Engine Proformace (10:1 compression)
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From: Stuart Fl
Engine Proformace (10:1 compression)
i have a 1977 1000cc motor that im upping the compression from 9:1 to 10:1 (boring and high domed pistons) and want to put the biggest cam possible but dont want the values to hit the pistons, anyone know what the largest cam i can put in without this happening?
also i want to get more power in 1st n 2nd gear, can i just change out those two gears or do all four need to replaced?
thanks in advance
-Billy
also i want to get more power in 1st n 2nd gear, can i just change out those two gears or do all four need to replaced?
thanks in advance
-Billy
You cannot change any of the transmission gears. You can change the drive chain sprockets. To get greater acceleration in all gears change to a smaller front sprocket or a larger rear sprocket. Let us know what is in there now and we can give some specific suggestions.
For cams i would go to the Andrews website and look at their offerings. They give complete specs for each cam set.
For cams i would go to the Andrews website and look at their offerings. They give complete specs for each cam set.
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Joined: Sep 2008
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From: Stuart Fl
You cannot change any of the transmission gears. You can change the drive chain sprockets. To get greater acceleration in all gears change to a smaller front sprocket or a larger rear sprocket. Let us know what is in there now and we can give some specific suggestions.
For cams i would go to the Andrews website and look at their offerings. They give complete specs for each cam set.
For cams i would go to the Andrews website and look at their offerings. They give complete specs for each cam set.
ok ill count the teeth and get back to you, i know there stock, i asked about the tranny gears becuz Vtwin sells "Wide ratio 1st gear sets" by andrews and it changes the ratio from 2.52 to 2.68 for more lower end torque,(page 813 if anyone had the book and wants to see wut im talking about)
and ive read the specs on the Andrews web site just not sure wut the clearances with be with the high domed pistons and figured someone here on the fourms has done this with there 1000cc and wanted to know what they did
If they are stock they are probably 51T rear and 21T front. Most of us change out the front to 23T. Probably not what you want for more acceleration. You could try 19T but it applies to the higher gears as well; hiway riding would suffer from higher vibration - i think they can be found on eBay etc.
Are those wide ratio gear sets for 4-speed Sportster transmissions?
Are those wide ratio gear sets for 4-speed Sportster transmissions?
Cruiser
Joined: Oct 2008
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When ever you change piston dome height or Valve lift you should check valve to piston clearance on any engine. It is an easy thing to do, put some modeling clay on the dome areas where the valves can meet the piston, install the head with no spark plug. Turn the engine over by hand, remove the head and measure how thick the clay is. Pinion can probably come up with a minimum clearance
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From: Stuart Fl
If they are stock they are probably 51T rear and 21T front. Most of us change out the front to 23T. Probably not what you want for more acceleration. You could try 19T but it applies to the higher gears as well; hiway riding would suffer from higher vibration - i think they can be found on eBay etc.
Are those wide ratio gear sets for 4-speed Sportster transmissions?
Are those wide ratio gear sets for 4-speed Sportster transmissions?
also when im looking at the cams and it says head work needed what do they mean by that?
Road Master
Joined: Aug 2006
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From: 500 miles south from Artic Circle
If they are stock they are probably 51T rear and 21T front. Most of us change out the front to 23T. Probably not what you want for more acceleration. You could try 19T but it applies to the higher gears as well; hiway riding would suffer from higher vibration - i think they can be found on eBay etc.
Are those wide ratio gear sets for 4-speed Sportster transmissions?
Are those wide ratio gear sets for 4-speed Sportster transmissions?
Yes there is close ratio gear sets for sportster, J&P item 620-461 but wide ratio I haven't seen.
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I have no experience with that but i believe that what you need to do is grind some metal out of the cylinder heads. Something about the effect of higher lift cams. Others can give a better explanation.
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billytopless, my 75 sporty is stroked and bored 30 over,all s&s with andrews cams.it has tons of torque and it will grab 120 mph really fast.s&s recommends a minimum of .060 valve to piston clearance but they say .080 is better.by the way my bike is very streetable and dependable.you might have to install compression relief valves in the heads.
