Exhaust Camshaft problem

Message

irich · #16 Post by **irich** » Sat Mar 10, 2012 11:06 am

Taqman wrote: Later models have a forged single piece camshaft so this cant happen.

Anyway - saga continues....

Ok so I got a leaktester

Instructions say basically fit it all up and apply approx 60psi and see reading. - well I can only get to 15 psi before the guage is reading zero leakage.
Can those that know confirm for me??

Do you know what year they changed?

I dimly remember inverting heads and filling them with oil to check for valve seating..

Have you tried a normal compression test?

Taqman · #17 Post by **Taqman** » Sat Mar 10, 2012 5:03 pm

Aladinsaneuk wrote:i guess you may have got away with it BUT - if it were mine, i would probably do the work anyway to be doubly certain its all good....

(A slight hiss and bubble at a low pressure..... what do you think the internal pressure of the engine would be at full chat? and if it were to fail.... it could well be catastrophic....)

In most cases it is the internal compression pressure that assists in sealing the valves to the seats and the rings to the bores.

The test should also usually be done with the engine hot, but I cant do this.
As I figure (hope) there is so little leakage (i.e. the engine is fine) the leakage guage just cant detect any significant loss.

The instructions did say that all engines will leak and big pistons tend to leak more than small.

I'm going to swap out the camshaft for a replacement one and see how it goes.

Taq

Samray · #18 Post by **Samray** » Sat Mar 10, 2012 5:24 pm

Taqman · #19 Post by **Taqman** » Sat Mar 10, 2012 9:03 pm

Samray wrote:

Would you like to elaborate on this a bit......

Taqman · #20 Post by **Taqman** » Sat Mar 10, 2012 9:08 pm

irich wrote: Do you know what year they changed?

2005 on was when they went to forged camshafts according to AF1

fatboy · #21 Post by **fatboy** » Sun Mar 11, 2012 7:28 pm

I agree with Aladin, sounds like you may have a slightly bent valve stem
I think if I was in your shoes I would have the head off, check the valve and guide and if there has been valve/piston contact make sure there is not a tiny piece of piston crown swarf lurking
If the valve stem is bent, the motor may be ok at low rpm but things could get interesting at higher temp and rpm. Abent stem will also wear the guide quicktime leading to oil burning
Head off is more time, money,hassle but a lot less hassle than a potentially destroyed piston, head ect
Be interesting to know if later cams fit
Good luck with it

Taqman · #22 Post by **Taqman** » Sun Mar 11, 2012 11:43 pm

fatboy wrote:I agree with Aladin, sounds like you may have a slightly bent valve stem
I think if I was in your shoes I would have the head off, check the valve and guide and if there has been valve/piston contact make sure there is not a tiny piece of piston crown swarf lurking
If the valve stem is bent, the motor may be ok at low rpm but things could get interesting at higher temp and rpm. Abent stem will also wear the guide quicktime leading to oil burning
Head off is more time, money,hassle but a lot less hassle than a potentially destroyed piston, head ect
Be interesting to know if later cams fit
Good luck with it

Tore into it tonight - results are not appealing - It appears that the exhaust cam has/had siezed in its bearings - When I tried to start it either it was already siezed or the bearing was starved of oil and the bearing nipped up - there is a 5mm wide band all the way around the cam and bearing where it looks like metal has transferred.

In comparison the replacement cam I have from a 2nd hand cylinder head rotates freely in its original head, but feels really 'tight' when placed into the existing head - this is without the cam cap being fitted.

I think the cam bearings are FUBAR-ed so It looks like a head swap.

How easy is this? anyone done it? Can it be done insitu? or do you need to drop the motor. any special tools? - at the minimun it looks like I'll need a crows foot adapter to torque 2 of the cylinder head bolts

Feeling depressed now......

Nooj · #23 Post by **Nooj** » Mon Mar 12, 2012 12:16 am

Taqman wrote:
irich wrote: Do you know what year they changed?

2005 on was when they went to forged camshafts according to AF1

Interesting, as they stopped Falco production in 2003 and introduced the Gen2 Rotax RSVR motors in 2004

D-Rider · #24 Post by **D-Rider** » Mon Mar 12, 2012 12:54 am

If changing heads, you have the option to go for Mille bigger valve items - I think the cams may have a profile with longer duration too.

.... and wot Nooj said re gen 2 bikes (maybe because they often got things a year late in USA??)
However Falco production didn't stop in 2003 - mine was built in 2004 (registered in 2005)

back_marker · #25 Post by **back_marker** » Mon Mar 12, 2012 7:26 am

Taqman wrote: How easy is this? anyone done it? Can it be done insitu? or do you need to drop the motor. any special tools? - at the minimun it looks like I'll need a crows foot adapter to torque 2 of the cylinder head bolts

Never done the job but looked at a couple of years ago. Manual says the engine must come out, you may be able to get away with it but it may well be more hassle that it's worth. The problem is that the head is bolted to the cylinder from the bottom so you have to remove the barrel and head together and then seperate them. I seem to remeber that at the very least you would have to undo all but one of the engine mounts to get some movement, by which time it is probably just as easy to remove the whole thing and do the job on the workbench.

D-Rider · #26 Post by **D-Rider** » Mon Mar 12, 2012 8:18 am

.... and given the price that second hand engines go for, it may be more economic and less hassle to just swap engines.

That said, I'm not completely convinced that you are yet at the stage where you are sure you need to. The tight cam does need investigating ..... as lubrication to that camshaft,

Taqman · #27 Post by **Taqman** » Mon Mar 12, 2012 7:44 pm

More photos:

Ok this is what the cam looks like:

And the cam bearing and cam cap

Can these be salvaged or repaired?

Either way it will be an engine out job I suspect as the head will have to go to an engineering shop.

the bike is a 2000 model with 28,000 on it - I feel I could be looking at a big bill for a cheap bike.

Options

1. Replacement engine
2. Replace cylinder head
3. Upgrade opertunity and break the old girl

blinkey501 · #28 Post by **blinkey501** » Mon Mar 12, 2012 8:02 pm

Madhatter had an engine for sale i will text him and ask him if he still has it and what he wants for it if required

Falcorob · #29 Post by **Falcorob** » Mon Mar 12, 2012 8:13 pm

I'd be tempted to go for the replacement engine as has previously been mentioned.

Taqman · #30 Post by **Taqman** » Mon Mar 12, 2012 8:40 pm

blinkey501 wrote:Madhatter had an engine for sale i will text him and ask him if he still has it and what he wants for it if required

Cheers that would be nice - still in denial here - been looking at falcos and wondering how much I'd get If I broke mine......