YAMMIGOD,clutch help for vintage vmax.

[SamueLJackson]

Ike and I are having problems with our old max. After we changed carburetors engine wont pull right under 4800 rpms and we have tried different jets zillion times.. :cussing: Stock clucth spring in our max is comet yellow/white. Were can I find preload etc values for comet 102 c springs and what spring could or would be good for engament rpms 4800-5000.

Thanks guys

-sami-

[YAMMIEGOD 3:16]

DUDE, THIS FOR A 540 VMAX ? IF IT IS, THE SPRING YA NEED IS A COMET PURPLE. 207758 IS PART #. THIS SPRING SUPERSEEDED THE COMET 102c YELLOW THAT WAS STANDARD ON THE YAMAHA,s UPDATED WITH 102c. !! 3:16 (tony)

[Ike]

Yep. We are looking for help to clutch that 540.

Need a spring what rises the engagement to 4800-5000 rpm range. Will that purple do or is there a another one even better? Will weights have to be changed also?

And Tony, thank´s again.:bowdown: Comet clutches aren´t that well known for us. Sami can do almost anything with the Yamaha ones, but this is a hole another ball game.

Ike

[YAMMIEGOD 3:16]

PURPLE IS THE TICKET DUDE. WILL PUT YA RIGHT ON. ALSO YOU CAN ADD AFEW SHIMS IF YA NEED THEM TO PRIMARY COVER. COMETS ARE EASY !! 3:16 (tony)

[Ike]

Tony, seems like we are the only ones talking here! LOL Others are waiting and writing down this all...Thank you ! This is great info. :urock: :urock: :muahaha:

Sami , you got this now?

Ike

[SamueLJackson]

Jep I`ll got that now and I am ordering that purple spring tomorrow. Tony you make this all way too easy:bowdown: It would be awful job to test and tune by self so thanks again. Iam prepairing little vmx 540 surprise to our club members at our annual dragrace event under 600 cm3 class. My girlfriend wants to ride "little max" at that race and it suits for me because she weights over 20 kgs less than me.

Last year ike was surprised by little max. Ike said that "this sled wont go anywere" because we had huge bog at low rpms. But when Igot little max over bog to higher rpms I suddenly started pulling away from ike and my late piped xt 600 what he was running.

We have 3 monts time to prepair our sleds to that event. And now we will get more podium finishes. Last year we were 3th (me under 600 class) and Ike was 6th at class over 700. This year I will take part to under 700 class too with my srx.

Ike I think we have to order some stickers to our sleds with text YAMMIEGOD RACING

:super:

-sami-

[YAMMIEGOD 3:16]

DUDE, lol !! 3:16 (tony)

[VMAX535]

SJ, I drag raced VMX 549 for years and did very well. My buddies and I still vave a 84, 85 (the old drag sled) and a 86 that I run personelly. Need to know a few things first?
What clutch? 102C or 108
Stock secondary?? What helix?
What jetting. Are powerjets still in use?
Any engine porting or head milling? Let we know what you have and L'ii give ya my 2cents.

VMAX535

[SamueLJackson]

Vmax 540 is still stock. When we bought the sled it was a mess. And it took a year to find out the electrical problem of engine. Pulser coil wire was almoust broke and under tape. So when I measured coil resistance everything seemed to ok but engine wouldn`t run properly.

We had to replace orginal carbs too and now we are using bored 39.5 mm flat slide carbs. Carb swap had caused grey hairs:cussing: to me and I cant find right jets to get engine pull under 4800rpms. Top end is ok with 320 size jets and needle position is right too, belive me I have changed both million times. Pilot jet is now 42.5 and I have tried everything between 30 - 45.

So all info between piston mods and heavily modded race engine is welcome.

-sami-

[VMAX535]

SJ, The problem between idle speed and 4800 rpm may not be carbs at all. I have never run flat slides on any of my Vmax 540. Go to vintagemax.com and ask on there message board. Chuck (Vmax 540) may even see this and comment.

What I can tell you is that the 540's are very hard on clutch components (something we can go into later if you want) espesially rollers. If you have any movement between the pin and the roller it will effect performance when you nail it. What happens is the the roller position moves down on the fly weight at idle and it is like starting out in second gear. The same thing happens if the bushings in the flyweight are worn. These sled like tight drive belts. So ensure that the C-C measurement between clutches is set and then shim the secondary as needed. Also check the that there is no play in the jackshaft bearing. If the bearing is gone the C-C will be effected. Stock helix is ok 47? Twist secondary to B-3.

The A-3 weights in the primary 102C clutch are OK to use but if you need to buy new ones get some A-2's. The A-2's and the blue spring should work pretty good. Fine tune so your shift rpm does not exceed 8250 rpm.

Let me know how you make out.

Picture of my 96 800 with a ripsaw and my 86 540 in the background

/Dan

[BUBS SRX]

I second the YAMMI GOD stickers,Tonys been a great help to all of us.
I have 102c with c-1 weights,2 shims and purple spring and engagement shows 46-4700 on my tach which is probably not exactly rite but deffinetly less bog and no dog.I'm thinking about that digitron with tach and dual egt for my old girl.
Good luck fellas

[VMAX535]

Bubs, your c-1 might be fine on your 440 SRX. But will not perform very well on the VMAX 540. Motor will rev around 9000 rpm. Your 102C also has 2 an extra spacer between the spyder and the shaft. That is not required on the 540cc since the weight profile between A and C weights are totally different.

Good luck with you srx they are fun sleds.

[BUBS SRX]

Its raining here for days,I love for it to be the fluffy white stuff.We would be SO SNOWED IN!!!:i_need_sn
I understand,Your hp and gearing is different than 440 SRX.Have fun,I hope you guys have snow.Later

[YAMMIEGOD 3:16]

ALL THE A'' SERIES COMET WEIGHTS HAVE SAME SHIFT PROFILE. DEFFERENCE IN THESE ARE WEIGHT IN GRAMS. THE A-2 WERE 48.0 GRAMS. I THINK BUBSSRX HAS N-1 WEIGHTS IF HE IS RUNNING MY CLUTCH SETUP FOR A 1980 SRX WITH A COMET CLUTCH. N-1 WERE 46.6 GRAMS. THE PURPLE COMET SPRING (207758) REPLACED COMET YELLOW (203475). THIS SPRING WILL RAISE ENGAGEMENT TO 4800-5000. ! 3:16 (tony)

[BUBS SRX]

I ordered N-1 but they crossed over to c-1 just like the yellow to purple spring.I had your part# list in hand and watched the guy looking through the Comet book.I 'm not sure they are the same,I certailnly hope so.
We got some snow last night but nowhere enough to ride on.
Question?How would flat slide carbs affect the 80srx?better or worse?

[YAMMIEGOD 3:16]

I THINK I REMEBER THAT BUBS, I KNEW THEY CROSSED OVER SPRINGS. C-1 ARE SAME WEIGHT AND PROFILE AS THE N-1. THAT IS ACTUALLY A NICE SET-UP ON THE SRX. I WOULD GO TO ROUND SLIDES ON THE 80 SRX BEFORE FLATSLIDES. HEY, YOU DON,T HAVE A SPARE 1980 SRX GAS TANK TO YA !! 3:16 (tony)

[BUBS SRX]

I posted a link to one on ebay,I'm gonna need the spare on as I have crack in mine too.Sorry,Heres the link again.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=4604178064&sspagename=STRK

Hope this helps,No bids yet

[SamueLJackson]

I changed jets (main and pilot) and moved needle clip one step to leaner (2.from top). Engine pulls much better and throttle response is very good. I am using 300 size mains and 35 pilot jets. Yesterday weather was warm +4c (39f) so I think I will go to 30 size pilots to get engine even sharper from low rpms. I am planning to race old vmx against stock V-4 -92 at wednesday evening. After that I know can I go against new 600cc sleds at our club 660ft drag race.

I try put video (6.9mb) so you can hear sound of old vmx 540. If I cant put the video ike will do it later.

http://video.tinypic.com/player.php?v=v45bb7

-sami-

[BUBS SRX]

Sounds like you got her dialed in closer to where you want it,Running very nice!:rockon:

[SamueLJackson]

Little update..

