Honda ATV Forum banner

88 TRX350D Tank Rescue

5K views 52 replies 5 participants last post by  retro 
#1 ·
So a little backstory, the first fourwheeler I ever rode was a TRX350D. The mountain I worked at when I was a kid had a small fleet of Honda's and this was the oldest so it was the usual go to for cutting and marking mtn bike trails and race courses. The body was hammered but mechanically it was such a reliable machine it always seemed to survive another year. Keep in mind they were used just about every day year round in central NH.

A buddy found this thing on one of the local FB groups and knew I had been looking for a manual shift Honda 4x4. Outside of that, I didn't really care what year it was from. It was listed as needing a fuel pump and was picked up cheap. I couldn't pass up saving this thing.




I've already got it in the garage and began tearing it down today to assess some stuff and get it cleaned up. It needs a serious bath of Simple Green and a visit with the pressure washer when its not 30* outside. For now, the rear plastics and racks are off so I can access everything fairly easy and get it all cleaned up.

What is wrong:
1) No Spark
2) Dead Fuel Pump
3) Front Wheel Bearings are a little worn
4) Steering stem bushing is toast so the handlebars kind of rock around on the steering shaft
5) Rear Brake Pedal cable snapped
6) Rear Brake Handbrake cable seized

I already have a slew of parts on the way. (Pump, Ignition Coil, CDI, Stator, Pickup Coil, Fuel Pump Relay, Ignition Solenoid, Both rear brake cables, Acerbis Handguards, ODI Rogue Lock On Grips) I figure whatever doesn't fix it will be saved as a spare since parts are getting harder to find. Bringing my meter home tomorrow to start ohm'ing out various parts so I have a direction once the parts all get here.

Today I grabbed a new battery and put it on the tender so it would be fully charged. When the ignition is turned on the oil light and neutral light come on as expected. Push the start button and the solenoid and pump click lightly but nothing else. I can jump the poles on the solenoid and the starter spins freely and will turn the motor over. Pulled the plug to check for spark, jumped the poles on the solenoid and tried kicking it and have nothing there so it looks like a combination of issues.
 
See less See more
2
#2 ·
Looks like a great start to the project. You already have the "hard" part done, which is it looks good. More often that not these things look they have been through hell. Getting them running is the easy part.

Rob
 
  • Like
Reactions: retro
#3 ·
Thanks! The plastics definitely all in one piece but the shine from the rain has ya fooled :laugh: They are in pretty good shape with no real cracks. Just lots of spiderwebbing on the cockpit side of the fenders. Once its running I'm going to move on to the cosmetics.
 
#5 · (Edited)
NC shuts down whenever it snows so I got some extended garage time today.

Downloaded the Service Manual off here and went to town with the multimeter trying to diagnose this no spark thing.

1) Igniton Coil Primary coil resistance 0.3-0.4 where it calls for 0.1-0.2. Both Secondary checks were within spec. When checked from the CDI end of the harness, its .2-.4.
2) Pulse Generator - Ok
3) Alternator Exciter Coil - manual says there is a Bl/R wire (Black/Red Stripe) but there is not one in that bunch of connectors at the chassis end on my bike. I have Yellow, Blue/Yellow and Green/White which matches up with the 88+ Wiring diagram. Everything here seems to check out in spec.
4) RR Line - Ok
5) Charging Coil - Ok
6) Regulator - Ok
7) Ignition solenoid - Ok
8) Ignition switch throws 12v to everything it should once its pressed

Going to start with the Ignition coil and solenoid. Solenoid checks out on the meter, but I can get it to turn the starter when the poles are jumped, not when the button is pressed. Battery is fully charged and verified by both the tender and the meter when connected at various points of the harness. The Coil's primary resistance is at the limit or over depending on how its tested. Those two are easy to change.
 
#6 · (Edited)
I'd start with that solenoid too since you mentioned it weakly clicks when the starter button is pushed. Also check and clean the frame ground cable that comes out of the wiring harness under the seat, where it bolts to the top of the frame at the seat bracket.

3) Alternator Exciter Coil - manual says there is a Bl/R wire (Black/Red Stripe) but there is not one in that bunch of connectors at the chassis end on my bike. I have Yellow, Blue/Yellow and Green/White which matches up with the 88+ Wiring diagram. Everything here seems to check out in spec.
You might be looking at the wrong specs column in the manual? The Fourtrax & Foreman have differing systems:



Readings should be taken at the CDI harness plug after unplugging the CDI, so you'd notice if there are any faults... such that a wire is bad or plugs are corroded etc., between the CDI and other components undertest.

You mentioned that the fuel pump runs when the ignition switch is turned on correct?

