Autumn Rebuild

[heli_madken]

This was supposed to be a winter rebuild but overheating issues has brought it sooner.

The overheating issue I am sure was the Thermostat as it looks ancient. This is precisely why I am doing this rebuild, the bike was supposedly completely restored last year but I keep finding stupid things that havent been done correctly.

So here is my task list -

1. Remove heads, clean and check
2. Remove valves, check seats and general condition.
3. Replace valve stem oil seals.
4. Replace front and rear camshaft seals and gaskets.
5. Replace cambelts
6. Remove front transmission cover, general check, inspect water pump and replace gasket with Genuine Honda.
7. Remove rear wheel and check splines.
8. Re-paint exhaust.
9. Check carburetor float heights and replace float valves with original.

I have the heads off, everything appears ok except that there was a lot of unburnt fuel in cylinders 1 & 4, need some head scratching done. Valve seats look fine, the PO had claimed new oversize pistons fitted and they do look brand new with no step at all in the bores which look recently honed.

Next step it to clean everything up ready for re-assembly

Looks pretty bare at the moment -

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Lots of fuel sitting in No.1 intake -

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And in No.4 cylinder -

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Little bit of cleaning confirms pistons are new, I did a compression test a while ago which was a little low, hard to understand why with this setup -

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[heli_madken]

Anything to worry about? I can feel it with my finger nail

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[flyday58]

I'm gonna follow your thread, mate. I may be digging into my '76 Standard if I can't get it sold soon. Similar reasons due to the prior owner's neglect and rampant use of silicone sealer for everything he could think of. Clean looking GL you have there.

[heli_madken]

I am busy generally cleaning everything up and looking around for any problems.

One thing I noticed was the amount of gunk on the piston crowns and combustion chamber of all cyclinders. It isnt carbon deposits as the engine was only recently rebuilt, it is oily in nature and wipes off with de-greaser.

The engine isnt using any oil at all so its not from the crankcase. When I bought the bike I recall reading a recommendation from Randakk about Marvel Mystery Oil (MMO) so decided to follow his advice. Applied the instructions to the letter but only every second tank full. Recently I remember reading a piece from one of this sites 'Guru's' advising against its use due to the build up of oily deposits.

I firmly believe this is where this has come from, wont be using it again.

One other issue I have spotted when trying to lightly grind the valves seats to clean them up, No.1 and 4 exhaust valves had an excessive build up of material around the trumpet end of the stem which was preventing them from closing properly, after cleaning I have freed them up completely. I do recall finding the clearances set far too tight when I bought the bike whether the build up has settled on the valves whilst the clearances were tight I am not sure.

The seat isnt burnt as such but it is blackened, valve seat on the left has been cleaned -

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One question, why do I seem to have what looks like black silicone sealer everywhere, I thought the gaskets didnt need any extra sealing, or is this just a by-product of the gaskets themselves?

[Whiskerfish]

Having torn down a few after extensive MMO use I really doubt that is the issue you are seeing. As for that score I had a similar issue on the 77 engine I put in my dresser. I could not determine the cause of the score and it continued below the Piston at BDC so I split the cases to make sure I did not have a busted ring. I did not find the cause so i put it all back together and now have 30,-40,000 miles on it without issue. thread is here: https://www.ngwclub.com/forum/viewtopic ... 75#p668075

[scootsx2]

If you are chasing down an overheating issue, it can be more than just the thermostat. Have the radiator checked by a competent radiator shop. It may be clogged. It may also require a recore. Also check the water pump, flush the water passages in the engine, the fan and fan switch, and while you're at it, consider replacing the radiator hoses.

[robin1731]

Did you use premium fuel in this?

.

[heli_madken]

Having torn down a few after extensive MMO use I really doubt that is the issue you are seeing. As for that score I had a similar issue on the 77 engine I put in my dresser. I could not determine the cause of the score and it continued below the Piston at BDC so I split the cases to make sure I did not have a busted ring. I did not find the cause so i put it all back together and now have 30,-40,000 miles on it without issue. thread is here: https://www.ngwclub.com/forum/viewtopic ... 75#p668075

Thanks for your help, I am undecided about tearing apart the cases to check whats going on, the scoring looks to be worse on yours although mine appears to be coming from closer to the piston ring area as it stops short of the top of the barrel. I am prepared to pull the cases apart do you think it is worth it?

