[hi_gonzilla]

My Bike, 2003 Bonnie T100, 2k miles.
My exhaust valves were smashed! Rods bent. My mechanic could not figure out why. All parts were still in good shape, chain tentioner, cams, drives, chain etc. Still had a bad, timing problem. Any ideas what could have happened?
JG

 

[Phil-1100]

Valves have hit the pistons is the usual culprit, caused by lots of reasons, over reving, valve timing wrong, ham fisted rebuild

 

[Thrux-ton-up]

My riding buddy bent all the exhaust valves in his 06 Bonnie - over reving. Even though a rev limiter is employed, if you hit it hard enough, even when the rev limiter cuts out the ignition the weight/momentum of the bike/rider/crank/etc can still act to continue to increase the revs of the motor resulting in bent valves. He did no other damage and a new set of valves fixed him right up.

 

[RedBird]

Your 2003 T-100 has a rev limiter set at 7400 rpm. It would be near impossible to rev that engine enough to cause the problems you describe. Somewhere, somehow, a PERSON caused the timing to be off, IMHO. If you bought the bike used, then get it fixed properly and ride. If you bought the bike new, 223 miles per year will cause all sorts of problems, but not the ones you have described--these type usually have human intervention or a failed factory component.

I have a modified igniter on my '03 T-100, with a rev limiter set at 8100 rpm. I spool it up to 8100 at least twice each ride and often many more times. I have 24000 miles on my bike and no valve problems or any other problems.

 

[mikeinva]

If no one had the cams out i would check your valve springs they got to be weak to hit pistons at the 7400 rev limit.

 

[jboyette]

Is it possible...

..a downshift at speed to a too-low gear could overrev your engine well past the rev limit.

 

[sweatmachine]

..a downshift at speed to a too-low gear could overrev your engine well past the rev limit.

yes, it is possible. Don't do it!

 

[sweatmachine]

My Bike, 2003 Bonnie T100, 2k miles.
My exhaust valves were smashed! Rods bent. My mechanic could not figure out why. All parts were still in good shape, chain tentioner, cams, drives, chain etc. Still had a bad, timing problem. Any ideas what could have happened?
JG

that's wild, I can't believe it bent the rods too! Is he sure? Has it been torn down to the rods?

 

[mikeinva]

My Bike, 2003 Bonnie T100, 2k miles.
My exhaust valves were smashed! Rods bent. My mechanic could not figure out why. All parts were still in good shape, chain tentioner, cams, drives, chain etc. Still had a bad, timing problem. Any ideas what could have happened?
JG

what here you doing when it messed up?

 

[Derby Boy]

Me thinks there is a lot more to this story. I am curious to hear the answers to the questions asked.

 

[hi_gonzilla]

the story

purchased at 1800, broke at 2000. The idle was fast but not past 4krpm. I would not rev it crazy. I was going to get on the expressway when it started to sputter intermittently. I bailed out and turned to a surface road. Hit a bump, heard a whirring sound and it quit on me. Valves were diffinately bent like macaroni.
JG

 

[sweatmachine]

The idle was fast but not past 4krpm.

I don't understand what this means...

 

[mikeinva]

I bet something wont right when you got it sounds like the cams may have been out of time .How many valves did it bend?

 

[Calliway]

I don't understand what this means...

It means the idle was waaaaayyyy off....... lol.

Maybe he meant with the choke pulled out?

 

[sweatmachine]

purchased at 1800, broke at 2000.

well, sounds like someone sold you a bike with a problem. Who did you buy it from? An individual or a dealer? Either way, heads should be rolling...

 

[Geimer]

well, sounds like someone sold you a bike with a problem.

I think so too. More information is needed on the history of the machine. It sounds like someone has been messing with it without knowing what they were doing.
Idle was not past 4000 RPM... its that what was being said? Anywhere close to 4000 RPM is not idling whether you are twisting the throttle or not. Either cables were corroded or pinched or someone messed with the carbs in the wrong way etc.
So if someone was that inept with the idle speed what possibly could they have done with the cam chain tensioner?
hi_g gets 200 miles out of his machine... I do not see how it could even start if it were put together with the cams timed bad enough to do all that. BUT, if somebody messed with the cam chain tensioner... could it have been set in a way to allow it to run a while and then slip time a little later?
I think Hi_G you need to scrutinize the person who sold you the machine... you need some history... if you can get it.
I hope a T100 stays being your favourite machine... because they are REALLY good bikes. But if you are ever checking out another one considering it for purchase, try to get an experienced person with you to check it out too. I can't see how this bike was running anywhere close to normal prior to this event.
Good luck

 

[modre]

My Bike, 2003 Bonnie T100, 2k miles.
My exhaust valves were smashed! Rods bent. My mechanic could not figure out why. All parts were still in good shape, chain tentioner, cams, drives, chain etc. Still had a bad, timing problem. Any ideas what could have happened?
JG

I want to verify terminology here.

the valve heads and STEMS were bent?

when you say rods, it means connecting rods.

if you bent a connecting rod, the piston dome should be impacted and the mains/rod bearings/wrist pin bearings are suspect. any bad bearing (eggshaped/dimpled) will throw the travel spec out. you might be into some money here.

this engine sounds beat to me...maybe the head shaved?...domed pistons?...loose valve seat in the head? POSSIBLE: hung up stem in the guide can stick a valve open for impact when everything else looks right.

...and I'm not at all clear on your timing remark.

a bent valve will show as horrible compression that might be confused with timing.

your first move is to check for numbnuts parts installed...used bike?

next move is check someone didn't fudge the cam on bad advice. a high lift cam lobe can do that...and coupled to a tooth move?

then double check the deck height for a skinny head or base gasket.

valves can warp when cooled too quick...which is why dragsters put balls in the exhaust on a hot engine...and exhaust systems are so long...but my first guess here is some numbnuts did some engine work and doesn't know engines.

find someone who knows engines...not every shingle hung out there is valid.

I'd be glad to look at that for you and tell you exactly where the chicken sh*t in the buckwheat.

first clarify the situation on the bike ownership record, then we'll zero in on blame.

best guess
1. valve hung up in the open position
2. someone "hamfisted" was playing expert with cam timing or clearances.

I don't think revs are the culprit...heat and oil pressure may be.

edit: if there was a previous scramble and they didn't get the oil passages and pump pick-up screen clear, it can run a bit until the heat seizes a stem or whatever...this is what it sounds like.

can I see some pictures?
specifically of the valve stems where they run in the guides.

 

[Gregger]

..a downshift at speed to a too-low gear could overrev your engine well past the rev limit.

+1 on this. No rev limiter can prevent this from happening.

Is the cam chain still in one piece or did it break? A broken chain will also do the same thing bending your valves.

Did any of the valves separated from the stems? A broken valve face will destroy the engine at speed.

One other item, did you drive through any water or heavy rain? Water won't compress - bent rods....

 

[yonder]

2003 Bonnie T100, 2k miles.

Am I the only one bothered that this bike is 6 years old now and not even broken in yet?

 

[Durbud]

I've put 15,000 on my bike and it is just starting to feel broken in....