carb mods

[mtlmanalex]

i've just joined the forum , i have a '89 max , i had an '85 that i bought new in england and a '98 here in california , the v max is the only bike i've bought more than once , so now i'm on my third ! anyway , ive just finished a rebuild on my current bike , it was a 'e bay special ' ran rough looked like hell . i paid $1000 for it , i 'm scared to add up the receipts for it now . my post is regarding carb / jet kits , i rebuilt the carbs with all the stock yamaha parts , also added a dynojet stage 1 jet kit . i installed the kit as per dynojet instructions , when i rode the bike it was terrible , it wouldn't rev past 7000 rpm , poor idle , stumble eveywhere . i tried changing main jets smaller and bigger , tried different float heights , idle mix screws anything i could think of . i decided to go back to a base line setting and re-fit all the stock parts . i set the floats using the casting mark and verified the wet setting to factory spec , re- installed the mikuni 152.5 mains , set the idle mixture srews to 2.5 turns out from seated , refitted the stock airbox and filter , said a prayer , waited for all the planets to align , and fired it up . the difference is staggering , it idles pefectly warms up quickly , pulls top gear from any rpm , in any gear, i tried the 4000 rpm , wot test , it just pulls like a rocket ship . i haven't had it flat out yet , i got a bit nervous blowing past 140 mph like was nothing , this is what i remember !. there may be more power to be had but the bike runs so good everywhere , i don't think i want to mess with it . my advise to anyone contemplating a jet kit is think carefully before dropping $ 129.99 to make your bike run rough .

 

[maleko89]

+1, DJ stage 1 is a waste of money especially with stock exhaust/headers.

 

[dickvoodoo]

I wanted to see how far I could get without buying any kits, just using what is already there. '93 vmax / drilled stock pipes and shimmed airbox horn. Here are my carb mods through trial and error here in Michigan: shimmed diaphragm needles, sync'd carbs and lastly I cut (4) coils off each diphragm spring. The spring mod helped when you decelerate suddenly and then goose it, no more bog or hesitation. Be carefull if you try cutting the springs, only cut one coil at a time and test. To get all this to work right I also completely disassembled and cleaned all the internals.

 

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You could always tie the coils of the springs together to have the same effect as cutting without it being permanent. Great way to test things and then go back to baseline. Small pieces of light gauge wire will work fine for that.

No real reason to buy any jet kit if you have stock exhaust, drilled or not. Maybe change the mains for few bucks but other than that, shouldn't really need to buy anything else. Sounds like you already have needle shims if you need em.

If you're looking for an exhaust and jet kit, I have both for sale.....check the ads:biglaugh: