Starting with high compresion

linden · 01-08-2009, 06:47 AM

I have 12.5:1 compression 102mm piston and my bike hates to start. sometimes I have to tap the start buttin to get it to turn over. The relay just wants to click all the gd time it seems to be not so bad when she is warmed up but still occurs. It did the same thing on my last build also (12:1 piston with a .04 decked head stk bore) and figured it was just something i would have to deal with that high of compression. I have replaced the relay and the battery.

has anybody beefed up their ground and power wire i was thinking about using 4 ga. left over from my truck.

anybody else with high compression ever run into this?

686raptor · 01-08-2009, 12:41 PM

it's more than likely your battery. i have a 4mill stroke 105 bore 13.5 to one and i'm still running the stock wiring but with an oddesey brand battery.

ubetrun · 01-08-2009, 02:40 PM

A grizzly battery will help. Running a heavy ground wire from the negative battery terminal to the starter mounting bolt will help. Getting rid of the stock decompression mechanism and adding a mechanical plunger decmpression mechanism will fix it forever.

o3limited · 01-09-2009, 11:48 PM

what year is your raptor
also is the ignition stock or aftermarket if aftermarket what brand
do you no for sure your decompressioner on the cam is working right also is your cam stock

if the ignition is aftermarket some of the cheaper ones may have more advance then what you actualy needs more advance at the low rpms will make it harder to start
also obviously if your decompression isnt functioning right then that would cause it plus with a 12.5:1 if you have a stock cam that will creat more cranking pressure as the intake valve closes earlier abdc (after bottom dead center)

phucker · 01-11-2009, 05:30 PM

ya they are right about the battery, oddesy battery is the best, get one of those and some heavier battery cables and you will be good

cyclone · 05-20-2009, 11:46 PM

hey guys anybody has ahd problems with a 660 crank gone out of phace? would appreciate it if someyone knows what i'm talking about.

cyclone · 05-22-2009, 12:37 AM

duuuuhuuuu,,, pulled the flywheel and had a sheared woodruff key,,,
whoops almost made a mess with my new top end, hope this helps someyone.

MPTonyT · 05-22-2009, 09:19 AM

Now that i think about it the first time i ever took my flywheel off to do the one way the woodruff key was facing the floor and it fell and i never knew it was there. I put it all back together and it did crank and run but i did have to tap the starter button.

So yeah that'll do it.

01-08-2009, 06:47 AM	#1 (permalink)
linden Bolt-on Beginner Join Date: May 2008 Location: florida Posts: 165	Starting with high compresion I have 12.5:1 compression 102mm piston and my bike hates to start. sometimes I have to tap the start buttin to get it to turn over. The relay just wants to click all the gd time it seems to be not so bad when she is warmed up but still occurs. It did the same thing on my last build also (12:1 piston with a .04 decked head stk bore) and figured it was just something i would have to deal with that high of compression. I have replaced the relay and the battery. has anybody beefed up their ground and power wire i was thinking about using 4 ga. left over from my truck. anybody else with high compression ever run into this? __________________ 02 686 Last edited by linden; 01-08-2009 at 11:30 AM.

01-11-2009, 05:30 PM	#5 (permalink)
phucker I am smarter than you.... Join Date: May 2008 Posts: 1,967	ya they are right about the battery, oddesy battery is the best, get one of those and some heavier battery cables and you will be good __________________ RIP COOP, you are and always will be missed bud www.barkersexhaust.com www.jdperformance.net www.poorboy-performance.com/

05-22-2009, 09:19 AM	#8 (permalink)
MPTonyT Bolt-on Beginner Join Date: May 2008 Location: Tampa Bay, Fl. Posts: 174	Now that i think about it the first time i ever took my flywheel off to do the one way the woodruff key was facing the floor and it fell and i never knew it was there. I put it all back together and it did crank and run but i did have to tap the starter button. So yeah that'll do it. __________________ A Little Lower, A Little Wider, A Little Faster. If your friends don't ride.. You need new friends.

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01-08-2009, 12:41 PM	#2 (permalink)
686raptor Bolt-on Beginner Join Date: Sep 2008 Location: Billings, MT Posts: 57	it's more than likely your battery. i have a 4mill stroke 105 bore 13.5 to one and i'm still running the stock wiring but with an oddesey brand battery.

01-08-2009, 02:40 PM	#3 (permalink)
ubetrun Bolt-on Beginner Join Date: Jul 2008 Posts: 94	A grizzly battery will help. Running a heavy ground wire from the negative battery terminal to the starter mounting bolt will help. Getting rid of the stock decompression mechanism and adding a mechanical plunger decmpression mechanism will fix it forever.

01-09-2009, 11:48 PM	#4 (permalink)
o3limited Stock, ready to MOD Join Date: Oct 2008 Posts: 45	what year is your raptor also is the ignition stock or aftermarket if aftermarket what brand do you no for sure your decompressioner on the cam is working right also is your cam stock if the ignition is aftermarket some of the cheaper ones may have more advance then what you actualy needs more advance at the low rpms will make it harder to start also obviously if your decompression isnt functioning right then that would cause it plus with a 12.5:1 if you have a stock cam that will creat more cranking pressure as the intake valve closes earlier abdc (after bottom dead center)

05-20-2009, 11:46 PM	#6 (permalink)
cyclone Stock, ready to MOD Join Date: May 2009 Posts: 8	hey guys anybody has ahd problems with a 660 crank gone out of phace? would appreciate it if someyone knows what i'm talking about.

05-22-2009, 12:37 AM	#7 (permalink)
cyclone Stock, ready to MOD Join Date: May 2009 Posts: 8	duuuuhuuuu,,, pulled the flywheel and had a sheared woodruff key,,, whoops almost made a mess with my new top end, hope this helps someyone.