Help! I killed my CRM250 on its first outing!

[Mutley]

Hi guys,

New CRM250AR owner here from Hampshire in the UK.

I bought it as a winter commuter - I can go part X-country to work, and I was sick of the nutters on my commute.

I spent this morning green-laning - can't believe how well this torquey 2-smoke is suited to that. Then a blast home down the A3 when disaster struck. Sudden loss of power followed by a rear wheel slide. I've owned 2-strokes back in the day so I knew what it was.

The metal spigot that the water hose attaches to the cylinder head with had come out (seems a very strange interference - or in my case no-interference - fit?) and there wasn't a drop of water left in the bike.

Any advice on my options for top-end re-build? If I thought there was nothing to do but lift the barrel and head, check the need for a re-bore and get a new piston, rings and small-end I would do it myself, but I guess if I go that far perhaps I should get the crank and crank seals checked too? I don't really have the time for the re-build though, and would quite like to trailer the thing to someone who can do it for me. Suggestions please!

The bike seems to have a genuine 8k km, with lots of paperwork to prove it, also bills for two top end re-builds which makes the seizure a bit of a PITA.

Still love the bike and even with the inevitable repair think it was a bargain.

Also feel a bit like a kid who broke his toy train on Christmas day. . .

[knackeredMk1]

Sorry to hear your problem.

There should be hose clips on all water pipes.

Two top end rebuilds in 8k doesn't seem feasible without unusual occurrences. CRMs have been known to go 20k km + without top end attention. Any reasons given for the rebuilds by the previous owner?

The AR has a plated bore so that will be needed as opposed to a rebore. There are lots of articles that you need to read - viewforum.php?f=20

Whilst you have it apart you should check the crank, mains, etc.

CRMs (and all 2 strokes) can get fragile when you go at high speeds and have dropped the gearing to make it easier off road. High revs and small throttle openings (little oil) do not make good bed fellows..........

[fallenmikethebike]

You could ask the guys at Normandy Motorcycles if they'd sort it, they are CRM owners themselves.
01483235388.
I have no affiliation to the shop, other than I take my bikes there for their yearly MOT.
Mike

[Mutley]

Many thanks guys. Clearly lots of expertise and friendly experts on the site. I thought the two top-end re-builds were a good sign, but maybe not. . .

And I'll give the boys at Normandy M/Cs a bell fallenmike thanks for the tip.

[gregorious77]

If you end up breaking it first dibs on the PGM pretty please!!!

[fallenmikethebike]

The high temperature light didn't come on?
Perhaps also look at the myriad of threads about fitting a fan, always helpful on AR's.
Mike

[fallenmikethebike]

If you end up breaking it first dibs on the PGM pretty please!!!

Vulture
Mike

[helisupp]

2 rebuilds in such a small mileage, something sounds suspect to me, barrel should last 40k with 1 piston and rings replaced during that time.

Even though it seized it may not have written off the bore, I know that sounds strange but its true with these plated bores. There will be nothing wrong with the crank or bearings.

Hopefully you will be able to clean the aluminium of of the bore with acid and then put a new piston and rings in.

I am surprised it locked up with no warnings.

If you get stuck I have a very good complete spare AR barrel in stock ready to fit.

[Mutley]

In answer to the high temp. light and cause of seizure. I think that first the bike lost all its coolant while I was green-laning, and then came to grief getting a good thrashing riding up the hill to the Hindhead tunnel into a gale on the A3. First it lost power, then seized, then free'd up and re-started, but judging by the state of the plug there was quite a bit of burnt alloy in there. I was going through a lot of water off-road, otherwise the clouds of steam might have been a give-away. . . I'm also assuming that the temp warning light is in the water circuit - no water no light?

The thing that really puzzled me is the little L-shaped spigot with the small hose that enters (exits?) the cylinder head. That's where the coolant was lost - but not because the hose came off it, but because the spigot fell out of the head. It looks like an interference fit, but that would be v. insecure I would have thought on an aluminium head that was expanding and contracting all the time? (going to try to point at a pic of it here: http://media-cache-ak0.pinimg.com/origi ... b0180c.jpg ) I pushed it back in the hole in the head it came from, but could quite easily remove it again by hand. Something definitely wrong there, and aside from sorting the other top-end damage, I will need to find out how that coolant pipe spigot should affix in the head before I ride the bike again.

Thanks for the words of encouragement helisupp - I think I may strip the top-end down and take a look. It did strike me that a plated bore is much harder than a light alloy piston. Any good threads on the right routine for getting the barrel off while the engine is still in the frame?

[fishtail]

well I managed to get the head off in frame - an that was my first go... - u just have to take all stuff off.. rad - power valve servo - oil tank.. etc - suggest u take photo's! ( routin of rad pipes - and servo mountin especially - oh and coolant overflow bottle!

of course u have to protect the crankcase from debris ( gudgeon pin ) goin down there..

actually when my top end siezed - I decided to do whole rebuild - an I did find quite a few aluminium particles in the big end... ( no idea what the guys in the know have to say about this...? )

The pipe that u described sounds like carb de-icer feed - I put a short tube on there.. and made it a dead end... also required jubilee clips!

altho if u are getting hot like me ( I am alsways boiling over here.. ) - I am planning to re route that out from cylinder head back round to the rad inmput on the bottom RHS ... - ie bypassin the carb - but still gettin the water flow out the top of the cylinde head back to the radiator...

hope that helps!

[helisupp]

I think you mean this lower pipe on right hand side, going from head to bottom of rad.

[gregorious77]

My pipe there was loose on the spigot when I picked mine up and I secured it better asap.

[Mutley]

I think you mean this lower pipe on right hand side, going from head to bottom of rad.

Hi helisupp, Yes - just visible in the lower centre of your pic.

[helisupp]

I suppose you could clean everything up and put it in with metalset.

Assemble with a warm cylinder head so that it cools down on the adhesive, make sure you roughen pipe up to get grip.

[fallenmikethebike]

I suppose you could clean everything up and put it in with metalset.

Assemble with a warm cylinder head so that it cools down on the adhesive, make sure you roughen pipe up to get grip.

+1, you have been serially unlucky there, just don't go picking up any odd looking sticks you see laying about for a while .
Mike