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Discussion Starter #1
I tried an LED bulb shortly after we got the GROM but the low beam burnt out soon after, before I was aware that the OG Groms supply AC.

I switched to a halogen H4 55/60 bulb and have been using that for awhile. I've just realized tonight that it's dimming under throttle/load. If I roll off the gas, it gets brighter.

It's dimmer at idle, brightens up when raise the RPMs. When riding, it gets brighter from idle when you first give it gas, but it does go dimmer again under load.

Has anyone seen this?
 

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Discussion Starter #2
I should mention that this is with an SF rectifier.

It's possible that it could be my battery too. It sometimes is slow to turn the starter first crank. This was more evident after installing TB cam so unsure if related to cam profile.
 

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Discussion Starter #3
I charged and reconditioned battery overnight. Will see if there's any difference today.
 

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Discussion Starter #5
OG Grom comes stock with halogen, albeit 35W HS1.

It's the fact that it dims under throttle that's concerning me. Not sure why that would be happening?

Higher rpms should keep it consistently brighter?

Or is the fuel pump also starting to consume more power for example too?
 

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CDN do you have a multimeter (voltmeter, VOM) to check electrical circuits?

If so, some Q's may be answered. If not, it is a moot point to type further.
 
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Discussion Starter #7
I do have one.

Let me see if the battery charge had made a difference. I expect it's still the original and it was definitely stalling on first crank.
 

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I bought LED head light bulb on ebay back in 2015-16 time fame and they were the Turbo V16 model and they came in 2 per package and the price was about $16-20 back then so I bought 5 sets and they worked great for day time riding and night time riding, very bright.

Now I notice the price went up to around $40 each. I even used these on my other motorcycles and also my 82 RX-7 which I had to buy a housing that supports these bulbs.

I tried Halogen bulb but the current drain was too much for the grom.

https://www.ebay.com/itm/V16-H4-CREE-Turbo-Conversion-Hi-Low-LED-Headlight-Lamp-Bulbs-Kits-9600LM-6000K/262491156340?hash=item3d1db12f74:g:yooAAOSwND5dDeWi
 

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Discussion Starter #9
I bought LED head light bulb on ebay back in 2015-16 time fame and they were the Turbo V16 model and they came in 2 per package and the price was about $16-20 back then so I bought 5 sets and they worked great for day time riding and night time riding, very bright.

Now I notice the price went up to around $40 each. I even used these on my other motorcycles and also my 82 RX-7 which I had to buy a housing that supports these bulbs.

I tried Halogen bulb but the current drain was too much for the grom.

https://www.ebay.com/itm/V16-H4-CREE-Turbo-Conversion-Hi-Low-LED-Headlight-Lamp-Bulbs-Kits-9600LM-6000K/262491156340?hash=item3d1db12f74:g:yooAAOSwND5dDeWi
These are what I run in my XC90 and my Duke 390. I've been very happy with them, very bright because they use a CREE XHP50 emitter.



I had the second H4 setup spare from the pair purchased for the KTM, so put that in the Grom right away but the low beam burnt out within a week.



So, I haven't bothered to trouble shoot whether the bulb or the driver, partly because I didn't want to take the other assembly out of the KTM.

Knowing I still want to have a spare on hand, I've ordered another pair of XHP50 based bulbs from another vendor. Will see how they compare when they arrive in a few weeks.







I took the bike up the street quickly after dark and I don't think it's doing the dimming anymore. At least not during the 5 mins I tried... I'll test again in next days but thinking the battery might have benefitted from the reconditioning cycles the charger put it through the other night.
 

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Personally not a fan of the XHP series CREE chips in retrofit LEDs.

Yeah they are bright, but they mess with the beam pattern so much, that most of those lumens end up on places other than the road.

I much prefer the new small Phillips LED chips that some manufacturers are using in series to imitate the same position and light pattern as a halogen filament. This provides more light on the road.

Morimoto 2Stroke 2.0 is a good example of such bulbs.

Sent from my PH-1 using Tapatalk
 

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Discussion Starter #11
Personally not a fan of the XHP series CREE chips in retrofit LEDs.

Yeah they are bright, but they mess with the beam pattern so much, that most of those lumens end up on places other than the road.

