Bike project - 1975 Honda twin

bainbridge

bainbridge

bainbridge

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Joined
9 Dec 2009
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Location
Bristol
Bought a 1975 Honda CB200 twin last week. It's stood in a garage for 23 years. Covered in dirt and cobwebs.

The plan is to get it running, then get it roadworthy, then make it look nice.

This weekend I gave it a clean.

The tyres are holding air.

Petrol tank contained stinking fuel and is rusty.

I squirted a bit of engine oil in each cylinder and the engine does turn.

Removed both carbs and they are full of varnish and goo.

I've ordered some chemicals to clean the tank and carbs, and gaskets for the carbs.

And bought a new battery.

A fair bit of work needed before it's time to try and start it.
 
I owned a CB250 of a similar vintage, a bit earlier, in the nineteen seventies, revved like a monster. Top end strip down probably essential in my view.

A very good looking small twin of good pedigree.
 
Hi all

Thank you everyone for replying, I have been taking some pics as I go, but needed to get around to working out how to embed images without using BB.

Here she is when I got her:

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I've done a fair bit on the bike over the past couple of weeks, consisting of an hour or two after work in the week and the odd afternoon on weekends. I'm not a mechanic and this is the first bike I've had since I was 17!. Having said that, I am pretty handy with spanners and and am sometimes good at repairing (bodging) things.

The battery was crusty and empty of electrolyte, and dated 1996 :)

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After fitting a new battery, I was amazed to find that all the lights and electrics work except for the front brakelight switch.

I removed the carbs which were covered in varnishy goo. One litre of high strength nail polish remover later, they cleaned up nicely with a bit of elbow grease. Here is a pic of one of them done, to show a before and after:

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I also splashed out on 2 carb gasket kits for £8 each.

The fuel in the petrol tank stank, and the petrol tap showed signs of leakage. the fuel lines were solid and disintegrated upon removal. The tank had a fair bit of rust in it:

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After a bit of googling I bought 500ml of caustic soda, 500ml of spirit of salts, and a massive pair of gloves that go up to the shoulders:

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After a few days of the tank being sat outside full of chemicals, and flushed out and dried, most of the nastiness is gone:

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To be honest I was hoping to make it perfectly shiny and new in there, given the amount of work I put in, plus being out there in the rain doing it, but it's much cleaner and IMO good enough. Progress beats perfection!

A new fuel tap (petcock) gasket cost £4 and 1m of 5.5mm fuel hose was £5.50. For the fuel tap bowl gasket, an O ring from my own store of assorted O rings was a perfect fit.

The throttle cable had snapped. It's a 1 into 2 arrangement to pull the throttles in both carbs, and from what I could see was not serviceable, so I bought a new one for £15:

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Diddums said:
Maybe I should join you :cool:




@bainbridge have you got a Haynes manual?


I'd also find a Honda workshop manual if you can.
Click to expand...
Yes, I was given a box of bits with the bike and it contained a Haynes manual. Also, under the seat I discovered a document compartment and inside was a pristine Honda owners handbook. I don't think anyone ever knew it was there. It's really handy because it shows seemingly obvious stuff like ignition key positions and what does and doesn't work at each position, and other things that would not appear in the manual.
 
@bainbridge if you're not in a hurry, fill that tank with white vinegar and leave it for a few days, that's how I cleaned mine. Might not do much but for the few quid a bottle of vinegar it might surprise you. Make sure you get the 5% stuff though, the 4% stuff also works but not as good.

Then get some POR15 in it to seal it up for life.
 
We have a runner!

Refitted the carbs, tank and airboxes and while she failed to start using electric start, she started straight up using the kick starter.

The left cylinder has a loose stud for the exhaust mount and is blowing.
The right exhaust is blowing due to a hole at the bottom of the downpipe.
One of the carbs leaks from the overflow.
Speedo mph does not work, but odometer is working.
Rev counter moves from 0rpm to around 2000rpm and hovers around there at any revs.
I pulled the previously cleaned spark plugs after getting the engine warmed up and they were black.

So it's running, but the engine needs attention, as someone said here a top end strip down might be in order.

Instead of focussing on that I've been buying shiny bits from ebay :)
 
Update.

Fixed speedo. The wheel end of the cable was covered in crusty grease. Cleaned and oiled the cable and works fine.

Replaced exhausts. Controversial, but after discovering how hard it is getting hold of good condition replacements, I bought a 2-1 custom exhaust. So we're no longer going for a faithful resto with 2 separate exhausts, but it's a lovely exhaust and fits perfectly. Also needed to helicoil and replace the exhaust studs.

Front brake is a cable operated affair and was seized solid, pads, mechanism, pivot, everything seized. It's all stripped before refitting with new pads and cable, I'm respraying the caliper body and a few other bits.

Hopefully it will soon be a fully working bike.
 
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