Pocket Bike Engine Project

[lowracer]

I received my Dax fuel tank today, installed it, filled it, went for a ride & took some pics. Its larger than the temporary tank I started with (which is a good thing), but I noticed that the fuel cap spits fuel thru the breather hole & needs a better fuel cap to prevent this. Anybody got any good ideas? My other engines all have different fuel cap thread patterns from eachother, but they dont leak.
-Lowracer-

 

[lowracer]

I had to fix my new Dax 'fuel tank cap spitting problems' & came up with an easy & effective solution.
I have another smaller fuel tank that also has a crummy fuel cap that allows fuel to spit out at high revs or over bumpy terrain, but also allows the engine to bog & konk out by not allowing the fuel tank to breathe. I remember as a kid riding dirtbikes with fuel caps vented by a long length of tubing to keep fuel from escaping & allowing the tank to breathe.
I pulled the plastic insert out of each cap with a needle nose plier & drilled a small hole thru the top of the cap just a bit smaller than the fuel hose I planned on running thru the hole. I cut each end into a diagonal angle like this pic '/' making it easier to feed thru the tight hole. Then I grab the end with a needle nose plier & pull it thru a few inches. They work real well & now I can fill the tank close to the top & not have to worry about wearing fuel that spits out of the tank & onto me (front wheel drive) or konk outs. Here are 2 pics of both tanks.
-Lowracer-

 

[lowracer]

Ok,
I dont think the Red Loctite is holding up too well. I noticed that sound again...You know, that sound of compression coming out of the engine. Very glad I have this engine mounted in front of me to See & Hear all of its little Sights & Sounds.
I removed the suspect loose headbolt & inspected the threads. Threads looked good. I took it to the local Lowes hardware store to measure & its an M6 X 1.0 X 80mm cap bolt. Lowes doesnt carry long bolts, but McMaster Carr does & I ordered 10 @ 90mm's. I also ordered a bag of stainless steel split lock washers. I'm hoping that the extra bolt length finds threads inside the engine case, along with more Red Loctite, & the split lock washers will keep these bolts from vibrating loose. This engine is such an exciting screaming package that I have become quite fond of it & will order another if I can get a handle on the 'Mystery of the Loosening Headbolts'. At 'Ludicrous Speed' (Spaceball's) turning 10,000+ rpm's, something is gonna vibrate itself loose.
Will post my findings once all new items are installed.
-Lowracer-

 

[lowracer]

Ok,
I received my new headbolts today & ran down to the hardware store on 'Wimpy' (EH035 powered rear friction drive bike) to pick up some lock washers. I have a bunch of lock washers on order that haven't arrived yet but for 17 cents for 8 of them, I would splurge to get this project rideable today.
I posted a pic of the stock M6 x 1.0 x 80mm bolt (black one) & the new M6 x 1.0 x 90mm bolt (blue one). With 2 lock washers on each bolt, & Red loctite on all the threads, I am hoping that it stays tight. The longer bolts definitely grab more threads in the engine case & hopefully the lock washers help prevent vibration loosening. I took it out for a few test runs & so far so good. It sounds like it is all nice & tight even at ludicrous revs. Time will tell...
If it holds up, I may have cured the woes that many people have using these Cag type engines (especially the higher compression head kit hop-up versions).
I really want to finish up another bike project that is ready for the engine to go on it, I just need to order up another engine & will get another of these once convinced the head bolts stay tight.
-Lowracer-

 

[lowracer]

Oops,
I did a gearing experiment yesterday by changing my engine pulley from a 1.5" to a 1.75" in an attempt to lower my engine rpm's at higher speeds. It totally changed the way the bike felt (too tall). It made it tough for the engine to get 'on the pipe' & hurt performance all around. I'm thinking the clutch would have worn out if I kept it set up this way. I quickly switched back to the 1.5" pulley & called it a good $4.00 experiment.
-Lowracer-

 

[lowracer]

I pulled the trigger today on another engine, pipe, & expansion chamber purchase today for yet another MB project.
Here are a few pics of whats on order & will get a few more items to complete the job.
This will be the 2nd of the same engine (really love this motor).
I'll be swapping head bolts as soon as UPS delivers the engine.
The 90mm bolts with lockwashers & red loctite seem to do the trick.
-Lowracer-