shee rips Posted June 13, 2007 Report Posted June 13, 2007 if I was to shave my stock head .020 where would that put me for squish clearance? also where would that put me for compression? would it be safe on 91 octane if I advanced my timing 4 degrees with the head shaved? also would it require re-jetting Quote
bigboybanshee Posted June 13, 2007 Report Posted June 13, 2007 A lot of what you're asking depends on the elevation you're at. It'll have an effect on your compression, which in turn will determine what gas you run. What elevation do you ride at? The squish will have to be measured once you put the head on...do you know how to check it? Increasing the compression and advancing the timing should not require a jetting change, but it is always a good thing to check your plugs after you do the mods to ensure you're jetting is correct. :thumbsup: Quote
ClimbAnyHill Posted June 13, 2007 Report Posted June 13, 2007 A lot of what you're asking depends on the elevation you're at. It'll have an effect on your compression, which in turn will determine what gas you run. What elevation do you ride at? The squish will have to be measured once you put the head on...do you know how to check it? Increasing the compression and advancing the timing should not require a jetting change, but it is always a good thing to check your plugs after you do the mods to ensure you're jetting is correct. :thumbsup: How do you check for squish? Quote
bigboybanshee Posted June 13, 2007 Report Posted June 13, 2007 How do you check for squish? Well, the way we did it was by taking a piece of solder, maybe about 4" long, and made it curve at one end. You pull the spark plug, stick the piece of solder through the hole (the curved end) and push it to where the it's parallel with the piston and at the edge of the dome, then turn the engine over by hand and the piston will squish the solder. Pull the solder out of the hole and measure the squished part with a micrometer, and that number is your squish. Someone may be able to explain it a little better, but that is how it's done. I would recommend doing it a few times just to ensure the number is the same. If you have trouble, I could probably do a tutorial w/ pics for you :beer: Quote
shee rips Posted June 13, 2007 Author Report Posted June 13, 2007 haha sorry I forgot to say im any where from sea level to 3000 feet, but mostly below 1000 feet. And no I didnt know know how to check squish clearance. I guess that would have been a good thing to ask instead of for a clearance that i dont even know how to measure. thanks for that one bigboybanshee. simple but effective. :beer: i dont think i would have any issues from shaving the head .020 as people have gone much more on the stock head but i dont want to go too crazy with it, or spend the money to have it rechambered and/or run race gas. Actually it just came to mind, is there a thinner head gasket available that would accomplish the same thing? or does the stock head use o rings? thanks guys (and gals) :beer: Quote
Jhughes7 Posted June 13, 2007 Report Posted June 13, 2007 I am sea level and I was at 135 pre shaved head, Took .40 off and now at 170. IMO you should be fine with reg gas takin just .20 off. I run 4 To 1 Race gas and premium. Quote
bigboybanshee Posted June 13, 2007 Report Posted June 13, 2007 haha sorry I forgot to say im any where from sea level to 3000 feet, but mostly below 1000 feet.And no I didnt know know how to check squish clearance. I guess that would have been a good thing to ask instead of for a clearance that i dont even know how to measure. thanks for that one bigboybanshee. simple but effective. :beer: i dont think i would have any issues from shaving the head .020 as people have gone much more on the stock head but i dont want to go too crazy with it, or spend the money to have it rechambered and/or run race gas. Actually it just came to mind, is there a thinner head gasket available that would accomplish the same thing? or does the stock head use o rings? thanks guys (and gals) :beer: If I'm not mistaken, yes, there are different thickness of gaskets you can use to seal the head. Worst case scenario, you can buy the gasket material and cut your own, I know a few people that do it that way. You "might" gain some compression by going with a thinner head gasket, but most people change the thickness of the gasket to alter the squish, if it's too high or low. Be careful if you venture up to 3,000 feet. Elevation changes that drastic (0-3,000 feet) is enough to warrant a jetting change. :thumbsup: Quote
shee rips Posted June 13, 2007 Author Report Posted June 13, 2007 (edited) ya i know that i should change the jetting for that big a change in altitude but its kinda impractical to change jets in the middle of a ride. It seems to be jetted right for around 0 to close to 1000 feet, so running rich up the mountains doesnt seem to cause any problems other than lack of power and a little smoke, I just carry spare plugs. If it was jetted for up high and i came down to sea level then that would be another story but..... :shrug: It is also colder up there which may make up for some of the altitude(according to my theory anyways :geek: ) After looking around i see that many people have shaved their stock head, but would I be safe on pump gas with +4 timing(or any advance for that matter) combined with higher compression? I saw some pictures the other day of what detonation does to pistons and I dont want to take that chance :shoothead: it is nice to have a site like this to get this much information :biggrin: :beer: Edited June 13, 2007 by shee rips Quote
bigboybanshee Posted June 13, 2007 Report Posted June 13, 2007 Yeah, you'll be just fine with the timing increase. If your compression is over 160psi, then I'd start thinking about a 50/50 mix of pump and race gas, or straight race gas depending on how high the compression is... Just for reference though, on my trail bike I run 93 octane with 159psi compression and +4 timing. No problems so far Quote
ClimbAnyHill Posted June 14, 2007 Report Posted June 14, 2007 Well, the way we did it was by taking a piece of solder, maybe about 4" long, and made it curve at one end. You pull the spark plug, stick the piece of solder through the hole (the curved end) and push it to where the it's parallel with the piston and at the edge of the dome, then turn the engine over by hand and the piston will squish the solder. Pull the solder out of the hole and measure the squished part with a micrometer, and that number is your squish. Someone may be able to explain it a little better, but that is how it's done. I would recommend doing it a few times just to ensure the number is the same. If you have trouble, I could probably do a tutorial w/ pics for you :beer: Thanks for that explanation. Seems simple. I'll remember to get at you if run in to troubles in that area. Thanks again. Quote
shee rips Posted June 17, 2007 Author Report Posted June 17, 2007 im gonna go for it then. .020 and while im at it i will do a top end job, wiseco pistons I think. Thanks again for the advice. :beer: Quote
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