Pocket Bike Engine Project

I also bought a GT50R from Dax. I immediately stripped out a head bolt, so I switched to studs. I have not run it yet to see how it holds up, but here are some photos.
 

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I had enough thread left in the hole that I went with JBWeld. Since I don't expect to remove the studs it will probably be ok. Seems to be good and tight now. Otherwise I was going to try Permatex Thread Restorer.
 
How will 8mm bolts/ studs fit?
Why did you use studs instead of high grade bolts?

Lowracer I haven't ordered my bolts from mcmaster but will do so today or tomorrow.
You have a lock washer on your head bolts right? What's a lock washer compared to a normal washer?

Should I get studs or bolts from mcmaster for my engine that will come by next week?

Thanks.
 
Older farm tractors used studs instead of bolts. It seems that when you have a soft metal (block) and a harder metal (bolts) it is a recipe for stripped threads. Once you lock the threads of the stud into the block (red loctite and JBWeld for the stripped thread), the actual movement when tightening is between the nuts and the studs, both steel. Standard grade metal is sufficient for the 96 inch pounds of torque recommended for 6 mm bolts. I also chose to use nylock nuts, as you can see in the photos (this is what some China girls builders do also). It should more than suffice. If does not, I will post again.
 
GEJoe,
Let me know how that JB Weld holds up for the crankcase stud. I use JB often to initially set my rim pulley onto the spoked rim, but then I drill a few holes & bolt them together for added security. I've used JB weld on racks & it came apart (maybe due to vibration or movement) Not sure how that JB will hold up the way you are using it?

Gera229,
I bought a bag of split lock washers to both take up some extra space on those 90mm bolts & to hopefully keep the bolts from wanting to loosen. So far so good on both engines.
I like the idea of using studs & nylock bolts up top. Maybe one day I'll need to fix a problem & will change then. Its too bad these engines dont come from the factory with 8mm studs. It would allow higher compression & horsepower without as much fear of damage. I took a video yesterday riding 'The Beast' one handed holding my phone (vid recorder), but couldn't get any high speed action since at around 30-35mph the engine is kicking into the sweet-spot 'on the pipe' & I couldn't hold on using one hand & had to let off the gas...lol I dont have bluetooth so I couldnt send it to my computer to upload a link for all to see :(
-Lowracer-
 
So the engine was vibrating? I don't get your point for telling me that, but are you saying that if you used studs for the head then it will not vibrate as much?

What is the lock washer part number for mcmaster?
 
Gera229,
The JB Weld info was for GEJoe.
I didnt buy the washers at McMaster Carr (local Ace Hardware)
-Lowracer-
 
Oh ok. So type of bolts/ studs doesn't affect vibration.
I guess I am going to be getting head bolts (Not studs) and am making the right choice.
How long did you not need to tighten your head bolts so far?

If they last, then I think bolts would be better than studs. Maybe not as good, but the extra on the studs is not really necessary if that's the case.
 
Gera229,
My bolts are nice & tight since break-in.
You just gotta buy something, build something, & make it go.
Stress out over the fine tuning as you go...
-Lowracer-
 
Yes, once it's tuned correctly I think it should be good for a bit before tuning it again. (I had one of the 47cc engines before, but clutch springs often broke, so I sold it and never wanted one again and now I am back with people having no problems so I thought I should try again PLUS I never had a big bore kit like I am getting soon.)

Zero will ship me the performance clutch at no cost as a tester for him. The performance clutch has 2 shoes and 2 springs and looks like this:
http://www.motopartscenter.com/perf...n=file1&utm_medium=organic&utm_source=froogle

And I guess since you aren't having problems with the head bolts I will be getting them.

Thanks.
 
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Placed order in McMasterr carr today, now I would like to know should I get the fuel line from pocketbikeparts.com for $15? Is it worth it or should I buy one from a local store? Do they also have fuel filters that will work at a local store?

Ordered:
Engine stage 2 kit
90mm bolts from mcmaster carr

Here is what I have to order or buy from a local store:
Copper head gaskets
Exhaust
NGK spark plug
Fuel line

Throttle handle

Sprocket and chain. (Idk what sprocket and if they will fit the bikes and so).

Should I buy a complete mounting kit ready or should I make one? (I'm trying to go for the cheaper rout, maybe if a completed one is cheap then I may reconsider that route)

I'm buying a used mountain or road bike.

Let me know if I am missing any parts here.

Also I think I should start my own thread on my own build, but lowracer I will need you to reply in that thread to me because since you own the same motor you are of big help to me.
 
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gera229 said:
Yes, once it's tuned correctly I think it should be good for a bit before tuning it again. (I had one of the 47cc engines before, but clutch springs often broke, so I sold it and never wanted one again and now I am back with people having no problems so I thought I should try again PLUS I never had a big bore kit like I am getting soon.)

Zero will ship me the performance clutch at no cost as a tester for him. The performance clutch has 2 shoes and 2 springs and looks like this:
http://www.motopartscenter.com/perf...n=file1&utm_medium=organic&utm_source=froogle

And I guess since you aren't having problems with the head bolts I will be getting them.

Thanks.
Click to expand...

If your pb engine has a tapered crank nose, this clutch will NOT fit.:-||
 
Gera229,
I think if you are going to run chain drive, you are going to need some kind of gearing reduction (jackshaft or transmission). I run a v-belt using a 1.5" clutch pulley to 22.25" wheel pulley to 25" tire diameter to get correct gearing for a 11000+ rpm engine (15.6:1). If you are running the stock 6T chain drive pinion, your wheel spocket would have to be 94T for the same ratio...I dont think that size is available...
I do think you should start your own thread & I'll post on it.
-Lowracer-
 
Its a bit different than the math suggests. The drive pulley is 1.5", but the belt rides in the pulley @ 1.43". The rim pulley is 22.25" but the belt rides higher since the bottom of the belt is touching it (not the sides). I recommend doing a rollout test to verify gear ratio calculations. 1 complete revolution of my driven wheel gives 15.6 revolutions of my drive pulley (with my weight on the bike for tire squish). From that point its easy to calculate speed using an rpm meter.
-Lowracer-
 
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