1980 440 srx tips

M

mac daddy racing

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Joined
Feb 9, 2011
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Age
61
Location
St.Clair MI
I have a 1980 yamaha 440 srx that is pretty much stock other then a 108 comet primary clutch. I use this sled to oval race in a field with a few buddies every winter. What should i do to help it run better. What poundage should i set the secondary at to help with the hole shot. What gear ratio should I run? Is a 108 comet too big for the primary? Im pretty sure I have the jetting close and it wants to bog when u floor it from a dead dig. Im thinking my clutching is way off. It has stock carbs on it right now but I have a newer set of keihin 38 mm round slide carbs. Also I have heard people say not to mess with the timing, why is that? Are they already tuned hot enough from the factory?
Im new to the forum and any help would be great,
Thanks, Rick
 
ENGAGEMENT HAS TO BE 5500. I GO 17-31 GEARING. I HAVE NEVER USED A 108. YAMAHA CLUTCH OR COMET 102 WAY BETTER. YOU CAN MESS WITH TIMING BUT WATCH YOUR FUEL AND JETTING IF YOU DO. 3:16 (yammie tony)
 
so many variables but like tony said.. got to get the r's up on engagement.. these things are dogs below 6000 rpm.. powerband is up around 9000-9200 rpm.. what do you have for weights and spring.. what is your engagement rpm?...shiftout rpm?
 
80 srx upgrades

Thanks for the help, I purchased kits for both clutches from Aaen, they sold me a Aaen orange spring for primary, pink Yamaha spring for secondary and 10mb bushed 47.5 hi alt weights. The secondary spring didn't fit (O.D.) to big... so i used the spring the sled came with, its black with some orange on it and set it at 15 lbs. Every thing else looks stock, 136 lbs compression. big time bog off the line, then she flies ;) I know the engagement is not that high. I'm going thru the motor now, cutting heads and doing some mild porting and maybe those 38 round slides. Are the butterfly carbs ok or should i not waste my time with them. Thanks for the help. Rick and jesse, Mac Daddy Racing P.S. I need to learn how to time it, has a adjustable timing plate, marked it before i took it apart and i noticed it had double base gaskets equalling .040" , Is this the hot set up? Thanks again and I'll be out front.
 
80 Srx

YAMMIEGOD3:16 said:
ENGAGEMENT HAS TO BE 5500. I GO 17-31 GEARING. I HAVE NEVER USED A 108. YAMAHA CLUTCH OR COMET 102 WAY BETTER. YOU CAN MESS WITH TIMING BUT WATCH YOUR FUEL AND JETTING IF YOU DO. 3:16 (yammie tony)
Click to expand...
Thank for all your help
 
the aaen orange spring should be bringing you in around 5500 rpm and shifting out around 9000+ or - 200 rpm with them agressive polaris weights...i ran the purple spring#207888 with 2 shims..(it came in around 5700) and n-1 cam arms #209642(46 gram) with 18/31 gearing and a hauck helix.. i will dig for that and see if it has the degree stamped on it.. but it ran pretty sweet on my 78 .. you might want to give hauck a call and pick his brain on your srx, pat and his brother ran them back in the day and they went good too.......
 
80 SRX upgrades

Sorry again but with me being new to this site i don't know who Hauck is or his number or company he's from... any help would be appreciated. thanks Rick
 
BECAREFUL HERE. SOMEBODY ADDED THOSE GASKETS THE HEADS MIGHT ALREADY BE CUT. LIKE I POSTED I NEVER USED A 108, THE CLUTCH SET-UP RAMBLMAN POSTED WORKED GREAT ON A 102. 3:16 (yammie tony)
 
be careful

That's what I was wondering, squish was. 063" and compression was 138 lbs with worn rings, what should stock head cc be and total cylinder height be? Any idea. Thanks for all your help. Rick and jesse
 
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