Back to report that the 6 mm studs did not work out. The JBWeld pulled out the first time I went to tighten it. So I bought 5/16 inch all thread and retapped the block for that. Then I took a 2 inch 1/4 inch pipe nipple and cut it into 4 pieces of about 1/2 inch to make spacers to get the 5/16 nylock nuts elevated above the fins on the head. Grabbed the all thread with a vise grip just below the head and torqued to 100 inch pounds (Dax says the 6 mm bolts need 85 inch pounds). Took it for a spin today and it started real easy. I have converted the friction drive to a Dax chain drive because my Armadillo tires were giving off crumbs of rubber from the friction drive. Now all I need is a good break in. This time I am using Opti-2 at 36:1 ratio so my new piston does not seize up like the first one did by using 72:1. Looks like the 5/16 all thread will do the trick on the head. Pictures attached.
Pocket Bike Engine Project
- Thread starter lowracer
- Start date
lowracer
New Member
GE Joe,
Now that looks strong. If I ever mess up the threading on my crankcases, I'll definitely go 5/16" too.
I had a bad feeling about the JB Weld being used for a bolt anchor.
If you havent gone chain drive yet, try using a file on the points of the new friction drive roller to smooth off the points. I did that on my BMP kit from the advise of Jim the previous owner of BMP & what a huge difference it made for tire wear.
-Lowracer-
Now that looks strong. If I ever mess up the threading on my crankcases, I'll definitely go 5/16" too.
I had a bad feeling about the JB Weld being used for a bolt anchor.
If you havent gone chain drive yet, try using a file on the points of the new friction drive roller to smooth off the points. I did that on my BMP kit from the advise of Jim the previous owner of BMP & what a huge difference it made for tire wear.
-Lowracer-
Another question here:
You know the head on the big bore kit and it has 1 side of it that is flat?
Can you check one of your engines and tell me which way it faces please? (Toward the exhaust, toward the pullstart/ cgi, toward the clutch, or does it face up?)
Reason I ask this is because I disassembled my engine and did not check which way it was facing. I want you to check 2 of your engines and see if they both have a head that has the flat facing the same direction and which way is it facing?
For your interested, the pull starter outside frame was pushing on the head kit all the time, but when I made it facing the exhaust it was not pushing on it at all.
How I tested this:
Remove all head bolts but keep the head on
Now attach the pull starter while pushing down on the head
If you can spin the head then the pull starter frame is not pushing it (It was loose, make flat side face the exhaust to achieve this), but if you cannot spin the head around then the pull starter is pushing against it.
The reason is this: The pull start casing interferes with the right side of the head. When you make it face the exhaust the right side is flat.
Now I am asking which is the best position and why?
Please answer all questions so that I would not end up asking them again later.
You know the head on the big bore kit and it has 1 side of it that is flat?
Can you check one of your engines and tell me which way it faces please? (Toward the exhaust, toward the pullstart/ cgi, toward the clutch, or does it face up?)
Reason I ask this is because I disassembled my engine and did not check which way it was facing. I want you to check 2 of your engines and see if they both have a head that has the flat facing the same direction and which way is it facing?
For your interested, the pull starter outside frame was pushing on the head kit all the time, but when I made it facing the exhaust it was not pushing on it at all.
How I tested this:
Remove all head bolts but keep the head on
Now attach the pull starter while pushing down on the head
If you can spin the head then the pull starter frame is not pushing it (It was loose, make flat side face the exhaust to achieve this), but if you cannot spin the head around then the pull starter is pushing against it.
The reason is this: The pull start casing interferes with the right side of the head. When you make it face the exhaust the right side is flat.
Now I am asking which is the best position and why?
Please answer all questions so that I would not end up asking them again later.
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Please answer questions in my thread because I do not want your thread ruined by my questions:
http://motorbicycling.com/f4/my-first-motorbike-project-33877-3.html
By the way what is this 5/16" all thread you are talking about? Did he make the threads larger? (8mm).
