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Weak or no crank when bike is warmed up


klipsedeville

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I have recently run into an issue with my '02 vtec. Bike will start strong when cold. Cranks over easily as expected but after riding for a bit and turned off, the bike will crank over weakly or not even crank. I will have to allow it cool off for hours and then it fires up very easily.

 

Things I've tried: changed battery (brand new and one from a friend's VFR), swapped starter motor with same friend's that works for his bike, ran a direct wire connection from battery negative to starter motor bolt to allow for better grounding.

 

Problem still persists.

 

Bike will start easily if my buddy pushes the bike or I hook the bike up to a car's battery (doesn't crank if the car is not running and only cranks strongly if car's rev is raised).

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your bike could be overheating without your knowing it,  check coolant level under the radiator cap when engine is cold,  if coolant level falls too low [leaks, bad rad cap] the temp gauge will be inaccurate. 

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Given all you've tried, and the strange effect of needing to rev the jumper car engine to get the bike to crank!

I'd be suspicious of high resistance/burnt main contacts within the Starter Relay. I think the Starter Relay needs to be taken out of the equation by fitting a new one.

 

Trust your battery terminals are clean and tight and along with good clean connections at the Starter Relay, also check the main positive terminal at the starter motor, clean and tight. Also have a good look at Main Fuse A 30amp in the Starter Relay, make sure it doesn't look heat stressed and the legs are clean and making good contact, a little Ox-Gard on the legs might be of benefit.

 

Thoroughly check your charging system and if there's any doubts about your battery status, charge it then have it load tested.

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^^^^^^^  as you know, he can very easily test any possible starter relay problems by means of the simple expedient of bridging over the large nuts with a suitable metal tool, taking special care not to allow grounding or the bike to be in gear.......who's that dumb ? 😏

 

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2 hours ago, klipsedeville said:

ran a direct wire connection from battery negative to starter motor bolt to allow for better grounding.

Which bolt is this? Can you provide photo?

 

I think you lucked out by not frying your entire charging system by revving auto engine.

 

Do these 2 tests when it's warm and uncooperative;

 

1. battery voltage when everything's OFF. volts=???

 

2. battery voltage when pushing start-button. volts=???

 

3. voltage at starter lug (where solenoid cable attaches) when pushing start-button. volts=???

 

Just like doctor measuring your pulse and BP, numbers will give insight into what's wrong. Similar to physician's creed of "do no harm", we don't want to change anything in system. Otherwise you'll introduce additional variables into system, potentially causing extra faults and chasing your tail in circles. Only non-invasive, non-destructive passive measurements only. This is 5-minute fix with multimetre... or less in most cases...

 

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6 hours ago, Grum said:

Given all you've tried, and the strange effect of needing to rev the jumper car engine to get the bike to crank!

I'd be suspicious of high resistance/burnt main contacts within the Starter Relay. I think the Starter Relay needs to be taken out of the equation by fitting a new one.

 

Trust your battery terminals are clean and tight and along with good clean connections at the Starter Relay, also check the main positive terminal at the starter motor, clean and tight. Also have a good look at Main Fuse A 30amp in the Starter Relay, make sure it doesn't look heat stressed and the legs are clean and making good contact, a little Ox-Gard on the legs might be of benefit.

 

Thoroughly check your charging system and if there's any doubts about your battery status, charge it then have it load tested.

Got a brand new battery (12v 14amps really huge pack), even put in fresh one when it refuses to start. still same weak crank so I feel it's not the battery. Haven't tried jumping the starter relay but it clicks loudly as always. The 30A main fuse is clean and not signs of heat.

 

My readings when checking the charging system: idle no lights on 14.4v and @ 5k rpm 14.7v, when low beam is on: 14.0v, @ 5k rpm 14.2v, when all lights on 13.5v and @ 5k rpm 13.9 ish. Now when the fan kicks on ( i have a secondary fan installed. the delta PC fan) voltage drops to 12.9v with all lights on and @5k rpm doesn't get up to 13.5v. Battery volts with bike off is 13.5v

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6 hours ago, DannoXYZ said:

Which bolt is this? Can you provide photo?

 

I think you lucked out by not frying your entire charging system by revving auto engine.

 

Do these 2 tests when it's warm and uncooperative;

 

1. battery voltage when everything's OFF. volts=???

 

2. battery voltage when pushing start-button. volts=???

 

3. voltage at starter lug (where solenoid cable attaches) when pushing start-button. volts=???

 

Just like doctor measuring your pulse and BP, numbers will give insight into what's wrong. Similar to physician's creed of "do no harm", we don't want to change anything in system. Otherwise you'll introduce additional variables into system, potentially causing extra faults and chasing your tail in circles. Only non-invasive, non-destructive passive measurements only. This is 5-minute fix with multimetre... or less in most cases...

 

Guess I have been lucking to not fry the charging system. 😁 Now that I know this, not gonna attempt it again.

