A heart with no body; the Turbo 10hp Briggs & Stratton. Aka Timebomb.(56K beware!)

minibikekid

minibikekid

New Member
#81
#81
Same thing happened to my 3hp briggs because someone didnt run an air filter before i got it. Im guessing some dirt got in there and scared the cylinder wall up and the piston. Sucks about the 10 horse briggs, maybe you can bore it out and use a slightly bigger piston out of something else if it can match up with your rod. Good video of it though!
 
65ShelbyClone

65ShelbyClone

Well-Known Member
#82
#82
I'm not sure that dirt could take out the amount of metal that my cylinder lost. Then again, I'm not sure what did either. I'll know more when It blows up and I can tear it down.

I've been sorting out the spark control this weekend. So far I have it running on a transistor-switched coil the MegaSquirt is controlling. I also redid the crank trigger configuration and tried out the toothed wheel decoder feature in the software. It was a pain to sort out, so I just used a single trigger tooth. Somehow the firmware in the ECU got zapped and I spent an hour sorting that out.
 
minidragbike

minidragbike

Supporting Speed Nut!
#83
#83
I hope all of this adds up to big power, and not just a slightly better ignition timing and fuel curve?

The setup sounds very nice, but remember it will have to run as good as it looks. Why not start off with a modified motor? At least the parts would be heavy duty and make decent POWER from the start. That's what the outlaw prostreet guys do.
 
Last edited:
65ShelbyClone

65ShelbyClone

Well-Known Member
#84
#84
Luckily for me, the whole setup is ugly as heck. Big power would be a bonus at this point. :001_tongue: Keep in mind that when I started this project, the original objective was to scatter the engine. With how torn up the cylinder is after the seizure, this engine is done now anyway. I'm not sure what I will transfer the EFI and/or turbo onto. I'm really tempted to use my Kohler-powered Cushman.

I screwed with the ignition some more. I'm using a modified pullstart clutch hub as the trigger wheel. Turns out that I was chasing bad timing because that hub loosened up and advanced the setting. In the process the (stainless steel)flywheel key went bye-bye. My timing tape(literally printed paper and clear tape) also fell off of the flywheel. Intake backfires blew the throttlebody clear off the engine a couple times and the retarded ignition made for some long exhaust flames....lots of heat, too.
 
minidragbike

minidragbike

Supporting Speed Nut!
#85
#85
There is always problems. I ran into a bad one today. I have been running the stock cam in my Avatar minibike for years now. I added some new heavy duty springs last week. The motor ran it's best today turning 6,880 RPM with 14/50 gearing with a 41" tire circumference.

It did this for a good three passes, then it began to fall off a little at a time. Basically loosing 400 RPM every time my bike runs. I took the motor apart tonight and found my exhaust lobe had lost some of it's lift. It lost exactly 0.028" lift on the exhaust lobe, times that with my 1.2 ratio rockers and I was lucky I was even able to run at all. I was basically running with 0.032" valve lash on the exhaust. A little bit more and my lash cap would have came off. LOL

I will get it back up to speed before next weekend.
 
65ShelbyClone

65ShelbyClone

Well-Known Member
#86
#86
I got sick of that big clunky electric motor hanging off the engine, so today I removed the electric starter.



I must not know my own strength....:eek:ut:



Wait a minute, that wasn't here a little while ago. :confused1:



How did that get there?

 
65ShelbyClone

65ShelbyClone

Well-Known Member
#90
#90
I had the garden hose a few feet away in case of emergency. :thumbsup:

It just kills me that I didn't get it on video. It seized up three times before it let go. Each time it took about a half hour to get it cooled down and freed up. I didn't want to have two hours of video of it just locking up, so I didn't tape it. After the fourth round of "unseizing" it, it was zinging along pretty well at ~4500rpm. All of a sudden everything blew out the side with no warning at all. In my experience, they usually start bogging down before the rod lets loose.

It was really cool. Smoke was billowing out of the crankcase hole, that chunk of the rod was smoking, and the engine freewheeled for a good 10sec. :001_tongue:
 
Last edited:
65ShelbyClone

65ShelbyClone

Well-Known Member
#92
#92
I can't believe I forgot an "aftermath" picture. I hate bringing this defunct thread back, but here it is:



Here is why the engine was a loss to begin with:

 
minidragbike

minidragbike

Supporting Speed Nut!
#93
#93
I tell guys all the time about stock rods and pistons. But the bad part is only about 10% of them truely understand it. The other 90% has to shown the hard way.:doah:
 
You must log in or register to reply here.
Top