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Author Topic:   Odd marks in cylinder bore
posted March 02, 2004 12:01 PM
The engine is a 377 - 400 block, KB pistons, eagle 5.7 rods, scat crank running alcohol. Tore it down to freshen it up and found some odd marks in the cylinder bore - there are 1-3 marks in a bore and they're radially around the cylinder wall from .75-2" around the bore - not all the way... They don't seem to catch a fingernail when I run it over the marks so they're not deep scratches or gouges - the bores look good otherwise. Any ideas to what caused this and do I need to be concerned??

What it looks like to me is that it may have been some corrosion, rust or something on the bore that formed then got s****ed off the next time the engine fired? Could this be due to running alcohol?

Anyone ever seen this before? I'll try and get pics of it this weekend if I can...


posted March 02, 2004 05:46 PM
Yes I have seen them when I first started running alcohol.I found that if you do not put oil down the intake or run the engine on gasoline before you store it the alcohol will draw moisture and the cylinder walls will rust then when you turn the engine over it cleans the rust off and thats when you see the cylinder staining.I really dont think it will hurt anything because there is not enough rust.

posted March 02, 2004 07:32 PM
sounds to me like he's right could just be a lottle rust i'd try to wipe it off with some thinner or something

posted March 03, 2004 06:54 AM
i have the same on mine..hasnt caused any problems

posted March 03, 2004 08:52 AM
Thanks! That's what I thought it looked like but wanted to make sure - I figured it couldn't be too bad as almost all the cylinders have it.

What does everyone recomend to prevent this? I've heard run a little oil down the carb to coat the cylinders?? Would 2-stroke oil work as I've got that for the waverunner or just plain ATF or motor oil??

- Brian

posted March 03, 2004 09:10 AM
Fogging oil sprayed in the cylinders and down the intake before you store it for winter.

posted March 03, 2004 09:26 AM
Originally posted by NJantz:
When I ran minisprints on alcohol we had the same problem so at the end of the racing night we'd connect a gas/2stroke mixture to the carb and shut off the alcohol. Then let it run until the engine starts to stumble and shut it off. This purged the system of alcohol so you wouldn't get rust or stains and no more chalky powder in the carb.

Did the same thing for the same reason when I used to race gokarts.

posted March 05, 2004 06:30 PM
what I have done is a squirt bottle with two stroke oil shut off the fuel and squert the oil down the carb it cots the cyclender and helps fight the corrisison


posted March 07, 2004 11:09 AM
Pull the plugs & squirt some oil in the cyl. & roll it over a couple of times through the off season.

posted March 08, 2004 01:03 PM
Originally posted by Okie11m:
Pull the plugs & squirt some oil in the cyl. & roll it over a couple of times through the off season.

I ran oil in the cylinders during the off season, but this must have happened between races - of course it sat for 3 weeks between races twice last year when I was fixing other problems (tranny/rear and then rear frame damage)

I think I'll do the 2-stroke thing...

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