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Has anyone ever snapped a cambelt?; snapped cam belt
Topic Started: Sep 28 2015, 08:00 AM (1,439 Views)
markslashbill
Knight
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Has anyone ever snapped a cambelt?
Mine went on Saturday. My own fault I know.

Anyhow I was wondering if it buggers it all up. As it's a single I am guessing (hoping) there is a good chance the valves
won't have hit. Assuming the cam stops instantly and settles to its lowest point.

How easy to take the head off? Engine out or an afternoon's work?

Edited by markslashbill, Sep 28 2015, 08:12 AM.
R30 604, GL1100, XT600, C90
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stevo604
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God
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it all depends which cam is fitted 865 cam is standard fitment and will let the valves hit the head you might be lucky

take your top cam bolt out and at the end of the cam their is a number for cam fitted
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Monty
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Charlie Big Banana's
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the 865 was only fitted to the R30 versions, the DS had the 670 which wont hit the piston,

Suggest before you try to remove the head, to set the cam at tdc, all valves closed, then pump the kickstart and see if you still have compression, if not, head comes off in 30mins (if you know what your doing) sportax racing can supply the valves if needed, also does a good price on cam belts and all other things rotax
If it aint sharp I can play with it
My Utube Channel, lots of bike vids here. Subscribe if you likehttp://www.youtube.com/user/choppermark?feature=watch

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Gonzo250
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Working-class moto psycho
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I beg to differ on the 865 cam. Both engines I have...err, had, both out of standard DS models, had the 865 in them. Obviously my new one had the 865 as well.

So yes, from experience, I believe the 865 was used in both DS and R30.
I drink too much, I swear too much, I ride too fast and I crash too often.

It is a universal impossibility for me to leave my tools alone and my bikes standard. 'It must go faster!!'
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markslashbill
Knight
[ *  * ]
thanks a lot chaps. good idea monty I have a compression tester.

head comes off in 30 mins! well thats ok then if i have to replace a valve or so.
R30 604, GL1100, XT600, C90
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Gonzo250
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Working-class moto psycho
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Remember, to get the head off in situ, remove all engine mounting bolts bar the swingarm spindle to get the clearance needed to lift the head off and out.
I drink too much, I swear too much, I ride too fast and I crash too often.

It is a universal impossibility for me to leave my tools alone and my bikes standard. 'It must go faster!!'
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Sportax Racing
Anything & Everything ROTAX
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Cheers Monty, yes we can help if you need any parts.. I've only seen the 865's in the DS and 670 in the R30 but folk do swap them about. The 670 is safe unless you've had the head skimmed! Or flat out!

I also read some one did a test on an R30 with 670 did 110mph. Same bike with 865 only managed 90mph.. Must have got there pretty quick tho!

PS an OEM dayco belt is good for two years or 20,000km I'd recommend changing it every 12 Calender months if you're running an 865 or tuned motor..
Edited by Sportax Racing, Oct 28 2015, 10:30 AM.
www.sportaxracing.co.uk
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tommysdad
Earl
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Gonzo250
Sep 30 2015, 06:59 PM
I beg to differ on the 865 cam. Both engines I have...err, had, both out of standard DS models, had the 865 in them. Obviously my new one had the 865 as well.

So yes, from experience, I believe the 865 was used in both DS and R30.
My 99 604 DS has the 865 cam , and yes the valves do get bent when the belt lets go :goodgrief:
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I'm a man with a fork in a world of soup
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markslashbill
Knight
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Blimey has it been in the garage that long?

I have ordered the belt. Time to get it dusted off and on the road.
R30 604, GL1100, XT600, C90
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markslashbill
Knight
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I tested the compression . Compared with my GL1100 it showed about 40Psi against the wing 120PSI . Not 100 % sure of the gauge as it's a push fit type. Anyway stripped the head off and there appears to be no clearly visible damage. No blood or carnage in there. Maybe almost imperceptible scuff on inlet that could be imagination. Any ideas? I would have thought bent valves would be obvious . I am at a loss
R30 604, GL1100, XT600, C90
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Monty
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Charlie Big Banana's
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if the compression is low there are 2 tests you need to do, first like you have done, 2nd, now squirt a few cc's of oil down the plug hole and test again, if the pressure goes up then the rings are letting by, if comp the same then either bent valves or they need reseating, if you reseat also fit new valve stem seals, plus whilst the head is off, it pays to lap the head and barrel mating surfaces,
head O rings for sale in for sale section
If it aint sharp I can play with it
My Utube Channel, lots of bike vids here. Subscribe if you likehttp://www.youtube.com/user/choppermark?feature=watch

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Sportax Racing
Anything & Everything ROTAX
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160 ish psi normal for healthy valves. At least one pair of the valves will be bent. It may be an obvious bend but if unsure pop them in a drill and it will be more obvious.. in stock and available next day from our shop..
www.sportaxracing.co.uk
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jonny h
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this is how i roll!
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bent valves are not always obvious, i snapped a cam belt, running the 670 cam but head had been skimmed. i ran my bike for a whole year with bent Zorst valves, that was not noticed until i went to lap them in ;)
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,C26 604e, Posted Image

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markslashbill
Knight
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Ok thanks for the replies. I will have a look next weekend when I have a chance.
R30 604, GL1100, XT600, C90
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markslashbill
Knight
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Blast. On closer inspection after heating up to get rid of oil there is clearly a gap on the exhaust valves.

Double damn and blast...

Oh woe is me, on taking out the rocker arms the cam roller came out and fell to bits.
I salvaged 15 rolling pins but it looks like there should be 16.

Could the rocker roller have sustained damage in the bang?

Oh bollocks.
I suppose that means a new rocker arm?

Edited by markslashbill, May 3 2016, 04:03 PM.
R30 604, GL1100, XT600, C90
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Gonzo250
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Working-class moto psycho
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You may get away with a new roller.

But don't forget, all Rotax rocker arms are the same, from the 350 to the 604, obviously inlet and exhaust specific, so you may find one on that lovely auction site for not a lot.

Alternately, the fantastic chaps at Sportax will see you right with no fuss.

As for the valves... Erm... Oops... :X
I drink too much, I swear too much, I ride too fast and I crash too often.

It is a universal impossibility for me to leave my tools alone and my bikes standard. 'It must go faster!!'
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markslashbill
Knight
[ *  * ]
do we reckon this will fit?

ebay pegaso rocker

R30 604, GL1100, XT600, C90
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Gonzo250
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Working-class moto psycho
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Aye, that'll do you...
I drink too much, I swear too much, I ride too fast and I crash too often.

It is a universal impossibility for me to leave my tools alone and my bikes standard. 'It must go faster!!'
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markslashbill
Knight
[ *  * ]
Oh well, I decided to just order everything from the friendly people at sportax so I know its OK and I get it all together.
(Plus good advice)

Speaking of advice:

1. Change cam belt = £33 + 15 Minutes.
2. Don't change cam belt = £33 + 15 Minutes plus £335 + 2 Saturdays.


R30 604, GL1100, XT600, C90
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markslashbill
Knight
[ *  * ]
She's done!
Valves lapped in.
All back together.

She started

on - the - button!

what a great motor.
R30 604, GL1100, XT600, C90
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