all valves were correctly adjusted, prior to the valve failure I had only ridden about 10 miles and about 2 miles at 70 to 80 mph when the exhaust valve broke. The valve stem was moving easily in the valve guide. It was a simple case of the stem failing.


The savage engine is over square and a fairly torqeuy low revver, max revs is about 5,400 ? So no way should a valve fail due to being ridden hard. In fact the savage engine is in such a low state of tune that it sounds very comfortable at 80 mph, so much so that to me it feels as though there should be another 20 mph or so left in it. I have had bikes that were built in the 60's, 70's and 80's that revved to over 10,000 rpm and covered 50, 60 thousand miles of hard riding. As a rule of thumb that would be 20 times more valve life used than my savage after 20 thousand miles. Of course those bikes ran on leaded fuel were and tuned to run richer than a savage.

I sold a mate an old Yamaha XJ900F a couple of years ago that had done 64,000 miles, and he has added another 15,000. That bike has just had regular oil changes, diff oil changes, one new clutch set and  tyres as needed. It is still running sweet as a nut.

I am now convinced that the failure was due either to a flaw from manufacture, or lean running by previous owner(s), and the higher temperatures that would result.

So convinced am I, that I am putting in a bigger main jet, and I will be putting 2 new exhaust valves in the replacement engine before I install and run it.

BurnPgh wrote on 05/08/08 at 22:04:28:

There's a bit of a dilemma in there.  Your best gas mileage will be with her her running slightly lean but the lean mixture will cause her to run hotter than if she were adjusted slightly richer (and lend to backfiring).  Properly tuning her for performance will reduce mileage a bit but you'll have more power and a cooler engine.  I get about 45 MPG with my Amal Mk2 carb and average riding habits.  If I were to put the stock CV carb back on and ride in a more fuel-conservative manner (take longer to accelerate and don't exceed about 60 MPH), I'd get between 55 and 60 MPG.  At this point, I like the response I get with a straight slide carb over a CV but I'm keeping my stock carb just in case.  Either way, I live in Texas and I'll opt for a properly adjusted carb for a cooler engine.

Justin, I reckon it's one of them classic dilema's where you "pay's your money and takes your chance".

However,
I personally now believe I had the valve failure because a previous owner fitted a Raask exhaust, and ran the bike with a 130 main jet, (a 155 or bigger should have been fitted), this along with running unleaded UK spec petrol has meant the engine had been running too hot for who knows how many miles.

How many people on this forum have high mileage stock savages with over 20K and no problems?

If you have a stock bike it may do 40k plus miles with no problem?
Also what octane is the petrol you guys use in the states?
Here in the UK it is unleaded 95 octane which can cause "pinking" and hot running in older high compression engines that were designed to run leaded fuel.


I am having to buy a low mileage 2nd hand engine because of what happened to mine.
I started the thread to try and discover if this was a "known problem" with these bikes. One reply from T Mack has said that he has heard of it happening before.

I am getting 2 new exhaust valves from Alpha Sports which is in the USA sent over and will put them in before I use the replacement engine.

Next bit is what I have deduced and would do if I had a nice savage with 15K plus on it.

Run a bigger main jet, (US spec is 130, UK is 155 which is 20% bigger!) My carb had a 130 in it with a Raask exhaust.

Every 15K to 20K check cam chain, replace exhaust valves, (inlet valves will not be affected by the heat issue), and fit new valve stem seals.
If you replace the the exhaust valves and stem seals it will cost about $150, with new head gasket as well, as long as you can do the work yourself.
These bikes are so cheap to run that I consider that well worth the cost for peace of mind, and to avoid a potential failure of the engine and major damage.

However if you have a bike that has always used a stock carb / jets / exhaust, and has been well maintained it could possibly do a very high mileage no problems?