Yamalover700
New member
Okay so I’ve picked up a 1987 vmax 540 to restore, brand new crank, cylinders, pistons, connecting rods, carbs very clean, new plugs and are nice golden brown coloured, new comet 102 with purple spring and a-2 weights, secondary stock spring and c-2 setting with a progressive 45/39 degree helix, new belt, gearing is stock, removed oil reservoir and am running 40:1. The engine is just broken in now at 25km. The problem now is getting the max rpm out of it. I’ve tried everything for clutching from softer primary springs to heavy to different weights and different secondary helixes and springs and it doesn’t seem to be breaking that 7200 rpm point. It will revv about 7500 rpm when hammering on it doing about 10km and drop to 6900 and slowly build up to 7200. I am completely lost at this point and don’t know what to check next any help would be appreciated thanks
opsled
Active member
Get a stock helix and go from there.
Yamalover700
New member
I have 2 stocks and the helix I have on it right now runs better then the others maybe 100-200 rpm higher
had the same problem on my 86 it was the spark plug caps, sounds crazy but they were holding it back changed them out and it flys now.
Yamalover700
New member
I swapped the coils off a 1994 vmax 500 and it didn’t make a difference, think I should try another set of plugs and plug caps? I’m thinking it has to be something electrical
I think that purple spring is to light find one with around a 300 lb finish
Yamalover700
New member
Okay i figured it out. clutching was way off, i ended up using a blue polaris primary spring and polaris 10M/B weights and now its hitting 8000 full throttle and builds up to 8300 rpm thanks for the help guys
Charlie P
Member
I know when I had my 83 540, clutching was very important to keep it right. I was running a Riechard Yamaha dyno tune carb and clutch kits, really woke up that sled. I can tell you my sled didn't like the comet 108 at all. Never could find the right parts to make it work like the 102c. I ended up rebuilding the 102c and selling the 108 off. My 540 was a much stronger sled than my Vmax 600LE was when I first bought it after I lost the engine in the 540. Oil pump went out, right outside of Sayner, Wi. in 1996. Rode the crap out of that sled for 12 years or so. I did like the 95 Vmax 600LE better though. It did take some time but it ended up being a stronger sled than the 540.
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opsled
Active member
95 Vmax 600 clutches on an 87 540. Great clutches, overdrive, tons of tuning options. Strong.. Clearances and alignments are near perfect. Yamaha doesn't make a belt for these clutches in this application. It's actually a Polaris size. This Gates number fits perfect.
opsled
opsled
