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Post by barry48psi11dk on Nov 5, 2006 19:37:55 GMT -5
Hi All
New member , first post
I started riding my '80 SR500 a few days ago, not to bad to start when cold ( without choke) and runs well. Hard to start when hot, it sometimes starts but not pick up (stalls) I have the feeling it's a touch too rich. But the main problem is when I took it down the freeway, after about .5 an hour I was doing about 100 Ks (about 60 mph)when I gave it some more throttle ,and it started to rattle every time I gave it more throttle, then the rattle got louder and the engine started to die , I slowed down to about 60 Ks and the engine came back to normal, same thing happened on the way home , I'm using standard unleaded anybody else had this happen
Barry
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Post by wotavidone on Nov 5, 2006 20:36:29 GMT -5
Sounds suspiciously like your bike suffers the same probs mine does - pinging.
Definitely need premium unleaded. My bike has had some work done which appears to have raised the compression ratio - but even a standard motor doesn't like standard unleaded as far as I can gather.
I used BP 98 octane which all but eliminated the problem, until I found a friendly servo which helped me out with some av-gas.
That made the ol' girl go like s#@t off a shiny shovel as we say in this part of the world.
Need to study some of the posts on this site about starting. You will learn lots of interesting things about technique and hot start buttons, etc.
Along the way, you need to have a look at your spark plug and assess the mixture, but my advice is put in at least 95/96 octane fuel and see if the pinging is eliminated, then once you settle on an acceptable octane rating, look hard at your mixtures.
I dare say everyone running a non-standard exhaust and air cleaner setup has at least installed a bigger main jet. I got my bigger jets from a Yammy dealer, which is encouraging.
Hope this helps.
Mick
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Post by StewRoss on Nov 5, 2006 21:57:15 GMT -5
Hi, I agree, sounds a lot like detonation...this can be very bad for your engine and it will cause piston and head damage if you continue with it.... Immediately source high octane fuel before you ride it much more... Have you checked the ignition timing at all? It may be a fair way out...check it out! What piston is in it? If it's a high comp one then this is sort of expected in a way...the fix is higher octane fuel...headwork would also help if you have someone who understands squish etc... To get it at 100k's though is possibly a little unusual, more likely down low underload etc...if you crack the throttle open hard it may also do it. What sprocket sizes are you running? SR  |
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Post by wotavidone on Nov 5, 2006 22:46:03 GMT -5
100k's is where I got it in spades.
Seems like that is where the influence of the needle is reducing and the main jet is starting to be the major influence on metering fuel.
I guess down low the bike was rich enough that the mixture was inhibiting the flame speed somewhat, whereas much higher than 100 k's the stock ignition doesn't advance much more, the load is different, etc.
My spark plug looked starnge. With the needle lifted as high as it can go, the plug had a layer of soot over stark white porcelain. Sounds wierd I know, but that is actually a very accurate description.
Looking at the soot you woulda said too rich, looking at the procelain you woulda said too lean. Cleaning the soot off left a pure white procelain underneath.
It was only after I returned the needle to standard settings and commenced increasing the main jet size did I get a nice even tan colour.
Messing with the mixture until I got the even tan colour helped a lot, as did retarding the timing, but it was sourcing 100 octane fuel that truly fixed it.
Planning t o go back to standard timing soon.
Mick
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Post by StewRoss on Nov 6, 2006 3:17:25 GMT -5
Hi, Yes the SR's love high octane fuel...probably a byproduct of a less than perfect combustion chamber design... AVGAS is great...instant operation from nowhere and no more detonation at all...'course for eveyday operation it may not be a reasistic proposition. SR |
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Post by StewRoss on Nov 6, 2006 3:18:32 GMT -5
..err...I should look at these before I send them offf...'realistic' ...'everyday'...heh, heh...  |
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Post by wotavidone on Nov 6, 2006 18:45:29 GMT -5
Was talking to my mechanic mate last night.
A while ago he put a set of closed chamber heads on a 351 Cleveland in a Ford F100 truck.
If you are familiar with closed chamber Cleveland heads, you'll know what raised our eyebrows. They used to ping a bit under extreme acceleration even when we could get leaded fuel.
Imagine a flat surface with a kidney shaped depression just big enough to take the exhaust and inlet valves - this is what passes for a combustion chamber.
