Starting issue - input sought
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Elite HDF Member
Joined: Apr 2007
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From: Seattle, WA
Starting issue - input sought
Posted over in the 'Primary/Transmission/Driveline/Clutch' section ... but, wanted to ensure this gets visibility by the experts ... appreciate your input and ideas ....
Issue: starter does not 'do the job' when temps drop below about 45 degrees F.
Background: Since last winter, when my bike started fine in weather down into the mid-20s, I have done the following: BDL Belt Drive, Andrews TW37B cams, Big Bore 95" kit.
After some 'head scratching' ... I deemed the following info relevant to the issue: the BDL affected two area--(i) primary drive ratio and (ii) starter gear ratio; compression ratio and cold cranking compression (PSI)
The above table captures the above-referenced data at the top of the table [the lower part of the table illustrates the effect of the change in the primary drive ratio] ....
So, CCC in PSI was raised from ~159 to ~171 ... an increase of 12 PSI ... though this is relatively modest (and the Compression Ratio is a 'mild' 9.2:1) ... however, due to the combined effect of the starter gearing ratio and the primary ratio, the stock 1.2 kW starter is trying to turn the motor over at 618 RPM vice stock rate of 424 RPM ... an increase of ~46% in engine RPM ...!
I am thinking the combined effect of trying to turn the motor over at higher RPM at ~8% higher compression is causing the system to balk and not start at low temps ....
* * *
Possible COAs (courses of action):
1. Higher output battery and heavier gauge cables (Check) ... on order
2. Retard the ignition advance and richen fuel mixture at start-up (Check) ... done (and seems to have helped somewhat) ...
3. Heavy-duty starter that can handle the increased load ...
4. Compression releases ...
... anything else ...?
* * *
I am a little up in the air as to the relative cost/benefit trade-off of COAs 3 and 4 ... I am inclined to do 4 in conjunction with either head porting or replacement with high performance heads with compression releases (and increase compression ratio a little to about 10:1) ....
If I were to follow that course, I expect that COA 3 would be OBE (overtaken by events ... or no longer necessary) ....
I am also posting this in a couple other places to hopefully increase the views and hopefully get some experts to chime in ....
THX in advance ...
R/
'Chop
Background: Since last winter, when my bike started fine in weather down into the mid-20s, I have done the following: BDL Belt Drive, Andrews TW37B cams, Big Bore 95" kit.
After some 'head scratching' ... I deemed the following info relevant to the issue: the BDL affected two area--(i) primary drive ratio and (ii) starter gear ratio; compression ratio and cold cranking compression (PSI)
The above table captures the above-referenced data at the top of the table [the lower part of the table illustrates the effect of the change in the primary drive ratio] ....
So, CCC in PSI was raised from ~159 to ~171 ... an increase of 12 PSI ... though this is relatively modest (and the Compression Ratio is a 'mild' 9.2:1) ... however, due to the combined effect of the starter gearing ratio and the primary ratio, the stock 1.2 kW starter is trying to turn the motor over at 618 RPM vice stock rate of 424 RPM ... an increase of ~46% in engine RPM ...!
I am thinking the combined effect of trying to turn the motor over at higher RPM at ~8% higher compression is causing the system to balk and not start at low temps ....
* * *
Possible COAs (courses of action):
1. Higher output battery and heavier gauge cables (Check) ... on order
2. Retard the ignition advance and richen fuel mixture at start-up (Check) ... done (and seems to have helped somewhat) ...
3. Heavy-duty starter that can handle the increased load ...
4. Compression releases ...
... anything else ...?
* * *
I am a little up in the air as to the relative cost/benefit trade-off of COAs 3 and 4 ... I am inclined to do 4 in conjunction with either head porting or replacement with high performance heads with compression releases (and increase compression ratio a little to about 10:1) ....
If I were to follow that course, I expect that COA 3 would be OBE (overtaken by events ... or no longer necessary) ....
I am also posting this in a couple other places to hopefully increase the views and hopefully get some experts to chime in ....
THX in advance ...
R/
'Chop
Club Member
Joined: Jun 2009
Posts: 5,323
Likes: 37
From: NJ
Here's my expert opinion.
First off you are the man knowing all this stuff. Hats off to you. Secondly to even want to start your bike in twenty degree weather makes you definitely the man in my book. Lastly I'd go buy the biggest steroid aftermarket starter and bolt that in and call it a day..compression releases are cool too....good luck.
First off you are the man knowing all this stuff. Hats off to you. Secondly to even want to start your bike in twenty degree weather makes you definitely the man in my book. Lastly I'd go buy the biggest steroid aftermarket starter and bolt that in and call it a day..compression releases are cool too....good luck.
Ultimate HDF Member
Joined: Jan 2008
Posts: 6,532
Likes: 132
From: SoCal
You might be able to change the clutch basket ring gear and the starter pinion gear to help the starter out, I don't think a bigger starter motor is a good answer, you need better leverage. Compression releases may be enough by themselves but at that low temp?????? I don't know if they're enough by themselves. Maybe.
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Elite HDF Member
Joined: Apr 2007
Posts: 4,919
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From: Seattle, WA
Yeah ... I know that was another COA ... swap out to a Compu-Fire 10/84 ... would reduce the ratio by 15% ... might be enough ....
I think the bigger starter motor is something of a 'band aid' ... but, if it works ....
I had been (am) contemplating heads anyway ... so ....
Of course in a few weeks when it warms up, the whole issue will be moot until the fall ....
I think the bigger starter motor is something of a 'band aid' ... but, if it works ....
I had been (am) contemplating heads anyway ... so ....
Of course in a few weeks when it warms up, the whole issue will be moot until the fall ....
Intermediate
Joined: Mar 2011
Posts: 43
Likes: 0
From: Alabama
here ya go
your sugguestions are good i have a similiar ride with big cams big compression
starter ALL ***** RACING (lifetime warranty) 2.4kw
66 tooth ring gear
compression releases
Hvy battery wire
that will do it!
your sugguestions are good i have a similiar ride with big cams big compression
starter ALL ***** RACING (lifetime warranty) 2.4kw
66 tooth ring gear
compression releases
Hvy battery wire
that will do it!
Thread Starter
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Elite HDF Member
Joined: Apr 2007
Posts: 4,919
Likes: 23
From: Seattle, WA
Thanks for the feedback ...
I think 2.4kW may be a little overkill ... was contemplating 1.4kW or 1.6kW .... But, I may have to revisit the subject ....
I currently have the 66 tooth ring gear ... was considering going to 84 ... that would reduce the speed at which I am trying to turn over the motor (and reduce the burden on the starter motor) ....
R/
'Chop
I think 2.4kW may be a little overkill ... was contemplating 1.4kW or 1.6kW .... But, I may have to revisit the subject ....
I currently have the 66 tooth ring gear ... was considering going to 84 ... that would reduce the speed at which I am trying to turn over the motor (and reduce the burden on the starter motor) ....
R/
'Chop
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