New Purchase: 1986 350x!

[wonderboy]

So a friend of a friend had this 1986 350x. My friend helped arrange the meeting, and he pretty much just said to make him an offer, which I did and he accepted. Got a great deal!

So first the good:
- Original fenders with no cracks (except for one tiny one that will get stop-drilled)
- Original seat with no cracks / splits
- No case saver installed, but the crankcase is untouched where the chain usually punches through.
- Mostly all OEM and still there except for the stuff listed in the bad below.

Now the bad:
- Needs tires
- Rear OEM grab bar missing and replaced with big- basket rack (homemade)
- No mudflap on OEM fender (darnit!)
- Needs tank scoops (I've got a spare set ready to go)
- Needs fork boots (again, have a spare set ready to go)

...and I can't get it to run (yet).

So it's got fresh oil, clean gas, clean carb (not cleaned by me, so I'm gonna go back through it tomorrow) and I can't get it to fire. It's got spark, but low compression (about 60 PSI max after kicking it about a 5-6 times).

I checked the flywheel to make sure keyway wasn't sheared (giving wrong ignition timing). I can shoot gas in the carb or down the plug hole and all I've gotten in about 5 solid minutes of kicking it are a couple of backfires out the exhaust. It pretty much does NOTHING.

I'm thinking one of two things: stuck valve or jumped cam chain (changing cam timing).

Any ideas on how to both diagnose and possibly cure a sticking valve (without removing the head)? i've checked valve clearances and they seem correct on all 4 valves so if the valve is sticking, it isn't completely hanging open, it's just not closing cleanly.

Anyway, here are the pics:


What other ideas do you guys have?

[BarnBoy]

Awesome score!!

Few things...stuck valve will give you no compression. Jumped cam timing would still not change the compression....but you might hit the piston with a valve and thats no good. With 50-60 psi, no way its gonna run. BUT, were you doing the test correctly? Throtle held wide open, choke off?

If so, next step, put some oil down the plug hole and try it again. Kick 6-7 times, WOT, if the reading goes up significantly its rings, if not you may have other issues. Never hurt to check timing and all that, I'd also check your valve clearances. Sounds like that motor is coming apart to me.

[wonderboy]

Yea, I think that's the next step. I'll dump some oil down in the cylinder and see if that gives better compression. The machine sat for several years (inside) but I could imagine that the rings are stuck. I did kick it while wide open and choke off, although on the 350x, the choke isn't a butterfly choke anyway (it's just a fuel enrichment circuit). I'll give it a shot in the morning.

With regard to the cam timing, it could affect the compression since it affects the closing of the valves relative to the piston movement. I honestly don't know if it would have that significant of an effect but it was a thought. Like you say, piston rings are definitely a way more likely scenario. I just hope I don't have to pull the top end...

Gotta order other maintenance items for it: air filter, front wheel bearings, chain / sprockets. Lots to do!

[tapper190]

nice score!! Get your son to pull you around on the auto x (unless he has moved up to your 350x) to get things moving in the engine

[tapper190]

I didn't want to pay for the $125 for a aftermarket rear grab bar or the $300 range for the oem, so I made one this weekend, maybe a new piece for the tapperline products, lol.

[shortline10]

If the compression jumps up significantly after putting a little motor oil down the plug hole then I would bump start the machine and force it to start , the heat from running it can sometimes restore the compression from stuck rings and dirty valve seats .

[ATC King]

I didn't want to pay for the $125 for a aftermarket rear grab bar or the $300 range for the oem, so I made one this weekend, maybe a new piece for the tapperline products, lol.

That's a clean looking grab bar.


Is that used motor oil in the Tiki torch container? You must really hate mosquitoes; trying to give them cancer instead of just driving them away.

I certainly made a mess of some good torches when a friend done that and I tried filling the torches in the dark.

[ATC King]

wonderboy, if you'd like to give it a better shot at starting, you can remove the sparkplug, warm it up with a small butane torch, & throw it back in quickly just before attempting to start. Also, use the lowest octane fuel you can.

That's a little trick used to start small engines with low compression. It's certainly good to at least get something running good enough that you can check it out for bad sounds & see if the transmission and clutch function properly. No doubt it makes project planning easier if you sort of know what you're working with, before tearing things down.

[wild200x]

Nice score!!

[BarnBoy]

You're right that valve timing could affect compression, but I think it'd be obvious if that was your problem. Definitely try and get it fired up, might get lucky with stuck rings or a bit of carbon in the valves.

[knappyfeet]

A lot of folks make the mistake (me included) of kicking an engine over after it has been sitting forever with no use.

Sometimes the valves get stuck and end up knicking the piston and bending the valve. Here is a pick of my bent valve and nick off my 200X. It looks very small but I couldn't muster 15 PSI of compression........so I would see if your compression doesn't bump up with the oil in the cylinder trick. It very well may be just bad rings.

