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a.craw4d's CBR 250


a.craw4d

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I can probably count the number of hours on my hands that I've ridden a 2 wheeler. I learnt to ride a mates ct90 when I was about 9 or 10, and have had a bit of a play in a paddock on a cr125 in the late 90's. I've always liked the idea of having a bike but never done anything about it.

Until recently.

I did a deal with a mate, I made him an oil burning device and he gave me a weapon to try kill myself. We are both very happy :)

So it's a 1988 mc17 Honda cbr250. It's been sitting in a shed for around 8 years, it was jump started about 4 years ago where it broke the throttle cable. Has collected dust since.

I'll continue soon. Pic of this stunning example.

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And when I picked it up last week.

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When I picked it up it had a flat front tire, the front brakes were jammed up and no battery, needless to say it was a bitch to get on and off the trailer and into my garage.

Over the weekend the kids both sat on it and made vroom vroom noises, the misses even sat on it and admitted she likes the bike, just not the idea of me riding it (fair enough). And I pulled the front calipers off and pumped up the tire, yay now I can move it.  

So out into the sunshine and some space to see what I've actually got myself into, I chucked the fairings and seats back on.  The fairings are fairly rough with broken clips and cracks but hopefully I can get them to stay put for a while.

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Tank has had a repair in the past, obviously it was too much trouble to remove the fairing so it just got melted and distorted. If you look closely you can see the matty b spray can wasn't applied by a professional either.

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That redline though, wow.

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While I had it out I hooked up an old car battery with jumper leads and checked the electrics. All the lights and horn worked, I gave the start button a poke but the battery had no juice for that.  So battery went onto the charger and I set about pulling almost all the fairings off just so I could check the essentials, water, oil and general poking around and wondering how everything fits in there. It has oil, good. Has some sloshy stuff in the tank that smells like petrol still, good. Water? No idea how to check this, can't find a filler cap but the overflow had water in it, good?.

By this stage the battery was showing some charge so I hooked it up and gave it a crank.

It cranked over nicely but no signs of life. After some more cranking, head scratching and then noticing there was a fuel valve I turned it on.  Crank again and it starts showing signs of firing, have another check over the bike and notice now that petrol is dripping (a lot) from the carbs.

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Turned off the fuel valve and started mopping up petrol with a rag. Against my better judgment I decided to give it another go anyway.

 

 

And it starts!

 

And starts to rev up fast!

 

Quickly turn it off and come to the conclusion that when the throttle cable broke it must of been open.  So stoked that it appears to run nicely though. I started it half a dozen times throughout the day and it started first pop each time.

 

I think I'll aim to get this wof'd then work on tidying it up and restored to its former 80's spec glory.

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Feel free to tell my what I'm doing wrong.

 

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On 30/07/2018 at 20:56, kicker said:

 I think these have cam gears too from memory.

Yep gear driven cams.

 

I bring this up to date, today I pulled the petrol tank off so I could have a look at the carbs and remove the throttle cables.

Pulled the tank off and found the radiator fill point.

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It's full too which is good.

Pulled the airbox off, actually pulled it off because it had no bolts holding it on. One was sitting in there with the thread broken off.

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Threaded piece was loose in the carb flange luckily.

Not sure if you can see the piston things in the intake but should they all be sitting partly open?

Also the throttle butterfly's were closed and the throttle wasn't jammed open so any ideas why the motor would rev up when started?  It got up to about 6k before I shut it off. I did notice a little hose on the head going between cylinder 2 and 3 was cracked and falling to pieces.

Also any pointers to getting the carbs off?

I've undone all the little hose clamps on the 4 rubber inlet things that join it to the head but can't get it to move..

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Na carbs haven't been touched. When it was jump started about 4 years ago it ran and idled fine. 

I'm thinking maybe carbs are leaking fuel inside as well and that little hose I mentioned is letting air into 2 cylinders.

I'll keep trying to wiggle the carbs out so it can set them up on a bench and see what's happening.