 

The starter motor has 2 mounting bolts to the engine, I connected to the lower bolt more accessible and ran it directly to the battery negative. The positive wire was just cleaned it.

 

I will try the lab tests and share results.

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6 hours ago, squirrelman said:

^^^^^^^  as you know, he can very easily test any possible starter relay problems by means of the simple expedient of bridging over the large nuts with a suitable metal tool, taking special care not to allow grounding or the bike to be in gear.......who's that dumb ? 😏

 

lol. I tried jumping the terminals and it doesn't help.

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18 hours ago, klipsedeville said:

lol. I tried jumping the terminals and it doesn't help.

Ok, this rules out starter-solenoid not transmitting power as culprit.

 

 

2. what's battery voltage when pushing start-button. volts=???

 

3. what's voltage at starter lug (where solenoid cable attaches) when pushing start-button. volts=???

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On 3/12/2023 at 1:14 AM, klipsedeville said:

Guess I have been lucking to not fry the charging system. 😁 Now that I know this, not gonna attempt it again.

 

The starter motor has 2 mounting bolts to the engine, I connected to the lower bolt more accessible and ran it directly to the battery negative. The positive wire was just cleaned it.

 

I will try the lab tests and share results.

I don't understand the positive wire was just cleaned it. You need to run a cable from the battery positive to the positive lug on the starter where the cable connects. That way it tells you if it is the starter or something in between the battery and the starter.

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Never trust wires without checking resistance. I have seen wire that looked fine, but strip the insulation off and they were all green inside.

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17 hours ago, DannoXYZ said:

Ok, this rules out starter-solenoid not transmitting power as culprit.

 

 

 

2. what's battery voltage when pushing start-button. volts=???

 

3. what's voltage at starter lug (where solenoid cable attaches) when pushing start-button. volts=???

At cold start, battery voltage is 13.4v and when pushing start button it drops to 10.7v.

After bike has warmed up battery voltage is around 13.8v, when pushing start button it drops to 6v to 8v

 

At starter lug when hot I get similar voltage drop when pushing start button 6v to 7v ish

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51 minutes ago, jefferson said:

What happens when you jump from the battery positive to the starter terminal?

The weak cranking. Could an over-tightened manual CCT cause this? That's the only other thing changed on the bike. I switched to manual CCTs. Could they have been adjusted too tight?

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On 3/14/2023 at 8:17 AM, klipsedeville said:

The weak cranking. Could an over-tightened manual CCT cause this? That's the only other thing changed on the bike. I switched to manual CCTs. Could they have been adjusted too tight?

Guess that could be possible!

 

Have never liked the idea of manual CCT's as there is a fine line between under and over tensioning of a timing chain, a manual CCT won't compensate for any thermal effect on the chain, or normal wear and tear etc. No wonder Honda don't fit manual CCT's, maladjusted the results could be serious engine damage.

 

Who knows what method (if any) was used to set the correct initial tension?

 

The obvious question??.......... Did this problem arise shortly after changing to manual CCT'S?

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12 hours ago, Grum said:

Guess that could be possible!

 

Have never liked the idea of manual CCT's as there is a fine line between under and over tensioning of a timing chain, a manual CCT won't compensate for any thermal effect on the chain, or normal wear and tear etc. No wonder Honda don't fit manual CCT's, maladjusted the results could be serious engine damage.

 

Who knows what method (if any) was used to set the correct initial tension?

 

The obvious question??.......... Did this problem arise shortly after changing to manual CCT'S?

Well not immediately after changing to manual CCTs. I put in the manual ones 5 months ago and it just started this issue a couple of weeks back. I have backed out the manual CCTs to a point I feel slight tension from the chain. I can hear the chain slap slightly now. but the starting issue still persists.

 

 

On 3/13/2023 at 8:59 PM, klipsedeville said:

At cold start, battery voltage is 13.4v and when pushing start button it drops to 10.7v.

After bike has warmed up battery voltage is around 13.8v, when pushing start button it drops to 6v to 8v

 

At starter lug when hot I get similar voltage drop when pushing start button 6v to 7v ish

Looking at these voltage readings, could I be losing battery voltage somehow when the bike is running? Could the battery be recovering when cooled or what?

 

Another thing I noticed before now, I could take out the battery with the bike running and it wouldn't stall. But now, once the battery is disconnected, the bike dies immediately.

I remember helping a friend who had a weak battery on a trip. I would remove my battery while my bike was running and start his.

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  • 1 month later...

Hello guys. Problem fixed! For anyone having similar issues, pay attention to the starter gears between the starter motor and the starter clutch and use the correct gasket for the clutch cover!

 

It turned out I used a cheap gasket that was really thin, so guessing that when the engine warms up, the gear pins expand and cause the gears to lock tighter. Don't know if this is the case but by simply greasing the gears generously and using OEM gasket, problem was solved.

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