Changed mains smaller...again and now running 280 size jets. Engine pulls very sharp and spark plug color is now ok, left side little bit leaner than right. Tomorrov back to garage and make cold air intake "kit" and take plates out from air cleaner box.

I try to make a little video when driving test run...so back tomorrow.:4fzfpi:

-sami-

[SamueLJackson]

Now little max is as good as I can get in this time. I took plates of from air box and pilot jets are small, size 30. Engine gets cold air from outside. Mains are left 290 and right 280. Secondary is back to stock setup, sled didnt pick up speed with higher preload at secondary. And our track is loose soft snow so it is track speed what counts.

I tested max against my friends Lynx Enduro 500, 2004 (last rotax 500cc engine). That sled accelerates really fast as Lynx has always done. So sometimes he beat me and sometimes I was fasters.

Here is video of 660ft distance what i drove flat out, listen engine and watch little max spinning in soft, wet loose snow.

http://video.tinypic.com/player.php?v=vzbt34

-sami-

[VMAX80096]

I ran a comet 108exp with polaris 50 weights and an hp orange spring in the primary. Changed it to a polaris secondar with a straight 40 helix...way better bottom end....the stocker does not pull hard the first 100ft...mine liked to run at 7900 then slide up to 8100 tops....I also took the plate out the airbox and ran 370 mains....to get it crisp you have to run the needles lean.
If you really want to try something bolt on a set of 81 srx pipes!...it then will want to run at 9000, early models also have to run the 81 cdi so it will rev...try it first without and see you might get lucky and it will work.

[SamueLJackson]

Jep

the race on at saturday, my nephue will drive little max. It his first race and he is almoust 20 kgs lighter than me....:flagge_fi

[SamueLJackson]

Topic continues here:

http://www.vmax4.com/vbulletin/showthread.php?p=16628#post16628

[vmax-540]

Samual Jackson. You didn't say where you got the flat slides from, were they new ones or were they off of anothers sled? And you didn't say if it wouldn't accelerate under 4800 rpms or if it just wouldn't idel or run smooth , most of the flat slides that are off other engines are mostly reed valve motors & the max is piston port. The reed valves like to be rich on the bottom end so if it runs ok but just won't accelerate untill 4800 or so you may need to change the jet needle ,if they are new carbs that you gat from the aftermarket they usually come with is 6FJ40 and that is a very rich needle I would switch to a 6FJ41 needle as that works good on piston port engines. This would be a good starting piont. I hope this is of some help!:rockon: :xmas-smil

[SamueLJackson]

Started Max for this season and some answers for u qestions.
Engine idles smooth and throttle response is good, actually it was very sharp because weather was colder(0c) than last spring (+5 - +10). Engine wont idle when its cold but at normal temp it idles very well.

My problem seems to be now engine reving too high. I inspected rev gauge and its shows right readings. Engine revs flat out 8500-8600 what is too much. Engament rpms is 4800 and clutch spring is purple (stiffer purple) other wise clutch is stock.

And carbs are old used to be 38 mm size, bored to 39.5 mm. Dont remember what jet needle I am using.

I have to check clucth and secondary distance. Should it be 305mm or more?

My plan is run little Max at top speed race next spring so any advise to get more kmh(mph) is more than welcome

-sami-

[vmax-540]

If you are going to do speed runs on ice you can change the top gear in the chain case from an 18 tooth to an 19 tooth. Does little max have the update porting ? If not you need to get the rpms down to 8250 , try and loosen up the secondary spring a little, rule of thumb is for every change like from c-2 to c-3 you change the rpms 100 rpms. The stock setting is c-2 so try that . If you have yours set at b-3 that is a 50 degree differance, that is a lot!


:party: .

[VMAX535]

Get rid of that purple spring. It has to much rate. Go back to stock or use the recommended spring for the updated porting. I think it's White - Blue - White with a A-2 weight lightened to 46.5 gm. Do not exceed 8250 rpm as Chuck has mentioned if you are using stock cdi. It drops of the back of the power curve hard once you go beyond 8250 rpm. With either of these set-ups set your secondary to B-3 and fine tune from there. If you are not running studs in your track keep the secondary wound on the tight side.

