86/87 200X CAMSHAFT VS TR200 FATCAT TRX200SX difference??

[Dirtcrasher]

Anyone know why the camshaft has a different part number on the 200X versus the Fatcat and quad??

I believe those have a manual decompression but that normally holds a valve open and isn't on the cam, later Honda models have a mechanism on the cam itself.

I always thought the top ends were identical aside from that decompression lever. I never though the cam had a different profile...

[Shep1970]

Damn steve your right! Profile is slightly different.... Holding them in my hand they look identical, i always assumed they were the same. Dont tell my son he has the trx200sx in his or he'll have me swapping it out
Now who has the Fatcat or trx200d quad book? The trx200d has the same looking cam.


shep

[11GalleryATV]

The cam heights are slightly different ...

86-87 200x IN = 34.683 mm | EX = 34.557 mm
86-88 200sx IN = 34.371 mm | EX = 34.242 mm

The rocker arms, valves, valve springs, and valve seats are the exact same in both. The only top end difference seems to be the camshaft.

[jasong_10]

I'll try to remember to ask my father-in-law if he has the book for his Fatcat, pretty sure it's going to be the next resto project anyways.

[11GalleryATV]

The FatCat camshaft is the same as the TRX200SX and so is the complete top end ...

FatCat Service Manual:
IN = 34.371 mm | EX = 34.242 mm

[jasong_10]

The FatCat camshaft is the same as the TRX200SX and so is the complete top end ...

FatCat Service Manual:
IN = 34.371 mm | EX = 34.242 mm

Cool, thanks for the info.

[11GalleryATV]

No problem ... here are the respective pages from each of the service manuals ...

[jasong_10]

Been a while since I've played around with cam numbers, am I right to assume the 200x cam is more aggressive?

[11GalleryATV]

Yessir! The FatCat and TRX200SX are basically just the detuned (by cam lobe height) 200x top end ... I have no idea why Honda would do this as it seems pretty expensive to make something have slightly less power ... maybe to increase gas mileage?

[Dirtcrasher]

Good stuff guys, thanks for sharing!!

I recently found a Fat Cat connecting rod, but I have a feeling it is slightly different than the 86/87 200X crankshaft rod.

Crazy how Honda played with stuff with such tiny differences in order to achieve perfection!!

[11GalleryATV]

Yes, the 200x and FatCat connecting rod are different and are NOT interchangeable. I spent many hours researching this when building my 200x motor (I really wanted electric start). I came to the conclusion that the only connecting rod that fits the 1986-1987 Honda ATC 200x is the 1986-1987 HONDA ATC 200X and that's it!

I do believe the 1986-1987 Honda FatCat and the 1986-1988 TRX200SX motors are completely identical ... top and bottom.

Here is the 1986 200x connecting rod from Partzilla: https://www.partzilla.com/product/honda/13201-HB5-300
Here is the 1986 FatCat connecting rod from Partzilla: https://www.partzilla.com/product/honda/13201-HB3-300

You can see in the fitment sections the compatible machines with each of these parts ...

It fits both the FatCat and the TRX200SX

200x OEM Parts: https://www.partzilla.com/catalog/ho...1986/atc200x-a
FatCat OEM Parts: https://www.partzilla.com/catalog/ho...tr200-a-fatcat
TRX200SX OEM Parts: https://www.partzilla.com/catalog/ho...fourtrax-200sx

[dirtwheels]

I found a lot of this out when building my e-start 86 200x a few years ago. Ended up having a custom crank done up.

More info in this thread on what parts I used in case anyone is interested:

http://www.3wheelerworld.com/showthr...w-with-e-start