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Freshening up a $1500 '87 LT500R...

32K views 139 replies 16 participants last post by  DMoneyAllstar 
#1 · (Edited)
Well, I bought a 1987 LT500R this past winter from a Craigslist seller only about 6-miles away. The guy was a member on here and 1st time 'Zilla owner. He had bought the rig for $1500 from a guy in Michigan, and then dumped $900-$1100 into it...87.50mm bore / wiseco piston kit / wrist pin bearing from Trojan Motorsports in Monroe Michigan, new gaskets, new wheel bearings, new Maier hood, $600 of new tires, new chain, new sprockets (41T & 13T), 10mm studs, and new FMF powercore silencer. Also came with nerf bars, another jug, head, extra TM38 carb, aluminum grab bar, desert front bumper, roost boost ignition coil, and some a-arm skid plates. I sold the extra top-end stuff for around $200. So...this is a $1300 Zilla (bought my '88 for $1200, so I'm on a roll!).

The fresh '87 top end has a wiseco piston & rings, and has been ported/polished rather nicely. Also has a PWK39 carb and a PTR pipe. BUT...the novice owner has the head installed 180-deg off -- the head stay is in front! LOL Amazing it ran ok. I have not started it since I test rode it b/c I don't know what all is going on inside the engine. No telling what the guy may have missed, forgotten, or messed up.

Carb needs attention since the guy was ''buddy-starting'' it, and had to pull start it when I looked at it. But when it was running...holy mother of God...it was noticeably quicker than my '88. Idle wasn't set either.

And someone had drilled a couple holes in the lower a-arms about 3" from the ball joint to mount the skid plates (morons).

Race-cut fenders have some mediocre graphics that are peeling. Seat is perfect. Polished aluminum wheels all around.

I was working on a Rotax conversion on one of my FL350R buggies, but this Zilla has sat in the corner of my shop long enough. My plans are to turn this into a powerhouse duner with a lot of stuff I've got in my stash, and includes...

  • PWK39 turned out to 40mm (my stash)
  • Cool-head with 52cc dome (my stash, need to order o-rings for it)
  • New V3 reed cage/intake (bought on eBay for $85 new in April)
  • Swap out the a-arms with a spare set (my stash)
  • Add headlight w/ chrome brush guard (bought on eBay this winter)
  • Add lights/run switch cluster (bought on eBay this winter)
  • New clutch pack & springs (my stash)
  • Aluminum thrust washers (need to order them)
  • Top-end gaskets (my stash)
  • Case saver (need to order)
  • Add an Armadillo rear skid plate (my stash)
  • Replace rear brake pads (my stash)
  • Replace fenders with an uncut glossy set of Maiers (my stash)
  • Replace bars (Honda East)
  • Replace hand grips (Honda East)
  • Swap clutch cover and stator cover with my clear-coated set (my stash)
  • I've got a SS cover bolt set I may or may not use (my stash)
  • Battery, rectifier/regulator install (my stash)
  • EGT (my stash)
  • Trail Tech Vapor (need to order)
  • Z400 extended hubs & paddles (my stash)
  • Properly installed a-arm skid plates (my stash)
  • Frame skid plate (fab)
  • Check all stock wiring & make it perfect
  • Closely inspect frame for any cracks, corrosion, etc and repair
  • Compression test before & after
  • Leakdown check before & after
  • Jetted & plug chopped
  • Dyno'd and tuned locally

Stay tuned!...

D$
 

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#119 ·
Did a leakdown check and found the stock gaskets don't work with the VF3 reed cage & intake boot. The stock gasket misses the seal bead on the intake boot face. I had all kinds of bubbles there. Once I get that leak taken care of (correct gasket), I'm hoping the only leak left is at the p-valve. Getting some pressure build in the clutch case ("pfffft" when I take the oil cap off), so its either the wet-side crank seal or the p-valve. However, the p-valve is double-o-ringed. I really hope to find some time to get this thing leak-free, mounted, and started this weekend. All of the electronics are done. Just needs the engine checked & mounted. So close I couldn't take it anymore, lol. if I need a new crank seal, I'll have to order and wait.
 
#122 ·
#123 ·
Been forrrrrrrrrever, but I'm finally back on this engine install. Brand new o-rings through the entire pvalve, but still got that leak at the #10 o-ring. GRRRRR! Old #10 o-ring looked fine with no cut, too. Time to take it apart AGAIN. There must be a void or something on the pvalve bore.
 

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#124 ·
Ok...so.I took the end linkage off (duh) and confirmed the leak is at the double o-ring.

I don't remember, but is the pvalve shaft supposed to be able to push in/out a tiny bit? This one will move about 1-2mm. With it pulled out, the leak is much slower. But push it in and she gasps. I may need to check the schematic and maybe locate some slightly tighter o-rings (?).
 

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#125 ·
Replacement power valve assembly on its way. Snagged one off eBay on a best offer of $50 + $7 ship. New valve body alone is $107 (dealer price w/ discount), so I'm hoping this other valve is in better shape! Part will be here by Tues.
 
#126 · (Edited)
Replacement powervalve, new Honda base gasket (other one has a tear), and new small front cylinder stud (near p-valve window, current one is stripped) arrived. Also bought a pair of master cylinder cap screws to replace the rusty ones. Hoping to get things turned around this weekend. Would be a fun Happy-Fathers-Day gift to me to have this thing fiiiiiiiiiiiiiiiiiiiiiiinally running. =)

I've found pretty much whenever I buy a used LT500R cylinder, I should just replace ALL the studs, buy new hole locator dowels, but new OEM base gasket, pvalve seals, and plan on at least (2) heli-coils. These things have been around for a while and only a few people are gentle with them. No matter how good something looks, it will also have a lot of secrets!
 

