Author Topic: Discussion- Engine build for more low end torque.  (Read 1884 times)

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Offline EscCtrl

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Discussion- Engine build for more low end torque.
on: April 14, 2018, 09:45:53 PM
Consider this as me thinking out loud.

It seems, that cams are the place to tweak for more power down low. The CB-X, CBR, CB-F all use the same cams.

CB X, F, R cam part numbers.
14210-MGZ-J00 Exhaust
14110-MGZ-J00 Intake

The Rebel CMX500 uses a different intake cam and the Rebel is known to make good power down low. It's one of the positives about the small cruiser. The other good part is the cam price, at least for us in the US. I could be open to trying out the cam. I'm not sure if it would throw off a sensor and not run. I don't think our bikes have intake cam sensors. I'll have to look into that. I believe the lift is the same as the CB-X, F, R but the duration and/or timing is different.
 
PN 14110-MKG-A00 $41.36

Now the head-scratcher. Which PGM-FI unit? I think the part numbers are different for the different tuning. It could also be that the tuning is the same but the wiring connector could be different. Does anyone know or have a way to confirm? If the connectors are all the same, then the tuning is the reason for the varied part numbers. Could the connectors be repinned to use the CMX connector and PGM-FI unit? I know a lot of bikes can be IF the terminals are the same. They should be.

PGM-FI part numbers and prices.
CB-X 38770-MGZ-C93 $212.16
CB-R and F 38770-MGZ-A03 $212.44
CMX Rebel 38770-MKG-A02 $176.19

For those that want to go all out, there is a company, Wiseco, that makes high compression pistons. Combine that with the CMX Rebel cam, CMX PGM-FI if it will connect, good flowing exhaust, and good air filter, the CB-X should have good bottom end due to the cam and the hi-comp pistons will help the top end loss. 

No affiliation but I have run their products in motorcycles and cars with great success.
STD bore
http://www.wiseco.com/ProductDetail.aspx?ItemID=CK238&ModelID=5727&ModelYear=2014&AppID=53603

0.50 overbore
http://www.wiseco.com/ProductDetail.aspx?ItemID=40130M06750&ModelID=5727&ModelYear=2014&AppID=53452



Could it be as simple as a cam swap and PGM-FI to get better low-end performance? For $41.36 + 176.19 = $217.55 + 8.95 shipping $226.50 This could be a good deal to up low-end performance without much investment and no changes to the exhaust (for those that like it quite) or air intake. I am currently finishing up my workshop. Once I am all set up, I may seriously consider trying this out and maybe later I could go with high comp pistons, exhaust, and air filter. I really think the OE air filter and airbox can flow enough to support the changes. Maybe a K&N for the street riders.

My Honda parts pricing comes from the link below. I'm just a satisfied customer. They've always gone out of their way to get parts to me quickly without additional costs.
https://www.hondaparts-direct.com/index.htm

Offline Lysdexic

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Re: Discussion- Engine build for more low end torque.
Reply #1 on: April 15, 2018, 01:46:38 AM
Sounds really interesting - if you do go this route it might be good to dyno the bike before & after.
I don't have a lot of issues with low end torque (but hey, more is better) but acceleration in top gear could def be better.

Watching this space with interest!

Offline EscCtrl

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Re: Discussion- Engine build for more low end torque.
Reply #2 on: April 15, 2018, 02:17:52 AM
*Originally Posted by Lysdexic [+]
Sounds really interesting - if you do go this route it might be good to dyno the bike before & after.
I don't have a lot of issues with low end torque (but hey, more is better) but acceleration in top gear could def be better.

Watching this space with interest!

I'm a pretty big guy and I carry a lot of gear. Some more low-end would help me off road in some situations.

I don't know of a dyno close to me. It would be fun to do a few runs before and after.

Offline Roy McKenna

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Re: Discussion- Engine build for more low end torque.
Reply #3 on: April 15, 2018, 04:34:19 AM
*Originally Posted by EscCtrl [+]

Now the head-scratcher. Which PGM-FI unit? I think the part numbers are different for the different tuning. It could also be that the tuning is the same but the wiring connector could be different. Does anyone know or have a way to confirm? If the connectors are all the same, then the tuning is the reason for the varied part numbers. Could the connectors be repinned to use the CMX connector and PGM-FI unit? I know a lot of bikes can be IF the terminals are the same. They should be.