Take an inspection camera and see how the walls are. Good luck

[wonderboy]

Thanks for the info guys.

I tried oil in the cylinder. I actually used some heavy 20W50. Gave me maybe another 10 PSI, so I got maybe 60 PSI. I figured that wasn't that much of a difference, so I wanted to keep investigating.

I know this wouldn't affect compression, but may affect starting so I wanted to check for a blockage and removed the muffler. No blockage in the muffler. However, I did put my hand over the end of the header pipe and kicked it over by hand and it would suck my hand onto the pipe and then blow it off. I'd say the sucking was stronger than the blowing... (oh boy, that's gonna get me in trouble LOL)

I'm thinking bent/stuck valve. I've already pulled the cylinder cover off this morning and am gonna head back out and finish pulling the head off. Just had to confirm in the book that you do have to remove the motor to get the rest of the head off (dangit). Oh well, everything else is stripped off, so it really just means pulling the chain and the rest of the motor mount bolts.

Some good news from this morning though:
- The exhaust stud nuts came off WITHOUT SNAPPING THE STUDS!!! That's a first for me. 86 used acorn style nuts, so there is no exposed end of the stud. This has to be why. So no drilling out broken exhaust studs... YIPEEE!
- The cam journals look very clean and the oil pocket in the head for the cam lobes was full of oil. So no damage there. Very happy about that.



I'll update in a bit once the head is off with what I find. Gonna check the cam timing too before removing that, just to eliminate that as a contributor.


@ Tapper: Well put me on your list to buy one once you start making them!! I'm with you, I'm not spending 200-300 ridiculous ebay prices for one of these. Tell you what, I'll make you a good deal on a large ice fishing basket rack grab bar... LOL!!

[wonderboy]

Found it!


I have no idea what this is. It is a plastic tube. Initially, I thought it was an o-ring but this is hollow like wire insulation. There is no metal, it's all plastic thankfully! Looking at the valve seats and valves, I don't see any burning or erosion from not seating. I'm guessing that once this entered the exhaust valves, the engine stopped.

My find sure is looking a bit barren... LOL


So the cylinder is looking in really good shape. There is really no ridge that I can feel (just barely) and I don't see any scoring in the cylinder.

The cylinder is mirror smooth, so your seeing the reflection of the sooty/carbony top of the piston reflecting in the wall. I'll put this to top dead center and clean that off before reassembly (or maybe something else... keep reading below where I'm looking for advice)


So, now the thing I'd like everyone's advice on is how much should I replace/recondition.

I literally could throw this all back together now and I'm sure it would start and run. But I'm here...

Do I:
- Replace valve seals (I think yes, it is quick and cheap)
- Chuck the valves up in the drill press and clean the carbon/soot from them (I think yes)
- Lap the valves? I don't have the gear for this, but I'm guessing it's cheap for the little handle doo-hicky and compound. Does this really even do anything?
- Do a complete valve job? (not sure if I can get it done locally and how much $$)
- Ball hone the existing cylinder and replace rings (looks to be factory bore and rings)
- Upgrade to a Wiseco 10.25:1 and bore the cylinder and start brand new fresh? (I did this on one of my 85's and really like it)

Looking for your guys thoughts.

On a total tangent, I AM glad that I removed the motor now. Even if not to find this issue, the aluminum spacers on the motor mounts were JUST ABOUT seized onto the bolts. I had to on the bolts pretty good to break them free. This will give me the chance to totally clean the bushings, bolts, and Anti-Seize the ever-loving crap out of them on reassembly. Take this as a public service announcement: Make this a part of your annual or maybe every other year maintenance. Take out one set of motor mounts bolts at a time, clean the bolts, apply anti-sieze, and reassemble. Ok, end of public service announcement.

[BarnBoy]

Frank, quick work. Wonder where that came from...

Its apart now. Pull the jug, pull the piston. Check your crank make sure its in good shape. Then get the cylinder bored and honed, that mirror shiny is glazing on the cyl. It needs bored and honed, and a fresh piston and rings. Wiseco piston kit, $120, bore $50-75, gasket kit isn't too much, timing chain. Then buy new valves, and get them ground and the seats cut. $25 a valve labor, and maybe $15 a valve if you buy Shindy. Get a good Japanese brand, Vesrah is good too. You gotta start fresh, don't skimp out unless you're gonna sell it. I say you can do the complete top end for @ $300, barring any unforseen issues. Is the 350x 4 valve or 2? I forget...if 4 maybe bump that up to $350. Then its brand new!!

Definitely reassemble everything with antisieze...im going through fixing a siezed bolt on my 185s motor. Not pretty...dissimilar metal corrosion is real.

[350for350]

That looks like a piece of an old, broken off carb vent hose to me. judging by the color and apparent size. I'm guessing that someone didn't notice it break off while removing or installing the carb at some time. Then, all of a sudden, it wouldn't start.