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Discussion Starter #1 (Edited)
A couple months ago I was polling on which 4V for Honda engine mount pattern. As a result I found out that Takegawa has discontinued the DOHC. They may be working on a new DOHC or just going to the SOHC 4v. I do not know what their plan is.

The end result was another enthusiast and myself ordering the last Takegawa DOHC kits they had in stock at Takegawa. There may be some NOS sitting somewhere but all other sources we saw were about 2x cost.

I was about to build a Anima but this came up and it was time sensitive to buy the DOHC kit so here I am.

For the bottom end I have been looking at options and right now its TRX90 93-05.
I chose the TRX90 for a few reasons
+It is available in the US
+Has an OEM primary mounted clutch
+Has similarity to GB4 regarding the crank fitment(does require conversion kit to fit a CRF50 crank into TRX90 clutch)

Best of the best would be to get Honda Nice 110 bottom end and build off of that. High cost and parts are harder to source but, it may never break down.

I have also been collecting parts to better understand what I can swap and can't from other OEM Honda engines.

-TRX90 engine 2002
-CRF50 engine ? has high spline count countershaft
-ATC70 engine 1984 For transmission
-Looking for CT70H 4speed transmission
-Takegawa DOHC+D 106cc SCUT kit
-54mmx63mm Cylinder Procross Billet
-54mm Takegawa piston kit for DOHC
-15/15D cams
-30/30D cams
-Yoshimura YD-MJN 28mm downdraft carb
-HD stud kit for 69mm tall cylinder
-TRX90 kickstarter conversion kit
-TRX90 conversion kit to use CRF50 type crank

The TRX90 has the open of leaving it auto or converting to semi-auto/manual. Southeast Asia has kits for this with clutch covers, also hydraulic options.
I will be adding the kickstarter kit from DRATV TRX90 TRICK_ADD/ON KICK_STARTER ASSY_(263A/8DC)
Decide on 63mm tall cylinder(CRF50) or 69mm tall cylinder(TRX90) and matching crank. https://www.mototrade.gr/el/ / AASA has cranks that would work with TRX90 auto/semi auto and 69mm tall cylinder or short crank for 69mm cylinder
Convert to CRF50 crank for 63mm cylinder
Seeing what transmission ratio options I have for the TRX90.

The most likely short term build to get the kit together while I piece together a bottom end build is to throw the DOHC on CRF50/GB4 bottom end at 95CC with a billet crank mount clutch.

Will have to see where the TRX90 cases can go after that.

Also have 2nd GB4 cases to see what I can do with those in case I end up going that route in the end. I bought the ATC70 for the 4speed transmission and looking for the CT70H trans for 1st and 2nd gears to put together as close ratio with the ATC70 3rd and 4th. Get a 56-58x69mm cylinder and 56mm stroke from https://www.mototrade.gr/el/ / AASA. Other cylinder option TRP 56-58x69mm cylinder. TRP has 58mm pistons for 4 valve heads as well. 138-148CC all built up.
 

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You can convert the trx90 stock setup to full manual with some light machining/welding and a different clutch cover. Pretty simply operation. Cut down and lathe the one-way clutch mechanism and weld it solid to act like a oil spinner. Put chinese clutch cover on it and add kickstarter. I used a honda Nice clutch cover on mine but did have to do a little machining on the inside. Worked perfect.
 

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Discussion Starter #3
You can convert the trx90 stock setup to full manual with some light machining/welding and a different clutch cover. Pretty simply operation. Cut down and lathe the one-way clutch mechanism and weld it solid to act like a oil spinner. Put chinese clutch cover on it and add kickstarter. I used a honda Nice clutch cover on mine but did have to do a little machining on the inside. Worked perfect.
I have seen the pictures of your build with the cut and welded setup. I saw that CHP has/had the conversion primary drive gear for sale Ebay to use CRF50 type cranks so I bought a few in case I do that. https://www.ebay.com/itm/Primary-Drive-Gear-TRX-90-for-124SE-with-stock-TRX-90-Clutch-basket-/253235933294 . Requires additional oil tube to run stock type cover.