Also the '88 and up models kill the ignition if the motor overheats... so check the fan control circuits and oil sensor as well.

Finally, if IGN & Kill switches are good, check the regulator/rectifier connections (between each yellow wire and yellow to ground) as the manual shows.

Sounds like you are getting close...!
 

Attachments

#7 ·
I'd start with that solenoid too since you mentioned it weakly clicks when the starter button is pushed. Also check and clean the frame ground cable that comes out of the wiring harness under the seat, where it bolts to the top of the frame at the seat bracket.

3) Alternator Exciter Coil - manual says there is a Bl/R wire (Black/Red Stripe) but there is not one in that bunch of connectors at the chassis end on my bike. I have Yellow, Blue/Yellow and Green/White which matches up with the 88+ Wiring diagram. Everything here seems to check out in spec.
You might be looking at the wrong specs column in the manual? The Fourtrax & Foreman have differing systems:

Readings should be taken at the CDI harness plug after unplugging the CDI, so you'd notice if there are any faults... such that a wire is bad or plugs are corroded etc., between the CDI and other components undertest.

You mentioned that the fuel pump runs when the ignition switch is turned on correct?

Also the '88 and up models kill the ignition if the motor overheats... so check the fan control circuits and oil sensor as well.

Finally, if IGN & Kill switches are good, check the regulator/rectifier connections (between each yellow wire and yellow to ground) as the manual shows.

Sounds like you are getting close...!
Thanks for the extra insight. All of those tests at the CDI plug were good. I will clean that ground though and see if that helps any. The quad was sold with a dead fuel pump being the culprit. However it clicks when the start button is pressed but I don't hear it run or hum like a normal pump. Just a dull click. I've bucket tested it and its dead.

Now here is the kicker, the fan is hard wired to a toggle switch on the handlebars. But, its been like that for a long time. The oil light flickers on when the key comes on then goes right back off. Although it doesn't do it every time I turn the key on and off.

Is there a way to test the fan control circuits and oil sensor? I haven't flipped through the manual to test those yet.
 
#8 ·
Yeah those tests are in the manual. Your fan control box sounds like it is functional at least though, since the temp light comes on normally for a few seconds then goes off, when you turn the ignition on. The oil temp sensor resistance from the center connector post to ground should measure just over 10k ohms at room temp if I remember right... The spec is in the manual.

You can test the fan control unit by turning the ignition switch on, then unplug the wire (green wire I think?) from the oil temp sensor (it is under the little cover on the extreme lower- right side of the motor, just forward of the foot peg) and ground that wire. The fan should run while that wire is grounded. If not, check whether the previous owner left the fan motor connected to the harness coming from the fan control module, when the fan manual over-ride switch was added on.

You can still buy those OEM fuel pumps. Check around... its been a while since I shopped for them. They are a bit pricey at $121 + shipping on Partzilla, but the cheaper china knockoffs will waste both your time and your money, so... good luck!
 
#9 · (Edited)
I like what ya sayin what ya sayin (ZZ Top).

Thermo sensor will cause light to come on steady when circuit closed (low resistance or lead grounded); too high resistance will leave circuit open.

There are things you can test in the fan control and those you can’t. You can run the fan (to make sure it works) and you can test the oil thermo unit BUT can you test the fan control overheat circuit without running it?

I found my blue wire disconnected after mine overheated on the trail and quit. Connected it and fan works good. I had to drive it in low gear for ten minutes before it got hot enough to verify that it works.
 
#12 · (Edited)
Alright. Got home from a work trip and got to work.

I have spark now. New coil fixed it. However it still won’t hit. Fuel pump and relay work as they should. New solenoid fixed the starter issue. But it still won’t hit even on starting fluid.

Tried a new cdi, fuel relay and regulator...same situation.

Starting to run out of ideas.

Do these things still generate spark if the Run/off switch is bad?
 
#13 ·
If you got good spark while cranking it should fire. It sounds like you got everything working now (new NGK spark plug too?) so the next thing to check is the compression. It should reach max between 178-206 PSI with the throttle held open while cranking it with the starter. Let us know how it goes...
 
#15 ·
Ok, next two things to check are the timing chain slack and the valves lash. Valve lash should be .003" on both intake and exhaust valves, COLD motor. Take your pick where to begin... but complete them both before checking compression again. Do you know how to do those or would you rather have some help..?
 
#18 ·
Watching 24hr of Daytona in the garage so I pulled the valve cover. Cam chain is tight. Can’t find my feeler gauges so I’ll grab some in the morning, reassemble and set the lash.

