Hey Scotty, I have a 2002 Honda XL125V Varadero V Twin 125cc motorcycle with almost 20k miles. I got an aftermarket Arrow exhaust, and since the carbs were out of adjustment and running rich I thought why not rejet it for the new exhaust. I got it to a mechanic and he mounted the new exhaust, changed the oil and filter and adjusted the carbs, and it was running beautifully, throttle response was better than ever before, linear torque across the whole rev range, from idle to limiter. I was more than happy, but that didn't last very long. I drove 200 miles since the service and during that time it is running worse and worse, gas mileage is horrible, it should be 65 MPG but I'm getting 50. From 2-4k rpm, almost no power and hesitation, when giving partial throttle at elevated rpms and then full throttle it bogs and then responds, a lot of black smoke coming from the exhaust especially when hitting rev limiter (no, I'm not banging the limiter all the time, just tried it this time to see if there's smoke). When going close to redline, 500 rpm before the redline it like cuts out or missfires randomly, can not explain it correctly, no change it sound just makes micro jerks or lurches, not enough to make the chain untension but keeping it in tension and making little misfires, hope you understand. Also when I lower the idle speed to 1k RPM, the revs jump all over the place (I can't call it hunting but you get the idea), and below 900 it cuts out and stalls, before it ran fine even down to 600 even with closing the throttle fast. Factory idle is at 1400 and that's where i set it. Please help, I don't understand how it got out of adjustment in 200 miles and is running worse than ever before. Cold starting improved though. No oil burning, compression in spec for new engine. Thanks
@ScottyKilmer Thanks Scotty. I never liked carburetors, too much hassle to adjust properly while on FI versions you don't have to do anything, at least while all the sensors are working. Hope it's not bad carbs since there are those bikes with 60k miles with original carbs and engines, just new main jets.
odds are he did not rejet it correctly then . After time it will make engine run too lean or too rich and do that. It's all classic signs of bad carb, may just need
@ScottyKilmer Thank you Scotty. But the only think I don’t understand is that he rejeted the carbs and worked better than ever, but in 200 miles time it was working worse and worse and now it’s running worse than before the jeting. How could it get out of adjustment in 200 miles gradually? Maybe it’ll get worse If i drive more.
you change the exhaust, the carbs must be rejetted. Find a pro to do that