Honda Grom banner

1 - 13 of 13 Posts

·
Registered
Joined
·
38 Posts
Discussion Starter #1
So far I've changed the air filter and air intake pipe, full exhaust and iridium spark plug. Remapped ECU is on the way.
Next I want to change the fuel injector and camshaft. Should I take a 120cc with 4 holes, or 125cc with 6 holes?
About the camshaft, I'm getting one with 5.2 lift. The seller said, I could use it with the stock springs, but wouldn't reinforced springs be better?

Thanks for any useful advice.
 

·
Registered
Joined
·
76 Posts
So far I've changed the air filter and air intake pipe, full exhaust and iridium spark plug. Remapped ECU is on the way.
Next I want to change the fuel injector and camshaft. Should I take a 120cc with 4 holes, or 125cc with 6 holes?
About the camshaft, I'm getting one with 5.2 lift. The seller said, I could use it with the stock springs, but wouldn't reinforced springs be better?

Thanks for any useful advice.
Does your remapped ECU still retain it rev limiter,and if so has it been increased from stock?
 

·
Vendor
Joined
·
1,818 Posts
DO NOT change the injector on a mild stock bore. Won't help a thing, and you'll HAVE TO re-map from scratch. Intake, exhaust, cam, and tuner are the go-to first round items. Be aware that a modified airbox seldom performs like a properly tuned full intake, whether that's ours, or a reputable competitor. Regardless of what you do, it's all dependent on a proper tune. Maybe you have one, if not, it starts with a quality tuner, and quality tuning, not a ECU reset, or a price point import.
 

·
Registered
Joined
·
38 Posts
Discussion Starter #5
DO NOT change the injector on a mild stock bore. Won't help a thing, and you'll HAVE TO re-map from scratch. Intake, exhaust, cam, and tuner are the go-to first round items. Be aware that a modified airbox seldom performs like a properly tuned full intake, whether that's ours, or a reputable competitor. Regardless of what you do, it's all dependent on a proper tune. Maybe you have one, if not, it starts with a quality tuner, and quality tuning, not a ECU reset, or a price point import.
I didn't dare to get the cold air intake, cause where I'm driving roads are dusty as hell. Thought maybe I'll replace the intake snorkel with a 1.5 inch hose, but I was told that's overkill on a stock motor.
Got my ECU remapped by a reputable technician here in Thailand. Of course, I'd have to remap it if I change the injector. So you reckon changing just the cam and leave the stock injector would be better?
 

·
Vendor
Joined
·
1,818 Posts
Just realized I don't know what year your bike is. If it's a first gen Grom and you add a cam, you do intact want a new injector. If it's a new Grom, you for sure don't. Either way, get the bike properly tuned once the new cam goes in.
 

·
Registered
Joined
·
38 Posts
Discussion Starter #7 (Edited)
Just realized I don't know what year your bike is. If it's a first gen Grom and you add a cam, you do intact want a new injector. If it's a new Grom, you for sure don't. Either way, get the bike properly tuned once the new cam goes in.
It's an old one. So which one should I go for, the 120cc 4-hole (no name) or 125cc 6-hole (Keihin)? And should I change the valve springs?
 

·
Registered
Joined
·
874 Posts
DO NOT change the injector on a mild stock bore. Won't help a thing, and you'll HAVE TO re-map from scratch. Intake, exhaust, cam, and tuner are the go-to first round items. Be aware that a modified airbox seldom performs like a properly tuned full intake, whether that's ours, or a reputable competitor. Regardless of what you do, it's all dependent on a proper tune. Maybe you have one, if not, it starts with a quality tuner, and quality tuning, not a ECU reset, or a price point import.
Good advice. :)
I experimented with both a 140cc/min/ injector and a 120cc/min. injector just to see how they run with my totally engine internals with only intake and exhaust mods, and a stand alone self adjusting ECU so I can make all the changes I want without having to screw around trying to tune it.

The 140 wouldn't idle decently unless it was 2,000 rpms and didn't perform any better while taking a considerable hit on gas mileage.

The 120 did better. It could idle decently at 1,750 rpms, and had really great throttle response at low rpms with no gain in higher rpm performance. IF I was a stunter (I'm not), I'd run a 120 because it would make wheelies a LOT easier. It also reduced reduced gas mileage by quite a bit, so I went back to stock 90cc/min. injector as I'm a daily transportation rider.

Watch out for cams. You'll LOSE low rpm pull in order to GAIN high rpm performance. If you constantly ride around with a wide open throttle you'll like an aftermarket cam, and if you don't, you won't.
 

·
Registered
Joined
·
155 Posts
Just stick with the stock injector. I have the same set up and it runs great with just a stock injector. I do have an intake and seeing the issue with a lot of dust you could consider a dry intake filter like a sprint filter and there is a precharge filter that is available that should block a lot of dust. Even with a stock airbox and given a certain amount of dust all the time... your going to be paying for replacement filters any way...
 

·
Registered
Joined
·
5 Posts
I'd run stock injector. You'll need a completely new re map on your ECU if you switch to a bigger injector. Your stock v springs will be fine unless your limiter is set for over 10,000rpm. stock limiter is 9,250
 

·
Registered
Joined
·
874 Posts
Just stick with the stock injector. I have the same set up and it runs great with just a stock injector. I do have an intake and seeing the issue with a lot of dust you could consider a dry intake filter like a sprint filter and there is a precharge filter that is available that should block a lot of dust. Even with a stock airbox and given a certain amount of dust all the time... your going to be paying for replacement filters any way...
I put a shroud on my filter and it stays clean a lot longer. because road grit can't blow directly onto the element. :)
86063
86064
 
1 - 13 of 13 Posts
Top