carb ? 81srx with 44s

SRXfromHELL

SRXfromHELL

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Joined
Feb 5, 2005
Messages
107
Age
59
Location
Morris ,Pa.
I still have a lean condition at midrange , my 44s have #29 pilots and no air jet at all . will replacing the pilots with 35s and .07 air jets help ?
 

what slide cut away do you have and whats the needle and wheres the clip at??, thats the mid range.
 
the air jet and pilot # are supposed to be in these carbs from the factory without these in it possible im too lean midreange to mask the lack of fuel at idle to 1/4 ???
 
Id use the 3rd clip right off the bat, its the middle, then work up or down from there. The 81 srx needs alot of fuel down low, any piston port engine/cylinder reed engine does, so youll want to be rich on the bottom(big pilot jets and rich air screw settings) to have it rev up cleanly, being len will make it labor on rev up(slow) and will have a erratic idle.
 
I'm not sure where you should be on jetting but I will be going through this myself soon. The pilot jet in the stock 40mm butterfly carbs is a # 90 with a P.A.J. # of 0.7 and 1 3/4 turn out on the air screw. Total jetting on the PTO side was 417.5 and 412.5 on the mag side according to the book. The porting on the 81 is huge in stock form when compared to the early 439cc SRX engines. I am told the 81 engine needs fuel and should be setup close to what the 77 SRX engines were in jetting as they are both very hi strung engines. The HP they make and the RPMs they make it at are very similiar so I would try to get some 77 specs on jetting and start from there with your 44's. I guess Delaughter built mod 81 engines that were running 48mm carbs and putting out around 120hp so they are capable of taking some fuel. A friend of mine is running his 77 with 44mm non-powerjet carbs on a basicly stock 77 engine with Aaen pipes and no air box. He is running around 500 in total jetting and the engine handles it just fine. I would start big and work my way down on the 81 just to be safe.

Good Luck,

opsled
 
145 main is stock in a 81 srx, but they also have a #95 and 87.5/82.5 high speed power jets which enrichens the high speed mixture even more, so if you just converted the 145 to a hex jet your looking at a 260 main, but you need to figure in the power jet, and that would most likely be ((around)) a 320 or so, keep it rich and work down from there. If I had to guess, I would start with a 35-40 pilot, mid clip on needle and a 320 main, do the standard checks on plugs and piston wash and do each carb circuit seperately, to get it dialed in.
 
REAL TOUGH ENGINE TO TUNE. MOTOR LIKE A SOUR TOMATO UNTIL IT HITS 6000. THAN LOOK OUT. I ALWAYS USE THE STOCK BUTTERFLY CARBS ON MINE. REALLY GOT THEM TO WORK NICE. MOST THROUGH THOSE AWAY. JUST A SAFETY BLANKET WHILE YOUR TUNEING DROP ALTTILT PREMIX IN YOUR TANK IF YOUR STILL RUNNING OIL INJECTION. I ASSUME THATS GONE THOUGH. 3:16 (yammie tony)
 
thanks for the replies . I'm going to put pilot and air jets in these things and go from there , had the needles in the 3rd clip and had a real bad bog with them there but will try them there after I put the pilots and air jets in . Tony got any specs. for the older srx's that might help me get started . she's also bored to 68.5 mm , comet 102 , purple spring (5000 rpm engagement) B weights , and I'm using the airbox . I'm also considering using a set of stinger I have and removing the stock muffler
Kevin
 
PERFECT CLUTCH SET-UP. YOUR RIGHT ON. ONLY THING I MIGHT CONSIDER DOING IF I WERE YOU IS UP ENGAGEMENT EVEN MORE. ATLEAST 5500. ENGAGEMENT NOTCH WOULD TAKE CARE OF THAT OR TWO COMET SHIMS. WHISH I COULD SHOW YOU THE DYNO SHEETS I SAW ON THIS ENGINE BACK AROUND 1983. LET ME TRY TO WALK THROUGH THIS. I THINK YOU POSTED LEAN MID RANGE. FIRST STAY WITH A AIRBOX, I THINK I BLOCKED THAT POWERJET RIGHT OFF AND RAN A FIXED MAIN. THIS WAS WITH .38 BUTTERFLYS. I NEVER RAN .44 ON MY 81, BUT I DO KNOW .44 CARBS COME WITH A BIG MAIN JET STOCK AND A RICH CIRCUIT. I THINK THEY CAME WITH AROUND A 510 M.J. MOST OF THE PROBLEMS WITH BURNING DOWN WITH THESE SLEDS STARTED AT MID RANGE TO W/O. I WOULD SUGGEST WHAT DON SAID ABOUT CUTAWAY BUT ALSO RICHING BRASS. YOUR PROBLEY LEAN THROUGH WHOLE RANGE LIKE THESE GUYS SUGGESTED. MAKE SHURE YOU RUN GOOD FUEL IN THAT ROCKET. AND CONSIDER PREMIX IN TANK FOR BACK UP IF YOU STILL USE OIL INJECTION. CLUTCHING SET-UP IS VERY CLOSE. 3:16 (yammie tony)
 
DO NOT USE AIR FILTERS. The air box will work better...Listen to Tony. Are we talking good old summer time or winter????
 
