Valve bounce, maybe? stuffed two valves!

kevski

XS650 Addict
Messages
309
Reaction score
284
Points
63
Location
kent uk
Went out for a spin on Sunday, and what a bad one it was, on the way back home about a mile from home when the engine started rattling big time and lost a cylinder, limped home and could hear it was the left side i thought the motor was toast, only done about about 300 miles since rebuild, off with valve covers, left exhaust valve not closing hence the rattling, so off with tank, seat, panels, exhausts, brake lever, footrest and everything needed to enable motor removal, drain oil, nice and clean, Monday motor out top end off, had to cut the valve to drop it out bent both ends, guide has galled and valve obviously hung up and been hit by the inlet as it has the witness mark on it, the top was rebuilt and the valves and seats done by a very reputable engine builder, new stainless heiden valves, there was a good oil supply i always check this with open tappet covers, cam timing and tension fine, engine timing fine, carburation good, so what caused this is a mystery, only thing i can think off is valve bounce, i have a used head coming and have ordered new valves and a guide to rebuild the damaged one, any thoughts gentlemen?
 
Valve bent both ends hence having to cut the top, .75 oversize pistons, stainless valves, heiden strainer, paper oil filter heiden, boyer ignition, cam is stock, retainers and collects remained in place, I do accelerate hard and rarely go over limits, this xs I have only had up to about 90mph on only one occasion, but normally only drive at about 60 mph.
 
Will try to get a few pics tomorrow, all other guides are fine with the valves able to slide under there own weight through the guides, my only thought is there may have been a problem with the valve even though they were new.
 
One last question.
Did it start making noise at the exact same time as it dropped the cylinder or did you feel a miss and then noise?
 
Valve bent both ends hence having to cut the top, .75 oversize pistons, stainless valves, heiden strainer, paper oil filter heiden, boyer ignition, cam is stock, retainers and collects remained in place, I do accelerate hard and rarely go over limits, this xs I have only had up to about 90mph on only one occasion, but normally only drive at about 60 mph.
What valve springs are you using and what valves?
 
All other guides are fine.
20200522_071128.jpg
20200522_071311.jpg
 
Those valves are complete junk as I've seen the valve heads pop off,valve stem out of spec . Go buy some qaulity Kibblewhite valves or buy from smedespeed(spelling) from the UK or the company on the euro ebay selling good quality xs SS valves. Replace the cheap stock V/Ps with either kibblewhite springs or any alternative spring available over there. You need to replace those guides. You don't build a engine with substandard parts and expect
it to live long. I have an alternative spring that I'll be using but requires Moly retainers and shortned bronze valve guides. Schumann Motor works has the moly retainers with locks, Kibblewhite bronze guides and BWM single spring combine with stock inner spring.
 
Last edited:
Sadly I did not build the motor, I have already sourced a used head which came today, and I must say i am happy with it as there is no wear on the valve tips, seats and valves are good with no pitting so will be lapped in, guides are in spec, only thing is a 6mm tappet cover stud is stripped out, possibly the reason it has not seen much wear, very little carbon in combustion chambers, I shall make a 7mm to 6mm shouldered stud for this, in a week or two it will be running again, then i shall rebuild the old head.
 
Congrats on your outlook, kevski--no venting, putting the losses behind you and moving forward.

Hey Jack, don't be calling a product from Saint Jerry Heiden "complete junk," you risk being charged with heresy and flamed like me! You ought to know that an accomplished tuner and builder would never, ever hawk inferior goods on the strength of his reputation, just to make a buck.
 
Sadly I did not build the motor, I have already sourced a used head which came today, and I must say i am happy with it as there is no wear on the valve tips, seats and valves are good with no pitting so will be lapped in, guides are in spec, only thing is a 6mm tappet cover stud is stripped out, possibly the reason it has not seen much wear, very little carbon in combustion chambers, I shall make a 7mm to 6mm shouldered stud for this, in a week or two it will be running again, then i shall rebuild the old head.
If you're gonna throttle it,you'll need a good valve spring to keep the valves in check from bouncing off the seat.Here is the valve spring I spoke of and retainer. You can run a 420 lift cam with the set up if you choose to do so
The springs can be bought for about $11.00 US and retainers $50.00 nad are much stronger than stock and lighter.
moly retainer.jpg
moly retainer 2.jpg
20200429_141833.jpg
 

Attachments

  • 20200429_141833.jpg
    20200429_141833.jpg
    67.8 KB · Views: 207
I certainly will not bad mouth builders, suppliers or products that have been around for years on the strength that a part sometimes fails, I have known some of the so called best in the world fail with far more dire consequences, as it is it can be remedied and will be back.
 
Congrats on your outlook, kevski--no venting, putting the losses behind you and moving forward.

Hey Jack, don't be calling a product from Saint Jerry Heiden "complete junk," you risk being charged with heresy and flamed like me! You ought to know that an accomplished tuner and builder would never, ever hawk inferior goods on the strength of his reputation, just to make a buck.
Griz, I have nothing against Jerry but there's enough information out there with problems with those valves and from what I've seen in person nor
do I care what 650traders opinions are as I will continue to advise members of this forum what products to avoid based on my experience and of others
misfortunes. There's a reason why Hoos Racing uses kibblewhite valves ,they're a higher quality valve and the tulip head is based off the Harry Lillie
Harley valves.
 
We both call 'em like we see 'em, Jack. Have you had a chance to run that XS Performance camshaft yet? Make sure your dental insurance is paid up before you do, that thing will shake your fillings out!
 
I certainly will not bad mouth builders, suppliers or products that have been around for years on the strength that a part sometimes fails, I have known some of the so called best in the world fail with far more dire consequences, as it is it can be remedied and will be back.
Nobody is bad mouthing anybody but advising you to avoid certain products due to inferior quality and in the end it's up to you how you spend your money,that's what forums are for to guide you in the right direction to avoid engine failures.
 
We both call 'em like we see 'em, Jack. Have you had a chance to run that XS Performance camshaft yet? Make sure your dental insurance is paid up before you do, that thing will shake your fillings out!
Haven't decided what to do with that clone door stop yet,besides your experience and from others,I've also read that the cam lobes are soft causing excessive wear.
 
Back
Top