Big bored and now hard starting
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Road Captain
Joined: Feb 2010
Posts: 646
Likes: 159
From: New York
Big bored and now hard starting
Question for you. I have a 2007 street bob. I put 255se cams in it with big bore cylinders (3.875) and high compression se pistons. Put compression releases in the heads. Before I did the work the bike started fine. Now it struggles to start even when I push the compression releases in. I have a base power vision tune, when it's running it kind of coughs. Runs like crap, probably need a dyno tune. I don't understand why it starts so hard. Almost like the starter isn't big enough or not getting enough fuel (injectors)? Ignition issue?
Seasoned HDF Member
Joined: Mar 2021
Posts: 18,460
Likes: 3,723
From: backwoods
A tune might help. When I built my 2007 last year to to 103 I purpopesly stayed away from high compression .035 head gasket and MR103s. You will probably have more power than me though. I didn't do compression releases
But if it runs bad you need a syno or another tune to get closer. What did you tune it with so far?
But if it runs bad you need a syno or another tune to get closer. What did you tune it with so far?
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Road Captain
Joined: Feb 2010
Posts: 646
Likes: 159
From: New York
A tune might help. When I built my 2007 last year to to 103 I purpopesly stayed away from high compression .035 head gasket and MR103s. You will probably have more power than me though. I didn't do compression releases
But if it runs bad you need a syno or another tune to get closer. What did you tune it with so far?
But if it runs bad you need a syno or another tune to get closer. What did you tune it with so far?
Stellar HDF Member
Joined: Aug 2018
Posts: 2,406
Likes: 2,648
From: Milwaukee, WI
Test the battery, and check all the connections, the CCA for the stock motor is being exceeded, and if it’s never been replaced you also have a 18 year old starter, which also may be weak.
somewhere between the Battery, connectors or starter you probably will find the issue.
somewhere between the Battery, connectors or starter you probably will find the issue.
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Road Captain
Joined: Feb 2010
Posts: 646
Likes: 159
From: New York
Test the battery, and check all the connections, the CCA for the stock motor is being exceeded, and if its never been replaced you also have a 18 year old starter, which also may be weak.
somewhere between the Battery, connectors or starter you probably will find the issue.
somewhere between the Battery, connectors or starter you probably will find the issue.
Tourer
Joined: Mar 2014
Posts: 452
Likes: 228
From: Northford, CT
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Seasoned HDF Member
Joined: Jun 2015
Posts: 10,291
Likes: 7,773
From: West Central FL
How's the condition of the battery? High compression requires high cold cranking amps. If you aren't over 300 fuggedabodit.
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Road Captain
Joined: Feb 2010
Posts: 646
Likes: 159
From: New York
brand new battery with great cca
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Road Captain
Joined: Feb 2010
Posts: 646
Likes: 159
From: New York
just checked, 190-195 both cylinders. I fired the bike up without using the compression releases and it had no issues 🤷♂️