Honda-SOHC

Quote from: Underdog1 on September 01, 2018, 05:03:32 PM

So thankfully it seems it’s the washer on the oil tank drain bolt leaking rather than the oil hose, I’ll replace the washer at some point and see if it makes a difference.

The seats currently with a local upholsterer getting sorted, have received a Morgan carbtune pro so I’ll hopefully have the carbs dialled in soon (unable to work on it this weekend though).

The carbs are still dumping fuel seemingly randomly. I’ll put the bike away and switch the fuel off, tinker around with a few things and still no fuel dumped.. but when I come back into the garage the next day there will be fuel ok the floor. Sometimes it doesn’t happen for a few days and all of a sudden it justs dumps the fuel whilst sat doing nothing...

They floats seem ok, if they were at incorrect heights or whatever surely it would just overflow straight away?

I’ve had this recently on my 500. At first I thought I left the fuel tap on, but realised that the fibre washers in the petcock housing had failed and were leaking fuel through the tap down into the carbs. They would then overflow onto the garage floor.

Quick test is to lift the fuel tank, and place it on a flat surface with a tray under the petcock. If the petcock is switched off but fuel starts gathering in the tray, there’s the source of the problem.

Hope this helps.


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Thanks for the advice but as this has happened with a remote fuel tank too I don’t think it’s petcock related

I used wintersgreen and alcohol to soften carb boots too, worked a treat. I put them in a ziploc bag with the mix overnight.

Found that wintersgreen is expensive to buy in the U.K. (still a lot cheaper than buying new rubber bits though) - does anyone have a source for buying a decentish amount of the stuff (500ml+)?

Seemed ok on a 15 minute ride, came back in as the front brake was feeling pretty absent. I’ve got braided lines and a rebuilt caliper (reused the piston as it seemed ok) and new master cylinder, it’s been ok up until now but just felt like it wasn’t stopping the bike to the point where I met a car in the lanes and had to use the rear brake heavily to stop. Haven’t yet adjusted it as I can’t get the front wheel in the air without taking the headers off which means new crush gaskets, will get around to it soon though but I think it’s maybe more than just out of adjustment. It’s been bled properly and the lever is feeling hard.

Something else I’ve noticed is one of the oil lines has a small drip where the end fixing is crimped on. I take it this can’t be overhauled?



With regards to the carbs overflowing, I fitted the overflow hoses and since then not had anything out of them, can’t see why that would make a difference though.

UPDATE: just seen the price of those oil hoses 

Quote from: Underdog1 on August 26, 2018, 08:02:57 PM

I did fanny about with the peacock a fair bit during breakdowns

I should resurrect the old “Quote of the Month” thread



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Hah peacock! Bloody iPhone autocorrect always makes me post weird stuff 

The 12 quid ones are crap mate

Maybe I’ll stretch to the £18 ones then

Not had time to work on the bike today but quickly whipped the carb bowls off and fuel flows fine, embarrassingly I thought  the off and reserve settings on the pet cock were the other way round so half the time I was probably trying to start the bike in the off position!

Now it’s even possible that I ran out of fuel on the on position as I put a Jerry cans worth of fuel in  then continued to try and start the bike in the off position and I did fanny about with the peacock a fair bit during breakdowns, perhaps I filled the carb bowls up when I though it was switched off and then drove a mile or so with it actually switched off thinking I was on reserve until the bowls emptied again..

Anyway I can’t see any sparks at all at the points one of the spark plugs seemed loose and this is the colour they’re at

Check compression! Burned or leaky valves could be an issue.... build up of carbon on the stems can cause the valves to stay open once warmed up  (i had this issue back in the 80’s)... a re-lap of the valve seats transformed the motor. A compression test will help, when cold and also at running temp... keep going, you will get there.

Ok sounds easy enough, lapped all the valves and cleaned hem up during the rebuild but I’ll recheck clearances and do a compression test this week.. just need a compression gauge.

Are the cheap ones that come in a red plastic case (all over amazon and eBay) for about £12 good enough?

This kind of fault can be difficult to diagnose.... if its fuel starvation and you go through all the various components to ensure they aren’t blocked or damaged you will eventually eliminate it. For an electrical fault it will also be a process of eliminating the faulty component. If an electrical component is damaged, cracked, broken etc as it warms up it can lose connection then as it cools it reconnects.... so the only real way to diagnose it is to replace components one at a time until you solve the problem. The condensers are so cheap they should be changed anyway, if that works then its a cheap result... i would suspect the coils but it could be anything. Does it stop dead or begin to missfire and die gradually?

It dies gradually, seems like it’s not pulling properly and then stops acellerating but will maintain speed if I stay on the throttle, as soon as the throttle let off it dies.

I’m going to order new condensors, I assume the DS repro ones are ok? What about his repro coils?

Not too rich is it? Just chokes it when warm possibly.
What colour are the plugs?  Do they indicate rich setting or the opposite?

If rich,  crank it with throttle wide open to get more air in and it may go.

There are breathers into the float chambers of each carb that allow the fuel level to stabilise,  you can run into problems with filling if these are not all clear.

As a means of diagnosis,  when it stops you can open the throttle and spray some easy start into the carbs via the filters to see if it'll fire again straight away.

Just popped back out to ensure the battery was charging properly and it roared to life on the button no problems.

I did try cranking it with open throttle when I was stranded earlier and anything it seemed even more reluctant to start some how. By breathers into each float chamber do you mean the little tubes that join each carb bowl pair together (connected by a rubber tube)? I was meticulous in cleaning the carbs - soaked in carb cleaner, scrubbed, wire pushed through holes, multiple passes fully stripped down in a US cleaner, blew through with compressed air rebuilt with all new bits etc..

I’ll check the plugs out tomorrow, jetting is probably out and they haven’t been synced yet.

What’s a symptom of a dodgy condenser?