Lowracer if you keep track of your mileage, let me know how many miles your bicycle with the cag engine has by now.
My guess is you will never strip the threading on your engine lol so you won't need 5/16" most likely.
How do you thread metal though? Is it easy? How do you do it straight and accurately without messing up?
(I've threaded plastic before by hand and it was difficult to do it it so that it is threaded straight down and not at an angle.)
Please answer all of my questions in this thread and in my thread.
Thank you!
http://motorbicycling.com/f4/my-first-motorbike-project-33877-3.html
By the way what is this 5/16" all thread you are talking about? Did he make the threads larger? (8mm).
Lowracer if you keep track of your mileage, let me know how many miles your bicycle with the cag engine has by now.
My guess is you will never strip the threading on your engine lol so you won't need 5/16" most likely.
How do you thread metal though? Is it easy? How do you do it straight and accurately without messing up?
(I've threaded plastic before by hand and it was difficult to do it it so that it is threaded straight down and not at an angle.)
Please answer all of my questions in this thread and in my thread.
Thank you!
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lowracer
New Member
Gera229,
The carb on the engine thats on 'The Beast' was perfect stock for the pipe I am using.
The carb on Pocket Bike II, I changed the jet to a 70 to see what it would do & it runs the same. I bought a jet kit w/ multiple sizes just to experiment. I may change it back if I ever need to take apart the carb for a different reason.
-Lowracer-
The carb on the engine thats on 'The Beast' was perfect stock for the pipe I am using.
The carb on Pocket Bike II, I changed the jet to a 70 to see what it would do & it runs the same. I bought a jet kit w/ multiple sizes just to experiment. I may change it back if I ever need to take apart the carb for a different reason.
-Lowracer-
lowracer
New Member
gera229,
I didnt do any modifications to the engine. I think once its broken in & running perfectly, that would be the time to start messing with it if you still need more power. Personally, I think its got more than enough power for a bicycle just the way it is & if its running perfectly, why possibly mess that up?
-Lowracer-
I didnt do any modifications to the engine. I think once its broken in & running perfectly, that would be the time to start messing with it if you still need more power. Personally, I think its got more than enough power for a bicycle just the way it is & if its running perfectly, why possibly mess that up?
-Lowracer-
I was just asking. I was looking through the pocket bike planet forum and people there claimed that their stage 2 engines ran worse than the stock cylinders. They say that was because the stock porting was faulty and such.
Source:
http://www.pocketbikeplanet.com/showthread.php?t=48907
But if you say it runs better and have experience with both the stage 2 and stock cylinder kits, then I guess it's good.
Maybe I may experience it myself after breaking in and let you know the results (if it doesn't seem to produce enough power for me with the stock stage 2) when I get my mounting kit next week.
Source:
http://www.pocketbikeplanet.com/showthread.php?t=48907
But if you say it runs better and have experience with both the stage 2 and stock cylinder kits, then I guess it's good.
Maybe I may experience it myself after breaking in and let you know the results (if it doesn't seem to produce enough power for me with the stock stage 2) when I get my mounting kit next week.
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lowracer
New Member
Yeah, you need to get it operational 1st. There is too much info out there...
I cant see how a base one runs any better than mine?
I'm very satisfied with the one I got & after just a few tweaks (expansion chamber, plug wire, plug, copper gasket, headbolts) it runs strong.
-Lowracer-
I cant see how a base one runs any better than mine?
I'm very satisfied with the one I got & after just a few tweaks (expansion chamber, plug wire, plug, copper gasket, headbolts) it runs strong.
-Lowracer-
Oh I see, seems easy to replace.
Also I would like to ask, did you ever own a base cylinder kit (Are you are referring to stock cylinder kit)?
