What is the considered opinion on cam chain failure?
Discussion
Having had my cam chain snap / break on me and the car purportedly having only done 10 hours I find if odd that the chain could fail for reasons of revving.
It is more likely that the cam tensioner which was also changed at the same at the chain has failed. This then would allow the unadjusted chain to become loose on the non drive side of the engine and hey presto the chain overrides a tooth and breaks.
I think this is as simple as it need to be.
I notice on Hyabusa forums that there is a recommendation to install manually adjustable cam chain tensioners which do not rely on the internal spring (I suppose there is also a ratchet involved in the systems as well) they just put the necessary tension on the slipper/ chain and hey presto.
I also note that there was a recall in America for faulty tensioners.
A discussion on this would be useful as my engine is being rebuilt next week and I don’t fancy this arse ache again.
It is more likely that the cam tensioner which was also changed at the same at the chain has failed. This then would allow the unadjusted chain to become loose on the non drive side of the engine and hey presto the chain overrides a tooth and breaks.
I think this is as simple as it need to be.
I notice on Hyabusa forums that there is a recommendation to install manually adjustable cam chain tensioners which do not rely on the internal spring (I suppose there is also a ratchet involved in the systems as well) they just put the necessary tension on the slipper/ chain and hey presto.
I also note that there was a recall in America for faulty tensioners.
A discussion on this would be useful as my engine is being rebuilt next week and I don’t fancy this arse ache again.
thanks, i will ask radical about it. their response to me was that it was not a common failure. ??
they alos said that it was common until they started changing out teh chain and adjuster every time they refreshed the engine.
i just dont want the thought of this happening again when i am having fun. it sure will put a dampner on the proceedings if it happens again.
Dario
they alos said that it was common until they started changing out teh chain and adjuster every time they refreshed the engine.
i just dont want the thought of this happening again when i am having fun. it sure will put a dampner on the proceedings if it happens again.
Dario
The cam chain TENSIONERS are weak points. They were recalled on the early motors and replaced with an oil-operated one which is reportedly only slightly better. The chain can suddenly go slack off-throttle causing it to skip a tooth and blow up the motor.
First thing all Hayabusa racing motors should have is a manual cam chain tensioner like the one APE makes. It's stupid simple and can't ever go slack.
[url]http://hayabusazone.com/tensioner.htm[/url]
First thing all Hayabusa racing motors should have is a manual cam chain tensioner like the one APE makes. It's stupid simple and can't ever go slack.
[url]http://hayabusazone.com/tensioner.htm[/url]
I have spoken to radical about the manual adjuster and they say it is a no no. the fact that the chain expansion and contraction cant be compensated for by the manual system is why this should not be done in their opinion. they say they HAVE tried it and it snapped very soon after the first run.
i have asked them to upgrade mine to the roller chain version which they have never had snap on them.... but over rev and holding the engine on the rev limiter between corners is the stated reason for the failure. none of this was done by me in the 3 hours that i owned the car.
rebuild id £4.3K with new MK2 rods, new pistons, rings, new valves, new clutch basket, new garbox bearing and gasteks, labour and testing. as a track day car it hurts a little.
i have asked them to upgrade mine to the roller chain version which they have never had snap on them.... but over rev and holding the engine on the rev limiter between corners is the stated reason for the failure. none of this was done by me in the 3 hours that i owned the car.
rebuild id £4.3K with new MK2 rods, new pistons, rings, new valves, new clutch basket, new garbox bearing and gasteks, labour and testing. as a track day car it hurts a little.
Well, that's why Powertec is in business...to make money off you and tell you things that will guarantee they continue to make money off you www.pistonheads.com/gassing/icons/4.gif
Religious debates on manual vs. automatic aside, let me say that in order to tension the chain so tight it "broke within a few minutes" would be impossible. The motor wouldn't actually run if the chain was so tight it was possible to break it simply from chain tension.
