Bike is running, a quick piston question

Re: Bike is running, a quick question however.

Hey ZV,

Most pistons have an piston pin holes that are very slightly off-set towards the intake side of the cyclinder. The arrow is used to make sure that the piston is installed so that this piston pin hole off-set orientation is correct.

Off-set piston pin holes are used to reduce what is called "reciprocal loading" and for limiting piston wobble.

Note: these bicycle engines rotate in the opposite direction in comparison to traverse mounted motorcycle engines due to fact that these bicycle engines don't have transmissions and transmission "counter-shafts (counter-shafts rotate in the opposite direction of the transmission input shaft). These bicycle engines rotate clock-wise as viewed from the left hand or magneto side. Hence, in the case of these bicycle engines, the piston pin would be off-set to the exhaust side with the arrow indicating the proper orientation of the piston.

Re: Bike is running, a quick question however.

2door said:

I thought it would make the bike run backwards

Tom

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Ya, it threw me for loop when I first noticed it. Then I realized that there's no transmission counter(rotation)shaft.

These little engines can be both fun and funny at the same time...

Re: Bike is running, a quick question however.

2door said:

I thought it would make the bike run backwards

Tom

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aye... in mopeds it will make the timing off and maybe spin ur wheels backwards...

almost like reverse but different...

Re: Bike is running, a quick question however.

Wickedest1 said:

aye... in mopeds it will make the timing off and maybe spin ur wheels backwards...

almost like reverse but different...

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Except for one thing; mopeds don't have multiple gear transmissions and, hence, no counter shafts...

That's the difference.

Re: Bike is running, a quick question however.

FMB42 said:

Except for one thing; mopeds don't have multiple gear transmissions and, hence, no counter shafts...

That's the difference.

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seriously? did this guy just say mopeds dont have multiple transmission gears? MY puch maxi has za50 engine...2 speed automatic
there are about 100 different moped engines that have a multitude range of gears all the way up to 6...some are auto some manual...

http://www.mopedarmy.com/wiki/Main_Page

a ****en load of information shall await any and all whom enter henceforth...
please dont say i told u so

Re: Bike is running, a quick question however.

Wickedest1 said:

seriously? did this guy just say mopeds dont have multiple transmission gears? MY puch maxi has za50 engine...2 speed automatic
there are about 100 different moped engines that have a multitude range of gears all the way up to 6...some are auto some manual...

http://www.mopedarmy.com/wiki/Main_Page

a ****en load of information shall await any and all whom enter henceforth...
please dont say i told u so

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Please excuse me.

I don't own a moped. Never have and probably never will.

The few mopeds that I worked as a motorcycle mechanic were Yamaha QT 50 Yamahoppers back in the early 80s, and they didn't have multiple gears.

Meanwhile, I'm new to motorized bicycles so, again please excuse me. If I ever need to know anything about mopeds I'll be sure to ask you.

Have a great day.

Re: Bike is running, a quick question however.

FMB42 said:

Please excuse me.

I don't own a moped. Never have and probably never will.

The few mopeds that I worked as a motorcycle mechanic were Yamaha QT 50 Yamahoppers back in the early 80s, and they didn't have multiple gears.

Meanwhile, I'm new to motorized bicycles so, again please excuse me. If I ever need to know anything about mopeds I'll be sure to ask you.

Have a great day.

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Wasnt looking fer a pissing match...just thought people should do more reaearch into things before assuming or just saying something...hoppers r an amazing lil funbucket...i suggest you search cl fer a cheapy moped...will def give u an opportunity to expand ur 2 smoke capabilities...

the main reason for the arrow is totally un-scientific.

it's so the ring gap doesn't open into a port.

Wickedest1 said:

Wasnt looking fer a pissing match...

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Pissing match? Sorry, but I outgrew mini bike/mopeds and "pissing matches" when I reached 5 feet 7 inches and 145 pounds at age 14.

As for (or, as you say "fer") your pissing match comment on my "2 stroke (or, as you call them, "2 smoke") capabilities"; I've owned, maintained, and ridden a '75 and a 1/2 250 cc Bultaco Pursang MX world champion factory replica, a 1981 390 CR Husky, and an early '80s Honda CR 480 crosser. This is not to mention the '71 S3 350 triple Kawasaki, '76 RD 400, and the 71 and '72 Suzuki T500 2 cycle (that'd be "2 smokers to you) road machines that I owned/rode in the 1970s and '80s. And I'll also mention that I, as a professional motorcycle mechanic, was give the task of assembling one of Brad Lackey's practice bike engines while he was the reigning Open Class MX World Champion back in the early-mid '80s.

Btw, I didn't have much time to work on and/or test ride many "hopper/mopeds" when I was a Yamaha mechanic due to the fact that I, and my coworker mechanics, were performing factory warranty transmission R&Rs, and subsequent 150+ mph test rides, on early FJ 1100s that were prone to experiencing catastrophic transmission failures.

Anyway, I fully acknowledge your infinite knowledge of 6 speed mopeds (that are often limited to what...35 or so mph in the United States?)...

FMB42 said:

Sorry I was such a dick.
Im not used to people knowing what they are talking about. I admit defeat and dont want to ride motorized bicycles anymore. Im selling my motorized bicycle so I can go to europe and impress the europeans with my american accent. Thanks wickedest.

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No prob guy...no need to leave we accept any and all here...unfortunately

So for those 150+ mph test rides, to test the transmissions for catastrophic failure you actually got on the bike and rode it on the highway at 150 mph ? I call bull****.