'The (almost) everything was not right bike'

[Toadmund]

When I had a job, I inquired about wanting to buy a bike for a motorbicycle project. Some guy was willing to sell me one, he showed me the picture, I liked it, I offered 50 bux for it, he sold it to me.

What was the problem;
-Put the motor on, no space for the carbuerator, had to silver solder/fiberglass/wire/JB weld the intake pipe to a piece of 90Deg. copper fitting, it's on REAL good (I believe).
-Spent WAY to much time making my own top hat adaptor, cutting with dremel type tool, drilling, shaping stainless steel and the sprocket, after all that it looks like I'm going with rim brakes, the disc caliper ain't gonna fit. (Bike don't have disc brake fittings anyway) was going with rim brakes anyway for now. And the sprocket isn't exactly centered, not bad, but not 100% satisfied with it.
-Down tube was a fat one, good thing adapter was in kit.
-Clutch needed loosening and adjusting, easy to fix, real easy, I worried too much.
-Plus anything else that frustrated me, like spending more time looking for tools I just had, than building the bike, thanks ADD.

The good;
-motor was ported, casting humps ground down, cylinder bottom gasket was trimmed, head was polished, squish band and cylinder honed down on flat piece of rock wall/floor tile.
-Motor works, as I was busy I only used my bike for about a total of 30 minutes + -, it's raining today :-< , If the motors get more powerful after break in, boy, is this thing ever gonna move! It wants to go!
-motor runs real SMOOTH, does not vibrate much at all, idles real nice, I guess I got lucky with a nicely balanced crank.
-Bike is black and red and my motor is black, bike is small and looks real tight, good thing it's a slant head! I'm 6'2", but the bike fits nice.
-Just made a spring loaded chain tensioner, I hope it's durable enough, will make it better though, for now I just wanted a quick fix so I can ride the damn thing!
Oh yeah, the weather, thanks Mother Nature! Not!

Anyway, this is my first build, next one I will choose the right'er bike and git er' dun in 1/20th of the time this one took, and I may just buy the stupid top hat adapter and save myself the frustration.
But, I will probably make another one, just because I'm a tightwad and a DIY kind of guy.

PS, check out the seat, it's got a spring, and the seat post a cheap
a$$ suspension post I got on ebay for under $30.00 S&H included!
Real nice on the butt!

 

[Toadmund]

A few more:

 

[Toadmund]

Took the bike for a test run and inadvertently used the 'chain brake' the chain was tight, I was dumbfounded, how'd it get that way?
It was bound up inside the drive sprocket housing. Too much free play chain slopping around and bunching up in there during start up.

I've got to put a slack limiter in there, maybe an old brake pad right under the pivot? (where the tensioner wheel originally bolted on to)

A tie wrap (very temporary)

Just need a simple fix without re-engineering the whole bike, spent the winter doing that already.

Alright motorbikal jeeniuses I am open to any suggestions honoring the KISS principal, I am going to take a nap on it and when I get up I won't expect any answers, unless of course lurker #112 or #113 actually responds to my post.
Remember, I asked this post in the form of a question, you are bound to answer!

Update; the brake pad worked, for a short time.
I attached the pad bolt underneath the pivot and one end of the brake pad butted against the tension roller bolt, it stopped the top of the chain from slacking, but still allowed the spring to work, but with limited play.

The rubber on the brake pad broke up and allowed the bolt to travel.
So I pedaled home.

 

[dragray]

you can buy an offset intake manifold from sickbike parts.
i'm afraid that jb weld is not the best product to use on an intake manifold. It may hold up for awhile but it will eventually break down.

your chain tensioner is HUGE and over complex,
you need about 1/2 inch +- up & down in the chain.
if your sprocket is not centered as close as possible, your chain will come off.
also, these are notorious for the chains going loose, tight, loose, tight as the sprocket rotates, due to the center hole in the sprocket not being exactly in the center.

just my opinions.

 

[2door]

Dragray is right. If the chain alignment is right, and the rear sprocket is 'centered' on the rear hub you can get away with a loose or tight chain. If either is installed incorrectly all the chain tensioners, JB-Weld or any other bandaid isn't going to allow you to run without problems.
Center the rear sprocket on the hub and make sure the chain is running in a straight line between the engine drive sprocket and the rear driven sprocket. That will eliminate most, if not all of your problems.
As has been said here many times before; roller chain is not designed to run at angles. It can't 'bend around corners'. It must be straight and tensioned correctly. That includes the tensioner wheel (pully). If the tensioner isn't properly aligned with the chain path it will derail the chain because it will pull it to one side or the other and not guide the chain onto the rear sprocket as it was designed to do.

