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Thanks Goober, so far all of our TRX350/350D CDIs have been labeled Shindengen, so maybe they were the only supplier?

I keep forgetting that you are short on OEM carbs and are stashing away as many rearends as ya can... I'm over-optimistic I guess. I think its pretty cool what you are doing for the kid and his family though.
 

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Continuing mechanically... correct me if you find any mistakes here and I'll update this...

Most of the major parts will interchange with all years/models. All motors, front ends, rearends, swingarms, transfer cases, driveshafts, axles, etc., are interchangeable.

When swapping complete motors from bike to bike, you need only match the proper stator & flywheel, crankcase breather (Fourtrax models have a breather box while Foremans do not) type and starter motor type (86 starters and reduction gearsets were one of a kind, 87 Fourtrax & Foreman were one of a kinds, 88 & up the same) that was OE.

Topend motor parts (heads, rocker boxes, jugs, pistons, carbs, exhaust, cams, chains, guides, tensioner etc.) all interchange (same as ATC350X), with the only difference between years/models being a revised camshaft part number (87 & up cams are ground on a smaller base circle) and the compression release type. You can swap the 86-87 cable operated compression release into the 88 & up rocker boxes, and vice versa.

Front brake systems will interchange among all years/models as long as you transfer everything together from bike to bike... backer plates, drums and hubs etc.

Racks and bumpers are interchangeable among all years/models as long as you keep all Fourtrax rear rack/bumper pairs together and all Foreman rear racks/bumper offerings together. The Foreman rear bumpers are all longer (extend out the back further, adding overall length to the bike) than the Fourtrax bumpers.

Fuel tanks are identical among all models, but the Foremans include a sending unit for an LED fuel gauge.

Seats are interchangeable, only the covers and toolkit compartments differed. Most small plastic panels interchange as well, but there are some minor year to year differences between fenders used on the Fourtrax & Foreman models. Fender flares for the Fourtrax models were narrower than all Foremans and the later Foreman flares are styled a bit differently than the early Foreman flares. Front grills differ from model to model, not all are interchangeable.

Standard lighting systems differ between the Fourtrax and Foreman models.
 

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Don’t know if this makes a difference:
Early 86 Fourtrax had a round-edge elliptical starter gear cover; later models had a more sharply ovoid cover. Does this mean the side cases are also different?

Front bumpers are also interchangeable so long as the Fourtrax and Foreman racks/ bumpers are paired. Foreman front bumpers and racks bolt together where Fourtrax do not.

The 86 Fourtrax came standard with no front or rear carriers.

86-87 Fourtrax came standard with a bull bar bumper.

The 87 Foreman had a one year only shield-type bumper that bolted to the carrier.

The 88 and later Foreman had an oval hoop bumper that bolted to the carrier.
 

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Discussion Starter · #25 ·
Continuing mechanically... correct me if you find any mistakes here and I'll update this...

Most of the major parts will interchange with all years/models. All motors, front ends, rearends, swingarms, transfer cases, driveshafts, axles, etc., are interchangeable.

When swapping complete motors from bike to bike, you need only match the proper stator & flywheel, crankcase breather (Fourtrax models have a breather box while Foremans do not) type and starter motor type (86 starters and reduction gearsets were one of a kind, 87 Fourtrax & Foreman were one of a kinds, 88 & up the same) that was OE.

Topend motor parts (heads, rocker boxes, jugs, pistons, carbs, exhaust, cams, chains, guides, tensioner etc.) all interchange (same as ATC350X), with the only difference between years/models being a revised camshaft part number (87 & up cams are ground on a smaller base circle) and the compression release type. You can swap the 86-87 cable operated compression release into the 88 & up rocker boxes, and vice versa.

Front brake systems will interchange among all years/models as long as you transfer everything together from bike to bike... backer plates, drums and hubs etc.

Racks and bumpers are interchangeable among all years/models as long as you keep all Fourtrax rear rack/bumper pairs together and all Foreman rear racks/bumper offerings together. The Foreman rear bumpers are all longer (extend out the back further, adding overall length to the bike) than the Fourtrax bumpers.