I much prefer the new small Phillips LED chips that some manufacturers are using in series to imitate the same position and light pattern as a halogen filament. This provides more light on the road.

Morimoto 2Stroke 2.0 is a good example of such bulbs.

Sent from my PH-1 using Tapatalk
Interesting - first I've seen/heard of these. Good to know, thanks.
 

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Discussion Starter #12
CDN do you have a multimeter (voltmeter, VOM) to check electrical circuits?

If so, some Q's may be answered. If not, it is a moot point to type further.
I confirmed the bike still dims under load. Most noticeable on highway at WOT for a while. When roll off the throttle, lamp brightens up, almost flashes initially before staying bright until I go WOT again.

What are your suspicions WV? Are there any significant draws on system at WOT, fuel pump, injector etc?

I will go LED bulb regardless but would like to understand what's going on.
 

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I confirmed the bike still dims under load. Most noticeable on highway at WOT for a while. When roll off the throttle, lamp brightens up, almost flashes initially before staying bright until I go WOT again.

What are your suspicions WV? Are there any significant draws on system at WOT, fuel pump, injector etc?
There are not any significant draw on the system at high RPM that there is at a lower RPM.

First throw your VOM across the battery and raise the throttle. You should see a significant jump in the charging rate. If not, take one connection off of the battery (to the electrical system), test again (no RPM needed). This is your base battery voltage. There should be a difference between the two voltages.

Test & reply & we will go further.

The next time that you are out on the bike, pay attention to the RPM range(s) where you see the apparent voltage fluctuations.
 

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I confirmed the bike still dims under load. Most noticeable on highway at WOT for a while. When roll off the throttle, lamp brightens up, almost flashes initially before staying bright until I go WOT again.

What are your suspicions WV? Are there any significant draws on system at WOT, fuel pump, injector etc?
There are not any significant draw on the system at high RPM that there is at a lower RPM.

First throw your VOM across the battery and raise the throttle. You should see a significant jump in the charging rate. If not, take one connection off of the battery (to the electrical system), test again (no RPM needed). This is your base battery voltage. There should be a difference between the two voltages. Test & reply and we will go further.

The next time that you are out on the bike, pay attention to the RPM range(s) where you see the apparent voltage fluctuations.
 
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If you are throwing in an LED then make sure the power supply to the headlight is converted to DC. I did the same thing you did and the headlight burnt out in a day. I did the one wire AC to DC conversion and it's been good ever since. The high beam indicator doesn't work anymore, but I really didn't care about that. Hard racing has a video on the conversion. It's part of their double bar headlight install video here:

 

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Discussion Starter #16
If you are throwing in an LED then make sure the power supply to the headlight is converted to DC. I did the same thing you did and the headlight burnt out in a day. I did the one wire AC to DC conversion and it's been good ever since. The high beam indicator doesn't work anymore, but I really didn't care about that. Hard racing has a video on the conversion. It's part of their double bar headlight install video here:

I'm running the SF rectifier which I understood precluded the need to do the above mod?
 

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I'm running the SF rectifier which I understood precluded the need to do the above mod?
Ah you're right. I glossed over that detail in your post.
 

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Discussion Starter #19
There are not any significant draw on the system at high RPM that there is at a lower RPM.

First throw your VOM across the battery and raise the throttle. You should see a significant jump in the charging rate. If not, take one connection off of the battery (to the electrical system), test again (no RPM needed). This is your base battery voltage. There should be a difference between the two voltages. Test & reply and we will go further.

The next time that you are out on the bike, pay attention to the RPM range(s) where you see the apparent voltage fluctuations.
Voltage with key off 12.56V

Key on, not running, voltage drops to 12.17V

Running, at idle 13.45V

At 5000rpm 14.21V

Quick video that shows dip in brightness as I bring revs up.


 

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Put your VOM across the battery terminals and then retry the test (RPM). Best if your meter has a dial vs digital, but beggars can't be choosy. Does the voltage fluctuate when the headlight dims?

Now measure across the terminals of the bulb (inserted into socket and working) and retest. Same voltage? Measure the socket where the bulb inserts into (no bulb) Still fluctuating?

I wonder if it is a voltage regulator issue. Assuming our bikes have one...
 
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