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Discussion Starter · #1 ·
Guys,
I got the Grom head tooling to the point that I could start modifying one of my spare Grom heads. The chosen bore is going to be 61mm for a displacement of 170cc. It will require a sleeve & a new steel head gasket, but the base gasket works, and you will not have to modify the crankcase. I machined a combustion chamber today that should be ideal for the bore. You could use the stock chamber, but you will not make the same power. This chamber is a fast burn design.
More Coming.
Brian S



 

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How much would all that cost a regular schmo like me?
+1, and how are you going to deal with the extra fueling requirements?

Looks great!
Chris
 

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Discussion Starter · #4 ·
Price for a regular schmo?

Well,
To be honest, it's way too early to tell. I don't have a price on the sleeve yet, and Wiseco is just looking at a piston. I'm timing myself, when I do these machining operations, so that I can get an ideal of the labor involved. It will all start to come together around the 1st of the year. My plan is to have a complete kit, so that everything works together. Here's a good example. If you put in the 170 bore kit, and did not fix the air box, and induction system, you would probably only see 1/2 the performance gain. That does not make sense to me. I will make sure that Forum guys & regular schmo's get a special deal. That I can assure you.
Brian S
 

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Thanks BrianS. And Cytogrom all the stuff. I've read online the ECM will self correct or compensate up to like 187cc+ then anything past that you will need to buy the bigger throttle body with the larger injector.
 

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Great DIY thread! j/k ;)
That is nice work, the first "flowed" Grom head I'd say we've all seen. No empty promises here...and a planned package deal no less. Excellent.
 

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+1, and how are you going to deal with the extra fueling requirements?

Looks great!
Chris
That easy it has computer "ECU, ECM" so it should be reprogrammed

Thanks BrianS. And Cytogrom all the stuff. I've read online the ECM will self correct or compensate up to like 187cc+ then anything past that you will need to buy the bigger throttle body with the larger injector.
ECU, ECM can't self correct w/o a O2 sensor they can only do base line reprogrammed
 

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Are you resleeving the just because you want a specific wall thickness or was there not enough meat in the walls at all to bore to 61mm
 

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in for videos. in for more photos. in for some dyno charts
in for anythinggggg

:D:D:D
 

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There is a programmer on ebay US now and some other hop up parts.All are coming from Thailand.
I wouldnt trust any of that junk (no offense). Wait til quality US parts are out. Yoshimura has great stuff out and more in the works, K&N is making a filter, DynoJet is working on a Power Commander 5, etc. Big things coming :cool:
 

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Discussion Starter · #16 ·
RE-Calibrating the ECU

Guys,
I talked to Scott at DynoJet a few weeks ago. They are working on a Grom ECU box. They don't call it a PowerCommander, but it's the same thing. They already have one for the PCX150, which is a water cooled clone of the MSX125. It will work off the O2 sensor, reprograming it from 14.7/1 to 13.7/1. It will also hold 2 programs and be able to be changed out on the road, without a computer. It should be a nice part, $249.95, retail.
With all my work on liter & 2 stroke engines, I purchased one of the $700.00 dual digital wide band O2 sensor computers, that has down load capability. I can mount the wide band O2 sesors in a second welded fitting, and ride the bike watching the readouts, and then down load it after the ride. So once I put the DynoJet box on the bike, I can watch real time what it's doing. That way when I sell a kit, the customer will get a free custom map, so it's plug & play. The plan is to have maps for any combination of the parts I make. Not everyone will be able to purchase all the parts at once, I get that. But that rider still deserves parts that work correctly with his combination. A big bore kit with the air box will have a very different map, than say a velocity stack & a Uni filter. Engineered parts is the key.
Brian S
By the way, I'm a regular schmo too
 

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Guys,
I talked to Scott at DynoJet a few weeks ago. They are working on a Grom ECU box. They don't call it a PowerCommander, but it's the same thing. They already have one for the PCX150, which is a water cooled clone of the MSX125. It will work off the O2 sensor, reprograming it from 14.7/1 to 13.7/1. It will also hold 2 programs and be able to be changed out on the road, without a computer. It should be a nice part, $249.95, retail.
With all my work on liter & 2 stroke engines, I purchased one of the $700.00 dual digital wide band O2 sensor computers, that has down load capability. I can mount the wide band O2 sesors in a second welded fitting, and ride the bike watching the readouts, and then down load it after the ride. So once I put the DynoJet box on the bike, I can watch real time what it's doing. That way when I sell a kit, the customer will get a free custom map, so it's plug & play. The plan is to have maps for any combination of the parts I make. Not everyone will be able to purchase all the parts at once, I get that. But that rider still deserves parts that work correctly with his combination. A big bore kit with the air box will have a very different map, than say a velocity stack & a Uni filter. Engineered parts is the key.
Brian S
By the way, I'm a regular schmo too
I still haven't heard anything from Dynojet after letting them test my grom for a week. So. I'm calling them tomorrow and see where there at!
 

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Discussion Starter · #18 ·
Why am I resleeving?

When Honda die cast the cylinder, they used a cast-in sleeve. That means they put a sleeve in the die, that has been pre-heated, shut the die, and then shoot aluminum into the die under very high pressure. So, unlike, say a CB750 Honda, where you could heat the cylinder in the kitchen oven when Mom was not around, and remove the sleeve, to re-sleeve the cylinder means boring out the cast in unit. Honda probably did not want people to bore the cylinder big, because the max bore in the stock cylinder is 136cc. They trimed down the outside of the sleeve that is exposed below the casting. What's inside the casting will go larger. They will claim that they were reducing weight, which they were, but they really limited the over bore. You could go to 142cc, but the skirt, or exposed sleeve would be thin, that's what the Japanese shop does. It does add money to the deal, but there is no real way around it.
The bottom line is that this engines needs torque, and that is displacement.
Brian S
 

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When Honda die cast the cylinder, they used a cast-in sleeve. That means they put a sleeve in the die, that has been pre-heated, shut the die, and then shoot aluminum into the die under very high pressure. So, unlike, say a CB750 Honda, where you could heat the cylinder in the kitchen oven when Mom was not around, and remove the sleeve, to re-sleeve the cylinder means boring out the cast in unit. Honda probably did not want people to bore the cylinder big, because the max bore in the stock cylinder is 136cc. They trimed down the outside of the sleeve that is exposed below the casting. What's inside the casting will go larger. They will claim that they were reducing weight, which they were, but they really limited the over bore. You could go to 142cc, but the skirt, or exposed sleeve would be thin, that's what the Japanese shop does. It does add money to the deal, but there is no real way around it.
The bottom line is that this engines needs torque, and that is displacement.
Brian S
Anytime you say anything all I can hear is a big Tim Allen grunt for more power!
Keep up the great work sir and make us a little monster. Lol
 

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Awesome thread and "glad to hear" some people are facing almost the same issues like we do at the moment ;)
 
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