If you are chasing down an overheating issue, it can be more than just the thermostat. Have the radiator checked by a competent radiator shop. It may be clogged. It may also require a recore. Also check the water pump, flush the water passages in the engine, the fan and fan switch, and while you're at it, consider replacing the radiator hoses.

Thanks, The radiator was supposedly re-cored in the rebuild but it is hard to tell, pump does look new and I cant feel any play although I am going to strip it out completely, fan switch looks original so plan to replace, fan runs very strong, radiator hoses are new.

Did you use premium fuel in this?

Once only, why?

Thanks for your help everyone

[robin1731]

snip...….

Did you use premium fuel in this?

Once only, why?

Thanks for your help everyone

Extended use of premium fuel in an engine designed to run on lower octane can cause deposits to form on the piston top and valves like that.

.

[andorragl]

Extended use of premium fuel in an engine designed to run on lower octane can cause deposits to form on the piston top and valves like that.

How many types of fuel do you have in the US?
Here there are only two types 95 octane or 98 octane.
I always use 95. Unleaded of course.

[Whiskerfish]

We generally have 3 at most places. Our Octane rating system is different than yours I believe. our is like 86, 88 and 90 or 92
Some stations carry non ethanol but in the cities those can be few and far in between.

[ob1quixote]

If you are chasing down an overheating issue, it can be more than just the thermostat. Have the radiator checked by a competent radiator shop. It may be clogged. It may also require a recore. Also check the water pump, flush the water passages in the engine, the fan and fan switch, and while you're at it, consider replacing the radiator hoses.

And check your 7V regulator. As it dies, it can pass too little OR too much voltage to the fuel gauge and temperature gauge.

On mine, it sent me on a wild goose chase to figure out why my bike was overheating and I was running out of gas.
Turns out it was sending too much voltage, making my gauges read high.

Then it completely died, and found the source of my issues.

[heli_madken]

And check your 7V regulator. As it dies, it can pass too little OR too much voltage to the fuel gauge and temperature gauge.

Thanks I replaced the regulator with a GoldWingDocs item a few months ago, I am not relying on the gauge as I know they arent very reliable, its more that I could feel the bike overheating. I am hopeful that the thermostat was to blame as everything else appears to check out.

I have finished work on the heads for now, I used a chemical gasket remover rather than scraping. Cleaned the years of hardened deposits out of the exhaust ports and did some light grinding and polishing to improve the area, I know it wont make any difference to BHP but I enjoyed doing it and it has to help a little.

Left inlets as they are and re-ground all the seats -

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I have taken the engine out of the frame and removed the rear cover. There appears to be emulsified oil everywhere, the bike hasnt been out in the rain and the sump oil was fine, mystery

The PO had taken away the ratchet mechanism for the kick start and the external operating pivot itself which I am hoping to reinstate -

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The clutch seems incredibly dry, I should have thought it would at least have some oil around the casing? How is oil fed and scavenged to this area? The clutch itself did work fine however I am chasing down a 'clunk' that happens as the clutch finally releases, could be the 'half rotation clunk' but it does get worse as the bike warms up -

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Oh and shouldn't there be a grease nipple here -

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[Whiskerfish]

They say it is a oil bath clutch but near as I can figure it is just a oil mist. The grease fitting was a mid year change I think in 77. bikes before that did not have them. I really do not think it does much. Much better to just remove the final and do a manual greasing every time you swap the rear tire.

[heli_madken]

Thanks, I will take your advice, I will strip off the final drive and take a good look, moving the propshaft around it does feel fine nice and tight on the splines.

Tonight's job was to strip out the clutch, plates all look in good order and no sign of any issues at all and are coated in oil.

Springs though are not so good, the Haynes manual says wear limit is 34.2mm mine are all different lengths below 34.2mm the worse being 33.1mm so over 2mm shorter than new, I think it is definitely worth replacing these