Honda XLV750R Tech Tips

Contributions and comments welcome! Just email sharkey@zoic.org

General

Getting the Engine out!

The XLV engine is a big lump, and the frame is pretty tight around it. The easiest way seems to be to lift the frame off the engine.
  1. Remove the seat, tank, bashplate, pipes, carbs, coils, etc.
  2. Disconnect the battery earth and the starter motor lead, also any other engine wiring (generator, timing coils, oil warning, etc). Remove the battery.
  3. Remove the left hand lower frame rail.
  4. Drain oil, remove oil filter and oil cooler, also oil breather lines. careful! see oil cooler tip below
  5. Support the bike with a stand (milk crate?) under the engine block. Make sure it's narrow enough not to foul the lower frame rails.
  6. Use a couple of those ratchet tie-downs to steady the bike at bars and tail. Tighten them until they start to lift the bike just slightly ... the idea being to minimize the side-load on the engine bolts.
  7. Off with the wheels, forks, final drive. Pull on the shaft so the front splines disengage. This prevents the weight of the engine settling on the uni joint.
  8. Remove engine bolts. They won't slide out if there's too much side-load, so adjust the tiedowns until they will.
  9. So now you've got the engine separate from the frame, but still inside it. Make one last check that you haven't left breather hoses, etc, on.
  10. Lift the front up the frame up a bit, and guide the front head into the front frame opening. You can now get the splined driveshaft out of the swingarm, and pivot the back of the frame off the motor. Use the tiedowns to take the weight of the frame, and just swing it out of the way.
As always, putting the motor back in is the same, in reverse, only more frustrating. DON'T FORGET THE SWINGARM RUBBER BOOT!

Carbs / Fuel

Balancing

... is a bit of a bastard, but if the carbs are out of balance it'll run like a pig. Details are here: Carb Tuning for XLV750R

Needles and Springs

Thanks to Ruschie and Steve Curtis: On the Aussie model, the front and back carbs aren't the same.
  FRONT BACK
Needle:1CE3MN
Spring:16 turn
180 mm
15 turn
165 mm

Sliders / Diaphragms

The carb slides can get sticky and reluctant to move: this causes sluggish acceleration and much snap-crackle-and-pop on decelleration. Sometimes you can free them up by removing the airbox lid, spraying a little carb cleaner down and pushing them up by hand. They should fall back into place smoothly and rapidly.

Jets

Stock is #118 main and #42 slow. Mine seems better with #122 main and #40 slow, but then my pipe isn't exactly stock. The needles wear pretty bad, richening up the midrange and causing a lot of spluttering and backfire, going to #40 slow jets has helped this and fuel range is much improved.

Anyone with input on their favourite jetting, that'd be great.

(Or you could Play with EFI)

Fuel Pump


Heads and Head Covers

Rocker Eccentrics

The rocker arms pivot on an eccentric pivot, which is adjusted by the hydraulic lifter. The eccentric is usually biased towards the inside of the motor. If the eccentrics aren't held in place properly as the head cover is attached, they can end up locked at full extension, causing the valves to be propped open by ~2mm at all times.

It's pretty obvious when it happens ... the head cover won't sit flat on the head even at TDC, because the valve springs are being compressed.

You'd have to be an incompetent prick of a professional mechanic to miss this one, eh?

For some reason, this seems to happen more easily to the exhaust rockers. A gentle push with a screwdriver between the valve-stem end of the rocker and the head cover will realign the eccentrics to face inwards.

Rocker Covers

I don't know if this has been a problem for anyone else, but both of my original tappet covers developed hairline cracks which wept oil ... if the engine is always oily it's worth a look.

Valve Springs

The exhaust valve outer springs are painted green, but on older bikes this paint can be hard to spot. They are also around 2mm shorter and have one less turn from end to end.

The inner springs appear to all be identical.

Hydralic Tappets

Thanks to Rossco: If bad oil has been used the hydraulic tappets may get sticky and make a ticking sound, and the cam chain tensioners too may stick. Both of these are hard to fix as the rear tappet cover cannot be removed with the engine in place.

Sticky Cam Chain Tensioner Wedges

Thanks to Warren: The cam chain tensioner wedges sticking seems to be an ongoing problem for some bikes, and can't be readily fixed with the engine in.
While it's out, there's a possible modification - drill a hole in the covers above each tensioner, tap it and plug with a screw. If the tensioners stick again, remove the screw and use a tool to press the wedges down. I'm trying this modification myself at the moment ... yep, and it seems to work quite well. The rear cylinder bolt is awful close to the frame rail though, so access there is tricky. But it seems to be my front cylinder one that sticks anyway.

Oil Y-line bolts

Make sure these are the original ones, with a thin shaft before the thread. A 'normal' bolt will restrict oil-flow to the heads.

Cylinder Barrels and Pistons

Spark Plug Tubes

To remove the Spark Plug Tubes, find a bolt with a 27mm head. Steering head bolts are often this size on smaller, older bikes (Kawasaki Z250B, for instance). You should be able to find something like this at a wreckers yard.