If you have a choice when you run, select marginal snow conditions. The Vmax's of that era didn't respond very well to snow. 4 - 6" of snow would slow them down 30 - 40 km/hr.

Good Luck,

Vmax535

[RedWhiteandBlue]

Okay , are these flat slides or stock carbs?????

I see one major headache you will always battle with this setup. Stock carbs were 38mm Round slide POWER JETs. That allowed them to run better at mid upper throttle (smaller mains) and employ the extra fuel only at WOT when the power jets kicked in. I have seen many bore the stock carbs but only if they overbored the engine but never saw anyone have allot of luck with any other carb on a stock motor. Only thing flat slide carbs do is give you a little better throttle response in the middle of operating range (coming out of a corner and going wide again). For straight drags I would go back to stockers, blueprint that chassis and get the motor/clutch alignment spot on ( biggest boost as they are extemely finicky about that and you will pickup the best gain right there for no money). I have a 108 on my old girl still, can't remember the setup right now but Dan's setup above sounds awfully familiar. I could walk tripple 650's with that thing on ice, slowly but surely...Blue

[Ike]

I think they are flat slide carbs. The stockers were done. Complete junk...

Samueljackson has the latest on this.

Ike

[vmax-540]

Samual J. If you are looking for porting spec. then go to WWW.Vintagevmax.com (http://www.Vintagevmax.com) under articals and you can get to Factory Update Porting Spec.that will bring your stocker up from about 88H.P. to about 96 H.P. I did this years ago to my 83 and it made a big differants in the performance. The port timings are about the same as the 81 SRX but with the extra 100 cc.s you don't lose to much bottom end, I think it feals like it has more bottom end & midrange even thow the Dyno says differant if you can't get the specs from the website please let me know and I will email them to you as I still have them.




:xmas-smil

[VMAX535]

Samual J. If you are looking for porting spec. then go to WWW.Vintagevmax.com (http://www.Vintagevmax.com) under articals and you can get to Factory Update Porting Spec.that will bring your stocker up from about 88H.P. to about 96 H.P. I did this years ago to my 83 and it made a big differants in the performance. The port timings are about the same as the 81 SRX but with the extra 100 cc.s you don't lose to much bottom end, I think it feals like it has more bottom end & midrange even thow the Dyno says differant if you can't get the specs from the website please let me know and I will email them to you as I still have them.


:agree: Pay alot of attention to the transfer ports!!!!!!!

The sled in the picture has that mod done. It has run 104+ depending on conditions. The less snow the better.

http://i17.tinypic.com/2hzj1w7.jpg
/Dan

[SamueLJackson]

Thanks I`ve got specs from website.

-sami-

[Ike]

Got us a new , unused hood for the Vmax540. Cost me 50€... Added some heat shielding aluminium tape to it.

pics..

http://aycu27.webshots.com/image/6826/2001219699458218815_rs.jpg (http://allyoucanupload.webshots.com/v/2001219699458218815)

http://aycu21.webshots.com/image/7980/2001259802439663207_rs.jpg (http://allyoucanupload.webshots.com/v/2001259802439663207)

Ike

[Ike]

Sami was testing the ole Vmax yesterday:

"I finally found safe place to do some testing. long straight wit icy
surface, but still running without studs.

First ride.
-silver primary spring, 60 degrees at secondary, stock spring.
-rpms too high 8500-9000
-result first 146 kmh and 147 kmh results


Second run
- yellow/white primary spring, 40 degrees secondary stock spring. New belt
-rpms 8100-8200
- speed 158 kmh = 98.75 mph.

-sami-"

Ike

[SamueLJackson]

Speeds are measured by GPS:flagge_fi

http://i9.tinypic.com/34owksw.jpg

[vmax-540]

Congratulations ! Am glad to see you get it running like it should run . Yamaha did a pretty good job on the clutching on them,especially on ice, 98 MPH is a good number for the old girl!!