I'll going to see if with a CRF50 type crank I can fit a clutch cover with oil filter on it, china/Daytona/Takegawa

I may pick up a manual conversion kit while I'm in Philippines in August for ~$30.
 

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Discussion Starter #4
nice110cases.png
https://bikerzbits.co.th

I keep thinking about the NICE110 cases or some copies(thanks fatcaaat). I'll be in the Philippines in a couple months so I could buy real Honda cases and have my family there receive them.

I also found that in Malaysia there are several knockoffs/aftermarket versions of NICE110 cases usually labelled EX5 Class 1. These Class 1 cases convert normal EX5 to NICE110 cases as far as I can tell and have some really cheap options.

One middle of the road version are the Furious Once brand
Class 1 Crankcase Cover (RH) ? FuriousOnce Races Sdn Bhd
Class 1 Crankcase Cover (LH) ? FuriousOnce Races Sdn Bhd

fatcaaat has been working on convincing me to buy NICE110 parts OEM Honda.

This doesn't often get mentioned about the NICE cases. You hear about the oil pump, clutch, transmission, upto 66mm crank, being the same stud pattern cylinders as Z/crf50. I guess its given being capable of 66mm stroke but the cases accept a larger diameter crank. The diameter of a CRF50 crank is 87mm OD with 41.4mm stroke, TRX90 is 90mm OD with 49.5mm stroke. My CRF50/TRX90 case ID measure at 97mm give or take. There is some space left but not near what is available in the NICE cases. Even the NICE cases are clearanced to fit the 66mm stroke. I do not know what the OD of a 66mm stroke TRP crank is but I do see SE Asia cranks list as 102mm OD. With a 66 stroke and 102 OD and assuming 25mm pin. That is 66+25=91, 102-91=11, 11/2=5.5mm of wall thickness radial from the rod pin to the OD of the crank.

For an example of something I have to measure that is bigger stroke YX160(klxtopend) has a crank 97mm OD and a stroke of 57mm. The crankcase ID is 101.5-102mm. Note that 57mm stroke has been fit into CRF50 cases
 

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Nice cases stock will clear a 62mm crank but the internal webbing needs to be machined out a bit to accept 66mm. at 68mm stroke, the bottom of the connecting rod actually will skim against the transmission. Then you also need to consider your cylinder heights and connect rod lengths. 66mm stroke can be had with a 78.6mm cylinder height. But you can pull off a 56mm stroke with the 69mm height. Also, you need to consider your stroke and bore combo's. My understanding is that the geometry on these bikes means that you need to get a bore of at least 58mm for the 66 stroke to work else you are going to clip the bottom of the cylinder with the connecting rod. As an example, I have a 54mm bore on top of a 62mm stroke and it does clear but there's not a lot of clearance.

If your goal is to use the revs from that DOHC setup, then you probably want to do an oversquare setup with a large bore and a reasonable stroke to make power north of 10k. To do that, you probably shouldn't go any larger than a 54mm crank, and probably even better around 52mm and try to get that 58mm bore in there.
 

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Discussion Starter #6
What is the stock cylinder height of a NICE? 69 or 78.2mm? I have a look on TRP again I didn't notice different cylinders Cor 62vs66 stroke.
 

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Discussion Starter #8 (Edited)
Initial build
Trx90 cases/trans/clutch with CRF50 41.4mm crank and 57x63mm scut dohc kit. Manual conversion cover still needed. 106cc.

Upgrade to TRX
C90 Aasa 56mm crank, Aasa 58x69mm cylinder, piston??? Maybe trp 58mm for 4v if Piston pin height is right or Aasa maybe can supply. 148cc

NICE110 option
Get NICE cases trans and clutch. Stick to the 55.5-56mm stroke but perhaps lightweight with short clutch side crank for filter type clutch covers👌. 58mm Trp 4v piston or other. 78.6mm tall cylinder. 147cc
 

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Discussion Starter #9
Did some parts test fitting for the initial build.