There are two chain tensioners on the Hayabusa...the early ones with no oil line going to them are a GUARANTEED failure at some point. They can EASILY release full tension on the chain causing it to skip a tooth and blow up your motor (drop a valve).
The oil-operated ones have a fairly robust ratchet mechanism and are NORMALLY one-way only (they don't compensate for temperature). That ratchet can unlock though and cause the tensioner to go fully slack (chain skips a tooth, motor blows up).
A manual one can be adjusted too tight (will prematurely wear the tensioner blocks...the chain rubs on blocks through about 80% of it's travel) and will prematurely wear the chain. If it's set too lose, then there's a danger of the chain skip fatality. Normal adjustment is to set it to where you feel the tensioner blade rub, then back it SLIGHTLY off...this allows the chain to have some free movement as it needs but makes it IMPOSSIBLE to go slack to the extent it can skip a tooth.
When the motor is running, the "leading edge" of the chain is pulled tight by the crankshaft...the force of this depends on engine speed. If you are at full throttle, there is maximum tension on the chain...if you SUDDENLY release the throttle (oh say like at the end of a straightaway), the chain more or less suddenly goes "slack" and at that moment the stock tensioners (which aren't designed for a racing duty cycle) have two ways to not resist this movement...the spring or the ratchet can release. This can happen due to "normal" wear on the parts and/or inability to cope with this force due to not being designed for racing. It's at this moment that you lose that motor (interference motor, if you drop a valve you will destroy the combustion chamber, piston, probably the cylinder bore, likely the connecting rod and probably the crankshaft). Though this is PROBABLY less of a problem with a bone-stock 1300 motor (because that is essentially operating inside the tensioners design paramaters though under a much more heavy-duty cycle), the more power you get out of the motor, the more force on the chain and the less the stock tensioner can cope.
I HIGHLY recommend talking to some other reputable motor builders before plunking down all that money for their work if they're giving you stories about breaking chains with manual chain tensioners.
There are two chain tensioners on the Hayabusa...the early ones with no oil line going to them are a GUARANTEED failure at some point. They can EASILY release full tension on the chain causing it to skip a tooth and blow up your motor (drop a valve).
The oil-operated ones have a fairly robust ratchet mechanism and are NORMALLY one-way only (they don't compensate for temperature). That ratchet can unlock though and cause the tensioner to go fully slack (chain skips a tooth, motor blows up).
A manual one can be adjusted too tight (will prematurely wear the tensioner blocks...the chain rubs on blocks through about 80% of it's travel) and will prematurely wear the chain. If it's set too lose, then there's a danger of the chain skip fatality. Normal adjustment is to set it to where you feel the tensioner blade rub, then back it SLIGHTLY off...this allows the chain to have some free movement as it needs but makes it IMPOSSIBLE to go slack to the extent it can skip a tooth.
When the motor is running, the "leading edge" of the chain is pulled tight by the crankshaft...the force of this depends on engine speed. If you are at full throttle, there is maximum tension on the chain...if you SUDDENLY release the throttle (oh say like at the end of a straightaway), the chain more or less suddenly goes "slack" and at that moment the stock tensioners (which aren't designed for a racing duty cycle) have two ways to not resist this movement...the spring or the ratchet can release. This can happen due to "normal" wear on the parts and/or inability to cope with this force due to not being designed for racing. It's at this moment that you lose that motor (interference motor, if you drop a valve you will destroy the combustion chamber, piston, probably the cylinder bore, likely the connecting rod and probably the crankshaft). Though this is PROBABLY less of a problem with a bone-stock 1300 motor (because that is essentially operating inside the tensioners design paramaters though under a much more heavy-duty cycle), the more power you get out of the motor, the more force on the chain and the less the stock tensioner can cope.
I HIGHLY recommend talking to some other reputable motor builders before plunking down all that money for their work if they're giving you stories about breaking chains with manual chain tensioners.
