Linksep's Mini Bike Build Thread

[Linksep]

I had some time so I decided to test the compression on my little project and I was really pleased by the results! My $10 HF compression gauge read 105 psi on a engine that was probably 40* fahrenheit (that's 4.44* C to our friends outside the USA). I'd say that's pretty impressive for a 23 (or maybe 33?) year old engine with a known blown head gasket!

I took a few pictures so you could all marvel at the piece of junk that I just couldn't live without. I made sure to take detailed pictures of the blown head gasket; wet with gas from trying to start the engine one more time before I tear into it. I also found out that the governor arm is leaking oil which I didn't know (but wouldn't have cared about) before.

Phase 1 of my plan is to make it ridable (new wheel, reseal the engine) and then abuse it until I get bored. Phase 2 will involve stripping it down completely, grinding some of the terrible welds and using JB-Weld like body filler to smooth it out. After it no longer looks like it was welded by a two year old, I'll paint it and ride a little more, or more likely sell it and move on to the next project.

 

[Linksep]

Just a couple more pics of the messed up wheel/sprocket that someone decided to drill out and the front (unmolested) wheel.

 

[SpyGuy]

It's getting there .... looking good so far.

 

[Linksep]

This is fairly close to the state I purchased it in. The only thing I've actually been doing is disassembling, diagnosing, and researching. I think I have my shopping list in order so I'll be spending a little time on the MFG Supply website tomorrow getting parts on the way.

I can't wait to ride it! My buddy is putting in an offer on a mini bike and kart frame I found on craigslist tonight (same seller, bike and kart both need lots of work) so I may have someone to race.

 

[Linksep]

Well I started taking the motor apart and things just keep getting better...

The source of the head-gasket leak was a broken bolt. I have (what's left of) the bolt soaking in Liquid Wrench; hopefully that does the trick. If Liquid Wrench doesn't work my only other option is to drill it out and use a thru-bolt with nut on the other end.

There is some cylinder wall scoring, and the combustion chamber is REALLY carboned up...but the piston is pristine. That makes me think the guy that sold it to me used something poured in the spark plug hole to free a stuck piston, then busted the head-bolt trying to get in there to rebuild it...after he was done breaking things he decided to pass the buck on to someone else.

On the bright side, this will give me a chance to do my own tests of decarbonizing methods and engine restore in a can (If I can get that bolt out).