hercalmighty Posted October 15, 2008 Report Posted October 15, 2008 K got ya. Thanks for clearing that up Quote
J-Madd Posted October 15, 2008 Report Posted October 15, 2008 TABLE 2.1 Minimum squish clearancesCylinder size (cc) Clearance (mm) 50-80 0.6-0.8 100-125 0.7-0.9 175-250 1.0-1.4 300-500 1.1-1.5 If this is correct, it should be 0.040'' - 0.055''. Squish on most of my engines is 0.045'' The0.035 that I stated before may be a little tight. This is the minimun safe clearance; maybe not optimal for your setup, though. Quote
Snopczynski Posted October 15, 2008 Report Posted October 15, 2008 Dynoport pipe on 93 octane: .045" squish and 160 psi compression ought to work the best. Dynoport only reves to around 8,600 rpm. I usually suggest squish windows within .005", so you could go .045"-.050" Closer you are to the lower the number, typically the better it will run. Its a minimal difference though. Quote
bellracing2 Posted October 16, 2008 Report Posted October 16, 2008 Dynoport pipe on 93 octane: .045" squish and 160 psi compression ought to work the best. Dynoport only reves to around 8,600 rpm. I usually suggest squish windows within .005", so you could go .045"-.050" Closer you are to the lower the number, typically the better it will run. Its a minimal difference though. @ .045" do I need the chambers re-cut , or just a flat deck ? this a stock 05 never been apart Quote
Snopczynski Posted October 16, 2008 Report Posted October 16, 2008 Leave it till it blows up or you decide to add more compression. Whats the squish now? Quote
'04limited Posted October 16, 2008 Report Posted October 16, 2008 i just checked the squish on the motor im building and its at .060 is this to loose? i have 20 cc domes stock crank. thanks guys. Quote
magz Posted October 16, 2008 Report Posted October 16, 2008 i just checked the squish on the motor im building and its at .060 is this to loose? i have 20 cc domes stock crank. thanks guys. i would think it is, you may try changing to a thinner base gasket and if that doesnt help, may need to have the domes cut. Quote
'04limited Posted October 16, 2008 Report Posted October 16, 2008 i would think it is, you may try changing to a thinner base gasket and if that doesnt help, may need to have the domes cut. so what thickness gasket should i go with? Quote
bellracing2 Posted October 16, 2008 Report Posted October 16, 2008 Leave it till it blows up or you decide to add more compression. Whats the squish now? .073" Quote
Snopczynski Posted October 16, 2008 Report Posted October 16, 2008 so what thickness gasket should i go with? it depends on your current squish reading, and what gasket is currently installed on the head and/or base of the cylinders. Quote
dajogejr Posted October 16, 2008 Report Posted October 16, 2008 i just checked the squish on the motor im building and its at .060 is this to loose? i have 20 cc domes stock crank. thanks guys. What is the compression, what is the timing, are you running methanol or gas? Quote
Snopczynski Posted October 16, 2008 Report Posted October 16, 2008 .073" You could change it and probably benefit from some more compression and a better squish gap. I typically do coolheads though, they bring the squish down where it needs to be and you can set your compression where you want. Quote
mopar1rules Posted October 16, 2008 Report Posted October 16, 2008 so what thickness gasket should i go with? like snope said, it depends on current base gasket thickness. for example, lets say you have a current squish of .073" and you want to see .050" squish. you will need to have a base gasket that's .023" THINNER than the current base gasket used. if its a stock head, you can easily mill .023" off and be safe.....if its a dome insert style head, you will need to change base gaskets, but you will also lower the rpm that the engine makes peak power at. if a guy didn't want to drop the rpm of peak power, he/she would need the exhaust port, transfers and boost ports raised that same amount that the cylinders were dropped down from the thinner gasket......i believe. guys, correct me if i'm wrong. Quote
deckheight Posted October 17, 2008 Report Posted October 17, 2008 I was assuming that since there is no mention of pipes or cylinder porting we are talking about an otherwise stock motor. My "guesstimate" is based upon an otherwise stock motor w/a 65mm bore, making peak HP at apx. 7800 rpm, a premium pump gas compatable compression ratio, 12mm squish band width and .047" squish thickness. I am figuring an MSV in the mid 20's with this data. Like you say though, insert the 9,500 to 10,000 rpm data to the above and it is a whole different story... .055" clearance is bare minimum IMHO. With T5's and a dune port (or slightly raised exhaust port) I would be running .050"-.055" Thats roughly gonna be for a 9,500-10,000 rpm motor. Quote
deckheight Posted October 17, 2008 Report Posted October 17, 2008 Anybody mind if I add my .02 cents? Snopczynski can chime in and correct me if im wrong but what i believe he is getting at is a tighter squish will create higher pressures and not allow the engine to rev quite as easy or as much...but then again that kinda contradicts the fact that he runs .050"-.055" on a dune port to rev 9500 to 10000 and my bike is just over .041" and i know it revs that hard, so honestly i don't know! :biggrin: I would like to hear his take on this too cause my bike with .041" squish is only about 145psi due to the dome size/shape...so me saying the tighter squish will make higher pressures isn't always true. Im confused too Quote
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