My First Motorbike Project

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lowracer

lowracer

New Member
Oct 17, 2008
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I use 2 thin copper base gaskets on 'The Beast', but only one on my other 2 Cags. I bet you have your headbolts tightened up too much & unevenly torqued?
You can easily warp the head by overtorquing it. Its only thin aluminum. Also do a criss-cross tightening pattern (like lugnuts on a car) tightening each headbolt only a smidgeon at a time.
-Lowracer-
 
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gera229

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I actually put a double coat of copper sealant today and tightened the bolts in a criss-cross pattern a little bit at a time and it seemed to solve the problem. I do not know how much torque that is with hand power, but I used my wrist strength turning the allen wrench to tighten the bolts pretty hard (not my arm strength which would have been even tighter.)
 
Rocky_Motor

Rocky_Motor

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Nov 14, 2011
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Fort Collins & Boulder
You should really consider getting an inch-pound torque wrench. Head bolts are the single most important bolts to torque correctly otherwise you will more than likely always run into problems. At the least so that they are all of the same torque.
I got one at harbor freight for 20 bucks. I couldn't find any local stores other than that, that sold inch-pound torque wrenches... Harbor freight isn't the best quality but it works.

Unless you have some finely calibrated wrists there :p
 
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gera229

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Today the worst thing happened, while my engine was riding good, after I reached my destination I parked for a bit then I pulled the pull start and it literally broke the aluminum casing I do not know how so I had to pedal.

No leaks for me so far, I am happy. I just try to run it normally and not too hard for too long to maintain engine life.

It's pretty loud, someone told me it's very loud, but so far so good.



 
5

5-7HEAVEN

Well-Known Member
Aug 2, 2008
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Maybe you can weld on a flat aluminum plug for added strength at the center of the housing.

Keep a spare pullstart in your backpack.
 
Mike B

Mike B

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Mar 23, 2011
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Yeah.

I bought a base CAG for $90 shipped.

What do you think the parts will cost?

I bought a Solex kit for $250.

And 2 gas tanks and a fuel pump for $150.
 
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gera229

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An actual cag pocket bike for that price?
Used? I can get a brand new engine for $75-$80 shipped from ebay, but they're stock.

I don't understand why you are telling me to buy everything. My project is fully complete now, the engine is good so why buy a new one?

What's a Solex kit?

2 gas tanks for $150? Quite pricey, I just use the $20 gas tank that come with the 66cc kits.
 
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gera229

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So I got my pullstart in the mail today and put it on and guess what happens next?

The flywheel literally breaks off. What the heck? This aluminum is so cheap.
Do I have too much compression?
How do I check compression? My spark plug seems good so I don't think the piston is hitting the spark plug and thus there seems to be some clearance so I don't think the compression is too high, but correct me if I am wrong.

The rocket key that I got from Daves discount motors looks bent up and it looks like I need a new rocket key.

This time I have only 1 copper base gasket instead of 2 of them that I had with my previous cylinder. Should I raise the cylinder to reduce compression by adding 1 more copper gasket?

I feel like giving up this sport because of how much money it costs to keep on fixing it, unless someone is willing to donate :). Seriously I don't want to give up, but I just don't have the money.

Also 1 of the fins on the flywheel broke.

Another thing is the slot where the rocket key belongs to is worn out and I do not want to buy a new crankshaft (this one is already brand new ever since the bearing failure). It's worn out on the upper half of the key slot, so I hope the lower half is good enough to hold a key in place. I hope a new key will have little to no play in that worn out key slot. If the key lifts up and reaches the worn out part it would get out of place and cause damage and/or wear it out even more or even the key would bend or something which I doubt would happen if it's the correct size?

If the key flys out of the slot however (since that worn out part doesn't hold it very well so if the key lifts up it may fly out I guess), it would definitely cause damage I think and/or cause a great amount of wear.

Do you guys think the crank shaft is still usable with that worn out slot?

Here are some pics:

This is the worn out key slot on the crankshaft


This is the flywheel
 
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lowracer

lowracer

New Member
Oct 17, 2008
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Charleston, SC
Gera,
Aside from changing a few things on these Cags to prevent certain destruction (longer head bolts, copper base gasket, clutch springs, etc) I wouldn't be spending all my money doing hi-performance mods to an engine that isn't even broken in yet?
Many people race pocket bikes & mod their engines to race, but racing costs lots of money. The stock Cag stage 2 runs well & is already too powerful for an unsuspended bicycle...why mod it?
-Lowracer-
 
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gera229

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My engine does not have any mods whatsoever. What mods are you referring to?

This is a pure stock engine head kit and nothing really done on it.
 
lowracer

lowracer

New Member
Oct 17, 2008
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Charleston, SC
Yeah, I guess you haven't done many mods, just the reeds & rocket key.
In my experience, the Cag is a really powerful powerplant, but not very reliable or maintenance free. I have a few Cags, a Tanaka & a Subaru Robin. Of them, the 2 Japanese engines are by far the most maintenance free, reliable engines. But to be honest, I love the extra power of the Cags so much that I cant seem to keep them in storage very long...lol
-Lowracer-
 
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gera229

New Member
Sep 4, 2011
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With your new walbro carb you shouldn't have that many problems, tighten all bolts before riding (or even put lock washers everywhere to eliminate this need).

Actually, it's relatively maintenance free when the cylinder performs very well. Most failures are here and carburetor as well as heat but that has to do with the cylinder. Also stripping bolts just sucks so much that I finally bought a torque wrench from harbor freight. I found a $10 off coupon online and used it, would you like me to send you the coupon code if you don't have a torque wrench yet? The wrench is originally $20.

All the other parts don't matter because they do not break very often.

I am just unlucky to break the pull start and flywheel.

I'm going to use a regular woodruff key next and a flywheel I will buy, but that is still $25 wasted.

What do I do with the old flywheel? Cast aluminum?

Edit:
I decided to give out the code for the torque wrench anyway. If you buy online use coupon code 43454785.

Otherwise here it is: http://www.tundrasolutions.com/foru...wrench-recommendations-hftorquewrenchsale.jpg
 
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