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

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knackeredMk1
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Re: Had my crm ar for 10 years! Never missed a beat until now!

Post by knackeredMk1 » 13 Feb 2022, 14:55

Max CRM - get your cylinder rebored to fit a Mk1/2/3 piston and then get it nicosiled. The reason to get it rebored id so that you can get replacement pistons much more easily. OR you could just get it rechromed to the original setup. Witha new piston and rings it will feel so much better.

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

Post by MaxCRM » 15 Feb 2022, 09:15

777amia wrote:
11 Feb 2022, 16:51
Should still run and rev with 110 psi. Was the test done with the throttle fully open?
How does it not rev? Bogging?
The score doesn't look too bad, I've had bikes which looks far worse up there and run half decent. What's the rings look like further up the piston?
Might be worth checking vacuum pipes as one is for idle control. The valve looks clean to me, remove cables and check its free moving, which I think it will be looking at it.
Thanks for the replies.

I noticed a vacuum pipe was off, but wasn't sure if it was from when i'd started the mini strip down.

Before i whip the head or barrel off I think i will re-assemble and give it another go.

Either way, that compression is not great, so will have to look further. I'll report back on the tope end condition, as would love your thoughts.

Thanks all!

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

Post by MaxCRM » 16 Feb 2022, 22:16

Hi all,

No luck with starting the after re-checking all the vacuum pipes, so it is top end strip time.

I've removed the head and the piston has no bore/sizing marks on it, so I assume it is standard. Not been able to measure it yet.

I thought i'd read on here that you can remove the cylinder with the engine in the frame on the AR - is that right?

If so, what is the easiest way? The exhaust studs seem to be fouling on the frame down tubes - do you need to remove the exhaust studs, or the power valve cover(?) on the front of the cylinder, or is it an engine out job? I ran out of time in the garage tonight to properly investigate so any tips for tomorrow greatly appreciated.

Thanks!
Max

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knackeredMk1
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Re: Had my crm ar for 10 years! Never missed a beat until now!

Post by knackeredMk1 » 17 Feb 2022, 14:59

CRMs are much harder to work on than MX bikes but you should try fixing an MTX!!!

Easiest way to get the cylinder out is to remove the head studs.

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

Post by MaxCRM » 17 Feb 2022, 19:06

knackeredMk1 wrote:
17 Feb 2022, 14:59
CRMs are much harder to work on than MX bikes but you should try fixing an MTX!!!

Easiest way to get the cylinder out is to remove the head studs.
I hear ya!

It's not the head studs making life difficult on the AR though - it is the exhaust studs on the front of the cylinder fouling the frame.

I'll see if they come out without a fight... which is unlikely. If they give me grief, it'll be engine out.

Unless someone has a hot tip in the AR specifically.....?

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

Post by MaxCRM » 17 Feb 2022, 19:10

knackeredMk1 wrote:
17 Feb 2022, 14:59
CRMs are much harder to work on than MX bikes but you should try fixing an MTX!!!

Easiest way to get the cylinder out is to remove the head studs.
I hear ya!

It's not the head studs making life difficult on the AR though - it is the exhaust studs on the front of the cylinder fouling the frame.

I'll see if they come out without a fight... which is unlikely. If they give me grief, it'll be engine out.

Unless someone has a hot tip in the AR specifically.....?

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

Post by MaxCRM » 18 Feb 2022, 15:54

Update: I got the barrel off by loosening all engine mounts, removing the two smaller mount bolts and rocking the engine back slightly.

Piston measures 66.5, but i assume that is my crappy cheap verniers - with no markings on the top of the piston, I believe it to be original 66.4.

The bore looks great and the piston has only the slightest of tiny scores on it, no blow by, rings look good too. So after all that i am not sure it was the top end????

Either way, now it is stripped, i have followed CRMsam's lead and bought a 66.4 Wossner piston it from PJ Engineering + genuine Honda small end bearing, and top end gasket kit. For anyone interested, the whole lot was £170 delivered, so quite reasonable really. PJ are great too - really happy to help.

It's interesting that according to popular opinion and Leisure trail, 66.4 pistons are no longer available. Am i missing something or are they a new to addition to the Wossner range?

Lastly, as the top end was in such decent nick, i am not sure why my compression was low (110psi) - is there anything else i should be checking when building back up?

Thanks all.
Max

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777amia
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Re: Had my crm ar for 10 years! Never missed a beat until now!

Post by 777amia » 18 Feb 2022, 19:23

My cylinder came off without removing any engine bolts or the exhaust studs, doesn't mention this in the manual either, so that's a bit weird.
I've seen the wossner 66.4mm piston about for quite a while now, other members on Facebook have used them, although I think they are relatively recent addition to their range.
I should imagine the head gasket you'll receive will be for the earlier marks, AR is slightly different as it has a bigger hole in the very front head mount hole, can be sorted with a dremel to open up the hole to suit the stud.
With everything seeming good top end wise, only thing I can think is either your power valve was in the fully open position when you did the compression test or the throttle wasn't fully opened.

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

Post by pudzie83 » 07 Apr 2022, 22:51

If you have nickel bore then just a scratch can mess things up I had a RGV 250 that I had to sleeve (and rebore to max size :))
VIVA LA CRM!


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