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Toutsuite

hypercharger on dragstar 650

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So, I'm seriously toying with the idea of a hypercharger, to finally complete the intake-fueling-exhaust chain and squeeze some more power out of the 650. The thing I'm apprehensive about of course is the rejetting of the carbs. Seen a video of it being done to the specific bike, doesn't look *too* difficult. I'd like to ask Noise: how much fiddling with the carbs did you have to do to get it right mate?

 

  

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I had a vstar 650. I had hk pipes, hypercharger and rejetted it. Wasn't too bad. Just take it slow drilling out the brass plugs to get to the screws behind them. I took the carbs off the bike to do it. And i replaced the screws that hold the diaphragm covers on too, they strip easily. Theres a 650 forum that offers tons of support for those bikes.

 

 

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Yeah, I already bought the replacement stainless steel allen head screws for the carbs in anticipation (been doing my homework!). The bike's already been rejetted -not by me- when the v&h cruzers went on (1 or 2 jet sizes from stock), so don't think there'll be any brass plugs.

 

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Ok. It should be a piece of cake. I got the needle settings and screw settings from a forum member a long time ago. Wish i could give you a baseline to start with.

 

 

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The instruction manual for the h/c gives all settings and sizes so should be ok. 

 

 

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Update: well I should have known this would open a can of worms! All 16 screws seized, will take a herculian effort (and lots of drilling) to remove. I've bought the replacement stainless ones thinking this would be the hardest bit, BUT: 

Then noticed the carb joints (the rubber manifolds that go from the bottom of the carbs into the cylinders, are cracked to fuckery. So that's another couple of hundred quid just for parts then...

I'm going to take this to my mechanic. I've bitten off *way* more than I can chew here...

 

 

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Ok, so update no2: rather than buy the OEM rubbers, at £75+vat a pop, I found a pair of new ones on ebay for £40 ish from M&P motorcycles. Got the mechanic to fit these and swap all the carb screws out. On the vacuum membrane side (the brass covers) the new screws were too long (at 12mm) and were snagging the choke cable. Thankfully the mechanic had the right size screws (10mm and under). Further problems ensued when I discovered I had a vacuum leak from one of the new rubbers. Back to the mechanic it went, where is was discovered the O ring had snapped. Probably from carelessness on his part during installation. O ring replaced, and problem fixed, bike running fine again. 

So got her home and - somewhat apprehensively after all that as you can understand - I began the rejetting process. No needle shimming necessary according to Kuryakun, and indeed no new needles or shims provided in the jet kit that came with the hypercharger. Just replaced the brass side covers (ebay USA) as my ones were manky as all fook after all these years. On the other side of the carbs, one of the main jets was stuck to the brass tube, so that had to come out and the jet unscrewed with pliers holding the hex nut end of the brass tube. But other than that, rejetting was uncomplicated. I followed Kuryakun's recommendations for my setup (v&h pipes): 120 main jets, 35 pilot jets, PMS screws 1 1/2 turns out. The screws were 3 1/2 turns out from the previous rejet, so had to be wound back in two full turns.

I then proceeded with the installation of the hypercharger itself. This was completely straightforward - I had plenty of time to go over the instructions while the bike had other problems sorted out! So, checked choke and throttle were working properly, wheeled her out of the shed, fired her up - it took two or three tries as the fuel pump filled the carb float bowls - and...

SUCCESS!! She lives! And not only does she run, she runs beautifully!  The first thing I noticed is the complete absence of decel pop in the exhaust. I was getting a fair bit of that with the previous setup with the factory pilot jets and the pms screws 3.5 turns out, but now it's just gone. Completely. What about power delivery you ask? While the engine seems to be more eager throughout the rev range, it's at full throttle where you really notice a difference. There's a stretch of dual carriageway as you head south past the Blackwall tunnel  between the Greenwich and Blackheath exits, mildly twisty and uphill; during my first test ride / supermarket run, I bombed up that sucker like never before! Hoo boy. Yes, overtaking is now a much more confident affair. 

I am particularly pleased that the Kury recommended settings worked brilliantly first time. I haven't felt the need to go back and adjust anything. I haven't felt any flat spots in the power delivery. Though I expect I shall go for another dyno just to make absolutely sure. The only thing left to find out is what my fuel consumption is like. I expect my mileage per gallon to go down since I've gone up 10 to 11 jet sizes! I'll refill the tank after the first 100 miles and do the math.

 

 

 

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And the end result:

DSCF0020.jpg

DSCF0014_2.jpg

DSCF0034.jpg

DSCF0041.jpg

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Beind devils advocate here but how much performace came from fixing the carb rubbers.

10 to 11 jet sizes with no other work sounds like the exhausts were jetted bad too.

Hypercharger is before the carb so should not affect the jetting too much.

Sounds like a right result. Cannot beat the feeling when your bike feels fit and strong.

 

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Hi Cynic, 

 

fixing the carb rubbers was a preventative measure; the old cracked ones were only cracked on the outside, but were still holding a seal, though for how much longer who knows, hence their replacement. So no perf increase from renewing those (and none expected).

The jet size increase from 92.2 to 120 is a measure of how much more air the hypercharger lets into the engine. Or how very restrictive the stock airbox is, even with a k&n filter. Bear in mind, the previous jetting was done with the aid of a dyno, but I also had the stock filter on (more restrictive than the k&n) and quiet baffles bolted on to the normal baffles of the v&h's. 

 

Still haven't dyno'd it with the new jets, or balanced the carbs, so she may be running a bit rich and I might have to go down to 117.5 size... 

 

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Wow, had to ask, born cynic and all. 

I have read more than once that these things are just hype (getit). Going up 30 points on the jetting is HUGE. My gsx went up by those levels when TTS upped the horsepower, in the end by 40% from 62 to 104hp RWHP (dyno'd) consuming quite a lot of money at the time too.

You are really going to feel that at the pumps. My gsx went from doing 180-200 miles per tank new, when she was fully worked on you could, if you really caned it get 65, yes 65 miles to a tank. That's 4 gallons, gone! 600cc doing 16mpg:o. Actually got it down to just over 50miles on mad Sunday at the 2000TT.  Riding gently i could get 120 ish. Or 30mpg, hardly economical.

Properly planned and executed tuning is a beautiful thing. Its worth every penny, :D to feel the bike as is was designed to be rather than the average everyman version it started as. Its now YOUR bike more than ever.

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I've gone from 60+mpg to 51-54mpg. I can feel the increase in power, but will have to dyno the bike to know the exact figures. Remember she's a V-twin, not a 4-in-line high revver, so um, mileage may vary? (I'll get me coat...)

Edit: mpg went back up to 60+mpg after a couple of fillups and has stayed there ever since. Don't ask me how, I've no idea!

 

 

Edited by Toutsuite

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