1985 Yamaha RZ500

5/6/2020 Bought on Ebay. Arrived 5/11/2020

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Original Ebay description

“1985 Yamaha RZ500 V4 Michigan Clear title

I waited along time to fine this Original one, especially with very low miles (4660 miles) they just are not around any more.

Have owned from 2013, decided to get it running and go for a ride.

New Battery

New Tires

New Chain

New Wheel Bearings

New Tapered steering head bearings

Changed transmission Oil

Cleaned float bowls on carbs

New Shut off valve for fuel

New front Brake Pads

Amsoil Dominator Synthetic injector oil

New fork seals, Race tech Springs, Gold valves, Modified damper rods (per Race Tech) 20 wt oil

With modifying damper rods the Anti Dive units are inactive (left them for stock appearance)

This is a very nice mostly all Original RZ, Starts first kick most every time hot or cold, shifts and clutches fine, pulls all the way to redline, shifts and clutches as it should.

All lights work, horn, blinkers, brake light, gauge lights

Original Rock Hard handle bar grips ( I have Bicycle tape over originals so they would not hurt my hands)

I have sold other bikes through the eBay system with 100% Positive Feedback, Please review my feedback as a seller,

Ask all questions I am Honest and have no intention to mislead anyone.

Maintenance…

There were only 4 things that really concerned me

1 Puddle of fuel underneath the bike while idling. (see top left pic above)
2 Fork seal weep.
3 Odd vibration- felt a bit like the front drive sprocket was loose or something, maybe it’s the new chain on old sprockets. .
4 It might be surprising to you to know how many times you completely take both hands off the bars while riding. Adjusting clothing, visor, or just seeing how the bike tracks. Try look-no-hands on this bike and a wicked head shake occurs that’s violent enough to break your wrist if you leave it too long before grabbing it and shutting it down. Previous owner told me about it and he rebuilt the forks and re-newed head bearings but it’s not made a difference. I rode behind a friend who wanted to feel it for himself….it’s not just the front that shakes….the whole bike goes into a fit.

It’s the first bike I’ve had on the lift that I’ve been truly in awe of…

Definitely some kind of leakfest going on here, but from float bowls or that fuel line connection? we vow to find out which one and fix it.

Double sided tape keeping the seams together, not a terrible idea i guess.

Previous owner drilled extra holes in the belly pan to drain the escaping fuel that was being collected there. We are going to start at the other end of the problem, find why it's happening and remedy the problem. The fuel puddle is more than just minor irritation. If the excess fuel gets into the motor, it washes the oil film from the rings and cylinder walls....leaving no cushion between the thrashing piston and the bore walls....just full on metal to metal contact...not something you want.

Busy workshop...but everything is of course....nearly finished.

Not as much room to work on this as all the 70's bikes I've had my hands on recently....
It's crammed in there. — Not as much room to work on this as all the 70's bikes I've had my hands on recently.... It's crammed in there.

Seeing as the bike ran SO well I was really reluctant to even take a wrench to it, but I keep discovering things that justify my curiosity....I know I'll be finding bits of this possibly 35 year old air filter in the carb bowls

No, it's not a terrible fuel leak.....but, it's not going to get better. New o-ring and some fuel line clamps ordered. Fuel line is still supple.

Rebuilding the carbs….

Still in the toolkit, the wire that allows you to lift up the front of the tank and check plugs.

Particles of the airfillter appear in the fuel evacuated from the float bowls.

OEM gaskets and fork seals from Fowlers UK

Setting fuel height…

Yes it’s probably overkill but considering the hassles I’ve had with overflowing carbs it’s worth going the extra mile. ‘Darth’ on the Kawasaki Triples Owners Group patented the idea. Fuel height Corresponding with the updated float height of 24mm, the fuel height is 3.5cm, which is exactly where that black mark is on the right.

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Random Tasks….

Other OEM parts: O-ring and special rubberized/fabric washers to ensure the fuel is kept behind the screws....

Cleaned this area up a lot and then added a thin smear of Yamabond just to be sure.