At the time I asked him how this was gonna go with the currently available fuels.
He said - "I'm tipping its gunna ping badly, but the owner is insisting that it'll do for now. I've tried to talk him out of it but he reckons he will build a whole engine as soon as he can get the bucks together and this are the only heads he's got to get the old girl going for now. I even offered him a set of open chambers I've got here but he doesn't have the coupla hundred bucks. Can't tell him he's going to cost himslef more than that with dramas."
So he shook his head, fitted the things, and naturally it knocked like a jack hammer whenever the slightest bit of load came on.
So the lad, who at least admitted that he had been warned and it was his own fault, got together with his mate and did all the usual things, retarded timing, highest octane fuel he could find, rich mixture, etc. All to no avail.
The thing actually kept running after the key was turned off.
Musta had redhot sharp edges on the combustion chambers.
Anyway, my mate heard last night that the engine finally self destructed - smashed pistons, bent conrods, the works.
Find some high octane juice before you go much further.
Mick
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Post by StewRoss on Nov 7, 2006 1:36:46 GMT -5
Hi, Yes, I have seen aircraft engines with detonation...lots of damage...and it occurs quick as well! SR  |
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Post by colinjay on Nov 8, 2006 0:50:08 GMT -5
Hi all, just want to throw in my 2 cents worth to this topic.
I have been running my 78 SR, engine, rebuilt to STD specs in 1998 since its rebuild on STD unleaded with out any real problems. It is running a 17 tooth C/S sprocket and pulls my 120Kg riding weight at 100 - 110kph happily with out any signs of pinging on my daily ride to work which is all uphill/down hill through the Clare valley, infact I was lazy this moring and went up Neagles Rock hill in Clare this morning with out changing down topping the hill at about 70k's in top gear, throttle fully open labouring the poor old girl badly with out any sign of the dreaded death rattle.
So, I am of the opinion that unless the compression has been raised an SR should run happily on STD unleaded with out any undue problems.
I will say though, that my hot SR engine, which is currently mounted in a Husqvarna MX chassis, pingings when run under heavy load no matter what fuel I run in it except methanol. However on a measured compression ratio check it has a CR of 14.2 to 1 so it has a definite right to not like anthing under 100 + octane
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Post by wotavidone on Nov 8, 2006 1:01:43 GMT -5
That's where I'd like to be Colin - I really envy you.
I reckon the bloke I bought my bike from might have done a bit more than just throw a high comp piston in it.
I have also heard that early Wiseco piston were not very well designed with regard to the "squish band" which I only think I know what that is. The suggestion I have heard is that this makes them ping at lower compression ratios than other brands.
I've always felt the same way about engines - unless they have a bad fault from new, in which case don't buy it anyway - don't mess with 'em.
If you do, there will always be some trade off in reliability and operability I reckon.
This is something I intend to get too one day, a rebuild to standard specs.
I reckon I'll wait till I've got a second bike to ride so I am not grounded while I do it.
Until then Avgas is good.
Mick
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Post by barry48psi11dk on Nov 8, 2006 21:22:36 GMT -5
Hi all
Thanks for the replies , will try better petrol ASAP, getting back to the "rich " running , had a look at main jet , no number on it , will try to lower the needle if possible
Barry
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Post by StewRoss on Nov 9, 2006 3:35:14 GMT -5
Hi, Yes the standard engine should run on unleaded OK...they were originally designed to use it...even so I still run 98...up the compression and you start to have changes though... 14:1!!! Yep, that'll give you pinging problems...that is on any sort of standard fuel...that NASCAR? stuff might help for non-methanol burners. That's the sort of compression they run...it's not cheap of course...plus probably needs to be handled with gloves on...you can buy it here in Canberra for some exhorbitant price...jetting changes are needed as well. Not as much as methanol...I was considering it for my Honda... The early Wiseco's did have squish problems..I have one in the black CR, but AVGAS cures all...the later ones have changed in this area... SR |
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Post by fenz on Nov 9, 2006 5:43:35 GMT -5
I have had a bit of a play around with avgas in high compression motors and it is good stuff if you can get a hold of it.Tried mixing it 50/50 with standard unleaded with fairly good results (no pinging and nice grey pipe)But like i said it seems fairly hard to come by these days.
Have been running my SR on unleaded with Nulon valve saver addative seems to be o.k.
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