You can grind flats onto the threaded part either two for an open spanner or six for a ring spanner / socket. It's not as tricky as it sounds because if you hold the 27mm head in a vice, you can turn it one face at a time and thus get the alignment of the sides right. Well, right enough anyway. I ground mine down to 13mm, there's a little thread showing on the corners still but it works fine. If I get overenthusiastic I might finish it off to a proper 12mm on the mill, or just pound a cheapo 13mm 3/8" socket on the end ...

Remember, you don't need much torque to install this part.

Don't forget to vacuum and/or blow out with compressed air to clean all the grit out of the tubes ... otherwise it'll fall into the cylinder and/or cam chain journal.


Engine Guts

Clutch center nut

Thanks to Rossco: You also need to check the nut that holds the clutch basket on the shaft, clean and locktite the threads. Been known to come loose and destroy the engine, loses drive to the oil pump.

Steve Jordan writes: Clutch cable got a bit of slack in it and I thought it was the cable seizing up. Got worse within about a hundred klicks [...] Completely stopped disengaging [...] kept going as no apparent other problems. Stopped to rendezvous [...] Roll started and when I put it into third the oil light came on. Went out when I backed off and went on when revved and back off when idling, then on and stayed on. Stopped the bike and trailed it back home. Just pulled it apart and found the centre nut was loose.
My reply: Make sure [the clutch] engages properly and the oil pump drive gear pins and the clutch basket holes are still square and not battered to pieces by each other. You'll be able to feel the pins engage the holes. I've never had a problem when that center nut is torqued correctly, but you could loctite it if you're worried. It needs a _lot_ of torque ... 85 - 95 Nm = 62 - 69 ft.lb.

Electrickery

Removing the Generator

Do not prise coils!
  1. Remove the three screws holding the generator in and the screw holding the cable clamp. Replace the cross-head ones with hex head ones, you'll thank yourself for it some day.
  2. Remove the two little cross-head screws holding the earth ends of the exciter coils. Leave the lugs where they are.
  3. Put something in the center of the coils to lever against.
  4. Thread a 1" or so long M5 screw into each earth screw holes and lever very gently with a crowbar (one after the other)

CDI Exciter coils

See Chapter 17: Ignition and the Wiring Diagram.

Thanks to Rossco: The exciter coils that charge the cdi's can break down, any bike with more than 30,000 probably has had it done by now. Its an easy to get to part, under the left engine side cover.

These coils are part of the generator, which is under the LHS engine cover. The wiring runs up to under the RHS side cover, and then to the CDI units. There are two coils, each of which should be between 250 and 350 ohms to chassis. With the engine running, there should be a large AC voltage on each, 100VAC-250VAC. Be careful. If they burn out, one or both cylinders run poorly or stop working entirely.

Thanks to BT Humble: You can bodge around the exciter coils by using a mains transformer backwards. see the aus.moto thread "Whale Oil Beef Hooked" if you dare!

Mine lasted over 60,000 kms before they finally failed, both at once strangely enough. Oddly enough, when I replaced the coils fuel efficiency went up 25%, suggesting that a hot spark is essential, or something like that anyway.

Small Coil Rewinds in Geelong has been rewinding these sorts of coils approximately forever, and have done coils for several list members. They'll only do the whole stator, not just the CDI exciter coils though.

Steven J. Curtis writes:  "Andy Wheeler in Gosford [...] winds with heavier wire so that they don't burn out but you have less turns and therefore I got the fuel economy problem. He says the honda spec is 3500 turns of X gauge, he winds 3200 turns of the next heaver wire. That was enough on mine to drop the fuel consumption about 3 - 4 k per litre."

Ross Lawrence writes:  "[I recommend] Dave Turner [from Queensland] Ph 07 3402 4429. He works from home and does lots of the bike shop work in Brisbane, along with a fair bit of work sent from interstate. Dave also states that the insulation on the winding wire has been upgraded in recent times, apparently the old stuff was only rated to 140 degrees C but the new stuff is good for 200 degrees C. This may help to explain why they failed every so often, on the air cooled motors especially."

Rossco, Steve and I are all thinking of ways to eliminate the damned things. Presumably a DC-DC converter could do the job ... I think they're only drawing about 15W each ...


Oil and Oil Cooler

Oil Cooler Lines

Be careful removing the lower oil cooler line from the oil cooler. The connector gets quite seized and it is possible to tear the end off the oil cooler by applying too much torque. You can undo the other end of the line (where it attaches to the engine) far more easily.

I made the mistake, and ruined my oil cooler. I bought a replacement from a wreckers ... exactly the same thing had happened to it and they'd welded it up.

If you do need to remove this line, lock a spanner into a vice and use it to hold the octagonal extension out of the bottom of the oil cooler. You can now put torque on the connector without damaging the cooler itself.

Remember, a little WD40 / RP7 / etc goes a long way when dealing with seized threads.


Wheels / Suspension / Final Drive

Front Brake

The front caliper slides on a pair of pins, the pins are meant to be covered in grease, the grease is retained by three little rubber boots. The rubber boots fail every 20-30000km, and the grease gets out, the water gets in, the pins seize and the brakes turn to shit. To fix, disassemble, degrease, remove rust from pins, replace rubber boots w/ new, grease, reassemble. It's no sports bike, but adequate for a 90/90-21 ...

