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904 big bore
#516671 04/15/2013 1:59 AM
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Greenhorn
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well had the 904 kit installed on my '02 790, i had it installed by local triumph dealer it managed to do 800 odd klm's and the chain tensioner has let go. said it was going to cost me close to $1900 for damage to crank(crank $2500 being discounted to 1900 from triumph). Dealer said they would cover all labour costs. Dealer rang triumph and apparently the chain tensioner on the 270 firing engine has to be changed when you install big bore kit. Has anbody else who has had kit installed been told this ? Not happy about costs being thrown back my way i just finished paying them $1900 for cost of original job

Re: 904 big bore
triumphsrock #516672 04/15/2013 2:25 AM
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You must be referring to the cam chain tensioner.

Changed to what? Ive never heard of that before.


SOLD: 07 Black BA, 39mm FCRs, TPUSA stage 1 head, TPUSA 813 cams, TPUSA 10.8:1 pistons, TTP #3 igniter, Specialty Spares Long Cannons, Tsukayu Hard Bags. 82HP/55tq NEW: 19 Goldwing Tour DCT
Re: 904 big bore
Zmilin #516673 04/15/2013 2:48 AM
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Sounds like the mechanic may have botched the install. It happens.

Re: 904 big bore
Ryk #516674 04/15/2013 3:10 AM
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yes it is the cam chain tensioner. not sure all he said was changed due to 904 wiseco kit. i have 47800klms not sure if that makes any difference.

Re: 904 big bore
triumphsrock #516675 04/15/2013 5:09 AM
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It was the mechs. responsibility to survey wear and tear (general condition) of all the parts he handled and advise you that this or that part was worn beyond spec. and should be replaced. Perhaps he didn't even properly re-tension the chain? I shouldn't talk smack about a guy I don't know, and I wasn't there. But a lot of people install these kits, even with more mileage than you, without grief.

Re: 904 big bore
Ryk #516676 04/15/2013 3:45 PM
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my big bore was done when bike had about 60000 miles and 20000 later goes without issues


Grzegorz ......55 cubic inches http://www.flickr.com/photos/25172906@N06/ 904WisecoTPUSAcamsTTPignitorgutted Airbox"breath"airIntakeKeihinCR-ScarbsBlackEpcoExhaustS/SwheelsPortedPolishedHead
Re: 904 big bore
Grzegorz #516677 04/15/2013 10:18 PM
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I have 30k miles on mine and nary a skipped beat.


A word to the wise is not necessary. It is the stupid ones who need the advice. Pat
Re: 904 big bore
Dinqua #516678 04/16/2013 5:15 PM
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How can the cam chain tensioner cause a problem with the crank? If the tensioner fails, it usually causes the chain to come loose or break, changing cam timing and bending valves. Top end suffers, not bottom end.

What are the symptoms? What parts need to be changed? Did the bike quit suddenly?

I'll bet the chain broke because the tensioner wasn't adjusted properly.

The 904 conversion shouldn't cause any problems with the tensioner.


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Re: 904 big bore
Gregger #516679 04/16/2013 8:35 PM
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I would guess that the adjuster can break off and drop into the motor and then it goes crunch...lockup.


A word to the wise is not necessary. It is the stupid ones who need the advice. Pat
Re: 904 big bore
Dinqua #516680 04/16/2013 9:26 PM
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the symptoms were a sudden slight miss under accelleration at 80 ks followed quickly by a high pitch rattling noise. i pulled clutch and rolled to a stop. there was no lockup i was unsure myself how it could have damaged crank. i will go into dealer today to have a look at the damage.

Re: 904 big bore
triumphsrock #516681 04/16/2013 10:01 PM
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A word to the wise is not necessary. It is the stupid ones who need the advice. Pat
Re: 904 big bore
triumphsrock #516682 04/17/2013 9:08 AM
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well dealer said cam chain tensioner let go and the chain has damaged the gear on the crank. he said the cams had stayed where they were suppose to. he then told me there is a five week waitng period for parts and the crank weighs a lot which will cost alot to freight. god help me i can only take so much crap in 1 day

Re: 904 big bore
triumphsrock #516683 04/17/2013 10:53 PM
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Curious to know how much difference in power with the 904.

Re: 904 big bore
masterofillusion #516684 04/17/2013 11:26 PM
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I think if it is the mechanics fault you shouldn't have to pay anything.


I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
Re: 904 big bore
triumphsrock #516685 04/18/2013 4:37 PM
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Quote:

well dealer said cam chain tensioner let go and the chain has damaged the gear on the crank. he said the cams had stayed where they were suppose to.




Did the dealer state that the cam chain broke? If so, the cams would have stopped with the crank turning and I guarantee some valves would have bent.

If the chain didn't break, it could have rattled around against the chain guides because of the broken tensioner. The chain could have jumped one or more teeth on the crank sprocket causing the engine to stop and maybe not damage/bend the valves. I'd be curious to see a pic of the sprocket. I bet it could be repaired.

Did he have the sump pan off so you could see the damaged sprocket?

Good luck with the repairs. Too bad you live so far away, a number of us would have loved to pull the engine apart..


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Re: 904 big bore
Gregger #516686 04/18/2013 9:29 PM
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no the cam chain was intact. I will post a photo of crank a little later. that what I have been told is what happened. valves are good. wish I did live closer now I would rather trust the members of this forum than trust dealer and his mechanics. I have had two dealings with them now, hope the completion of this second one goes better.

Re: 904 big bore
triumphsrock #516687 04/18/2013 9:34 PM
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I ordered all the parts I need off Carlos at tpusa. cheaper for me to buy parts from him than my dealer even with freight included. to be honest I would rather give money to anybody but dealer. anyway I have said enough about them just cross fingers and hope things go well

Re: 904 big bore
triumphsrock #516688 04/19/2013 6:13 AM
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Loquacious
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Is there an opportunity to install the stroked crank from TPUSA? Might as well put the 988 Stroker kit in if it isn't much more....


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Re: 904 big bore
Gregger #516689 04/19/2013 8:38 AM
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there have been incidences of the cam chain tensioners being incorrectly installed (several threads on the ratnet) with bad things happening shortly after.
the tensioner is a ratcheting mechanism and if not re-set properly, then its all bad. If they are saying the crank gear is damaged, then I would insist on a new cam chain as well as it can not have been unscathed by this. I would also want a good look at the chain guides for damage as well.


05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
Re: 904 big bore
mag10 #516690 04/19/2013 4:56 PM
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One other option rather than purchase new is to get a crank from PINWALL CYCLE PARTS. $189.00 plus shipping.


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69 BSA Firebird Scrambler
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Re: 904 big bore
Gregger #516691 06/15/2013 9:07 AM
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well got a call on the 23 of may saying bike was ready to be picked up. i got on bike and noticed rear brakes must have air I thought typical fix this when I get home, well I made it 1.9 klms from bike shop and the F=====g thing has locked up and sent me sliding down the road. I finally got a call from dealer saying where the machine shop had welded case the bearing had gone blue and also spun another and half chewed out another. the bike is still in pieces at bike shop where they are now saying they will repair everything at no cost to me. $1600 job has turned out to be just under $4000 and a trip down the road on my arse. not to sure if I want to get on this once reliable ride to get it home.

Re: 904 big bore
triumphsrock #516692 06/15/2013 9:50 AM
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Wow,this is a triumph dealership your having all these problems with.Not good.I have had no problems with my cam chain tensioner.But I my dealership has hiccups too.

Last edited by marty; 06/15/2013 9:56 AM.

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