Question - Starter issue
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From: Seattle, WA
Question - Starter issue
Posted the below thread over in the 'Primary/Transmission/Driveline/Clutch' section of the Tech forum ... but, thought since there were various aspects it might be worthwhile to get some visibility in a couple of other places as well ... appreciate your taking a look and offering 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
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