86/87 honda 200x project (again)

[Shep1970]

I've been searching/reading and only found 3 or 4 posts about trying this and have come across no
Final word if it'll work or not. I needed a cheaper project this time around so here goes.

86/87 honda 200x bottom end (actually the whole motor except left case cover)
The 86-88 trx200sx left case flywheel cover(pullstart is bolted to it)
I'm not looking for a pullstart motor so a plate will/can be made easily enough.
The 200x motor has the shaft/bung hole for the starter idle shaft (pic)
The gear select shaft is shorter for the 200x. The trx200sx shaft will be used w/litte mod (it doesn't need reverse lever/arm that extends past (pic)
The trx200sx flywheel cover case(pic) fits almost perfectly on the 200x motor.
The 200x gasket needs to be used. One 3/8" (small) gasket surface i'd have to address

Ok, so what i need to find out which would stop this project is..
The crank pin is it the same size for the trx200sx/ honda 200x? Length woudn't matter so much as diameter. Different part #'s but???

The crank would need to be split, i need shaft area for the starting gear and oneway bearing (pic)
I would need to swap crank halves. The outer crank bearing is the same on both.
(Six month project no rush). And yup thats a big chain hole(not by me)pic
Thanks for any help!
My outcome would be clutched 6-speed,kick start,elec start

Shep
or maybe i should just get out and ride more...

[yaegerb]

maybe I missed it, but what are you trying to do? What's the goal here?

[Shep1970]

Really just to have electric start on a 86/87 200x but keep manual tranny. Also i like tinkering/working on these as much as riding them.

Shep

[dirtwheels]

I'm working on a similar project right now. Have all the parts to do it but the issue lies with the crankshaft. The bearings and thrust washers are a different diameter. The 86 200x thrust washer is 2mm larger in diameter. Not sure about the exact size of the bearings or the pin diameter difference yet. Working on that. It appears though that the 200x may have bearings that are a bit larger/stronger than the trx200sx.

This is a side project right now so I work on it when I have time. PM me if you want to talk about it more.

[Shep1970]

I'm working on a similar project right now. Have all the parts to do it but the issue lies with the crankshaft. The bearings and thrust washers are a different diameter. The 86 200x thrust washer is 2mm larger in diameter. Not sure about the exact size of the bearings or the pin diameter difference yet. Working on that. It appears though that the 200x may have bearings that are a bit larger/stronger than the trx200sx.

This is a side project right now so I work on it when I have time. PM me if you want to talk about it more.

Yup, i've been trying to find the #'s. Been thinking and sometimes too much, but i wonder if its possible to get the crank pin
Turned down to size or vise-versa to fit crank half that i need? If its been done or doable. I've got a machinist neighbor with all the goodies but like u this is just a side project. I'll be sure to pm u if any progress is made.
Ps - its just a motor project, when i get old and cant kick anymore i can still ride my favorite bike.
Shep

[dirtwheels]

Measure a few things this evening on the TRX crank sitting in my garage as well as searched the internet for info on the 200x crank. Here is what I found....

The 86-86 200x connecting rod pin has a 31mm outside diameter and the big end of the connecting rod has a 39mm inside diameter.
The TRX200sx connecting rod pin has a 30mm outside diameter and the big end of the connecting rod has a 38mm inside diameter.

So thats why the part numbers for the connecting rods, rod cage bearings, and thrust washers are different. Assuming, the TRX200sx side of the crank could be bored out 1mm to accept the larger pin, you would still need to weld on (add some weight) to that side of the crank since the shoulder on the 200x side will be of slightly larger diameter, or the 200x side would need to be turned down or drilled out to make it even.

Thats it for now. Once. I get the crankshaft out of the 200x bottom end, I'm going to take both over to a shop near me that does this kind of work and get their opinion on possible options. If it is possible, I'm guessing it is not going to be cheap.

[YTZ drew]

Harry's Machined Parts in Northborough does good work, I have used them and they're close to you. My go to for the past few years has been Ken O'Connor Racing in Brooklyn CT, he is great and knows his stuff. You can't go wrong with either one. Cool project! I love building frankenHonda engines. My next will be a first gen 200x bottom end, manual clutch with a 200 auto left crank half for a pull start setup. No more finicky kicker gears for me.

[Shep1970]

Harry's Machined Parts in Northborough does good work, I have used them and they're close to you. My go to for the past few years has been Ken O'Connor Racing in Brooklyn CT, he is great and knows his stuff. You can't go wrong with either one. Cool project! I love building frankenHonda engines. My next will be a first gen 200x bottom end, manual clutch with a 200 auto left crank half for a pull start setup. No more finicky kicker gears for me.

