ball_socket
Member
Summary
• I have a ‘22 JA55.
• This tutorial uses most of the original parts from the CT bottom end, with a few Grom/Monkey and aftermarket parts.
• My conversion is working but there are still some issues that need to be ironed out (see below).
• My apologies if this post is somewhat long-winded or if I come off as a smarty-pants cunt. That’s not my intention. I tend to get rather autistic when I write these kind of things and I error on the side of adding more detail so that somebody who wants to do this but maybe doesn’t have a lot of automotive or mechanical experience can do so.
My Story
My original plan was basically to break down a Grom bottom end, put an aftermarket 5-speed transmission in it, paint it silver, and swap the CT top end onto it. That way I could leave most of the original motor in tact if I ever wanted it or if I ran into some roadblock preventing the conversion from being completed. So I bought a blow Grom motor, tore it down, spent forever prepping it for paint, painted it, and found that the “Matte Crypton Silver Metallic” paint I purchased from automotivetouchup.com was way too dark (it’s more apparently in real life/in sunlight).
(Left: stock cover paint, "protector" ring painted with Scratches Happen, right: entire case painted with automotivetouchup.com)
I then tore down the CT bottom end. I found that other than the case paint color (the Grom case is black), there is only one difference between the Grom and CT cases: the right Grom case has two perches molded into it for attaching the “oil separator plate.”
When I discovered this I debated whether I should order a Monkey right case (because it’s silver and has the perches) but decided against it for three reasons: 1) It costs money 2) The semi auto bikes (CT and Super Cub) don’t have the oil separation plate, and 3) The newer motor design doesn’t have it. So how important can it be? Well it turns out it might actually be important; my clutch is dragging when pulled in all the way (make gear shifts crunchy and neutral hard to find at idle). I think there are several reasons for this: 1) I’m using an SMR 6-disk clutch, which will have less total separation between plates when fully disengauged compared to the stock Grom 5-disk plate. 2) My Magura clutch lever doesn’t have the same adjustability as a stock Grom lever/cable (I bought one and tried it), and 3) The lack of oil separation plate, I think, is causing drag between the plates and the basket due to oil circulation – I believe the separator plate’s purpose is to eliminate this drag. I realized that because I was reading a Grom forum where one member mentioned that he had failry bad clutch dragging issues with his Grom one time when he over-filled the engine oil, and after draining some oil the dragging went away (must have been spilling over the top of the separation plate?)
These are my theories… I will put a TB Parts 5-disk clutch in along with a Monkey right case and hopefully that will fix the clutch dragging.
Tools & Materials
”*” denotes items that are not strictly necessary or have some other special consideration.
• * ‘14-20 Grom 125A Service Manual from Helminc.com
• * ‘21 CT125A Service Manual from Helminc.com
• ‘13-20 Grom flywheel/stator puller tool (I used 150620/MP8 from Hard Racing)
• ‘13-20 Grom crankshaft assembly tool (I used Kitaco 674-1432700 from Hard Racing)
• ‘13-20 Grom clutch/oil spinner socket (I used a Chinese Special from eBay but if buying again would either try the one Drow sells or get the real Honda tool 07716-0020100)
• Tusk Crankcase Splitter 17-8668
• Clutch/flywheel holder tool (I bought PP2332 from Hard Racing but just use my hand and a small impact gun instead)
• * Small impact gun (I have a Makita XPH11ZB)
• A Penny (or Honda 2.5mm gear holder tool 07724-001A100)
• Dremel or file to notch out right side plastics to allow clearance for the clutch cable receiver, and to remove metal from the back of one of the right-side plastics mounts if using a Hymec (see below).
• A tube of Hondabond
• Blue threadlocker
• * Assembly lube
• A complete, or semi-complete gasket set including new exhaust doughnut (+ extras for oil changes -- see below) & Grom oil spinner gasket 15439-K26-901
• Honda Matte Crypton Silver Metallic (NH-A40M) paint. I had a bad experience with automotivetouchup.com, and used scratcheshappen.com paint (https://scratcheshappen.com/shop/touch-up-paint/honda-matte-crypton-silver-nh-a40m/) to paint the Monkey “right protector” – see “My Story” above. For the right case cover, inside the circular center portion of the protector, I used “Flat Black” High-Heat Rust-Oleum 248903.
