My CRM tried to kill me today :(

[clint]

Hi all,

My bike was very difficult to start today which is very unusual. Usually if it hasn't started within a few kicks I put a new plug in and it will fire with 1 or 2 kicks but today even with a new plug it took me about half hour to start. I headed off to my local tracks for the enduro day, there's a bypass that is about 2 miles long just before I get there, about 7 miles from my house. When I got about a mile down the bypass the back wheel locked up. I think actual poo came out but I didn't come off. Managed to drag it off the bypass and onto the verge where a friend rescued me and the bike from.

I'm going to strip the top end down tomorrow to investigate the damage. Immediately after the kick was seized solid as was the back wheel in neutral. When I got home and it had cooled, the bike rolled in neutral and I pressed the kick with my hands once but it sounded like a bag of spanners being shaken. Also I noticed oil over the front of the crankase (behind front wheel) that appears to be coming from the bottom cylinder gasket or maybe exhaust, this defo wasn't there before as I had cleaned the bike well before putting it away last so would have seen it.

I will check the operation of the auto lube pump, cable etc but am lost to why it's seized if it's been getting oil which it appears to have been as I have clear tubes coming from the pump. Could anyone point me in the direction to look for likely culprits to the seizure as the bore was only done in November (obviously with new piston and rings) and don't fancy fixing it if it's going to seize again.

In the mean time I'm just hoping all I need to replace is rings and gaskets but won't know till I see inside.


Clint

[knackeredMk1]

Running lean because of air leak is no. 1. Lack of two stroke, run out of water, partially blocked jet, big end gone.

Difficulty to start might suggest bore was already damaged - less compression .

Running at high engine speed with very little throttle is a factor in some seizures. Honda didn't design the bike to be run like that. They designed it to be used with much taller gearing than is generally fitted now, thus lower revs and more throttle (oil) when cruising. I am increasingly coming to the opinion that owners who use very low gearing should adjust their oil pumps so the marking on the cam goes past the pointer on the pump body on full throttle. Not to have them matching on full throttle as per the manual. Or keep the speed sub 50mph.

[twistednuts]

When it eventually started, did it smoke more or less than usual? Did it sound ok?

Is the radiator still full?

Are you still able to use the same underwear, or did they need binning?

[clint]

[quote="knackeredMk1"]Running lean because of air leak is no. 1. Lack of two stroke, run out of water, partially blocked jet, big end gone.

Difficulty to start might suggest bore was already damaged - less compression .

Running at high engine speed with very little throttle is a factor in some seizures. Honda didn't design the bike to be run like that. They designed it to be used with much taller gearing than is generally fitted now, thus lower revs and more throttle (oil) when cruising. I am increasingly coming to the opinion that owners who use very low gearing should adjust their oil pumps so the marking on the cam goes past the pointer on the pump body on full throttle. Not to have them matching on full throttle as per the manual. Or keep the speed sub 50.[/quote]

I shall have a good look for air leaks, 2 stroke was brimmed before I left, water is still bob on maximum line as it has always been since buying the bike, I will have a look at the jets as I haven't cleaned the carb for a while, big end will be checked when removing the piston. I do think the bore may have been damaged before I left as it has never been such a pig to start. I was full throttle 6th gear when it seized on a dual carriageway

The gearing is low, 14:50, it came 13:50 but with a 14 tooth spare front that I swapped over.... The pump was past the line when I checked not long after purchase so I put this "right". How far past the line would you recommend? It was set quite far past previously, pretty much as far as it could go on full throttle. The plugs tended to be black alot though and since putting pump back to stock they've always been a nice colour, not once seen a white plug come out of it (got through about 4 this year). would that indicate mixture is fine?

[clint]

[quote="twistednuts"]When it eventually started, did it smoke more or less than usual? Did it sound ok?

Is the radiator still full?

Are you still able to use the same underwear, or did they need binning?[/quote]

It smoked alot more than usual. white clouds but it cleared to very little as usual. Defo more smoke than usual though when it eventually started. Something else I forgot to mention..... It was poor in 1st gear but seemed fine once going... which it has never done before either.

As for the pants they'll be ok. Actual poo coming out I suppose is more hypothetical poo (never let the truth get in the way of a good story). was pretty bloody scary....