Your right Harry's in northborough does good work, he does my cylinder work. Funny thing, in the 80's there was a suzuki dealer in front of him on rt.9 got my first bike there. Now its a adult toys/smoke shop.
I still can picture the row of bikes along the road. Ended up w/alt 185 the salesman talked my dad into it. Of course two years later i was at honda buying something better!!!!

Edit-- i've got a few parts i need on order so i'll see how it goes.
I have the trx shift shaft now, it will be an easy swap, chop/cut/weld but not yet.
trx crank coming today.
The flywheels are identical-timing marks, depth except of couse one-way bearing on trx.
Also the crank half shaft where the keyway is, its larger by 4mm on the 200x so the trx200sx flywheel wouldnt work anyway if the 200x shaft was long enough. So tomorrow i should have both cranks side by side.

Oh. And the starter idle shaft fits like it belongs in the 200x.
Holy crap i've already spent about 2-hours on this piston pin trying to remove it, i made jig/tool too. The wife was trying to sleep in the next room and i was making soooo much noise.
(Next day)
Two jaw puller had it apart in two mins this am. this piston is junk anyway.

[Shep1970]

Well a little progress i have both cranks ready- large end bearing (same), crank halves shape/design (same), webs measured across (same), diameter (same)
The pins-31mm (200x), 30mm(trx)
I went to use my bearing splitter for large bearings (gone) my brother borrows things, sometimes i get things back.......
Im pretty sure i have the 200x bearing and shims i just have to find them.
Talked to a machinist next door he said it was a no-brainer to lathe down the crank pin.(but to have harry's do it)
I think i have all the parts i need, im just not sure if they can reuse the crank pin or if i should get a new one?
All the bills are due so it'll be (hopefully) next wk when i can drop it off.


Shep

[Dirtcrasher]

You may be able to find a good pin.

Those pins are finish ground on a lathe for a certain spec for hardness that the needles can ride on.

So, they get an A1 or an O1 rod, harden it and finish grind to size.

Some shops do that as well....

IDK if you can trust a pin once it's removed. I always put a tack of weld on them anyow...

[Shep1970]

Steve, thanks yup i found a pin an hour ago and bought it. Its only the width of the left web about 3/4 of an inch that would be turned down off the 200x pin, so the 30mm trx half could be pressed on. Im just really curios if it'll work, the 200x crank is in real nice shape i almost hate to do it. I still have a couple good spares so i should be ok for a while though.
Cases are split patiently waiting.
Shep

Edit- i still havent had the shop look at cranks yet. Today i realized that i need to cut the fingers off the starter (prawl)?
Because the pullstart wont be used, but part of it is needed to fill the sealed hole in outer case shell.(pics)


Edited-added pics
Well i ended up using a bearing splitter that was a bit larger than needed but it worked great..so cranks are ready to make the trip. I also thought the oil/timing chain gear was the same in the past, but its different. Anyway here's pics-


Couple new pics- waiting for correct gasket though- im going in a different direction w/fatcat cover.

[dirtwheels]

Here is the 200x motor with the starter mocked up in the frame for fitment.
Everything fits pretty well. Had to make a spacer for the carb intake to clear the starter. The little triangle point at the bottom of the fatcat case cover clears the frame by about 1/8". Debating cutting it off.

[Shep1970]

Nice!!! Do you think the shift shaft is long enough? Outside frame, its hard to tell by the pic. Are your starter shafts inside/ installed? Did your length work ok? Just really curious between trx/fatcat length u know what i mean?
Thnx
I have extra motor mounts/bolts if/when u need em there yours.
Shep

Edit here's the difference between starter shafts, fatcat is shorter by 2mm
So the fatcat shaft is needed in there (thanks dirtwheels)

[dirtwheels]

The original 200x shifter shaft still works good without modification. The shifter arm is a little closer to the case cover than the 200x but still clears it.

Yes, the starter shafts from the fatcat are installed in there. Everything lined up real nice and spins good without any modifications.

Thanks for offering the bolts. I just temporarily stuck those in there to hold the motor. I have the correct bolts and mounts.

[dirtwheels]

Shep, how is your project coming?

Here is the latest on my project. Got the crankshaft back yesterday from CrankWorks. It was at the shop for the last couple of months. Rebuilt, fully balanced and ready to go. Here are a few pics. You can see where they drilled and welded to balance it. Looks like they did a nice job.