chrome scratched in cylinder???

ssvincels1 · Jun 19, 2012

i removed the cylinder off my 50 cc grubbe skyhawk last night after 400 miles of operation and noitced that the chrome was scratched off vertically in 2 separate location right where the ring end gaps meet up.
i ran 30:1 lucas 2 stroke oil the entire time, i this normal?
or was it getting hot, plug was a nice tan color for the last 200 miles.

Mr. Minecraft · Jun 19, 2012

Well, this engine is a chinese built engine with no quality control. That happens in all the HT engines. Mine has scoring in it as well. I just run it till it quits.

EDIT: The scratches are called Scores and the general term that applies to having scratches in the cylinder is scoring.

2door · Jun 19, 2012

Sorry Mr. Minecraft but I'll have to disagree with you.
Cylinder wall scoring/scuffing/scratching doesn't happen with all HT engines. If there is cylinder wall damage above normal wear something is amiss. Either too little oil or the wrong type, excess lean condition or just abuse. Any engine, regardless of point of manufacture, can experience premature wall wear or damage if not lubricated correctly or if the piston rings are broken (not uncommon) or not positioned on the ring guides right.

I'd have to ask the OP what oil and at what ratio is he running. Also his riding habits. Excessive WOT and improper lubrication might be his problem. I'd rather see the plug a little darker than "tan", more a light chocolate color.

Tom

DareDevil · Jun 21, 2012

Hi ....Could also be the tension of the oil ring .... does it have a expander behind it..might have to cut of two flats of the expander to reduce the tension....it all comes down to quality control....DD

fx-2 · Jun 21, 2012

DareDevil said:
Hi ....Could also be the tension of the oil ring .... does it have a expander behind it..might have to cut of two flats of the expander to reduce the tension....it all comes down to quality control....DD

There is no oil ring in HT engine . Just two compression rings , that all . Dan

DareDevil · Jun 21, 2012

Hi Dan...Thanks .....it comes back to the quality of the parts and the quality control...I would say the tension of the rings it to high..I raced 2 strokes for 30 years..... try and buy some good quality gapless rings......DD

bigbutterbean · Jun 22, 2012

if you put gapless rings in an ht engine, wouldnt you need a piston that accepted gapless rings? ht engines have pins on the piston where the rings line up. If you put gapless rings on an ht piston, the rings would bulge out over the pins and probably score the cylinder anyway. these engines and kits do have bad quality control, but not every issue can be traced back to qc, nor can every issue be fixed simply by slapping in some aftermarket part.

DareDevil · Jun 22, 2012

Hi ... Yes you would need a better quality piston to suit the gapless rings...I just dont use lower qualty products...old story ..you get what you pay for....DD

ssvincels1 · Jun 22, 2012

i was just wondering if any has had any similar expierence's. i realize these motors are as cheap as they get, that's why i bought an entire top end when i ordered my motor.

thanks for the input guys

Pilotgeek · Jun 22, 2012

Mine has two tiny spots where the chrome flaked off. It looks like the cylinder I got was slightly misshapen at those points and bulged out a bit, causing the rings to wear those spots faster. It runs well and gets good compression now that it's worn in. I would be worried if it scratched down the entire cylinder like that. Maybe take the rings and sand down the sharpness of the edge where the ring gap is.

bigbutterbean · Jun 24, 2012

the question is, does the engine still run the same? if the scratches are deep enough, it will cause loss of compression, and it doesnt take much. if you have lost compression, you are better off replacing the top end than anything else. I personally would not recommend sanding the cylinder at all, especially if you already have another top end. just bear in mind that when you replace the top end, you will need to follow break-in procedures again.

Bikeguy Joe · Jun 24, 2012

I have never had even the smallest problem with any china engine.

I think it boils down to who's doing what to these things.

Use the proper oil, in the right amount, break it in correctly and you should be good to go.

Bikeguy Joe · Jun 24, 2012

These things are not "pug and play, where you can just slap on on a frame and hope it runs forever. Think "1935" when everything demanded a little bit of knowledge.

Search

chrome scratched in cylinder???

ssvincels1

New Member

Mr. Minecraft

Visionary

2door

Moderator

DareDevil

Member

fx-2

New Member

DareDevil

Member

bigbutterbean

Active Member

DareDevil

Member

ssvincels1

New Member

Pilotgeek

New Member

bigbutterbean

Active Member

Bikeguy Joe

Godfather of Motorized Bicycles

Bikeguy Joe

Godfather of Motorized Bicycles