[clint]

Oh and once it started it sounded fine. haven't checked inside the rad but will check. what would an empty rad-full reservoir indicate? failed water pump I assume?

[knackeredMk1]

This is my opinion - Setting what level the oil pump goes past the manual settings is very much a guestimation and no one can replicate the oil supply that Honda made when building these bikes unless they use pretty similar gearing to the original settings.

Those of us who use lower gearing for more flexibility when greenlaning do not generally go faster than ~50mph on the roads and so do not stress the engine much. Those who use lower gearing when racing only use high speeds at full throttle and then for very short lengths of time compared to on the road. For your own safety you need to recognise that a bike with tyres that are designed for mainly off road riding are not going to stop a bike on the road anything like as quickly as if it had road tyres on.

I think it is a matter of 'wanting your cake and eating it' in that if you want low gearing for off road flexibility then you cannot thrash a CRM on the road and you must limit your speed. To go faster you must make the gearing taller and more comparable to stock.

[knackeredMk1]

Empty radiator would probably mean a leak or cylinder head gasket gone.

[clint]

I've been meaning to put the gearing back to stock since buying the bike but not got round to it. I know my bike would never stop if I needed it to on the tires it has so usually am pretty careful but the road was empty so opened her up. Could high gearing and full throttle have seized the bike? If so I'll be putting it back to stock gearing (or close to) once repaired as I ride more on road than off road

[twistednuts]

Just wondering if there might of been a head gasket issue with the water in radiator.
Was it white smoke or steam?
If water had got in the combustion chamber it might of rusted the bearings slightly if bike has been stood a bit.

Just clutching at straws really, its just the fact that it was unusually hard to start which might give a clue to why it siezed.

I ringed my old mk2s neck pretty much most of the time, flat out on motorways sometimes and it never was a problem.

It deffo sounds like there was somet amiss, cos youd hardly set off before it happened

[clint]

[quote="twistednuts"]Just wondering if there might of been a head gasket issue with the water in radiator.
Was it white smoke or steam?
If water had got in the combustion chamber it might of rusted the bearings slightly if bike has been stood a bit.

Just clutching at straws really, its just the fact that it was unusually hard to start which might give a clue to why it siezed.

I ringed my old mk2s neck pretty much most of the time, flat out on motorways sometimes and it never was a problem.

It deffo sounds like there was somet amiss, cos youd hardly set off before it happened[/quote]


White smoke defo not steam.. It had been stood a week but I've had no issues starting it (with a brand new plug) when it's been stood for a week before.

I agree that the hard starting has got to be related... even if it's just something (rings maybe) had gone last time I went out.

[twistednuts]

It all might become clear when you strip it down.

Hopefully not too much damage done

[clint]

Yeah hopefully not. Don't fancy spending most the value of the bike on fixing it! I've already eyed up a cylinder & piston on ebay for £180 or make offer so worse case scenario may not be that bad (compared to cost of a rebore/cost of piston kit).

a little bit of luck and it's just rings.... but I won't hold my breath..

[knackeredMk1]

My guess is, and it is a guess, as I can't see the damage and I wasn't there when it happened, that the damage had been accumulating over a number of rides and this was the straw that broke the camel's back.

The exact cause of things can be very hard to determine and lean running for what ever reason may well have been a contributing factor. Running a bit rich with a little too much oil may limit slightly peak power but it is never going to reduce engine longevity whilst running lean with too little oil is.

Cost of rebore ~ £40. Cost of Wiseco piston kit ~£100. Total ~ £140
Cost of that barrel and piston ~ £160 + you need to get the power valve which is on eBay at ~£40. Total ~£200 for a second hand piston, rings and an unknown bore.
No brainer

You have also got the gaskets and new little end on top of course..........

[clint]

Knackeredmk1... I really think you've hit the nail on the head with your "guess". I thought a rebore would cost much much more than that you've made my day at £40 and I will be "unwatching" that cylinder. Was going to ring SEP tuesday and enquire about the price.

I'll get some photos uploaded once I have the cylinder off so you can see exactly what I've done but at £40 for bore and £100 for piston I'm not half as worried as I was before

Thanks for all your help and advice.... If I'd followed your advice in this thread /viewtopic.php?f=6&t=8639 it probably would have not happened (I never did check the piston/bore)