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Another valve spring broke!

C

Crispin

Joined Mar 2008
538 Posts | 4+
The Wirral, UK
All, another spring broke, this time significant damage to engine (piston/liner etc). This is the 3rd spring to fail on me in the last year...

I recently had a race cam fitted & the ports polished to get a few more ponies.

The mechanic looking at it now has suggested there may be interference within the springs (i.e. when they compress the coil is flattend)?

Taffy, I've looked up your dual springs on e-bay, and am considering purchasing. Will these be suitable for a race cam set up? Presumably prevention of coil flattening is a product of correct height adjustment during installation, i.e. springs are not "unsuitable", only the fitment/adjustment can be incorrect?

Please advise, looking to order today if possible for delivery to the mechanic.

Thanks

Crispin
 
I'd say that the OEM's are prone to failure due to poor manufacture in these later years. the DVSK's suit anything that isn't as aggressive as the OEM cam so if the flanks are flat or convex you are 100% good but if they are concave like the OEM cam then I'd say no as a precaution.

i have them in stock.

regards

Taffy
 
Thanks Taffy, the mechanic believes the flanks (ramps?), are concave?

So where does that leave me, are there any springs I can get which will give me a reasonable degree of reliability (or at least better than the conical ones)?

Thanks

Crispin
 
a race cam shouldn't have concave flanks. i'll try and find a photo of the two types. a standard cam will have any of the following written on the ends

53
55
01
08
53_08_2.sized.jpg


regards

Taffy
 
the springs i guarantee with the cam on the right but not on the left. it might work with it, it probably does work with it but i haven't tested it.

and this is my top end cam which looks very similar to the torque cam in that the cam is convex on the flanks.

LX1_near_edit.jpg


regards

Taffy
 
Thanks Taffy, I have the one that came out of the bike when the race one was fitted, which has 82-08 4/5169 on it, so "08" as you mentioned above. I can see the slight concavity you mention (see photo);

DSC_0161.jpg


I'll ask for the code from the cam currently installed just to be certain, and ask for a closer inspection of the flank profiles.

Cheers

Crispin
 
Hi Taffy, the mechanic had a closer look, and the flanks are indeed convex!

Order placed through friend, so thanks for the info!

Cheers

Crispin
 
well i finally did it! i tried the '53' cam with the DVSK today at lt hadham and after ratt;ling the revs it came through ok!

so the good news is that a DVSK can be fitted with that nasty old '53' and '55' cam going back to year dot. oddly enough the '53' pulled how i remember it and veterans of this site will recall that i at firs,t couldn't detect much difference and it was only over a few rides it became better and better. the old valve tappet racket was back, sheesh i don't miss that!

anyway, for those that simply want a DVSK upgrade (from whoever) then it seems 100% feasible in the 35/30 heads (and the 400s 35/27) as for the 01-03 37/30s well the difference is a few grammes over the 35s for the 37s. it's a really small amount. so i can't say for sure but lets put it this way...the 400 revs to heaven and the other engines (bar the 470) can't and don't rev that high? the 32mm exhausts will be good becvause my 35mm inlets are good. that leaves the 37s to test. but really - 4gms??? i can't see it.

now that REALLY proves how shyte those conicals are doesn't it!

regards

Taffy
 
Hi all, well I'm finally back on the road this week after this "spring break" (seems more like a "summer break" having been off the road for the last 3 months!), hence my absence.

A chap local to me did the re-build, which took far too long to sort. You live & learn...

Anyway, thanks to Taffy for sorting out a great deal on parts & doing some honing work on my piston liner, which was speedily expedited on his part!

Its still early days obviously, but wow! what a difference these dual springs make to the engine noise.... what noise??! (apart from the ridiculously loud exhaust)!

I need to run in the engine now. Anyone got an idea of approximate running hours before changing oil/hitting full revs??

Thanks

Crispin
 
Hi Crispin and welcome back after your summer break. I would run the bike on a non synthetic oil for about 30 miles or so, don't ride it like a ***** either, accelerate hard through all the gears, not to the redline line but hard, then slow down to first gear and do it again and again. Don't tootle around, you need to get some gasses behind those new rings to force them onto the newly honed bore, your 1st ride is the most important ride as this will determine how you engine performs for the rest of it's life (not long being a berg).
Then dump the oil and put in synthetic of your choice. Jobs a goodun.

Regards Freaky
 
Hey cheers Freaky, thanks for the advice. I don't think I've been pushing her nearly hard enough reading your post, so I'll have a bit more of a push on today, change the oil, ramp her up over the next week or so, & then give it the beans next week!

Many Thanks

Crispin
 
Howdy folks, I think I've now done the necessary running in, however, I cannot get the lower screen filter out, the bolt head has progressively rounded over time, and I cannot get it to turn any more.

Would people think I could get away without taking this filter out & cleaning it this time, (I have emptied all oil out & changed cartridge filter), & wait until the next oil change when I can get a new one lined up & can therefore "destroy" the other one if necessary during removal?

Thanks

Crispin
 
you'll be fine. just get a new one ready for the next change.

regards

Taffy
 
a few weeks ago I installed KTM DVSK during rebuild of my engine.I am running 37/30 valves and 53 cam and everything is perfect. I had measured the spring forces at different lenghts(installed and max lift).If you are interested find my post about DVSKs or go to my gallery.
 
Thanks Taffy, think I'll get myself a few and have a spare too!

Cheers Faust, I'll take a look @ your info. I cannot believe the difference in the engine noise with these DVSK's, the motor sounds so quite now.

Crispin
 

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