Project CBR250. Why punish myself.

[akeizm]

Hey guys,

Well I'm trying my hand at a project bike. I have done 2 cars before and I've had the itch to turn a spanner on something in my spare time. I bought this 250 off ebay with full knowledge it would be in a poor state. The plan is to strip it down, clean it up and rebuild the engine.

This will take a long time to finish unless I really feel like pushing mainly because of space. I have a full garage in my unit with my ute, 954, workbench and all my tools so I don't have the space to fully strip it. So I'll have to wait until I move (whenever that will be, I own this unit so selling will be a pain!). At the moment shes outside under cover and also gets covered up. So I guess I'll fix up the smaller bits until I can bring it inside and do the frame etc.

But, here are some pics for you guys.

Here she is in all her, unloved glory. Sun damaged and dirty


Another shot. The engine covers are barely scratched.


The ODO. Doubt these are the original K's but 1st time I've seen a reading that isn't all over the shop.


The new look for her when I'm done


Not a good start. Ripped the carbs off and found water in 2 of the intake ports. This would have been from the original fuel tank having no fuel cap. Would explain why the tank was completely rusted on the inside.


My work space


The 2 carbs that had water in them


Strange, one of the carbies has a hole in it. It has some resin in it though. How the hell do you get a hole there?



After cleaning out the bowls and vacuum chambers I install new parts (with 115 jets and 3 washers (original + 2 more) under the needles) and close them up


Cleaned carbs with airbox fitted. The boots that connect the carbs to the head are in good condition, must have been replaced...and their red! I have since put the carbs in a clean plastic bag for storage.


Now on another note, I picked up a full stainless steel exhaust for the 250 off ebay (not a chinese setup, well the can is I got it from a mate) for $80. I'm not sure if I'll use it or not though. Mainly because of the headers. They're ID is 24.5mm which is 1.5mm smaller than stock MC22 headers. Would the advantages of a 4-2-1 outweigh the slightly smaller header size?





Well thats my project so far. Who knows if I'll finish it or I'll part it out hahaha but over my christmas break I'm going to pull the motor out and see what sort of damage is in there. I'm expecting rust and a bent rod (from the previous owner telling me the carbs dumped fuel into the engine).

Cheers, Marc.

[jlyall]

Sweet that dirty water in the inlets does not look good, though you may as well set yourself a good project, perhaps a good excuse for porting if there is any rust in the inlets :0

[vitamine27]

why rebuild the engine? is compression low? just clean the carb, put good oil in it and pass it to some learner for it's next crash

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to bend a rod, you need a lot of stored energy in a high revving engine, then dip the whole show into water,

(you can actually run a heavy water mist into a fast revving engine, like from a garden hose, to dislodge carbon deposits from pistons, if car engine is overrunning from carbon deposits acting as glow plugs), lots of dirt bikes get drowned, then drained out with no problems after water crossings

[akeizm]

I want to rebuild the engine for experience. But I can't check compression or even see if it turns over if there is water in it (risk of anyway). But jlyall I was looking at doing that. There is some rust buildup around the valve guides from a quick glance.

[Aduro]

drain the oil, fill with fresh, pull the plugs and crank it to throw any water out of it. def take the head off at some point and see how mucyh corrosion and shit has built up around those two sets of intake valves though.

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also that full system will likely blow your engine up. I'll take it off your hands though

[Pronto]

Looks like a great learning experience. I hope to some day to do something like this.

Loving the Konica Minolta fairings!

[akeizm]

Yea I got them from Ozzy on his November deal. They're quite nice finish wise, good gloss finish with no peel, sharp paint lines and only 1 minor sticker imperfection (slightly wonky) but we'll just have to wait and see how they fit.

One thing I wanna get sorted though is peoples opinion on the exhaust, mainly the size of the header pipes being slightly smaller than stock.

[Aduro]

In all seriousness if your going to be putting a full system on your going to be wanting it Dyno tuned anyway if your doing things properly so the smaller diameter shouldnt matter if its tuned correctly. I'd say the lack of turbulence from colliding exhaust gases will make for better flow anyway. And if as you say their not chinese and are some jap manufactured ones then they may be that tad smaller for a good reason.

[akeizm]

Yea will have to get it dyno'd. Well the only thing that makes me say that it's not chinese as the finish of the welds etc look great and I had final collector expanded to fit the muffler quite a bit and it didn't crack. Where the flanges were welded onto the header pipes, I do need to clean up the weld on the inside a little.

[Aduro]

Azzdspaz had an identical system on his 250 today. Though he bought it with the bike so doesnt have alot of info on it. According to lane his carbs are stock and his bike seemed to run well enough (though I didnt ride it)