YAMMIGOD,clutch help for vintage vmax.

Update and VIDEO of test run, 660ft

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-
 

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.
 
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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
 
Flat slides on vmax 540s

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

Samueljackson has the latest on this.

Ike
 
Update porting

Samual J. If you are looking for porting spec. then go to 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
 
vmax-540 said:
Samual J. If you are looking for porting spec. then go to 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.
Click to expand...
: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
 
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Got us a new , unused hood for the Vmax540. Cost me 50€... Added some heat shielding aluminium tape to it.

pics..





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
 
Speeds are measured by GPS:flagge_fi

34owksw.jpg
 
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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!!
 
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