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Must be a stuck float or dirty float needle valve?  You have to be pretty brutal to get carbs off, pull one side up then the other, sometime you need a pry bar, and put some rubber grease on the boots when you refit them

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I'll keep plugging away at getting the carbs off, I undid the 2 screws by each intake trumpet and removed the top plate piece. Now the 4 carbs all move a bit on their own but they're all joined by little bits of loose tube, I'm worried bits will fall out and I'll have no idea where they came from so I might chuck the top plate back on.  Will google for a CBR type forum for some tips and tricks.

 

On the fairings side of this I'm going to try strip the matty b off so I can see the original paint lines and get new vinyl cut.  I think most of the original markings are underneath.

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Just none of the writing appears to be there and so far I haven't found anywhere that can supply an original decal set.

I won't bother trying to smarten up these fairings, some zip ties will keep them secure until I find a good set. The left front was really rough and bad fitting, once removed it turned out to be a bad fiberglass copy.

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Probably best to learn to ride with these ones anyway.   

 

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Got the carbs off. You can see that little hose I mentioned.

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The rubber connector pieces onto the head don't look too flash either so I'll replace those.

Started pulling carbs apart and found why they were leaking.

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That's the float bowl seal, appears to have cracked and shrunk.

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The others all had cracks and gaps in them. I'll replace all the screws as well as most were well used and abused. Had to cut some to use a flat head screwdriver on them.

I'm slowly making a list of bits I need.

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The floats look clean and move freely. I'm not going to strip this side any further.

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Flip it over and open up the other side. There were a couple of missing screws on this side which ment 1 carb was just kind of floating there.

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Also read a tip to give each screw a good tap with a hammer before trying to undo them, seemed to work a treat, all but the really rounded head ones undid. The I got a bit more serious.

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Yes I use the makita tool set when working on carbs.  Put a cut in the fucked screws and undid them.

Diaphrams all look good. The springs are rediculously long but if that's what's ment to be there then I'm not going to argue.

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I won't go any further from here. Just a good clean, new seals and screws.

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I've found the carb float bowl seals on ali as well so I'll chuck those in with my order.

While the petrol tank was off I thought I'd empty and clean it. Gave it a good shake first and I could hear bits rattling inside it.

About a liter of brown petrol came out and left this in the bottom of my oil change tray. I was actually expecting more water than that.

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I should mention that clean petrol ran from the fuel line before I test started the bike. Giving it a good shake just mixed up 30 years of crud from the bottom of the tank.

I'm getting a mate to steam clean the inside for me. Then I'll just chuck petrol back in it. Will keep an eye out later for a tidy tank.

 

When fluffing around with this yesterday the back brakes somehow started jamming up, and I didn't even touch them.  So I guess next up is rebuilding the front and rear calipers.  Wish me luck.

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Man I love CBR250s, my first bike was an MC22 and by the time I sold it I could ride the wheels off it. I've got an MC19 engine in the shed that I'm planning to build a custom around. When I was stripping it and trying to remove the carbs I could lift the entire bike by the carb haha but yeah all the rebuild kits and even the rubber mounting boots are on aliexpress; you can get pistons and ring sets too haha.

My first bike had an 'OVER racing project' muffler and on song it was still one of the best sounding bikes I've owned. Definitely look at an aftermarket muffler. Looking forward to seeing this thing restored to glory!

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Not much progress.

Removed all the brake calipers. The rear pad shim doesn't seem to belong here.

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Got the rear piston by pumping it out while still attached. Had a little bit of crap in it.

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Managed to pump the fronts most of the way out before I ran out of fluid.

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Hopefully I can clean up the pistons ok and just replace the seals. Will have more time tomorrow to try get these all apart and cleaned up.

Anyone got a piston removal tool I can borrow?

 

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Made my own piston removal tool.

A bolt, few nuts and small nails to suit.

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Turn until it jams up and turns the piston. Easy as.

Pistons all cleaned up nicely with bit of scotchbrite.

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The rear piston has a bit of pitting but mainly above where the seal sits so hopefully it'll be ok.

Before and after scotchbrite.

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Just waiting to hear back from the local Honda people if they can get new caliper seal kits now.

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