81 Srx

N

nysrx

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Anyone know how many 81 SRX were produced. What was the main problem these sleds had. What kind of power did they produce.
 
'81 Srx

I'm not sure how many of the '81s were produced--it was definately a high production run though because there were lots of them around (not running anymore of course). The main problem with these sleds, in my opinion was that the engine was just too high-strung for trail riding. They make very little power below 5500 rpm and make peak power somewhere in the 9200 rpm range. To get them to work well, you need a high clutch engagement speed which makes them quite erratic for riding. The factory butterfly carbs were not very forgiving (nor the engine) when it came to tuning and always seemed to be plagued with lean spots throughout the engine's rpm range. Engines with higher miles usually experience crank problems because of the high rpm and also because of the rather long and poorly supported mag end that runs through the gear case (water pump, oil pump drive).

I can tell you this though. The '81 engine has more potential for max. horsepower than any other year SRX. It has huge ports and lots of transfer area and makes an excellent small bore "stuffer engine". I've spent the last three weeks with my first stock '81 SRX, jetting 38mm roundslides and doing lots of clutch work--and it's working very well. My buddy has a real nice '79 SRX that consistently wins the vintage classes at drag races, and my '81 is now faster from the holeshot right to end of 660'.
 
VERY ACCURATE INFO ON THE 81. ONE MORE THING I WILL ADD. DO NOT CONFUSE A 81 SRX WITH THE 82 SRX. TO TOTALLY DEFFERENT SLEDS AND OUTCOMES. 3:16 (yammie tony)
 
YAMMIEGOD3:16 said:
VERY ACCURATE INFO ON THE 81. ONE MORE THING I WILL ADD. DO NOT CONFUSE A 81 SRX WITH THE 82 SRX. TO TOTALLY DEFFERENT SLEDS AND OUTCOMES. 3:16 (yammie tony)
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Do tell? I have only heard stories about them, but my local Yamaha dealer who played with all that stuff in the day says that they were a force to be reckoned with!

I bought a new 83 540 and enjoyed it for over 10k with only blowing up the stock primary and one ring at 8500k. It went like snot if it was kept well tuned and beat the hell out any competition in the day. In 92 my brother in law bought a new 650 RXL to beat up on me, just before the aforementioned ring incident, and, we were about even. After the new rings, I beat him! He hated that.

I had never seen an 81 run until one night when I stopped in at the dealer and they had just finished tuning an 81 with 35000k on it!!!! Yes that's correct, 35000! It showed its age, but you could tell that it had been very well maintained. I was offered a chance to take it for a rip and it floored me! It would have dusted my 540 easily! Thats when the dealer started telling me about the 500's.

So do tell, please!! G.
 
Thanks, I have read the article before, but he only hints at the performance, in that, the lake racers would have been happy with it!

In any case, I'd have another 81 to 91 in a heartbeat, with 83 graphics, plastic ski's and modern rear suspension.

That, and throw in a nice warm, piped, 600 twin, flatslides and an aluminum bulkhead, it would almost be too much to hope for! Very cool little sled, Darth Vader on snow! G.
 
mrviper700 said:
81 srx was the "stroker", big stroke and big port area!
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Yup, Turn a 439 cylinder upside down next to a 437 cylinder and you will be amazed at the difference. You couldn't port a 439 far enough to match.

Their potential is over looked by many. Good parts are hard to find but they are capable of more HP than a 77 and can be gotten down close to 300lbs on a severe diet. Not for the average tuner though.

opsled
 
Actually, in looking at them, it seems like they have more capability but they really only have slightly more, if any. And that is only after 25 years. :) There never were any that I have ever seen or heard of being as fast or making anywhere near the HP of the old design until just lately. With todays new pipe technology and computor port programs, DRP has gotton a couple to make very good HP. Even at that, he is making better HP than ever with the old design too.
 
Here are some pics, 439 on right, 437 on left, judge for yourself. I am told that a Delaughter 437 mod can run with the best of them including 77's. The 81 was a one year wonder that was plagued with problems, in a heavy sled (compared with older SRX's) and had a bad rep. Because of their issues and the fact that Yamaha wanted them gone it's not surprizing thet they never became to popular to racers back in the day or even today. They were basicly gone before they really got going in the racing scene and not much in the way of aftermarket or performance stuff was ever developed for them.

opsled
 

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Pat Hauck had a '81 that won it's mod-stock class a number of years in a row at the World Series of ice drags. He knows alot about that engine. Does anybody have contact info for Dave Delaughter? Thanks in advance!!
 
MY 81 SRX STILL LIVES TODAY, SEEN IT TOTALLY RESTORED AND RUNNING AT VINTAGE SHOWS. 94 MAX HAS A 81 SRX THAT IS A NUMBERS MATCH ENGINE AND LOWER CASE TO THE CHASSIS. I THINK MR VIPER MATCHES ALSO. I HAVE ALL FACTORY YAMAHA RECALL NOTICES THAT WERE SENT TO DEALERS. THEY WERE TODAYS F-7 lol. ANOTHER THING NOT MENTION WAS THE AWSOME RACE INGITION THE 81 SRX,s HAD THAT WERE DETUNED VERY EARLY. VERY SIMILAIR TO THE 77 SRX. 3:16 (yammie tony)
 
I understand there is a SSR running a 1981 srx built by Dave Delaughter,according to the report on vintage sleds,it really pulls out of the corners,but had some problems and crashed,hope to see it At Ironwood this weekend,Dave can be found on the vintage sleds forum under the user name DRP.
 
htgindy said:
Pat Hauck had a '81 that won it's mod-stock class a number of years in a row at the World Series of ice drags. He knows alot about that engine. Does anybody have contact info for Dave Delaughter? Thanks in advance!!
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You might want to check that. Pat's '76 Canadian SRX is probably the fastest Mod Stock SRX ever. Call him.
Dave Delaughter 763-498-3400
 
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Yup, he had that very sucessful '76 too. I have pictures of him launching his '81 at the World Series in '87 and have talked to him about that sled on a couple of occasions. Thanks for the contact # though.
 
On the ignition system the original stock 81 srx had a curve of 8 degrees flat, the new update "trail" kit they put out for them was a 12 degree curve that started right at engagement speed and finished at the same 8 degrees of the original box, this is the 8r9 box or 1982 srx500 box. I have both for mine, there is also a differance in the flywheel and stator.

another thing on Phils pic, notice the intake length between the 78-80 and the 81, way shorter!! this is a common mod to the early engines.
 
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