noises when going fast ?

[Guest]

I'm typically a fan of 50:1 in most two strokes but for these, I would run it 25:1.

FYI, small two strokes used in radio control airplane models often have an oil percentage from 17% to 20% (and higher) for exact same reason. At 20% oil percentage, that is 25 oz of oil per gallon of RC fuel. Crazy, itsn't it. Now, car model engines typically run as low as 7% oil to 14% oil (depending on fuel brand) because they value performance over longevity of engine.

 

[erikvilla]

I am still breaking in the engine and ive been using 18:1 for my mixture which is about 7 oz of oil to the gallon . I purchased the new bushing from www.thatsdax.com and im gonna re-asemble my engine hopfuly by next weekend, but i still have two 80cc bikes running now so i have something to play around while im waiting to fix this engine

 

[Guest]

7 oz per gallon is a nice round figure and no harm is done by using it. Pull plug every month and brush it off is all you need to do.

If you use AMSOIL 100:1 you can probably go down to 4-5 oz per gallon. The reason 100:1 AMSOIL can be used at that ratio for an engine that calls for a 50:1 ratio is that this 2 stroke oil has very little volatile solvents as a base for the 2 stroke oil. Most 2 stroke oil are 50% solvent carrier base....AMSOIL 100:1 isnt.

 

[Guest]

Back to original question:

If you can't find obvious problem such as loose s**t on engine or a worn connecting rod it COULD be detonation caused by any of the following:
1. Engine is too hot
2. Too lean of a mixture setting
3. Combination of above
4. Carbon on plug or piston which is causing preignition

If this is detonation (pinging) you need to resolve the problem because detonation is VERY damaging to an engine. A quick fix is to try higher octane fuel and see if you have the noise. If you do, it ain't detonation.

 

[JosephGarcia]

Back to original question:

If you can't find obvious problem such as loose s*** on engine or a worn connecting rod it COULD be detonation caused by any of the following:
1. Engine is too hot
2. Too lean of a mixture setting
3. Combination of above
4. Carbon on plug or piston which is causing preignition

If this is detonation (pinging) you need to resolve the problem because detonation is VERY damaging to an engine. A quick fix is to try higher octane fuel and see if you have the noise. If you do, it ain't detonation.

I have a pinging noise that I cannot identify. I hear it only at idle, no other time. I looked at my piston once through the exhaust port and it looked like it had some carbon on it. you say this is very damaging to an engine but It's been running fine for months.

I also heard from someone else that a pinging noise was caused by a small metal shaving loose inside the crankcase.

a friend of mine said it was the gears in the clutch section of the motor weren't greased enough, after they were regreased, the noise got alot better, but I still hear a small pinging,

 

[Kielohawk]

This just happened to me. The upper bearing (bushing) on the arm just went out.

Dan

 

[Hugemoth]

Let us know if you find a source for these bushings. I'd like to have a couple and the engine sellers don't seem to be able to get them. I'm sure I could make them out of a larger bushing from a bearing shop but it would be time consuming.

Moth

This just happened to me. The upper bearing (bushing) on the arm just went out.

Dan

 

[OldPete]

Accurately measure the piston pin diameter, the rod small end bore and note the width of the rod's small end. Then do a Google with those dimentions. I forget in which order most all catalogs have them but that will be easy to note.

I would not use sintered bronze bushings that are impregnated with graphite or oil for some reason and I don't know why, except I have never seen them used in any con-rod.

If I found bushings that would just thumb press into the rod, I would be tempted to use them with a red loc-tite install. The bore of the small end and the bushing would get a lite sanding, just to break the surface, before the install w/Mr. Red.

A machine shop could ream the bushing real close to dimention.

Cleaning out the crankcase is another issue.

 

[Kielohawk]

You can buy the bushings here as of today. Brand new item he just added..

http://www.thatsdax.com/ENGINE_KIT_PARTS_PAGE_4.html

Dan

 

[OldPete]

Buy it!

Deburr the edge of the rod's small end hole, then draw the bushing in with a fine threaded bolt with stiff washers on both sides.
First make sure the rod's small end itself was not damaged. Start the bushing very straight, it may take a few attempts with only light pressure from the fine threaded bolt.