Had my crm ar for 10 years! Never missed a beat until now!

[Crmsam]

]Hi all struggling a bit with the old girl! After sorting a when on demand problem (power valve cables had rusted to the butterfly!) she ran the best she had for years power all the way up again! Big big smiles! Then suddenly thud and she stalls wasn't fuel to instant! And would not start again burbled a few times so went back to where I was (power valve) all looked good! Checked spark, all good, thought fuel? so carb cleaned no joy, so had carb off and sonic bathed back on and still no joy! Checked spark with spark indicator still good, stuck a little brake cleaner in the cylinder and it tried but no where near started! Did a compression test down to 65psi 90 when I wetted the rings with fuel!! That's where I am! I'm no mechanic but like having a go but need help! Is that a low enough compression not to start? Please help as she has not been out for a year!! And I'm all outta ideas suspect a head gasket change possibly??
Kind regards Sam

[Gammakeith]

If your compression tester is OK then, no, that's insufficient compression. My AR was very hard to start on 140 psi which what I was getting with worn rings and a scuffed bore. The "thud" you mention does sound like it might have seized. Regardless, if the compression reading is correct (always worth checking your gauge on another engine) then you will need to strip the top end down and investigate. The AR has a Nicasil bore so its a right pain if the bore is damaged.

Godd luck!

Keith

[knackeredMk1]

You haven't got enough compression. What you have described is very much like a bike running lean before seizing. Two strokes run their best when bordering on running too lean. I suspect that for whatever reason your bike was too lean and the engine suffered the consequences. You will probably need a new piston etc and possibly a replate of the bore.

If you do need a replate get the bore taken out to 66.5 or 67.0mm as the original 66.4 is difficult to find pistons for.

You also need to find what caused the running lean.

viewtopic.php?f=20&t=5267

[Crmsam]

Hi thanks for the info!! The bikes not siezed I will take a look at the head is the top end easy enough to get to or is it an engine out job?

Kind regards sam

[knackeredMk1]

It hasn't seized solid but it looks very much like it tried. If you find that the piston has smeared over the piston rings then that is what has happened.

Taking the head off is relatively easy, but you have to take quite a few bits off first. You don't have to take the whole engine out even to get the cylinder off. If you look up the exhaust port that will give you an idea as to what has happened and if the engine has done a partial seizure. Usually seizures happen on the exhaust side of the piston as that gets the hottest.

[Crmsam]

Thanks again time and help!! I've had the exhaust off checking and attempting to clean and ckeck movement of the power valve! What do you mean by smearing? Piston looked OK I thought? I also checked it the other side as I had the reed valves out too for inspection?

Thanks Sam

[Gammakeith]

Hi Sam,

It will be easier to strip out and clean the power valve properly with the barrel off which you really need to do to check the top end properly. Low compression means something is definantly amiss. Power valves need to be free moving else put it will put a strain on the expensive ECU. As knackered says, you can often see evidence of a partial seize on the sides of the piston or on the ring lands. If you lower it so the rings are visible then you may see signs of aluminum from the piston being pushed past them. This prevents the rings moving correctly and results in lowered compression. Nikasil is very tough so you may be lucky with the barrel.

Keith

[Crmsam]

Hi kieth thanks for the heads up again! I will strip down to investigate then! Do you know how to post pics so I can show you my progress and get your thoughts? Kind regards Sam

[Gammakeith]

Its a pain as you need a photo hosting site. I previously used Photobox but they blocked free use. I haven't investigated since.

Keith

[Crmsam]

That is a pain!! I found a engine break down on line so that's a good start! Will get the gaskets etc from leisure trail too as I need a few extra bits as well! hopefully get away with the bore like you say! Any extra bits I can do while I'm there?

Kind regards Sam

[Gammakeith]

Check crank bearings and run a leak down test (if you have the facilities to make it up) to make sure your seals are ok. This could be important if you can find no reason for a seize (assuming that is what happened). Leaky crank seals on the magneto side could suck air and lean off the mixture.

Check balancer shaft and bearings as they are weak on these bikes. Strip and clean the power valve.

There may be other things.

Good luck!

Keith

[fallenmikethebike]

Hello, just happened to passing and read this thread. Nobody's mentioned the inlet manifold!!. They are a really well known source of unfiltered and additional air entering the inlet tract, and usually eventually leading to, well the same as above. Good luck.
Mike

[knackeredMk1]

Very long time no see Mike! How's it going?

[fallenmikethebike]

Hi Steve,yes mostly good thanks. I'm still, [ well when allowed CV19 permitting] kayaking, and enjoying the challenges. My garage is now quite an embarrassment, just one little Honda 110 Wave sitting out there sulking. Now wall to wall kayaks. The little scooter is transport for when white water kayaking, as we might finish 5-10 miles away from where we started. So the little Wave gets parked up at the get out point, and then I hop on it back to the get in point to pick up the van. It always makes me giggle riding it when I think of some of the bikes I have had in the past.
I see you're still fielding the questions, and are still attracting new members, which is good.
I saw my old CRM in the bike shop a while ago, poor old "Lill" looked an absolute mess from the outside, and the internals were even worse off apparently.
Loads of money to put her right.
To say I haven't missed Green laning, wouldn't be entirely true,but do not miss the agro that can and does go with it. However, even the seemingly inoffensive paddling of a kayak down a river can seem to get some people extraordinarily hot under the collar, go figure !!
I hope you are well? Any plans for riding again?
Regards.
Mike

[Crmsam]

Hi all again i see a few have given me other leads to look at! I have stripped the engine removing the head and the bore!! Here what I found!
1. The h gasket seemed OK (I know it would be hard to see a fault!) but the front threaded stud bolt was very oily and carboned up could this of been where pressure was going?
2. I put a little fuel on the crown of the piston expecting it to seap past the rings it didn't and sat there for over half an hour!
3. I removed the bore seem fine can still see the honeing
4. Measures piston looked for I d marks nothing really present my caliper said 66.5
5. Rang leisure trail apparently no original piston or aftermarket kits available it's a re bore to accept a 66.5 piston
5. 400££ to sort that little lot out! Ouch
6. Could it be that my piston is a 66.4 and my calipers are out or could the piston of already been done! (pretty sure that's not the case as I've had the bike for 10 years!)
7. Considering trying just new gaskets before I go for the rebore would you guys try that first?
8. Oh and investigate the few other bits people have mentioned!

Kind regards Sam