Engine shakes, and my new plan!

[ImJay]

Long time no see, DIYGK!
Well due to studies and my financial state my gokart may have been put off for another year.


But for now, since I managed to get a 6.5hp clone from a friend I thought I would make something that has been on my list. I'm hoping to do something on the budget end to get my hands dirty like a shopping trolly with an engine, or a little kids peddle car engine powered, to learn some more about small engines (and hopefully small turbos).

I started the engine up and it runs, though shakes a lot (like the exhaust gasses aren't fully released). I've tried two different valve lashings though neither really eliminated it (but 0.002" intake and 0.003" exhaust seemed to make the shaking less).

Anyone have some ideas that I should go through to remove the shaking?


Thanks,
Jay.

 

[landuse]

Is the engine bolted down?

 

[ImJay]

Is the engine bolted down?

The engine is clamped to a bench, but it shakes a lot more than any other stationary engine I've used.

I may add that it jumps a lot on one stroke.

 

[solomon]

Any kickback when you start it? Inspect the flywheel for broken or damaged fins possibly throwing it off balance. My car was shaking really bad, thought it was running on 1/2 the cylinders. Turns out, the fan has several fins broken off and threw it wayyyyy off balance. Just a thought..

 

[ImJay]

Any kickback when you start it? Inspect the flywheel for broken or damaged fins possibly throwing it off balance. My car was shaking really bad, thought it was running on 1/2 the cylinders. Turns out, the fan has several fins broken off and threw it wayyyyy off balance. Just a thought..

Every now and then on some pulls there is kickback.
The flywheel is all nice and dandy, no fins missing.

I might add that when it is clamped down very well to my bench the jumping is almost non-existent, though if just placed it looks like it's jumping rope.

Could I just play with the exhaust lashing by a few thousandths? And would it be worth opening it up and checking the cam and crank alignment, and inspect the push rods?

 

[mckutzy]

I think is sounds about right. When I first started my motor, it was just clamped onto a stool frame, It bounced around a bit when ever I had reved it. but after I had mounted it to the motor plate on the bike it was fine.

 

[solomon]

Make sure your flywheel key isn't partially sheared, had a Briggs motor that had occasional kickback and the key was half sheared. If thats fine then I'm sure its normal vibration

 

[ImJay]

All is fine on the Engine, not broken parts and whatnot, so I guess it should be okay.
Thanks for the help, you two!

 

[ImJay]

Hm, gave it a longer run today and it's fine idling, though when I give it some gas it shakes and vibrates so much that even bolted down it starts to wiggle everything.
After a bit of run time it's fairly hard to start.

Any more ideas of things I should be looking for/changing?

 

[mckutzy]

I think we need pics and most likely a short vid on this to give any better estimation of an issue.

 

[fowler]

Sounds like out of time

But u can't adjust spark timing can u

 

[solomon]

Do a spark plug chop, wonder if its not running really rich and overloading the motor with excess fuel

 

[ImJay]

I played with the idle and mix a little, and on a higher idle it seems to shake less, so I'll continue playing with that and the valve lashing.

Thanks for the help everyone, though one day I'll learn how to do the timing!

 

[fowler]

Actually the mix

Remove the air filter
See how it runs

 

[ImJay]

Without the air filter it shakes a lot more.
I'll keep tuning it and see if I can get something stable, else I'll upload a video of it here.

Thanks everyone!

 

[fowler]

It shakes more

Ok how does it go if u play with the choke?

 

[ImJay]

Playing with the choke does help a little, but it shakes more on the bottom end/lower idle.

Even when I bolt it down on a metal bench it shakes the whole thing when I give it some gas.

 

[fowler]

Try cleaning the carb

May be running lean

U may as well as the next thing u are going to have to do is pull the side cover and check timeing

 

[ImJay]

I give it a clean tomorrow.

I don't have a timing light so that's off the list for now, though as soloman said before I'll check the key again an maybe do a spark plug chop.

 

[landuse]

You don't need a light to check your timing on the engine.