Parts I'm Currently Using
• Stock top-end
• Stock 14/39 sprockets
• * CT left & right cases (see below)
• Grom crankshaft 13000-K26-B00
• Crankshaft bearing 91001-KWS-901
• Grom crankshaft drive hardware: 94303-03050, 15341-KPH-900, 23125-KPG-T00, 90741-KGH-900, primary drive gear “B” if using a new Monkey right case 23122-K26-900 (see below)
• Grom neutral switch 35759-K26-C01
• Grom clutch receiver & linkage parts: 22821-K26-900, 22810-K26-C00, 22815-166-000, 91305-K26-900, 22847-K26-900
• Grom oil spinner & hardware: 15431-K26-900 (I used a lightened spinner from Steady Garage), 90432-KPT-A00, 90231-087-010, (spinner gasket, mentioned above), 15441-K26-900, 3x bolts 95701-06014-00.
• CT gear shift spindle (I used the return spring from the Grom, which although looks beefier, actually had less tension than the one on the CT: 24651-K26-900)
• ‘19-21 Monkey right case cover, protector & hardware: 11330-K0F-T00, 11370-K0F-T00, 3x 19639-GBC-000, 3x 33715-GB0-900
• * Yuminashi 5-speed transmission for Grom/Monkey (see notes below about popping out of gear)
• * SMR 6-disk Grom clutch (see notes below about plate separation and clutch dragging)
• * +60% stiffer clutch springs (or whatever you want, my new TB Parts clutch came with its own springs)
• Hard Racing ‘13-22 Grom billet clutch lifter plate HR-BSP
• * Magura Hymec hydraulic clutch lever for Grom 2100004-20 (can use OEM Grom parts or an aftermarket cable clutch)
• * Male-side kickstand Sumitomo connector kit MTW-3 from Corsa-Technic (or you could ghetto-rig something for free)
• * Yuminashi oil pump (good time to upgrade)
• * Takegawa CT125 “crankshaft support adapter” 01-10-0145 + WickedGrom’s left crankcase cover mod
• Grom/Monkey Oil Separator Plate 15661-K26-900 and 2x bolts 95701-06016-00
• OEM disks/plates (or TB Parts -- what I am trying next)
• * Hard Racing Shift Shaft Support Bracket (for the CT since you’re using the CT gearshift spindle). Some say these help with finding neutral, some say they do nothing.
• Takegawa or Kitaco 5-speed transmission (see notes about finding neutral and popping out of gear below)
• * KOSO Cam Chain Tensioner for ‘14-20 Grom (if you plan to do any power mods, this is a convenient time to replace the tensioner)
• I have a ‘22 JA55.
• This tutorial uses most of the original parts from the CT bottom end, with a few Grom/Monkey and aftermarket parts.
• My conversion is working but there are still some issues that need to be ironed out (see below).
• My apologies if this post is somewhat long-winded or if I come off as a smarty-pants cunt. That’s not my intention. I tend to get rather autistic when I write these kind of things and I error on the side of adding more detail so that somebody who wants to do this but maybe doesn’t have a lot of automotive or mechanical experience can do so.
My Story
My original plan was basically to break down a Grom bottom end, put an aftermarket 5-speed transmission in it, paint it silver, and swap the CT top end onto it. That way I could leave most of the original motor in tact if I ever wanted it or if I ran into some roadblock preventing the conversion from being completed. So I bought a blow Grom motor, tore it down, spent forever prepping it for paint, painted it, and found that the “Matte Crypton Silver Metallic” paint I purchased from automotivetouchup.com was way too dark (it’s more apparently in real life/in sunlight).
(Left: stock cover paint, "protector" ring painted with Scratches Happen, right: entire case painted with automotivetouchup.com)
I then tore down the CT bottom end. I found that other than the case paint color (the Grom case is black), there is only one difference between the Grom and CT cases: the right Grom case has two perches molded into it for attaching the “oil separator plate.”
When I discovered this I debated whether I should order a Monkey right case (because it’s silver and has the perches) but decided against it for three reasons: 1) It costs money 2) The semi auto bikes (CT and Super Cub) don’t have the oil separation plate, and 3) The newer motor design doesn’t have it. So how important can it be? Well it turns out it might actually be important; my clutch is dragging when pulled in all the way (make gear shifts crunchy and neutral hard to find at idle). I think there are several reasons for this: 1) I’m using an SMR 6-disk clutch, which will have less total separation between plates when fully disengauged compared to the stock Grom 5-disk plate. 2) My Magura clutch lever doesn’t have the same adjustability as a stock Grom lever/cable (I bought one and tried it), and 3) The lack of oil separation plate, I think, is causing drag between the plates and the basket due to oil circulation – I believe the separator plate’s purpose is to eliminate this drag. I realized that because I was reading a Grom forum where one member mentioned that he had failry bad clutch dragging issues with his Grom one time when he over-filled the engine oil, and after draining some oil the dragging went away (must have been spilling over the top of the separation plate?)
