15 year old builder, new to this forum.

[toby w]

hi iv'e just moved over from motored bikes forum to this one. Im a 15 year old builder with two of the 66cc kits built. and a custom honda gx160 powered 4 stroke build. I live in a hilly area and both of the two stroke kits burnt up after just a few hours of running. they always overheat even only a 2 or 3 minutes after starting them. Im starting a new build of a 2 stroke and need some advice, but I will put that in another thread. I just thought I'd introduce myself. i'll add a few photos of my past builds. (

I'm in the uk where these bikes aren't very popular)

 

[Venice Motor Bikes]

Hi & welcome to the forum...

The very first thing that came to my mind when I read your post is that there's zero reason TWO new engines should overheat & burn up so soon after their first start up!

How much oil are you mixing in the gas? (& what kind of oil)??
& you're not trying to break-in the engine standing still, (are you)???

 

[wrench]

Yeah, 2 engine's should not burn up the first day,
LIke Venice said what's your oil mix ?

Is that a score mark on the piston?
Is the pin that holds the ring in place still there?
What's the inside of the cyl look like?

These New engines, the case should be checked for metal shavings or casting slag
Also clean off any casting slag from the ports or anywhere else ya see it
.

 

[toby w]

both used conventional oil with a 25 to 1 mix that was mixed in a separate fuel can.
I didnt check the engines for casting flaws but the engines were broken in by riding around at about 15 to 20 miles an hour. I have quite a few steep hills that peak at about a 20 to 25 percent grade. but I always peddled if i needed to.

those are score marks on the piston
both wrist pin clips are still there
and the cylinder has light scoring with a few heavy gouges

 

[toby w]

is this normal for the two strokes?. when they are started up they have a crisp clean idle but after only a few minutes the engines can't sustain an idle and make a louder grinding noise. they also lose a lot of power.

 

[Venice Motor Bikes]

both used conventional oil with a 25 to 1 mix that was mixed in a separate fuel can.
I didnt check the engines for casting flaws but the engines were broken in by riding around at about 15 to 20 miles an hour. I have quite a few steep hills that peak at about a 20 to 25 percent grade. but I always peddled if i needed to.

those are score marks on the piston
both wrist pin clips are still there
and the cylinder has light scoring with a few heavy gouges

What do you mean 'conventional' oil?? (You need to use '2-cycle' oil).
Post a picture of the exact oil you used.

Also... that engine in your picture doesn't look brand new. :/

 

[toby w]

sorry for the confusion. the conventional was in regard to either conventional, semi-synthetic and full synthetic. it was conventional 2 storke oil.
that engine in the photos has about 6 hours on it.

 

[toby w]

this is the oil

 

[curtisfox]

Welcome aboard.
What size rear sprocket you running, sound like it may to high geared for what you are doing?...........Curt

 

[toby w]

Welcome aboard.
What size rear sprocket you running, sound like it may to high geared for what you are doing?...........Curt

i was running a 44t

 

[wrench]

those are score marks on the piston
both wrist pin clips are still there
and the cylinder has light scoring with a few heavy gouges

Good, the wrist pin clips are still there
There are also pins that hold each piston ring gap clocked in position,
That's what I was referring to,
Sometimes they pop out, I can't see if it's still there by your pic,

 

[Venice Motor Bikes]

I'm placing my bets on 'user error'...

The fact that two new engines died in the same way within a few hours of their first startup isn't a coincidence to me.

I think that oil might be a little 'sub-par' because the label says it's for gardening equipment... I would use a high quality (non synthetic) 2-cycle oil made for motorcycles
Also... if you were only running the bikes 15-20 MPH, that's a little too slow... The engine is working harder because it's below it's RPM powerband; & there's also less air flowing over the engine to cool it. (& to top it off, you said you were riding up some steep hills!

For your next engine, I suggest breaking it in with 32:1 high quality 2-cycle oil & ride the bike at 'wide open throttle' for a few miles on level ground!

 

[curtisfox]

I was also thinking you may want to go with a bigger rear sprocket 48 tooth in the hilly area........Curt

 

[toby w]

I was also thinking you may want to go with a bigger rear sprocket 48 tooth in the hilly area........Curt

how much difference would that make?

 

[curtisfox]

Slow you down a tad, but give you less strain on the motor.............Venice would no more about the speed change.......Curt

 

[Tom from Rubicon]

2 Stroke engines do like a break in cycle,. In the early 1980's I had a side job as a Ultralight Aircraft mechanic.
New owners paid me an hourly wage just to do the engine break in on their Rotax engines.
Gradually bring the engine under light load to mid range. for forty minutes. Go WOT for ten minutes. Then let it loaf for ten sucking in fuel and oil to cool and clean the cylinders. Repeat three times.

Being in the UK as you are. The photos of the country side are unmistakable.
Penzoil is always my first oil choice.
Amazon.com: Pennzoil 4056 2-Cycle Air-Cooled Engine Oil - 3.2 oz. : Automotive

Tom

 

[Greg58]

Welcome to the forum, I have had good luck using the heat cycle method, I’ve never had an engine problem. I make two to three runs end to end on the 1/2 mile road we live on and let the engine cool till I can touch it, then repeat. I don’t run it wide open but don’t baby it either. After three to four cycles, depending on how the engine is sounding and the temperature I run it longer.

 

[toby w]

2 Stroke engines do like a break in cycle,. In the early 1980's I had a side job as a Ultralight Aircraft mechanic.
New owners paid me an hourly wage just to do the engine break in on their Rotax engines.
Gradually bring the engine under light load to mid range. for forty minutes. Go WOT for ten minutes. Then let it loaf for ten sucking in fuel and oil to cool and clean the cylinders. Repeat three times.

Being in the UK as you are. The photos of the country side are unmistakable.
Penzoil is always my first oil choice.
Amazon.com: Pennzoil 4056 2-Cycle Air-Cooled Engine Oil - 3.2 oz. : Automotive

Tom

I've got some stihl chainsaw oil that i will give a try on my new engine

 

[toby w]

My new engine has arrived along with some professional photos of my bike. I took the top end off the new engine and cleaned up the ports and gave it a wipe with some oil. I also rinsed the case with methanol spirit a few times to clean out any shavings of aluminium. will this make the engine last a bit longer?

 

[Greg58]

My new engine has arrived along with some professional photos of my bike. I took the top end off the new engine and cleaned up the ports and gave it a wipe with some oil. I also rinsed the case with methanol spirit a few times to clean out any shavings of aluminium. will this make the engine last a bit longer?

I think so, I have found some bad casting slag in the ports on a couple of cylinders in the past, that’s why I disassemble each engine before I run it to make sure all is as it should be.