The dratv trx90 Kickstarter kit barely engages the gear. I'd say wrong size gear on the Kickstarter shaft.

The special clutch drive gear from chp engages have the width of the clutch gear at best.

I played with how I can made custom spacers and get the crank gear and clutch basket aligned. So that can be overcome. The Kickstarter on the other hand, just looks like wrong size gear. Not much I can do about that except find one that fits right.
 

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Did you swap out gears on the trx90 trans, or are they the stock gears. I have the dratv kick shaft in a engine and it's working fine. But it's seen very little use. In my ignorance, when I installed it, I never even looked to see how well the gears meshed.
 

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Discussion Starter #11
Did you swap out gears on the trx90 trans, or are they the stock gears. I have the dratv kick shaft in a engine and it's working fine. But it's seen very little use. In my ignorance, when I installed it, I never even looked to see how well the gears meshed.
Stock TRX90 transmission at the moment.

I'm going to take it back apart and count teeth and ask dratv if it is as they intend it to be.
 

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I've purchased more than one of these kickstarters from DRATV as I've done at least 3 conversions...everyone of them was a perfect match to the stock trx90 transmisssion. Never an issue including on the 150cc Poor Man's Nice engine. That said, my gears meshed perfectly, these do not.
 

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The last ks I got from the doc has a 21tooth pinion on it...it's supposed to be 22 according to the website. 21t looks like yours.
IMG_20190603_190844796.jpg IMG_20190603_190801363.jpg

I have a different KS, that has a 23t pinion. Don't know what motor it originally came from tho. It meshes perfectly.
IMG_20190603_191015675.jpg IMG_20190603_191041464.jpg

34t on the countershaft 1st gear.
 

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Discussion Starter #15
Thanks kirrby. I bet mine has 21T on it. I worked chassis last night but I'll pull mine down tonight so I can talk to DRATV. Seems they have done the bait and switch
 

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Discussion Starter #16 (Edited)
EDIT: DRATV corrected the issue

Confirmed 21t on the part I received. The ratchet is coarse compared to 3speed models. I looked on my gear ratio chart collection and CT70HK models had 35T first gear and XL/SL70 had 34T first gear.

Gotta love the bait and switch, hope its honest mistake but is sounds like they have been doing this a while since kirrbby got a 21t as well.

Best I can tell the Honda NICE110,Wave100,etc pinion gear is what would fit this shaft assembly and work with the coarse ratchet
28211178000: Pinion,kick Start Honda - buy the 28211-178-000 at CMSNL
 

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actually what you got there is non-compatible with honda cases. you need to drill into the case and tap to use that setup even if it were the right gear size. You should get something that looks like what Kirby shows in his pic above...that's what all mine looked like and I think it was even a Honda part but he does a good job protecting what part number. Don't think it is a Nice direct compatible although a nice gear looks exactly the same as what Kirby has shown.

I have a complete Nice engine sitting here that's broken down in pieces. I could take some pictures perhaps over the weekend when i can get back in the garage.
 

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The 2 shafts that I pictured...the pinion gears appear to be the same, EXCEPT for the number of teeth. I'd bet a dollar that they're interchangeable. And, I'll bet that cmsnl NICE pinion gear will work with the DRATV shaft parts.

But...the NICE pinion says 22teeth. DrATV says 22 teeth. I'd hit DrATV up and say, "I need the correct pinion for this part." It could have been...two...honest mistakes. I believe the 21tooth pinion that we have is their "heavy duty 3speed kickshaft". The doc has told me before that they have to assemble the trx shaft before they ship them. Could be that the help has been doing them wrong. Give them a chance to make it right.
 

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Discussion Starter #19 (Edited)
Fatcaaat I think you have some of kirrbbys pics and mine confused. He showed one that has the steel plate that mounts inside the case mine doesn't have that.

I contacted dratv and they are shipping me a new pinion gear and a new flat washer that pairs with it. So in a couple days I'll swap it out and have it resolved I hope.
 

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Discussion Starter #20 (Edited)

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