How "rare" are the 81 srx's considered? Found one for $3000 in good shape , runs good....Sorry didn't mean to crash your post.
 
vmaxx4 said:
How "rare" are the 81 srx's considered? Found one for $3000 in good shape , runs good....Sorry didn't mean to crash your post.
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Not that rare unless it's still in the crate. Jon Bertolino has been selling some that are near mint for under $2000. Very cool sled though.

opsled
 
I wonder just how many are left though?? with all the problems, trade in programs and all, alot had to be destroyed. Its gotta go up in value soon, it is a 1 year only machine!
 
The machine I am looking at is owned by a dealer and has always been his. He told me he knew of 81's going for $2000 not running. :dunno:
 
I THINK THE 81 SRX IS GONNA END UP BEING VERY RARE IF IT HAS MATCHING MOTOR TO THAT CHASSIS. I MEAN SAME NUMBERS ON MOTOR ARE MATCHED. THAT MEANS SLED CAME WITH THAT MOTOR. MANY BOTTOM ENDS WERE CHANGED AT DEALERS AND ARE UNSTAMPED. !! 3:16 (yammie tony)
 
mines still got the original engine.....I completely rebuilt the engine, never fired it up yet. The windshields if stock yamaha bring stupid $$$

I know the parts sure are jumping in price for these sleds, just hope the value of the sleds jump along with the parts, the NOS yamaa seat cover I got last year for $100 was alot more this year on ebay, come on price surge....LOL
81 srx440 is kinda unique,they are a 1 year only sled, I think they will bring some big coin in the future, thats why mine will sit on a shelf and wait it out, all original right down to the stickers on the toolbox and all. I even got brand new yamaha ski rubbers and only need to get a set of ski decals from Jon bertolino for the completion of the sled.
 
DON, I MIGHT BE WRONG, THE ONES JOHN HAS SOLD ARE NO MATCHES. YOURS IS THE ONE TO HAVE. 94 MAX (mark ) HAS A NUMBERS MATCHING ONE ALSO. I DON,T THINK MINE MATCHED, BUT IT STILL LIVES TODAY. GUY RESTORED IT. ONLY PROBLEM WITH THE 81 SRX IS PEOPLE AT SHOWS THINK ITS THE 82. THEY COME OVER AND SAY, HEY THAT SLED WAS NEVER RELEASED. WELL IT WAS, YAMAHA SOLD A ZILLION OF THEM. BUT MOST BLEW UP. 3:16 (yammie tony)
 
YAMMIEGOD3:16 said:
DON, I MIGHT BE WRONG, THE ONES JOHN HAS SOLD ARE NO MATCHES. YOURS IS THE ONE TO HAVE. 94 MAX (mark ) HAS A NUMBERS MATCHING ONE ALSO. I DON,T THINK MINE MATCHED, BUT IT STILL LIVES TODAY. GUY RESTORED IT. ONLY PROBLEM WITH THE 81 SRX IS PEOPLE AT SHOWS THINK ITS THE 82. THEY COME OVER AND SAY, HEY THAT SLED WAS NEVER RELEASED. WELL IT WAS, YAMAHA SOLD A ZILLION OF THEM. BUT MOST BLEW UP. 3:16 (yammie tony)
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Tony makes a very good point and I should have thought thing through a little better before I gave my last response (sorry and thanks Tony for covering the bases). I'm sure Jon has had some #'s matching originals and I'm sure that some were not. As Tony said most of the engines on these sleds have had work done to them and alot will not have matching #'s even if the original block is still in the sled due to gear case issues. There are quit a few 81's out there but many have had engine transplants and most are not in pristeen original condition. There is no doubt that their value will continue to rise but as with anything else condition, miles and originality will command top dollar. If the one you are looking at is an original #'s matching sled in pristeen, original, running condition with low miles or flaws $3000 may be a good price. Most of the ones I see that are nice and sell for the $1000 - $2000 range will have flaws could include the #'s matching issue, nicks, scratches, seat flaws, wrong clutch, gold cad gone on suspension and under hood parts etc. Super nice 81's with out any flaws are VERY!! hard to find so if you are looking at one like that you could have one that is well worth the money he is asking. mrviper700 is right, they are a one year wonder with alot of issues but they are also very cool and in the right hands fairly dependable under the right conditions. Pound for pound they were as fast as any 440 out there and would compete very well with a 77SRX if they weighed the same.

opsled

PS Someone asked about ski decals recently and I know Jon has reproductions but here is a pic of an original left side one that I have if you want to know what they look like.
 

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