Hard lessons learned from mopeds

It might be helpful to others if I laid out moped/noped lessons that I, unfortunately, learned the hard way. So, in no particular order, except how they come to me now, are my hard-learned moped lessons.

1 – Learn how to snug up bolts, nuts, screws, etc., and not over-tighten them. You don’t have to do your best Incredible Hulk impersonation when tightening up that exhaust bolt or nut. I’ve snapped off two exhaust bolts now. The second one wasn’t so bad because I’d been through the process before and had the tools and know-how to fix my screw-up. Nevertheless, it’s better to avoid this mistake than to commit it. I also snapped off a cylinder stud with a torque wrench because I didn’t know how to properly use a torque wrench. That was a lot of heartache and pain.

Rule 1 corollary – When using a torque wrench, turn it slowly so you can give it the opportunity to click. Also, make gradually progressive adjustments to the torque setting. In other words, tighten your bolt with several attempts and increasing torque settings. Don’t just go to 7 ft-lbs from the get-go and try to tighten it up. Always store your torque wrench with it fully loosened.

2 – Never use a cylinder with a damaged cylinder wall. Minor scoring/scratching can be honed away. Anything that can’t be honed away is a potential disaster waiting to happen. I re-used a cylinder that had a piston rust-seized inside it. I honed it but it still had a little damage around the exhaust port. It was rough from rust or where the piston had seized and the honing process didn’t clear it up. I used it anyway. Well, before I had the bike broken in, some of the cylinder wall broke off and severely scratched the cylinder and piston. I pissed away good money and a bunch of time on that project.

3 – I read that a Puch E50 cylinder head would work on a Yamaha qt50. The Puch head has a ton more cooling surface area. I thought this was a no-brainer. Problem is the Puch head is 38mm in diameter and I was using it with a 40mm piston. You can’t use a smaller cylinder head with a bigger piston unless you get that cylinder head re-worked to the same diameter as the piston.

4 – You rarely get the rest of the story on moped forums. Someone posts a question or problem and others offer suggestions; however, the original poster rarely follows up to share the final outcome of the scenario or others don’t provide you with all the details you need. Like above – yeah, a Puch E50 head has the same bolt pattern as a qt50 but that doesn’t mean that it is 100% compatible. You still have to make it work. Don’t accept all you read on moped forums as gospel. You’re often missing a large part of the story.

5 – Speaking of moped forums – you are in the best position to evaluate what is wrong with your moped. You can post a question on a forum but others are relying on you for all the information that they need to evaluate your issue and offer suggestions. Often one problem can have multiple causes. For example, someone on mopedarmy.com posted that her qt50 didn’t have any power. I can think of a half-dozen reasons right now for why that might be the case: (1) clogged exhaust; (2) clogged air filter; (3) air leak; (4) improper jetting; (5) insufficient fuel delivery; (6) damaged piston/rings/cylinder. There can be a multitude of reasons why her qt50 lacks power, but if I’m not there to see it and hear it and ride it, I can only speculate from the other side of a computer. Now if she took a video that might get us closer to a solution. You can ask for help but take into the account the limitations resulting from seeking that help on a forum.

Rule 5 corollary – Provide as much relevant information as you can about your issue when posting to a forum. Include a video if possible.

6 – If you change something on your moped and something later goes wrong, start with what you most recently changed when seeking a cause. It’s easy to discount recent changes as the source of your current problem. More often that not, that recent change has led to your new problem.

7 – This may be my #1 rule but I’ve listed it down here at #7. If you have trouble starting your moped, ALWAYS, ALWAYS, ALWAYS check the spark plug. Hell, change it out with a new one. Find a good deal on a dozen plugs and buy them so you always have plenty laying around. I’ve fixed more hard starters by changing the spark plug than I can count. And I’ve wasted more time trying other fixes when a new plug later did the trick than I care to remember.

8 – Always up-jet when you do something that adds more air to the engine. New exhaust – up-jet. Larger top end – up-jet. High flow air filter – up-jet. Hell, I’ve had to change jetting after replacing a bald back tire with a brand new one. In this case, I had to down-jet because the engine could propel the bike so much easier with a brand new rear tire.

9 – Never be afraid to take some time away from a problem. More often than not, it’s better to stop what you are doing and have some time for reflection. An hour or a day away from a problem can give you time to consider other alternatives or come up with a solution you might not think of in the heat of the moment. At the very least, time away from an issue gives us time to recharge and take on the problem full of fresh energy and vigor.

10 – Don’t take a shortcut instead of waiting on parts to arrive in the mail. Yeah, you got the new performance exhaust on and you just can’t wait to try it out. Those new main jets are going to take a week to get here. Who has time for that? Let’s ride this beast! Aw crap, engine got to hot and soft seized. Now I have to wait on more parts and my moped don’t ride no more.

11. Learn to leave well enough alone. I love experimenting with mopeds. I love to make non-stock parts work on mopeds. I love to put performance parts on mopeds. It’s like that monster truck arcade game where you’d “earn” cash during the race and then upgrade your truck between races with new suspension, tires, engine, etc. Only this is better, I get to actually ride my fire-breathing beast after I upgrade it. Unfortunately, upgrades and, especially, performance upgrades can lead you down a road littered with other issues you never foresaw when you bought that performance exhaust or top end kit. And how much bang for your buck (and your time) are you really going to get from that top end kit. 5-6 mph? 7 or 8? Hell, you might want to keep it stock and see where a little tinkering will get you instead. Chances are you can squeeze 2-3 mph that way and then wonder if a few more mphs are really worth the big bucks and all the time and effort.