Rear Brake

Back brake is rubbish, can be made less worse by fitting new shoes (perhaps slot them with a hacksaw) and adjusting the pull rod setup carefully for maximum leverage.

Forks

Proven Suspension sell replacement progressive forksprings for the XLV.

The fork seals are tricky to get back in because the bores they live in are quite deep ... I use a 40x32 PVC pipe joiner, with the ID turned to 44mm and the smaller OD=52mm. If you don't have a lathe handy you could always just file it out, not much needs to be removed. This slips down over the fork leg with the smaller end bearing on the seal, and then I whack it in with a bit of steel pipe slipped over the fork leg.

Rear Shockie

Your options:
  • Get the shock rebuild. It's officially unrebuildable, but there are folks out there doing it anyway! Rossco recommended RAD Shockies in Brisbane.
  • Rebuild it yourself.
  • Bitubo make replacement shockies for the XLV. I just fitted a shiny IZE (adjustable preload and rebound damping) to mine (see photo at left).
  • Bounce around like a mad thing on a shock made of soggy cardboard ...

Rear Wheel Bearing

The larger of the two rear wheel bearings seems to wear out its seat (I've seen this on two XLVs, 65k and 72k, and heard about it from many listmembers), and too much play at this bearing can seriously wear the spline drives. Check it every now and then.

  1. Remove rear wheel
  2. Remove final driven flange
  3. Insert axle through bearings
  4. Wiggle axle and look for bearing free play.

The problem is, once the bearing can move a little it wear the seat a little more ... if left, the problem increases. And then the weight of the bike is supported by the final drive bearings, via the splines. Not good for the splines, which are meant to only take rotational loads, not axial ones.

If it's real bad, the rear wheel needs to be machined and a sleeve inserted to fix this problem. This fix seems to have worked well on my XLV -- at least 30,000km have passed.

Thanks to Greg Scott:
pic1 I thought you might find a use for some pictures of my 'saved' rear wheel bearing to go with previous 'common failure' notes you have published before.

The inboard bearing had worn loose and enlarged the hole. It was only after the replacement set of bearings failed that I had it checked out properly, and found that the bearings were almost a millimetre too close for the spacer (nipping the bearing). Whether this had resulted from the spacer fretting between bearings or the outer race wearing the alloy hub, I don't know.

The machinist sleeved the inboard bearing and re-worked the shoulders to match the new spacer tube from Honda. The repair looks pretty good, and it has saved the bike!

NOTE: When removing or reinserting bearings, heat the hub to approx 100 °C (eg: so water sizzles gently on the hub). This prevents damage to the aluminium seat and causes the bearing to 'lock' into place.

Less worn out bearing seats may be fixable with Loctite 641 ... normal Loctite nutlocker doesn't work, but 641 is designed for the purpose and seems to have worked on my other rear wheel bearing -- the RHS bearing started to spin a few thousand ago. On advice from a local garage, I staked the bearing seat with three circuits of punch marks with a centerpunch, raising many little craters in the aluminium seat. Then I liberally coated the area with loctite 641 and installed the bearing. It seems to work -- the loctite retains the bearing, and the punch marks retain the loctite.

Spline Drive

The spline drive in a shaft-drive bike is quite vulnerable to damage if not looked after ... even more so on an off-road bike where dirt and hard knocks are common.

To protect the splines, they should be packed with MoS2 (Molybdenum Disulphide) grease. Get a thick layer of grease all over them, don't be afraid to make a mess! Make sure you don't get grease in the brake drum though ...

This grease is retained by 2 O-rings ... one on the base of the Final Driven Flange (attached to the wheel) and the other on an 'O-ring carrier' inside the ring gear splines. Make sure these O-rings are present and in good condition.

There are also spline connections at either end of the shaft and the uni joint ... if you remove the final drive, repack these with grease as well, and make sure the rubber seal at the back of the engine is in place correctly.

Photos to come ...

Swingarm Bearings

These wear out easily, especially the right hand one for some reason. You can undo the locknut with a pin punch, but getting the pivots out will require a 17mm Allen Key :-(.

I ended up drilling, tapping and installing grease nipples in the pivot pins. Then discovered how easily the seals back out, so the seals now have tiny grease outlet holes drilled in them. On the up-side, I can now grease my SA bearings every ride, on the down-side, now I have to do so!

Thanks to Rojaws:

I reckon the right hand swing arm bearing wears because the seal on the pivot pin is prone to working loose and exposing the bearing to road dirt. I put a garden tie around the neck of the pin and so far no more trouble.

Copyright (C) 2001-2004, Nick 'Sharkey' Moore. All Rights Reserved. These Tech Tips are all things I've stumbled upon by trial and error, or heard of from other enthusiasts. I am not a professional mechanic and disclaim all responsibility for the accuracy, safety, legality and/or usefulness of this information. Don't you hate this disclaimer stuff?

Got a comment or a contribution? Mail sharkey@zoic.org