Ebay has used ECM's for both motorcycles for comparison.  I don't think you are going to like the comparison if you were to try putting a CMX in the CBX. 

CB500X ECM ebay ad with pics.

CMX Rebel ECM ebay ad with pics.
Roy McKenna

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Re: Discussion- Engine build for more low end torque.
Reply #4 on: April 15, 2018, 04:52:17 AM
I think the cam might work but I wouldn't put it with the rebel ECU-why you ask- well the Rebel turns less RPM's less HP so I think the Rebel ECU might cut the power off early-looking for more low end power I have heard you say you don't drive fast due to your size and the amount of stuff you carry- one less tooth counter sprocket- problem sloved
Last Edit: April 15, 2018, 04:56:31 AM by motorboy
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Offline Oyabun

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Re: Discussion- Engine build for more low end torque.
Reply #5 on: April 15, 2018, 07:56:29 AM
I think with the rebel cam you'd make serious compromises.
I've reposted it here earlier - over on te forum dedicated to the cbr500, we had a long discussion about such a project (the rebel was not available at that time) and one member from down low had an -almost- full build.  He used an aftermarket cam, polished the throttle bodies, worked a bit on the airbox changed to a cat less header and aftermarket can and finally dyo tuned the whole thing with a wideband O2 sensor on a dyno.
He gained power everywhere, but the majority of the gains is low to mid range (4000-7000 with almost 30% plus about 5k) and then at the top end (due ro the rev extend feature of PCV).
Back then Ive made a comparison fhart of the dyno measurements he got which I attach.
Unfortunately the block halves have to be separated to change the pistons so that is a major work. Keep in mind, that there are other tested methods to bump CR. You can shave some of the head, use the OEM piston from the japanese domestic CBR/F/X400 family, or use stock 2003-2004 CBR600RR pistons. But again. It is a major work to do - but increasing CR gives a bump everywhere in volumetric efficiency thus in power and keeps economy.


Offline EscCtrl

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Re: Discussion- Engine build for more low end torque.
Reply #6 on: April 15, 2018, 07:54:01 PM
*Originally Posted by motorboy [+]
I think the cam might work but I wouldn't put it with the rebel ECU-why you ask- well the Rebel turns less RPM's less HP so I think the Rebel ECU might cut the power off early-looking for more low end power I have heard you say you don't drive fast due to your size and the amount of stuff you carry- one less tooth counter sprocket- problem sloved

That's the info I was looking for RPM cut off.

I wouldn't want to up the rpms with a sprocket change for more torque. I do ride fast and hard. I just don't get on the interstate much. I do need to occasionally to make up some time. I am a fat guy but slowly losing weight. I do carry a crapload of gear which I am going to be working on. I'd like to get my set up down from 60lbs to 40lbs across both side cases and trunk.


*Originally Posted by Oyabun [+]
I think with the rebel cam you'd make serious compromises.
I've reposted it here earlier - over on te forum dedicated to the cbr500, we had a long discussion about such a project (the rebel was not available at that time) and one member from down low had an -almost- full build.  He used an aftermarket cam, polished the throttle bodies, worked a bit on the airbox changed to a cat less header and aftermarket can and finally dyo tuned the whole thing with a wideband O2 sensor on a dyno.
He gained power everywhere, but the majority of the gains is low to mid range (4000-7000 with almost 30% plus about 5k) and then at the top end (due ro the rev extend feature of PCV).
Back then Ive made a comparison fhart of the dyno measurements he got which I attach.
Unfortunately the block halves have to be separated to change the pistons so that is a major work. Keep in mind, that there are other tested methods to bump CR. You can shave some of the head, use the OEM piston from the japanese domestic CBR/F/X400 family, or use stock 2003-2004 CBR600RR pistons. But again. It is a major work to do - but increasing CR gives a bump everywhere in volumetric efficiency thus in power and keeps economy.



I was trying to think up a way to help the lower end. I've read the build threads around about the CBR. That's to much for a daily rider. I have no problems tearing down an engine for upgrades. Most others wouldn't go that far. That's what made me look at the CMX cam and PGM-FI unit. Something some others maybe interested in doing. I see now that it wouldn't work well. Oh well, ideas come and go.
Last Edit: April 15, 2018, 07:56:24 PM by EscCtrl