I had ordered the OEM fuel clamps for this application but decided to go old school. I have more trust in these hose clamps. Previously there were no clamps of any kind so I think with the new o-ring, rubber washers and minimal use of liquid gasket....it will be fine.

There was about 1/8 inch play with these original cush rubbers, replaced them and now much better.

cleaned up the rear wheel and original OEM sprocket....PO added a new chain but not sprockets, but as much as I feel you should always renew sprockets with a new chain this looks good for it's reported 4,660 miles. I also dropped both wheels off at the local shop to have the 'balancing beads' removed and classic wheel weights applied. I'm hoping that this will help eliminate the deadly headshake.

Next...fork seal replacement. Although PO had replaced them, they were leaking.

As mentioned at the top, forks were redone adding Race Tech springs gold valves and modified damper rods which eliminate the operation of the anti dive system.

Forks back on, all carbs back on....tank in place...

Synchronized the carbs, added fuel, turned tap to Prime and stood by to tap the float bowls should fuel start spewing out the overflow pipes....but not needed. In fact I heard the floats snap shut.

Lubed every cable and did some cleaning....

Cleaned up the elephants ears and reassembled with new foam gaskets.

Brake bleeding prep...the only way the get the master cylinder somewhat horizontal is to get it off the lift and turn the front wheel left full lock. Despite the antidive mech being rendered non-functional still had to bleed the brakes after dismantling the forks.

started on fourth kick. So far so good. At time of writing (2/15/21) most of Nashville was under a sheet of ice....but should be up to 57º by Feb 23, just warm enough for a test ride.

As of Mar 16 been out on it twice and no more fuel leaks. Very happy. Bike is now so quiet with the new filter- seems a shame but I like the fact it's fully stock and still pulls like a train. Sounds a bit different just sitting at tickover- can't describe it- almost like it's pinking- yet....the performance is great. I put in new OEM recommended plugs (NGKBR9HS) which were different than what was installed- could be that.

Apr 16 '21. Thanked myself for labeling the overflow pipe ends. When I set the petc**k to prime, bike became incontinent, but I was able to tell which carb had a float stuck and tapped it with a socket extension. Flow stopped. It appears most 500's have this problem no matter what you do- remember these are brand new valves and seats. Even when setting the float height the floats would get stuck....the valve piece would simply lodge itself diagonally in the tube....bike is still running great though

Sep 11 2021 Fitted a new Motobatt battery. Not the most straightforward task.....

....had to remove the tail piece and large side panel....

....and some heat shielding....but bike now seems much happier when you switch it on and it cycles the YPVS. :)

Oct 27 '21 I've been without a car for 28 days now so been largely running errands on my bikes....every other two wheeled dream has some kind of issue whether it be the fact it's killing spark plugs (H2C) , maladjusted floats (H2) leaking from it's filters (Triumph Tiger) or jumping in first (Darmah) or having no fork oil left (998) or having no lights (MT250) or cracked tires (FZ) or unruly flat spot (81 LC) or no fairing and it's getting a little chilly (82 LC) or generally just being too goddamned dangerous (Hardley).....who knew that the over complicated RZ500 would be the most reliable of the collection. It''s still gushing fuel from time to time out of the carb that is most inaccessible by a socket extension but it appears to have cured itself for the time being. Wobble is still there and have noticed the bike being a little unsettled on 80/90mph long freeway sweepers between my house and the yoga studio. I think it's the rear Shinko being mismatched with the front Avon 3D Ultra.

August 12, 2023-Stuck Choke

Been running around on the 500 fairly regularly. Yesterday I tried to pull the choke lever and it wouldn’t go up all the way and settle in place like it usually does. I could pull it half way to what it’s used to. Started fine and bike performed 'ok' but something didn’t feel right, like it was maybe running on three cylinders.

Getting home, the exhaust of the Left Lower cylinder was not as hot as the others. (It’s also the Left Lower carb that has overflowing from time to time- usually fixed with a tap with a socket extender).

Took the carbs off and the one of the four choke cables that won’t pull as far as the others is the Left Lower. And guess what- the cold start plunger is locked in place all the way in it's home. It won’t budge. I guess I should be glad that it's not stuck open or should I say closed.

