Evans 125 Posted July 1, 2007 Posted July 1, 2007 Hi, this is my first ever motorbike, a 2001 yz 125, the bike is great even tho when i bought it i had 2 send the barrel of for a new sleeve, piston etc. Now i have got the bike running, i have problems with the carb. The over flow consistantlty runs when bike is idleing. Ive stripped it down and checked the float, its all free to move and when raised stops the flow of air if u blow into the fuel intake. I now need too run the bike only opening the tank flow slightly, but this is just starving the bike of fuel, but to much and petrol runs out of the carb over flow big time. Ive adjusted the carb so now there isnt alot of movement of the float before it should stop the petrol, but it doesnt, anyone help, thanks
Chris Heath Posted July 5, 2007 Posted July 5, 2007 Hi, this is my first ever motorbike, a 2001 yz 125, the bike is great even tho when i bought it i had 2 send the barrel of for a new sleeve, piston etc. Now i have got the bike running, i have problems with the carb. The over flow consistantlty runs when bike is idleing. Ive stripped it down and checked the float, its all free to move and when raised stops the flow of air if u blow into the fuel intake. I now need too run the bike only opening the tank flow slightly, but this is just starving the bike of fuel, but to much and petrol runs out of the carb over flow big time. Ive adjusted the carb so now there isnt alot of movement of the float before it should stop the petrol, but it doesnt, anyone help, thanks Hi there, I had something similar on a TZR 125 although the leakage was worse when the bike was switched off. My investigations at the time led naturally to the carb and also to the fuel cap which had a routing machined into it to allow venting. What appeared to have happened was that the vent had become blocked from the bike living outside and the fuel tank was pressurising with the heat generated by the engine (because it was right above it and fuel expands with rising temperature). Have you checked the venting in the fuel cap? Add to that the TZR looked as if it should have had a vacuum operated fuel tap etc. which had been modified etc. etc.! Hope this helps. Kind regards, Chris Heath
Evans 125 Posted July 5, 2007 Author Posted July 5, 2007 Hi there, I had something similar on a TZR 125 although the leakage was worse when the bike was switched off. My investigations at the time led naturally to the carb and also to the fuel cap which had a routing machined into it to allow venting. What appeared to have happened was that the vent had become blocked from the bike living outside and the fuel tank was pressurising with the heat generated by the engine (because it was right above it and fuel expands with rising temperature). Have you checked the venting in the fuel cap? Add to that the TZR looked as if it should have had a vacuum operated fuel tap etc. which had been modified etc. etc.! Hope this helps. Kind regards, Chris Heath i had a look at it today with the bottom of the carb off and held the valve up with my finger but fuel still run in, so i think the seal has gone on the jet that the valve sits in, so fuel is channeling around it, but now i broke the float, any ideas where i can buy one and for how much???
Chris Heath Posted July 6, 2007 Posted July 6, 2007 i had a look at it today with the bottom of the carb off and held the valve up with my finger but fuel still run in, so i think the seal has gone on the jet that the valve sits in, so fuel is channeling around it, but now i broke the float, any ideas where i can buy one and for how much??? Hi there, I'm not sure I fully understand the test you carried out that unfortunately resulted in the damaged float. Take heart, the same thing happened to me when I stripped the TZR carb. These float arrangements are desperately, DESPERATELY fiddly and subject to very fine tolerance. You may have noticed a small tab on the float hinge that is used to adjust the height when the chamber fills with fuel, this may have been mal-adjusted when the you first encountered the problem or the fibrous seat washer may have decayed. I strongly suggest you use this 'opportunity' to inspect the rest of the carb to see if anything else is amiss. The parts are usually easy to source, it's just a question of how much you can afford. I'm lucky in that I had a bike breaker near me who sold me a fully functioning carb for £20 which went a long way to sorting some of the trouble and provided me with some useful spares. Ebay is always a good source for these things because they're easy to find because they have such a powerful search engine. Do try your Yam dealer just as a reference point. Traditionally people shy away from main dealers due to a reputation for high prices but I've found that's not always the case. Most often with carbs however the main dealer mantra seems to be 'if it's outside the carb we can get it, if it's in the carb, it's a new carb jobby'. Also (this may sound silly) but consider an entire bike that's a write off because you'll get what you need hopefully and a whole lot more. Hope this helps! Kind regards, Chris Heath
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