These are my theories… I will put a TB Parts 5-disk clutch in along with a Monkey right case and hopefully that will fix the clutch dragging.
Tools & Materials
”*” denotes items that are not strictly necessary or have some other special consideration.
• * ‘14-20 Grom 125A Service Manual from Helminc.com
• * ‘21 CT125A Service Manual from Helminc.com
• ‘13-20 Grom flywheel/stator puller tool (I used 150620/MP8 from Hard Racing)
• ‘13-20 Grom crankshaft assembly tool (I used Kitaco 674-1432700 from Hard Racing)
• ‘13-20 Grom clutch/oil spinner socket (I used a Chinese Special from eBay but if buying again would either try the one Drow sells or get the real Honda tool 07716-0020100)
• Tusk Crankcase Splitter 17-8668
• Clutch/flywheel holder tool (I bought PP2332 from Hard Racing but just use my hand and a small impact gun instead)
• * Small impact gun (I have a Makita XPH11ZB)
• A Penny (or Honda 2.5mm gear holder tool 07724-001A100)
• Dremel or file to notch out right side plastics to allow clearance for the clutch cable receiver, and to remove metal from the back of one of the right-side plastics mounts if using a Hymec (see below).
• A tube of Hondabond
• Blue threadlocker
• * Assembly lube
• A complete, or semi-complete gasket set including new exhaust doughnut (+ extras for oil changes -- see below) & Grom oil spinner gasket 15439-K26-901
• Honda Matte Crypton Silver Metallic (NH-A40M) paint. I had a bad experience with automotivetouchup.com, and used scratcheshappen.com paint (https://scratcheshappen.com/shop/touch-up-paint/honda-matte-crypton-silver-nh-a40m/) to paint the Monkey “right protector” – see “My Story” above. For the right case cover, inside the circular center portion of the protector, I used “Flat Black” High-Heat Rust-Oleum 248903.
Parts I'm Currently Using
• Stock top-end
• Stock 14/39 sprockets
• * CT left & right cases (see below)
• Grom crankshaft 13000-K26-B00
• Crankshaft bearing 91001-KWS-901
• Grom crankshaft drive hardware: 94303-03050, 15341-KPH-900, 23125-KPG-T00, 90741-KGH-900, primary drive gear “B” if using a new Monkey right case 23122-K26-900 (see below)
• Grom neutral switch 35759-K26-C01
• Grom clutch receiver & linkage parts: 22821-K26-900, 22810-K26-C00, 22815-166-000, 91305-K26-900, 22847-K26-900
• Grom oil spinner & hardware: 15431-K26-900 (I used a lightened spinner from Steady Garage), 90432-KPT-A00, 90231-087-010, (spinner gasket, mentioned above), 15441-K26-900, 3x bolts 95701-06014-00.
• CT gear shift spindle (I used the return spring from the Grom, which although looks beefier, actually had less tension than the one on the CT: 24651-K26-900)
• ‘19-21 Monkey right case cover, protector & hardware: 11330-K0F-T00, 11370-K0F-T00, 3x 19639-GBC-000, 3x 33715-GB0-900
• * Yuminashi 5-speed transmission for Grom/Monkey (see notes below about popping out of gear)
• * SMR 6-disk Grom clutch (see notes below about plate separation and clutch dragging)
• * +60% stiffer clutch springs (or whatever you want, my new TB Parts clutch came with its own springs)
• Hard Racing ‘13-22 Grom billet clutch lifter plate HR-BSP
• * Magura Hymec hydraulic clutch lever for Grom 2100004-20 (can use OEM Grom parts or an aftermarket cable clutch)
• * Male-side kickstand Sumitomo connector kit MTW-3 from Corsa-Technic (or you could ghetto-rig something for free)
• * Yuminashi oil pump (good time to upgrade)
• * Takegawa CT125 “crankshaft support adapter” 01-10-0145 + WickedGrom’s left crankcase cover mod
Parts I am going to try/would recommend starting with
• ‘19-21 Monkey right case 11010-K0F-T00 (has perches for oil separator plate, unlike the CT right case)• Grom/Monkey Oil Separator Plate 15661-K26-900 and 2x bolts 95701-06016-00
• OEM disks/plates (or TB Parts -- what I am trying next)
• * Hard Racing Shift Shaft Support Bracket (for the CT since you’re using the CT gearshift spindle). Some say these help with finding neutral, some say they do nothing.
• Takegawa or Kitaco 5-speed transmission (see notes about finding neutral and popping out of gear below)
• * KOSO Cam Chain Tensioner for ‘14-20 Grom (if you plan to do any power mods, this is a convenient time to replace the tensioner)
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