Fuel tanks are identical among all models, but the Foremans include a sending unit for an LED fuel gauge.

Seats are interchangeable, only the covers and toolkit compartments differed. Most small plastic panels interchange as well, but there are some minor year to year differences between fenders used on the Fourtrax & Foreman models. Fender flares for the Fourtrax models were narrower than all Foremans and the later Foreman flares are styled a bit differently than the early Foreman flares. Front grills differ from model to model, not all are interchangeable.

Standard lighting systems differ between the Fourtrax and Foreman models.
I was looking at the 86 that "almost runs" (kinda like being almost pregnant, right?)

It will pop a bit when I turned it over with a little starter fluid, but didn't really act like it wanted to fire. It had a cheap china carb on it that I'm pretty sure is a 300 carb. I figured I'd rebuild an OEM carb, put a new spark plug in it, and see if it does any better.

That said, the rest of the 86, after looking it over, is rougher than the 87 that the kid brought me. One of the rear shock nuts twisted off, lot of stuff like the voltage regulator is hanging loose, so I'm wondering if it wouldn't be easier just to swap the 86 motor into the 87 Fourtrax.

Am I correct that this will be a direct swap? If I need to swap starters I need to swap starter and the starter gears under the cover, and then the 87 starter will work on the 86 motor?

Hoping I can get one running without opening up a motor just yet.
 

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Don’t know if this makes a difference:
Early 86 Fourtrax had a round-edge elliptical starter gear cover; later models had a more sharply ovoid cover. Does this mean the side cases are also different?
Yes, the 86 left side cover is one of a kind as well, because of the unique starter, unique reduction gears set, and rounded oval shaped reduction gear cover. The 87 & up starter and reduction gears (extended armature shaft in the starter motor with a support bearing in the cover) set use the same style left side cover and reduction gears cover.

All 86 & 87 bikes used an automatic cable operated compression release with a lever coming out of the right side cover next to the kickstarter, so the right side cover and kickstarter assemblies under that cover differ from early to late as well. All parts will swap between the early & late models on the right side, as long as you carry along all of the affected parts along.

88 & up bikes also have a single-wire oil temp sensor on the right side, while the 86 & 87 have a two-wire oil temp sensor. Those are interchangeable to match your harness.

Thanks for adding so much to this conversation!
 

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I was looking at the 86 that "almost runs" (kinda like being almost pregnant, right?)

It will pop a bit when I turned it over with a little starter fluid, but didn't really act like it wanted to fire. It had a cheap china carb on it that I'm pretty sure is a 300 carb. I figured I'd rebuild an OEM carb, put a new spark plug in it, and see if it does any better.

That said, the rest of the 86, after looking it over, is rougher than the 87 that the kid brought me. One of the rear shock nuts twisted off, lot of stuff like the voltage regulator is hanging loose, so I'm wondering if it wouldn't be easier just to swap the 86 motor into the 87 Fourtrax.

Am I correct that this will be a direct swap? If I need to swap starters I need to swap starter and the starter gears under the cover, and then the 87 starter will work on the 86 motor?

Hoping I can get one running without opening up a motor just yet.
Yeah, you can bring the entire motor along, but you must include the starter motor from the 86 Fourtrax motor... and vice versa. 86 have a short armature shaft while 87 & up have an extended armature. Other than that starter issue, those two Fourtrax motors are identical. No other parts need to be brought over...

EDIT:
I didn't answer your question did I... LOL
Anytime you swap starters between an 86 and a later motor you must bring along the left side cover and reduction gears set and cover & starter motor... to match.
 

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Discussion Starter · #28 ·
The 86 seemed to have a starter than worked sometimes, and didn't work others. I'm thinking it's the one way, but it could be gears. I guess the simple solution is to pull the starter gear cover and inspect them.

I've noticed on this pile of 350's that almost every motor the starter gear cover is off, with starter gears missing on some of them. Guess that's a common problem in the 350's?
 

