Big Bore Install - Issues
Cruiser
Joined: Sep 2012
Posts: 203
Likes: 0
From: Livingston, La.
You need to do several things before coming to any conclusions like piston slap which I'm willing to bet you don't have.Fill your tank with the highest octane fuel available in your area. If it is not at least 92, add a octane booster like the one from Amsoil. If your area has a problem with the amount of Ethanol in the fuel then add treatment for that also. Try dropping your plug range a little colder and use Iridium plugs.You stated that you installed high compression pistons but did not say what your final ratio is. Your builder needs to tell you what head gaskets were used and if they decked the heads any to raise the CP any higher.If you continue to run a pinging motor it will give up the ghost and let you know where the problem lies.
Tourer
Joined: Aug 2011
Posts: 388
Likes: 36
From: USA
RE: slow cranking when hot.
I have a GS1100 with a 1166 kit in it. Compression was raised .25 from 10.25 to 10.50 I think. It also has aftermarket cams (Webb). It does not start as well when hot compared to cold. If it sits for 5 or 10 minutes all is fine again. IIRC.
I did two things that made it better. Replaced the ground and cleaned up the oil from the frame ground (right below breather tube (duh, what where they thinking)). Next I degreed the cams. They were off, maybe 5 degrees, its been a while.
Getting the cams right made the most difference. Having clean carbs so that it will fire up with minimal rotation helps too. BTW, its pretty fast.
Aside from that, I just attribute the slower cranking to the higher compression, cams and a starter/battery made for a stock bike.
I have a GS1100 with a 1166 kit in it. Compression was raised .25 from 10.25 to 10.50 I think. It also has aftermarket cams (Webb). It does not start as well when hot compared to cold. If it sits for 5 or 10 minutes all is fine again. IIRC.
I did two things that made it better. Replaced the ground and cleaned up the oil from the frame ground (right below breather tube (duh, what where they thinking)). Next I degreed the cams. They were off, maybe 5 degrees, its been a while.
Getting the cams right made the most difference. Having clean carbs so that it will fire up with minimal rotation helps too. BTW, its pretty fast.
Aside from that, I just attribute the slower cranking to the higher compression, cams and a starter/battery made for a stock bike.
Road Warrior
Joined: Apr 2010
Posts: 1,648
Likes: 37
From: Monroe, Louisiana
[QUOTE=FL-kruzen;11832752]Thanks for the help guys. I put a whole freaking can of octane booster in and she quoted right down. Your right, I do have high compression pistons. The other issue I have noticed is after shutting down the engine when hot, it tends to be hard to restart for some reason. My bike Is Carbed with a Mikuni 42. What would cause a hard to start condition when hot?[/QUOTE
You didn't mention if it is not turning the engine normally or just not starting. If the engine is not turning good it is probably the high compression. If just not starting, it is probably flooding due to the carb having to be so rich at idle from not having a good vacuum signal. Try not pumping the throttle any and just cracking it slightly to keep the idle circuit from drawing fuel. If it is turning hard from high compression and no compression releases sometimes you can pump the throttle a couple of times and hold the throttle open about 1/2 way.
You didn't mention if it is not turning the engine normally or just not starting. If the engine is not turning good it is probably the high compression. If just not starting, it is probably flooding due to the carb having to be so rich at idle from not having a good vacuum signal. Try not pumping the throttle any and just cracking it slightly to keep the idle circuit from drawing fuel. If it is turning hard from high compression and no compression releases sometimes you can pump the throttle a couple of times and hold the throttle open about 1/2 way.
Road Warrior
Joined: Jun 2012
Posts: 1,672
Likes: 17
From: Orange, VA,
Mine is a little harder to start after the S&S 97 inch big bore went in, compression went from 9.3 to 9.7, mostly a little harder when it is hot like right after filling up with fuel, when I get my new S&S heads they will have compression releases.
Road Master
Joined: Mar 2013
Posts: 925
Likes: 15
From: So. Fla.
RE: slow cranking when hot.
I have a GS1100 with a 1166 kit in it. Compression was raised .25 from 10.25 to 10.50 I think. It also has aftermarket cams (Webb). It does not start as well when hot compared to cold. If it sits for 5 or 10 minutes all is fine again. IIRC.
I did two things that made it better. Replaced the ground and cleaned up the oil from the frame ground (right below breather tube (duh, what where they thinking)). Next I degreed the cams. They were off, maybe 5 degrees, its been a while.
Getting the cams right made the most difference. Having clean carbs so that it will fire up with minimal rotation helps too. BTW, its pretty fast.
Aside from that, I just attribute the slower cranking to the higher compression, cams and a starter/battery made for a stock bike.
I have a GS1100 with a 1166 kit in it. Compression was raised .25 from 10.25 to 10.50 I think. It also has aftermarket cams (Webb). It does not start as well when hot compared to cold. If it sits for 5 or 10 minutes all is fine again. IIRC.
I did two things that made it better. Replaced the ground and cleaned up the oil from the frame ground (right below breather tube (duh, what where they thinking)). Next I degreed the cams. They were off, maybe 5 degrees, its been a while.
Getting the cams right made the most difference. Having clean carbs so that it will fire up with minimal rotation helps too. BTW, its pretty fast.
Aside from that, I just attribute the slower cranking to the higher compression, cams and a starter/battery made for a stock bike.
Club Member
Joined: Jun 2009
Posts: 5,323
Likes: 37
From: NJ
I never get a slap when lugging.
Buddy got a slap after his 103 build.
A c clip was installed improperly on piston and the pin holding the piston to the rod popped off and pin was working it's way out.
Buddy got a slap after his 103 build.
A c clip was installed improperly on piston and the pin holding the piston to the rod popped off and pin was working it's way out.
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Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
Fit a more powerful starter motor! There are plenty out there, up to 2.4 kW. I have been using my stock starter on my S&S 107", which does have ACRs, but it finally gave up the ghost. You may well be able to 'get by', but a beefier starter will improve life!
Tourer
Joined: Aug 2011
Posts: 388
Likes: 36
From: USA
GS1100E. It's an '83 frame with the red and has an 81 or 82 motor with a welded crank. I bought it in 2009 and since the motor was painted black, I assumed it was '83 also.
Last edited by GoofySB; Oct 4, 2013 at 11:27 AM.