Syd
2nd Gear
Posts: 189
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Post by Syd on Mar 1, 2012 23:41:17 GMT -5
I have a 72 Kawasaki H1B 500 (Points model) which has mid range performance problems with mainly what seems to be the middle pot load around 4,000-4,500 rpm +. The engine has just received a complete overhaul with new conrods, 61mm Wossner pistons & rings, seals, sleeves, crank overhaul, bearings, gaskets, clutch, coils, leads and caps, battery, rectifier, new NOS breaker plate, points and condensers and new K & N air cleaner and new throttle cable and exhaust pipes and many other parts etc. Carbs fully refurbished with:
NOS Mikuni Needle jets # 172
NOS Mikuni Needle jets 5DJ19-4 clip (Also tried 3 clip but no difference)
Prepro Decals 100 Main jet (Also tried 95's but no difference)
Mikuni pilot 30.
Cutaway 2.0
Air screws set at 2 turns (have tried over range of 1 1/2 to 2 1/2 turns)
Float levels 24.5mm
Plugs NKG B8HS set at 0.5mm
Points set 23 deg BTDC (2.94mm)
Kaw air cleaner has additional air intakes for engine no's KAE-61607 up
Bike looks really smart and starts after 1-2 kicks and idles really nice, however the bike starts to misfire under load etc. Have checked for air leaks, checked idle, all electrics, tried an NOS H1 air cleaner, swapped carbs and also coils however no difference. LH & RH plugs look good (light brown), however centre one seems darker and wet.
Kawasaki issued a factory bulletin in May 5, 1973 see: hhghtyujrtyurtyu/mraxl/bulletins.ht ... 073%20H-23 which relates to the H1B with a factory mod with new air box with extra air vents and carb mods which has been fitted to my bike. My carbs are correct with cutaway 2.0 and air screws at 1 1/2 turns as per the factory bulletin. My HIB original riders hand book states spark plugs to be either B8HS for around town or B9HS for open road. Gap to be 0.4-0.5mm.
Have also tried swapping coils around, but no change. I have not tried a larger gap on the plugs. Any ideas on a fix would be most welcome.
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Post by Jim on Mar 2, 2012 0:44:30 GMT -5
I think your URL for the factory bulletin might be a bit tainted by the KTW effect.
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Post by lc on Mar 2, 2012 1:13:45 GMT -5
.5mm is only .020in gap. You might try opening them to around .025in. I'm sure some of the "B" riders here can give you further advice on this one.
That wet center plug might be a smoking gun too. Have you tried a different set of plugs? Perhaps the float valve on this carb is not sealing properly? (Or the float is leaking fuel into it).
You say you have new exhaust pipes. What exactly are they?
A declining battery voltage could give you a weak spark too.
The H1B has the early weak charging system, both structurally and output wise (with no warning light to alert the rider of trouble). Have you actually checked your voltage across the battery with the engine above around 2000 rpms (voltage should be around 14V)?
Does it rev cleanly up above your reported trouble area?
Sometimes when these bikes sit for a while excess oil will build up in the crankcase. During subsequent running this oil is thrown into the combustion chamber and will foul the plugs (especially during the first heat cycle). A full throttle/high rpm run will usually clear it.
However, You must also be careful if this situe exists as if too much oil is thrown up into the combustion chamber a bent connecting rod will occur. The easiest way to clear the crankcase is to remove the spark plugs, tie a rag across the cylinder heads, push the bike down the street as fast as you can go and kick it into first gear (throttle held wide open). Any excess oil will spray out at a great rate!!
J
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Syd
2nd Gear
Posts: 189
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Post by Syd on Mar 2, 2012 1:34:07 GMT -5
J, Thanks for your comments which are all good points to check out. The battery and rectifier are new, however I have not checked the charging system. There is a good spark on all three plugs, however it seems strange that the middle cylinder seems to produce a wetter sooty plug when the LH & RH seem fine. I opened the B8HS plugs out to 0.024", however no change. As stated earlier, the bike has just had a complete rebuild, therefore I would not have thought oil in the crank case could be a problem but I will check this out.
The rubber air inlet is not standard as the centre bridge has been cut out and removed - could too much air be causing the centre carb to play up because of this?
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Post by lc on Mar 2, 2012 1:47:39 GMT -5
Oil in the crankcase can show up at any time if its associated oil line check valve is seeping (allows oil from tank to drain through the pump and into the cylinder with the bike parked).
Modified stock air inlet? This could be doing some sort of resonance thing from the other carbs. On a CLEAN road try removing the rubber boot completely and run with open carbs and see what happens.
Also these bikes (500s) tend to like ignition timing in the 24-25 degree range.
Again, check your charging system as the alternator rotors fail often (especially if over revved in the past). A healthy charging system is critical to a good ignition system.
If you are running stock mufflers BE SURE baffles are clear and varmints (mice) have not built a nest inside too (center pipe?).
J
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Post by JA-Moo on Mar 2, 2012 2:46:16 GMT -5
Did you sync the carbs?
