Honda-SOHC

Hello! Sorry I've been away for so long ... my Kit Car was getting jealous of the attention the CB750 was getting, so started jumping out of gear (worn dogs on a Fireblade engine). So I spent the next couple of months replacing the engine and then enjoying the car  . Now winter is here (along with lockdown mk2) I am putting my efforts back in to getting the bike ready for summer 2021.

The good news is, before having to concentrate on the car the bike started pretty much straight away after I cleaned the carbs and put fresh oil in etc. I had an issue with cylinder 4 not firing due to the lead coming loose from the coil, but that was a quick fix.

Now although it's running which is great, it is very lumpy, so I am thinking my next step is to send the carbs off for a proper clean and rebuild.

What other adjustments/checks should I be looking to make on a bike that's been sat for 20 years? Valve clearances? Cam chain tensioner?

Thanks as always for your help!

Update 15.5.20

Hello! First of all, thanks for all the help so far! There really is a wealth of information here.

On Boris Johnson's orders, a few more weeks at home have meant good progress on getting the CB running! I even let her enjoy some sunshine!

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Apologies for the late update … I've been either in the garage or trying to keep a 3 year old entertained!!!

So, I'll summarise the progress since the last update …

I managed to clean up the carbs. All jets are clear and I've cleaned the bowls. I also rebuilt the accelerator pump as the diaphragm was hard and brittle. After reading every bit of info I could find (and then some) I decided it was a good idea to check the function of the accel pump before refitting the carbs. The new diaphragm gave a good squirt of water when tested assembled in the bowl … but I had a blockage in the nozzle of carb no. 2. Plenty of perseverance on cleaning the nozzles (and STP carb cleaner) later and all 4 were squirting as they should! New seals and gaskets and the carbs were rebuilt.

Fuel tank cleaned! It turned out that the tank was in pretty good condition, with just a few mild spots of rust. SO I decided to use a less aggressive method of cleaning and went for Bilt Hamber DeoxC. This worked really well! I would highly recommend it. The inside is now looking nice and clean. I also cleaned the filler cap and chain whilst doing it.

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Oil has been replaced. I drained the old oil from the crankcase, oil tank and filter assembly over a couple of days. New oil filter has been fitted and new oil put in. I put a very small amount of oil in to the inspection holes at the top.

Engine turned over by hand. Spark plugs out, I very nervously leant against the kick start with my hand … half expecting it not to move, half expecting it to feel horrible. I'm very happy to say it turned over nice and smooth. Very pleased!

Electrics checked. I fitted the new battery and tried the electrics … everything seems just fine! Every single bulb is working as it should! Horn works. Indicators flash (accompanied by a rather annoying buzzer. Do they all have these? If it's 'Honda' it stays. If not it's going!). Starter motor also works well (tried with the plugs out after refilling with fresh oil).

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Next steps:
Set and fit the spark plugs … fit the tank and put fresh fuel in and see if she wants to start!

Update 5.5.20

First of all, thanks for all the comments and advice.

Yesterday I decided to see what horrors lay waiting inside the carbs, and I was actually pleasantly surprised! There was plenty of varnish, but in general the insides were in pretty good condition. All jets seem to be as they should. I also manages to free the 2 stuck slides which had been 'varnished' shut with the help of the wife's hair dryer. Once they were heated they slowly slid out without much force at all! Very happy! I then used STP carb cleaner to remove the varnish from the metal parts and give them a good clean. I do think they would benefit from a complete service so I have reached out to Harpers for that (thanks for the recommendation Roy).

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Next on the list of things to tackle is the petrol tank. I have to say, when I cleaned the 20 years of dust off the tank, the original candy presto red colour in the sunlight is stunning! Though there are a couple of minor blemishes to the paint work I may need to remedy at a later date.

The main issue is … rust. Pics are attached. I am undecided how to tackle tis. I know some people recommended the POR15 sealer kit, and others steer clear from sealing and use an acid. Any advice in this area is welcomed! My main concern with the sealer is the horror stories I've heard of it going wrong, or even peeling apart at a later date. Again, maybe I should just take the plunge and give it a go! Also there is a small dent in the front of the tank which I may try and get removed using PDR, but I wouldn't be able to do this once the inside is sealed.

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Bikes done just under 22,000 miles, but has been stood since 1999.

Hard to tell if there's any leaks to be honest.

Might start taking them apart later and see what condition they're in internally.

Update 30.4.20

So, the past week has finally enabled me to make some progress on the F2.

I have removed the carbs from the bike. I really wish I had the knowledge to strip them down, clean them and put them back together myself … unfortunately I just don't! The throttle wouldn't actually open so I fear something has seized anyhow, so it's probably best that I let an expert work on them. That may hold me up though unless I can post them due to COVID-19. Any recommendations for someone to do this for me would be gratefully received!

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I've also been having a quick look inside the tank and the barrels using an endoscope camera. The good news is that the barrels look OK, but the inside of the tank has quite a lot of rust! I'll need to treat/remove this and flush the tank out before trying to start the bike.

I've also been doing some online retail therapy. New oil, oil filter, air filter, fuel lines, fuel filter and battery are on the way.

Thanks.

Yep, plan is first to get the engine running (well) first. Then sort running gear and finally spruce up the bodywork etc.

I'm planning to send the carbs to a specialist to be rebuilt … they are the one thing I don't fancy tackling myself! If needs be, I'll pull the engine out and do a bench rebuild.