Perhaps when the fuel has completely evaporated I may apply a little heat. Nothing else wants to make it move. There’s not even a bit of ‘give’. It’s like it’s welded in place and I’m reluctant to use any more force than a sharp wee tug.

I also checked the float height. It’s spot on at 24mm. I can’t remember where I got that 'new' height but I feel like it was a responsible source.

The float valve seat is OEM and I replaced them and bowl gaskets in Aug of ’22. All looks good there so it doesn’t explain the intermittent overflowing nor the ugly looking float bowls.

UPDATE: a little bit of heat from a heatgun encouraged the little blighter out, but after a good polishing of both the plunger and the bore, the plunger is not interested in going back in and the last thing I want to do is force it.

completely standard carbs which have been 'rebuilt'. this just means new valve and valve seats and gaskets.

heat gun application brought it out and I gave it a good polish...

The Fix

Steen Løkke on the Yamaha RZ/RD/RZV500 Owner Facebook Group suggested there might be some corrosion in the bore so I got a 7/32 drill and wrapped it with some fine emery cloth and (relatively) carefully ran it in the bore until the plunger would descend to the bottom and return on it's spring without any friction.......

... Rechecked float heights on both, then I re-assembled everything....and the bike is back to its normal self. Starts easy and really pulls strong thru the power band. Such a great bike and only just about to turn 10k miles.

Dropping A Pot/Plug Oiling—

Getting near the bottom of the list of potential culprits causing my RZ500 to drop a cylinder or two or three.

Interestingly it was running well for a bit, then I left it for a week and on starting it went from a healthy 4 to 3 to 2 to 1 cylinder so my current suspicion is that it’s the Non Return Valves out of the oil pump allowing excess oil to get into the cylinders. BUT my question is: we know where the oil lines originate- the oil pump- where do they end up?
Crankcase at bottom of cylinders?
Inlets?
I’ve never dismantled the engine completely so I don’t know and I can’t see where terminate.
I was hoping to replace the oil lines but now I'm not so sure it's accessible enough to do so, and instead I may just splice in some new inline non-return valves.

I’m preparing to get to the oil pump and take off the brass NRV’s (Non-Return Valves) to see if they can be cleaned/made effective and/or I will install some inline NRV’s (part# 8CH1316A00) https://www.cmsnl.com/products/check-valve_8ch1316a00/ but I’m wary of doing that if I have to leave the original Non Return Valves in place. STOP PRESS: just read Ange's 'Check Valve' thread and not only learn that there is an opinion that you CAN leave the OEMs in place AND/BUT embedded within was the link I've been searching high and low for.....something to replace the OEM NRVs with just a straight thru pipe (no valve) with the right thread and a barb https://www.advancedfluidsolutions.co.u ... 668-p.asp?. Thank you V4 Stroker

What I’ve done so far to remedy the pot dropping situation.

Cleaned Carbs and meticulously (took hours) set float height to 24mm (the updated measurement)
Checked fuel heights. All equal.
Lubed all related cables and adjusted where necessary the:
-throttle cable freeplay
-carb sync
-YPVS cables
-oil pump adjustment
No difference.

Replaced CDI- with an OEM spare from E-bay. No difference.
Replaced OEM Coils with new ID coils from Yambits. https://yambits.co.uk/rz500-ignition-coil-p-86722.htmlNo difference.
Replaced Rectifier with a spare working rectifier from a friend. No difference.
Replaced Motobatt battery with Shorai Lithium Battery LFX09BL2. No difference.
Checked compression- basically 100 all round- which is good for a 10,000km engine.
Replaced NGK BR9HS’s with Iridiums BR9HIX’s. Was better for a while.
Replaced BR9HIX’s with B8HS’s AND replaced the OEM caps with NGK Red Competition Plug caps.
Was better for a while and then like I said above one morning went from 4-3-2-1 cylinder. I know it sounds like fuel starvation but plugs were oily.
Took off bottom pipes and up ended them to see if they were full of oil. Not a drop came out.

Anyway- that's the latest...if I do replace the valves and there ends up being no change, I'm not sure what else it could be other than perhaps the...stator or god forbid...crankseals?