikuni is a good carb but they are very angle sensitive. Good luck. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted November 24, 2017 Report Share Posted November 24, 2017 A standard TY175 carby mounted on a TY175 should not have any problems due to riding steeply downhill if the float height is right and the float valve is sealing off. They normally work perfectly. The float valve does not last forever. I think I'm on my third float valve in the TY175 I've had for 41 years. If it is a wear problem causing the valve to pass, you should see a band on the needle surface that is not shiny (where it touches the seat) and the rest will be shiny. The needle taper should be shiny all over. If the problem has developed over time, it will probably be the float valve passing. If you don't know the history of the problem, it could also be that the float height has been set wrong. Quote Link to comment Share on other sites More sharing options...
spen Posted November 24, 2017 Report Share Posted November 24, 2017 A good source of info'....... http://www.mikuni.com/pdf/vmmanual.pdf 1 Quote Link to comment Share on other sites More sharing options...
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