King motor 29cc loss compression after tuning.
 

Hi. Today when i ride baja something shot and engine loss compression. I thought it was pullstart but it's not it. Pullstart run slightly and <span lang="en" class="short_text" id="result_box"><span class="hps">when the piston</span> <span class="hps">moves</span> <span class="hps">to the top </span></span><span lang="en" class="short_text" id="result_box"><span class="hps">it</span> <span class="hps">sounds</span> <span class="hps">metallic and run hard. What's happened? Recently i changed oryginal carb to walbro 668, pipe to ddm dominator and NGK Iridium spark plug. </span></span><span lang="en" class="short_text" id="result_box"><span class="hps">Power</span> <span class="hps">strongly</span> <span class="hps">increased, did engine</span></span><span lang="en" class="short_text" id="result_box"><span class="hps"> could not stand</span> <span class="hps">this power?
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RE: King motor 29cc loss compression after tuning.
 

Maybe you ran it too lean?

Pull the plug and check the piston. You might have burned it.

Bill S.

RE: King motor 29cc loss compression after tuning.
 

I don't think so, I ran it rich (1,5 turn on h needle), it smoked perfect and spark plug also is perfect. It <span lang="en" class="short_text" id="result_box"><span class="hps">burn</span> <span class="hps">only</span> <span class="hps">7 liters</span></span>...

RE: King motor 29cc loss compression after tuning.
 

Pull the head and inspect. If the engine ingested something you may only be out a head but running it more could blow the whole thing

RE: King motor 29cc loss compression after tuning.
 

http://imageshack.us/photo/my-images/402/imga0007k.jpg/
http://imageshack.us/photo/my-images/715/imga0006h.jpg/
http://imageshack.us/photo/my-images/811/imga0005n.jpg/
http://imageshack.us/photo/my-images/846/imga0004.jpg/
http://imageshack.us/photo/my-images/228/imga0003r.jpg/

It doesn't look good...
OK, what now? I intend to mount zenoah 36mm piston to the KM engine. Did it works together?

RE: King motor 29cc loss compression after tuning.
 

I had a needle bearing let go on my km 28.5cc engine,

It left worse drag marks down the side of the piston and liner than that of what is on yours,

I cleaned the engine out and reassembled it using a new bearing it would not start and compression was way down,

So I pulled it apart, replaced the piston ring as they are real cheap, i thought i would try to work with what i had
and it was back to running great, even pulling wheelies

You need to take a look and see what made the marks on your piston, clean out the motor with petrol and replace the bearing if that done the damage,

You may well need to replace the whole motor, but I would definitely try a new piston ring on what you have first,

Some pics on this post http://www.rcuniverse.com/forum/fb.asp?m=9001819

RE: King motor 29cc loss compression after tuning.
 

The head is done. The marks on the transfer roofs are death to that cylinder. The piston is also done for. Inspect the crank, find out if a needle came out of one of the needle bearings. If not, and there is no damage to the crank or cases(sometimes they can be bad) just throw the 36mm head on with a good gasket, fresh piston and new bearing.

RE: King motor 29cc loss compression after tuning.
 

Ok, thanks for opinions. I noticed two more things. First &gt; http://imageshack.us/photo/my-images/88/imga0027k.jpg/
The engine can run with it? Second thing &gt; http://www.youtube.com/watch?v=kw_n_...ature=youtu.be - it's normal?
i'm going to buy this kit - http://www.davesmotors.com/s.nl/c.88...t.A/id.8021/.f but i've got 2 bolt in engine not 4. Did i can drill in the engine?

RE: King motor 29cc loss compression after tuning.
 

Nope you can't drill the extra 2 holes. Just get this and use you other parts like fan, carb, pull start, covers ect (That's what I did)..

http://www.ebay.com/itm/4-BOLTS-30-5...item2a1d08f727

RE: King motor 29cc loss compression after tuning.
 

Did you have this kit? It's <span lang="en" class="short_text" id="result_box"><span class="hps">suspiciously</span> <span class="hps">cheap... </span></span>how many gallon you have on it?

RE: King motor 29cc loss compression after tuning.
 

Yep I bought the kit cos of the 4 bolt head , and it's 30.5cc too. Runs great too (just do a careful break in. Then your good to go)..