Annoying engine sound

[Nickledyme]

This has been bugging me for about a week so here it goes. Not sure how to explain it but it kinda sounds like the pinging of an empty soup can. I have checked the muffler,clutch,tightened all nuts n bolts. I had my bike guy check it n took the top off my motor and everything is perfect. I have a 66/80cc am using 7oz Lucas Semi Synthetic Blend to each gallon of gas. I just took the carburetor apart and moved the needle one notch leaner. I'm kinda new to this so maybe me and my mechanic are missing something here.

 

[butre]

Is it gear chatter? If so, try cutting a mousepad to fit in your clutch cover, that eliminates most of the chattering noise. Sometimes there's some play between the small gear on the end of the crankshaft and the clutch gear and that can be pretty noisy.

 

[Nickledyme]

I took it up to my mechanic and think it's the muffler. I took it off and shook it hard as I could but no noise or anything. I revved up and got down close to the muffler and can hear something making a racket. I wanna rip the thing apart but don't have money for a new one or a spare in case I mess things up. Warped my back rim yesterday so I'm all tied up with that. Would a steel rim work good on these bikes? I've had nothing but issues for 3 months of having this thing.

 

[Fabian]

I I've had nothing but issues for 3 months of having this thing.

Only 3 months?

I had nothing but issues with my bike for 2 years before getting it properly sorted out and to be reliable for every day use.


Really, 3 months is nothing in this game...

 

[butre]

I had problems for about 6 months before I got mine to be perfectly reliable. This is the kind of thing you need patience for. You'd be quick to get 6 months worth of patience if you start doing real projects.

 

[Nickledyme]

I'm patient don't get me wrong but 3 months is a long time when it's your only way to work which is 12 miles away. I'm lucky to have somebody with years of experience who has built hundreds of these bikes. I couldn't get the steel rim I wanted without waiting a week which i can't do right now. I'm hoping aluminum alloy will hold up for awhile until I get the steel rims I want.

 

[074KU]

A 36 hole steel rim suitable for rim braking will warp quite easily (the kind most older mountain bikes are fitted with standard) I went through 4 of these on the rear wheel in the early days in a matter of months. I would suggest buying something for use on a down hill MB for the rear wheel at least. My latest rear rim is a DT-Swiss and I have had none of the buckling issues I found so annoying with normal Steel rims.

 

[Fabian]

You would be surprised at how durable double wall aluminium rims can be. My bike used to have a set of base model Quando double wall aluminium wheels and they were bullet proof; never breaking a spoke from ordinary riding, with the rear wheel not even breaking a spoke when the rear derailleur smashed into the wheel several times in the early days of sorting out chain resonance and chain suck problems.

After 50,000 kilometers (30,000 miles) of riding, the hardening wore away in the rear hub, so the wheel was replaced with a base model Shimano double wall aluminium wheel, as it was on sale; going cheap.
Although the rim seems of similar strength to the Quando brand, the Shimano spokes keep breaking at the flange point where the spoke meets the hub.

I am suitably impressed by the durability of double wall rims, and from my experience, the Quando brand of wheels are a durable product.

 

[HeadSmess]

more than likely, if it emanates from the muffler, and its rattly sounding, tis just a loose baffle. irrelevant. you cant damage much by removing them anyway. just possibly your hearing?

usual trick is remove the piddly lil 10mm outlet and drill it out to take 13 or 16mm or so pipe. your bike guy says anything about backpressure and advises against it? he isnt such an expert. he hasnt fixed your simple rattle

you can examine it to a degree by removing the nut/bolt at the end of it... if present.

its also a twostroke, sure its not just the sound its meant to make? not normal with the stock exhaust, really, that ding ding ding thin wall tuned pipe "marbles hitting a tin" sound, but?

everything else is just as possible.. the clutch cover buzzes like an angry hornet, and the gear mesh is far less than desirable. like they missed a tooth on one of the gears... or the centres are wrong. these engines are just noisy to start with

hmmms. he took the top off? whole cylinder or just the head? could be dinky lil end bearing.


real way of eliminating the muffler as a problem is to eliminate it... wear some earplugs and really, you will be amazed at how many of the "smaller" sounds you can actually hear... even the chain squeaking... if the sounds gone, its in the muffler, just a loose baffle, no major concern, put it back on and live with it

as for rims and wheels. spoke-key and clothes-peg. start truing so easy if you just stop and look at how a wheel is put together. or search the net. wheel building is an easily learnt art.

you can tension the spokes properly so the wheel doesnt collapse. while ive amazed myself by how bad i can let them get, every loose spoke is a section of rim that is unsupported, therefore has no strength. the strength of a wheel is more than the sum of its parts. its fitting them together properly that does it yes, of course, the better the parts are to start with helps.

my main preference is that the rim im scavenging starts off fairly straight. even found one with 36 valve holes seriously, theres a hole between each spoke... had a pair once. musta threw one out.

last thought. engines nice and tight and solidly secured, and the buzz isnt in the frame, possibly?

 

[Nickledyme]

Thanks guys y'all are great! The rim I got probably isn't anything special as it just says "Aluminum Alloy" on the sticker. The spokes are tight as can be along with the bearings. I'm gonna run it without the muffler and see what happens. I don't know a thing about drill sizes or any of that stuff yet. So, I'm gonna try the simple stuff first before I jump in over my head.

As far as the engine goes he took the whole head off and checked inside. He said it was smooth and no sign of any damage. All the bolts on the engine head are tight as I tightened those last night. All screws on all covers are all set as I check those each night I get home. The chain and tensioner are solid, although I did find one loose bolt but not sure what it is.

It's the nut underneath the carburetor and has the clutch cable running thru it. It's very hard to get to. I did manage to tighten it a bit and seems some of the sound went away. I still hear some noise when I'm under acceleration except uphill. I'm halfway figuring this out I guess lol