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Syd
2nd Gear
Posts: 189
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Post by Syd on Mar 2, 2012 4:30:54 GMT -5
Thanks for the comments - First, the pipes are new Japanese made H1 reproduction pipes that are now available. I will check the electrical charging side as confirmed earlier. All the oil lines and NR valves were stripped and cleaned in a ultrasonic cleaner, dried out and reassembled prior to the final engine rebuild. Carbs all synced and in fact we have even tried another set of H1 carbs with the same set up, however no joy.
We have tired the bike without the air inlet inlet manifold and it did seem to improve slightly.
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Post by Walms on Mar 2, 2012 5:48:07 GMT -5
I had a weak or suspect coil ground cause the bike to misfire mid rpm.
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Post by autofobe on Mar 2, 2012 8:09:18 GMT -5
Like LC said,these like timing at 25.With stock pipes & air cleaner you are likley still a couple of points high on your main jet.Pull off the boot & give it some air.Full battery is a must. Check the enritchener cables & make sure they are seating.Possible centre spark plug boot.How bout the plug it self?
Don, your the man here.
Brad
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Post by Walms on Mar 2, 2012 9:23:09 GMT -5
One thing Syd, you didn't mention if it clears out after the mid range problem... My comment only applies if the problem starts and remains, if it clears up, timing would be my first thought, jetting the 2nd...
More times than not, you'll be part throttle through that range so I'd leave the mains at 100 and reduce the pilot to 27.5 or 25 instead... See if that changes things.
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Post by zambia on Mar 2, 2012 10:27:34 GMT -5
I know it has been mentioned, but I am now leaning toward an incorrect fuel level or float height...or perhaps a sticking float valve. My stupid H2 had this problem for a whole year, and it was intermittent. Every now and then the valve would stick and the cylinder would flood. I finally figured it out when I realized that on any prolonged uphill climb, the bike ran way better -- on a prolonged descent, the plug would foul!
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Post by Jim on Mar 2, 2012 10:35:48 GMT -5
Funny Z, that story sounds exactly like what happened to my H2 a couple years ago, except I had a prolonged climb on the same ride I noticed the problem. I got 45 miles before reserve on that ride! I put the float needles in the lathe and turned off the rings that had worn in them, and they've been fine ever since.
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Syd
2nd Gear
Posts: 189
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Post by Syd on Mar 2, 2012 13:20:27 GMT -5
Timing has been set up as per Kawasaki factory bulletin 32 H-12 (H1-B ignition timing)
"There has been some confusion concerning the proper ignition timing of the H1B. It is the purpose of this bulletin to clear up this situation. Optimum ignition timing for the H1-B is 23 deg. (2.94mm) BTDC. However, as the graph below (not copied here) shows, if new points are initially set at 23 deg. they will soon retard 1 deg. because of rubbing block wearing-in, and then advance to more than 25 deg. (from contact erosion) where detonation causes piston holing and severe engine damage. Since engine performance varies little from 19 deg. to 25 deg., the factory recommends that new points be set at 20 deg. BTDC (2.23mm). From this setting the timing will advance to 23 deg. by itself in a matter of a few thousand miles. After 3000 miles, point wear levels off, so that when the points are adjusted after that time, they should be set at 23 deg. until they are replaced. If plug fouling and sluggish performance is a serious problem on a new H1-B, advancing the timing to 23 deg. right away may solve the problem, but it will be necessary to check and adjust the timing frequently during the first few thousand miles to prevent engine damage due to over advanced timing."
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Post by lc on Mar 2, 2012 13:21:28 GMT -5
Thanks for the comments - First, the pipes are new Japanese made H1 reproduction pipes that are now available. I will check the electrical charging side as confirmed earlier. All the oil lines and NR valves were stripped and cleaned in a ultrasonic cleaner, dried out and reassembled prior to the final engine rebuild. Carbs all synced and in fact we have even tried another set of H1 carbs with the same set up, however no joy. We have tired the bike without the air inlet inlet manifold and it did seem to improve slightly. This is a true head scratcher!!! When you swapped out the carbs were the enrichment plungers retained on the cables (The point being are they rigged properly with about 2mm slack in the cable at rest when installed in the carbs)? You still need to verify the charging system is healthy. However assuming it is: Is there full system voltage getting to the coils through the ignition switch? This value should be very close to what is measured at the battery. (Perhaps the contacts in the switch are worn and/or vibrate at the problem RPM)? Has the wiring between the points and the coils been checked? How about the point/condenser setup, have you tried an alternate set (especially the condensers)? Both Walms and I have asked: How does it run above the problem RPM area? The following is unlikely but possible: Your repro pipes are copies of early H1s. I believe they have the triangular baffle like the 69-71. The H1B muffler is unique to itself with a tubular baffle. As such the early H1s have quite a bit different slide/needle/needle jet/ jetting setup. You have effectively combined the early muffler with late carbs. Do you have access to a set of functioning early H1 carbs to try? J |
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Post by lc on Mar 2, 2012 13:27:17 GMT -5
The timing of the H1B was backed off from the usual 25 degrees because the factory was afraid the points would wear and advance the timing and damage the engine.
The actual fact is the rub block section (that follows the cam) continues to wear faster than the points. As such in service the gap actually closes and results in retarded timing.
You can ask anyone operating a "B" and I'm sure this will be confirmed (with accumulation of use the bike gets doggy as the points close/timing retards).
J
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