Tom

 

[Toadmund]

you can buy an offset intake manifold from sickbike parts.
i'm afraid that jb weld is not the best product to use on an intake manifold. It may hold up for awhile but it will eventually break down.

Not if I can make my own, the JB is just added as insurance, the pipes are silver soldered together, although it's not completely airtight, it's not bad.(do you mean gas eats it, or it will fail physically, or both?)

your chain tensioner is HUGE and over complex,
you need about 1/2 inch +- up & down in the chain.
if your sprocket is not centered as close as possible, your chain will come off.

I think it looks over complex because of the bracing. And the bracing is what I had and my budget barely allows.

also, these are notorious for the chains going loose, tight, loose, tight as the sprocket rotates, due to the center hole in the sprocket not being exactly in the center.

That's why I made a tensioner, for now I just want to ride my bike, fix the centering later, believe me it's on my mind, but the offset does not seem to be the problem, my chain is staying on, it just was getting bound in the drive sprocket during starting with the clutch engaged, I just fixed the problem I believe, I will test it tommorow, I will post a picture if it works.
[/QUOTE]just my opinions.[/QUOTE]
I value your opinion.

If either is installed incorrectly all the chain tensioners, JB-Weld or any other bandaid isn't going to allow you to run without problems.

Heh, just JB as extra re-enforcement only on intake pipe mod.

make sure the chain is running in a straight line between the engine drive sprocket and the rear driven sprocket. That will eliminate most, if not all of your problems.

It's good, my only prob now is perfecting my tensioner.
This is my first build, so I'll have trials and errors, I've identified my chain problem, slack chain during start-up.
My sprockets line up well, I will let you guys know how my mods worked out.

Thanks for your advice, I will work smarter not harder next time!

 

[Toadmund]

OK, here I am, seems my fix is working real good, I have no chain issues at all, went to my brothers place about 3kms away.
Kept the motorized bicycle a secret from him all winter, now he wants one, he took it for a burn and could't believe how it could move!

So here is a pic of what I did, finally found a use for that hunk of rubber I found.
The rubber acts as a bumper to stop the upper chain slack that got bound up in the drive sprocket.
See, sometimes crap I bring home does get used for something.

Yeah I know, looks even more over-complicated, but it works for me.

 

[tooljunkie]

find a straight edge,short enough to line up the two sprockets.i used a piece of flatstock and curved one end to seat more on the big sprocket,and did my best to get chain in line with the sprockets.it makes a difference.

in the beginning if my MB riding the chain derailed and broke the case in front of the drive sprocket.

 

[Toadmund]

I ditched the chain spring tensioner setup long ago, it was more problems than it was worth, just using the stock tensioner mounted with inner tube to not move.

Bent tensioner to align with chain.

And bought a quality KMC 415HD bmx chain.

A lot of hassle behind me.

KISS principle here.

 

[Dan]

Cool, sounds like ya got her going.

Like problem children. Problem builds choke ya up the most and make you feel the best when they do good.

 

[Allen_Wrench]

Well, Toadmund, from what I can tell, you're getting the condensed-version of a crash course in Motorbike Building Trial-and-Error. The things you're learning now through this experience will come in handy later on. Just keep it safe and keep it smart and you should be okay.
BTW: could we see pics of the whole bike at once?

 

[Toadmund]

I'm installing an RT carb at the moment.

Took off my NT carb with the copperr 3/4' 45Degree elbow, and went to size up the new wide ported intake I got from BGF so I can dummy up the carb and hardware to make my new offset, looked nice, but DAMN! the mounting holes are too wide!

So I took a round bastard and reamed out the holes and built up a good sweat filing the holes inward, dremeled flat the welds, then filed, can't go further, still I cant use washers or bolts, went and bought allen bolts. so I hacksawed a threaded furniture panel retainer to use as a spacer, but I didn't know the sawed end would strip and bind as I screwed in the bolt. No bolt is safe with that spacer.

I need a better hacksaw blade now, to try it again.

Getting the bike ready for spring sends you buying stuff.

I'll post some pics when I'm done and what I did.

I had fun motorbicycling last summer.

(this is the condensed version post, the longer one resides in my head, it's even more dry and boring than this short version)