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#127 ·
That's the problem with power valves, how do you tell exactly where the air (leak) is coming from?

Did an older RM that drove me crazy. Once I got PV cover and vent sealed, still wouldn't know if it had a cases or seal leaks .
Runs fine, didn't change any jets, doesn't smoke (excessively, lol, it's a 2smoker)
 
#128 · (Edited)
This air leak was 100% between the valve shaft and the double o-rings. That's where the bubbles were coming from.

I really don't know if a leak here can/will even muck up your fuel/air and your jetting. I just prefer -0- leaks.

Had to tap the threads in the pvalve position-lock bolt hole (the one that points up on the bottom of the cylinder) -- it was stripped so bad the stock bolt actually fell out. Its now M8 thread. I need to turn down an M8 bolt with a nub end. Yet another piece of evidence this jug once had a rough life.
 
#129 ·
Well the new pvalve set screw/bolt is done. I lied, its M7 (not M8). I took a 25mm long hex bolt, cut it to length with the metabo, filed with the metabo disc and a hand-file, chased threads with a die, and after a few iterations of filing it fits perfect. Test fit the jug on the lower end, and there are no clearance issues with the slightly larger hex head.

New factory pvalve stud in the jug. Old one was a bit chewed. Also have a new factory nut to match.

Also got the old front master cyl screws out and new ones in (with anti-seize). Topped off my fluid as well.

If kids are in bed on time tonight, I'm planning to work some late night hours in the shop and get the top end back together. I'm using some brush-on copper gasket tack on both sides of the new OEM base gasket. So I'll get the jug on with bolts/nuts hand-tight tonight, and then will torque-to-spec in the morning, followed by a leakdown check tomorrow evening.
 
#130 ·
Anyone know what the #8 o-rings are made of? Its green, so I'm thinking its HNBR or maybe even Viton. For the price...I'm guessing HNBR (Viton is never cheap). I ask because I wonder if I can soak them in some oil that's doped with some seal swell (or methanol) to get them to ever-so-slightly swell up. Only looking for like 5-10% swell.
 
#131 ·
Replacement pvalve installed, new gasket installed, top end installed. Even without the base bolts/nuts torqued to spec, the leakdown test proved the crankcase would only drop roughly 0.3psi over 1min (drop from 8psi to ~7.7psi). This time when the crankcase was above 5psi, the o-rings somehow "seated". Up until ~5psi the double-orings were still leaking air. And then when I was over 5psi, its like the seated and stop leaking air. From a leakdown test perspective, as it sits I would ride it (obviously would torque everything down first). But I'll check the base gasket, seals, head gasket, head nuts, etc.

Also noticed the small M6x1.0 stud that goes through the pvalve window...it needs to be about 1-2mm longer. I have a new factory stud and new factory nut. The nut is a lock-nut, but the there aren't enough threads to engage the locker. So I used some high strength loctite and just tightened it good.

Factory base gasket FITS PERFECTLY. Plus the copper sealant (can with brush) is good stuff, but it doesn't spread as nice as the rattle can version. I always coat my base and head gaskets in the stuff. Makes assembly easy and its a good sealer.
 
#132 ·
Engine installed, pwk39 carb installed with 185/55 jets; new motion pro throttle cable, clutch cable, airbox & boots installed. Has great spark and 144# comp (new top end not broken in). Need to figure out why my kill-tether isn't killing spark, but the on/off switch works as it should. Need to clean & mount the tank and she's ready to fire up. :Smoke:
 
#133 ·
I can remember when you started this. Seems like the site is dead now a days which sux. AND for some reason I don't get notifications from here anymore when someone posts to one of my subscribed threads.

Anyway keep up the good fight. It can get tough at times for me. lol
 
#136 ·
Holy hell, is this thing still on?? Beuhler? Beuhler??

She's running! In the end, i had to ditch the clutch cover with the extra feature to prevent an oil leak. Pulled the parts off that weird cover and SCRAPPED IT. Still don't have kill tether rewired tho, but tested run/stop switch beforehand, and installed/tensioned chain as my emergency stall-stop fail-safe.

Buttoned 'er up and she started easy. Purrs like a kitten! Sooooo nice to see & smell exhaust out of this thing. #MarathonBuild

More to come with 5 more vacation days lined up.

-Dan
 

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#138 ·
Well the Pro Design Cool Head o-rings weren't sealing worth a damn. After it ran for 10-15sec twice, she didn't want to start. Trouble-shooted everything. Finally pulled engine and head and saw evidence of leak. Coolant does NOT like to burn. Got the stock head back on it and ready to go back into the frame.

I've been running my '88 Zilla with a stock head for years now with -0- issues.

Also putting up my other Zilla engine for sale (on CL & evilBay). Needs a clutch basket. Make me an offer!
http://toledo.craigslist.org/snw/5411215414.html
 
#139 · (Edited)
This rig is up & running! And its for sale on CL.

http://toledo.craigslist.org/snw/5428064026.html

Just installed a new stator coil and plug cap. The coil looks pretty old and has been beaten up by my flywheel tool, so bought a new factory coil (31240-19A00). And the plug cap wasn't right, so I bought the factory one (33510-2-A02). Both parts are high quality (not the crap from evilBay). Well worth the extra $.

Starts as easy as my other one now and idles nice. New owner may have to tweak the carb to their liking, but its a PWK with idle adjustment knob and mixture screw. Easy-peasy!
 

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