Oh, incidentally, I'm not recommending agains the roller chain...far from it...the chain is designed for a 175HP motor...that's about what a Powertec (stock) 1300 makes...their 1500 motor is in the order of 200-210hp and that's much more than the stock cam chain was designed for.
Before you correct me that it's "252hp"...uh lets just say...NOT heh.
Before you correct me that it's "252hp"...uh lets just say...NOT heh.
Dariot,
i have just had my 1500 rebulid after cam chain failure - didn't do many hours either. Engine is still out of the car, so I am thinking about converting to the roller chain. Two questions: Ist it the verniers and chain only, or are there other parts also involved, plus how much does the kit cost approx. (also still suffering from rebuild cost). Your help is greatly appreciated!
Thx
Felix
i have just had my 1500 rebulid after cam chain failure - didn't do many hours either. Engine is still out of the car, so I am thinking about converting to the roller chain. Two questions: Ist it the verniers and chain only, or are there other parts also involved, plus how much does the kit cost approx. (also still suffering from rebuild cost). Your help is greatly appreciated!
Thx
Felix
Roller chains can be bought from -
www.hayabusacentral.co.uk/
or from across the pond from -
www.schnitzracing.com
Cost in the UK is £250, from the states $250 (£120)
Kit includes new adjustable sprokets and a new crank sprocket.
I am still in two minds over this, not seen any race engines with roller chains yet only drag bikes. At the moment I think I am going to run the hydraulic tensioner and the standard chain but make sure the chain is checked a lot more frequently.
www.hayabusacentral.co.uk/
or from across the pond from -
www.schnitzracing.com
Cost in the UK is £250, from the states $250 (£120)
Kit includes new adjustable sprokets and a new crank sprocket.
I am still in two minds over this, not seen any race engines with roller chains yet only drag bikes. At the moment I think I am going to run the hydraulic tensioner and the standard chain but make sure the chain is checked a lot more frequently.
Noneedtolift.
All the works done now and I had the roller chain installed. It comes complete with all of the sprockets needed. I imagine and hope that they timed up the cams with the adjustable sprockets. I read somewhere that the chain guides need to be trimmed because the radius of the new chain differs because of the chain thickness. This was side guides and the top guide.
I did not go for a fixed adjuster as I would not have had Powertech backing with the replacement.
The engine now has a 30 hour warranty on parts and labour.
just about everything was changed from cam chain to valves, clutch basket, gearbox bearing, new design ARROW conrods, pistons, rings, in fact I don’t know if there was anything original left.
Total bill from powertech was £4,300 including VAT and Radical charged another £700 to remove, replace, flatpatch and shakedown. So I kissed goodbye to £5,000. And that was just 6 weeks and 3 hours after buying the car and trailer for £25K.
BUGGER.
Still I fetch it tomorrow from Radical and then it’s off to Rockingham on Sunday to see how she goes. 2 weeks later I am on track at Bedford.
All the works done now and I had the roller chain installed. It comes complete with all of the sprockets needed. I imagine and hope that they timed up the cams with the adjustable sprockets. I read somewhere that the chain guides need to be trimmed because the radius of the new chain differs because of the chain thickness. This was side guides and the top guide.
I did not go for a fixed adjuster as I would not have had Powertech backing with the replacement.
The engine now has a 30 hour warranty on parts and labour.
just about everything was changed from cam chain to valves, clutch basket, gearbox bearing, new design ARROW conrods, pistons, rings, in fact I don’t know if there was anything original left.
Total bill from powertech was £4,300 including VAT and Radical charged another £700 to remove, replace, flatpatch and shakedown. So I kissed goodbye to £5,000. And that was just 6 weeks and 3 hours after buying the car and trailer for £25K.
BUGGER.
Still I fetch it tomorrow from Radical and then it’s off to Rockingham on Sunday to see how she goes. 2 weeks later I am on track at Bedford.
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