I did palm the valves to ensure the stem retainers didn’t fly across the garage and all the valves all move freely. So none are stuck.
 
#19 ·
Because pictures are cool. Valve cover and rocker assembly off, threw on the new ODI rogue lock on grips and some Acerbis handguards. Also touched up a lot of the metal in between diagnostic attempts today.
 

Attachments

#20 ·
Are the rocker heels (where they follow the cam lobes) in good condition? Is the cam timing correct too?

To verify, rotate the motor until both cam lobes are facing down and the "T" mark on the flywheel lines up with the mark in the left side cover. That is TDC on the compression stroke... The two marks on the cam sprocket should be a fairly close match (never perfect due to chain wear) to the top surface of the head. Photo attached... Have fun!
 

Attachments

#24 ·
Cam and rockers have signs of wear but nothing crazy. No grooves I can feel. Cam gear looks ok and is engaging the chain just fine and the chain is tight.

Long story with how this thing was supposed to come with a parts bike but the seller renigged in that deal, I’m beginning to think he knew this thing wasn’t running and had no clue how to fix it.

Guess I’ll reset the cam timing, set the valve lash and give it a whirl.
 
#26 ·
Ok. Found the T on the flywheel side. It was just above that second tick mark. That aligned the cam gear marks at the top of the head as they should be regardless of whether the gear is on backwards or not.

Here’s the kicker...

Cam lobes facing up at TDC? 180* out of time compared to the pic Retro posted last night saying they need to be installed facing down.
 

Attachments

#27 · (Edited)
Just turn the crank one full revolution and stop at the "T" mark again... and those cam lobes will be facing down. When lobes are facing up the motor is at TDC at the end of the exhaust stroke/beginning of the intake stroke... Crank makes two revolutions per each cam revolution on 4-stroke motors.

I can see where that cam sprocket was installed right at one time... the previous owner messed up... one thing to worry about here is whether the backwards sprocket install has damaged the chain or not.

The cam sprocket has an approximately .090" relief machined into the inboard side of it so that the upper sprocket centerline will be directly over the lower crank sprocket centerline when installed. Installing that upper sprocket backwards has caused the chain to be pulled sideways out toward the left, off center... follow me? The opposite side of the OEM cam sprocket has a .010" relief cut in it so while it was installed backwards the chain was deflected sideways approximately .080"... !!! That is enough deflection from center to ruin a new chain in just a few minutes... and no wonder the chain is tight. It is probably howling too.

You'll have to recheck the chain (yank the tensioner back out and note the plunger depth remaining) once you get it installed right and have turned the crank a few revolutions by hand.

Take your time here... double check everything after its together and after rotating the motor several times to allow the chain tensioner to self-adjust naturally. DO NOT EVER rotate the crankshaft backwards.
 
#32 · (Edited)
Aye... those cam journals and the exhaust rocker arm (can't see the intake rocker well enough) are junked!!! The cam journals in the head will look much worse than the cover does, so the head is bound to be junk too. Cam is shot too, judging by the condition of the rocker arm(s). That motor might need a complete rebuild top to bottom...

That one is junk for sure.
 
#34 ·
I can see the exhaust rocker heel is worn out (it wore a concave shape in the center of the heel where it wipes the cam lobe. Those heels should be convex shaped and smooth) from valve lash being run too loose... correct me if I'm not seeing what you see... and it was starved for oil.

The cam journals were starved for oil, I can see aluminum transfer rolled out into the journal oil wedge edges (see your photo attached below where I circled the oil wedges areas). When you take the camshaft out of the head you'll find the lower journals will look even worse. The camshaft is not supported properly anymore because of excessive journal clearances on both ends, it has been, and will flop around like a fish on the riverbank...

I see a lot of silicone RTV gasket sealer on that cover which means that the oil pump pickup screen is probably plugged up with silicone chunks... no oil pressure... Silicone RTV is a killer in these motors.

Unfortunately, there might be extensive wear & damage found throughout the motor. I'm sorry man... this sucks eggs.

I'd look around for a used motor at this point unless you are willing to split cases and replace the crank, oil pump, head & whatever else in the topend and bottom end is shot... likely extensive...
 

Attachments

#40 ·
Attached are pics showing what those journals & oil wedges should look like in the head and the cover. Note the shape of them... oil is fed from the top cover and the shape of those wedges trap oil that feeds the bottom half... anytime you see aluminum rolled up out of those journals on either the cover or the head, its junk and the cam is flopping around in the journals and it isn't oiling the bottom halves (in the head) anymore. Sorry man... I feel bad about it too...
Bookmarking this. Good info to have when I start pulling these motors apart on these parts bikes.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top