Just wondering. Of course stage 2 kits are supposed to perform better, but based on this source people have reported stage 2 kits running worse than base (Stock cylinders if that is what you are referring to) cylinder kits and this man summed it up to why they produce less power and how they can be made to be stronger than stock with real performance gains:
Here is the source, it's a pretty short and brief and a good read:
http://www.pocketbikeplanet.com/showthread.php?t=48907
But then again, more performance means less fuel efficiency.
Thank you.
Also I would like to ask, did you ever own a base cylinder kit (Are you are referring to stock cylinder kit)?
Just wondering. Of course stage 2 kits are supposed to perform better, but based on this source people have reported stage 2 kits running worse than base (Stock cylinders if that is what you are referring to) cylinder kits and this man summed it up to why they produce less power and how they can be made to be stronger than stock with real performance gains:
Here is the source, it's a pretty short and brief and a good read:
http://www.pocketbikeplanet.com/showthread.php?t=48907
But then again, more performance means less fuel efficiency.
Thank you.
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Ok, so I was looking over this thread again and found this post interesting. Post #57.
But what was the problem when your engine went weak and shut down? Why would it only work with choke on, but not with choke off?
Does it work perfectly with choke off now?
(Lowracer did you have this problem before? If so please answer those questions)
Thanks.
lowracer
New Member
The fuel caps on these Dax fuel tank & Pocket bike fuel tanks are crap. If the tank cant breathe, the engine dies. I just bought a motocross dirtbike breather tube for <$3.00 on eBay & its awesome. The tank can breathe & fuel doesnt jump out onto you. See pic.
-Lowracer-
-Lowracer-
Attachments
NEAT TIMES
New Member
lowracer/cannonball 2
Do you think the fuel vacum locking at high rpm and work load damaged or scored the pistons?
When my large Husky chain saw`s 88cc and 119cc were run completely out of fuel in a big cut by crew member`s, they melted piston`s and worse!!
Ben, did you ever find out what happened to yours ?
Think I would prefer diaphram carbs on all my mab builds. Last month we fired up 3 chain saw`s that had been stored in a alum unvented truck box for 4 yrs without running. They all started and ran perfect by adding fuel.
Ron
Do you think the fuel vacum locking at high rpm and work load damaged or scored the pistons?
When my large Husky chain saw`s 88cc and 119cc were run completely out of fuel in a big cut by crew member`s, they melted piston`s and worse!!
Ben, did you ever find out what happened to yours ?
Think I would prefer diaphram carbs on all my mab builds. Last month we fired up 3 chain saw`s that had been stored in a alum unvented truck box for 4 yrs without running. They all started and ran perfect by adding fuel.
Ron
lowracer
New Member
NeatTimes,
The damage was probably caused by loose head bolts (leaning out) which seems to happen to alot of these cags upon break-in. I created similar havoc accidentally by changing jets to a smaller size (leaning out) & had to buy a new head kit to fix my 2nd pocketbike engine. I bought Cannonballs blown engine (my 3rd pocketbike engine) & rebuilt it with a new head kit. I also noticed the carb clamping bolt was stripped & prevented a tight seal at the carb inlet (maybe that could have caused the extra air seepage)?
I've run into fuel tank vacuum issued in the past & had it konk out my engines but never did it lean them out or blow an engine. Just a bit of fuel starvation.
-Lowracer-
The damage was probably caused by loose head bolts (leaning out) which seems to happen to alot of these cags upon break-in. I created similar havoc accidentally by changing jets to a smaller size (leaning out) & had to buy a new head kit to fix my 2nd pocketbike engine. I bought Cannonballs blown engine (my 3rd pocketbike engine) & rebuilt it with a new head kit. I also noticed the carb clamping bolt was stripped & prevented a tight seal at the carb inlet (maybe that could have caused the extra air seepage)?
I've run into fuel tank vacuum issued in the past & had it konk out my engines but never did it lean them out or blow an engine. Just a bit of fuel starvation.
-Lowracer-
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