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Yeah, starter reduction gears seem to fail more often in the 86 Fourtrax than later models. In 87 they added a support bearing that might have helped... Those covers generally have to come off each time a starter motor is removed, so sometimes they don't get put back on.
 

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Good info here! I'm trying to decide what to keep from my '88 Foreman, to store as backup parts for my '86.

I was hoping to keep a lot of the electronic bits, but I guess they won't work? Mainly I was going to keep the fuel cutoff sensor thing (in the right rear fender) and some of the relays (?) That are mounted under the plastic above the front axle.
 

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The fuel cutoff relay, the fuel pump, the fan control unit, the ignition coil, the pulse generator, the spark plug, solenoid and the battery will all interchange between your 88 & 86. Nothing else electrical will, not even the stator or regulator/rectifier or any of the switches. The primary wiring harness and fuse box is a no-go too.

EDIT:
As you know the fenders don't interchange either... not without some drilling.
 

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Another difference I noticed, on the 86 models, the air box drain tube (see pic) was an actual long tube whereas on the 87 and up models it was just a little black valve. Any idea why?


Sent from my SM-G550T1 using Tapatalk
 
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Another difference I noticed, on the 86 models, the air box drain tube (see pic) was an actual long tube whereas on the 87 and up models it was just a little black valve. Any idea why?


Sent from my SM-G550T1 using Tapatalk
Cuz the long drain tube melted when it hit the exhaust header? That’s what mine did. LOL
 

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Haha that very well could have been the case. I'm not sure why it was so long, on every other ATV I've had it's always been a short drain valve.

Sent from my SM-G550T1 using Tapatalk
 

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I picked up an 88 the other day just to part out. I wanted to assess the motor but the CDI is bad. Went ahead and tried an '87 CDI that I repaired recently. They're both DC ignition but I noticed the 88 model adds a "revolution research line". It's an additional wire coming from the 88 stator that isn't present on the 87. Anyhow, it's obviously not doing anything with an 87 CDI hooked up but it runs fine. I had to use my spare 87 model ignition switch too. I don't know what the long term consequence to the CDI might be to continue running it like this but I was able to get the answer I wanted on the motors condition. I would bet that an 88 CDI wouldn't work with 87 stator, but the opposite seems to be working just fine. Just thought I'd share.
 

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Thanks for that detailed explanation Retro. That will help a lot in my parts search. I don't like the fact that I can only use ignition system parts off another 87 if I can't find new. At least I'm less likely to get the wrong part like I almost did on some NOS I found on ebay where the seller claimed his brand new ignition switch worked on all models from 86-89.
do you have a pin out of cdi plugs for the 1986 trx 350?
 

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These questions come up from time to time and its hard to remember everything, but electrically (wiring harnesses, switches, ignition components) it goes like this:

86-89 (thru 93 in Canada) all years and models can use the same spark plug, Ign coil, pulse generator and battery. But thats it.

86 & 87 TRX350 Fourtrax models have an AC-CDI ignition (a battery is not required for spark) so all ignition & electrical parts are interchangeable between those two years and thats it, with the exception of the spark plug, Ign coil, pulse generator and battery as mentioned above.

87 TRX350D Fourtrax Foreman is one of a kind. It has a unique DC-CDI ignition and all switches, wiring harness, fuse box, stator and other ignition components fit that year and model only, with the exception of the spark plug, Ign coil, pulse generator and battery as mentioned above.

88-89 (thru 93 in Canada) TRX350D Fourtrax Foreman have a revised DC-CDI ignition (added a "Revolution Research Line" circuit in the CDI) and all ignition components, switches, harness, fuse box, stator & other electrical components can be interchanged among those years only, with the exception of the spark plug, Ign coil, pulse generator and battery as mentioned above.

There were many mechanical differences and changes made among those models and years too. Anyone interested in more confusion...? :)
Is this discussion still alive I have some of the same questions and looking for parts as well as having parts
 
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