Carbs ,Carbs, Carbs , Never should have did it !!!!! Help

[mooney1858]

Help please Well this is what i did , i bought a dynojet kit a k/n filter and a yosi slip on !!!!! I have taken out the 117.5 mains and put in the 122.0 and have the air/mix screws out about 2-2 1/4 . And the fuel needles on the 3rd slot down from top there r 6 slots . My problem is that now my idle is at 800 or 2,500 rpms and at top end at 11,500 it falls flat .And if i go from 1 1/2 to 4 turns out on the air/mix screws its the same !!!!!! Do i need to raise the needles up or what please help me !!!!!!! THANKS Its a 98 750

[UFO8MyCow]

I would start with setting your pilot screws at 2 1/2turns out and moving the clips down one slot and see what that does. if it gets better than adjust your screws from there and if it gets worse than move the clips up two slots.

[md86]

http://66.47.68.116/tech/carbtune,CV,high_rpm_engines.html

[trinc]

dyno w/ sniffer will be the quickest way. post the air/fuel mixture throughout the rpm range & we'll be able to help with adjustments.

tim

edit: you did install the donut in the air filter, right ? ( the large one )

[mooney1858]

Yes

I did use the big one !!!!!!!!! but why the big gap in idle ?????? can any one tell me please

[UFO8MyCow]

dyno w/ sniffer will be the quickest way. post the air/fuel mixture throughout the rpm range & we'll be able to help with adjustments.

Just try and get it running pretty good before you take it to the dyno shop then you can fine tune it there

[The CyberPoet]

Re: Carbs ,Carbs, Carbs , Never should have did it !!!!! H

...and at top end at 11,500 it falls flat

I found this to be true with all the 98+ DynoJet (& K&N kits which are dynojet kits relabeled).

Also: normally your kit should have come with a coupon for a free dyno run. Use it and ask them to print the fuel-air ratios on the output sheet (instead of the HP/Torque info) -- the F/A ratio info is much more relevant to tuning it right.

TIP:
For best throttle response, put the OEM carb springs back in and take out the DynoJet springs.

Good Luck!
=-= The CyberPoet

[Special K]

If you're doing all those changes you GOTTA have a set of gaugues to SYNCH those carbs. You can use carb sticks or gauges, but they GOTTA be synch'd.....................

[KatDan]

wouldn't 11.5K RPM be hitting the rev limiter?

[Mr. Clean]

Well I went back and read my Dynojet instructions (yes I kept them). First you used WAY to big of main jets. Try the 120 jets. Second your air/fuels mix screw needs to be set at 4.5 turns per the instructions, not 2.5. Set your needles to the #3 clip. If you get better results you should sync the carbs next. I'm basing all this on a jet kit for a 98+ 750 because that is what in your ride profile.

[katana91]

wow 4.5 tuns out, the pre98 750 dynojet kit tells you to put them at 2.5 Arnt the carbs the same on the pre's and 98+

[Mr. Clean]

Nope, carbs are different. I think the 98+ are 4mm bigger. I'll have to check my service manual.

Now when I was tuning my carbs i ended up using 122 main jets and the air/fuel mix screws are set at 3.25 turns and the needled are set at clip 3. But i am running a K&N, full D&D exhaust, and I have a Wiseco 771 kit installed. So I had to start at what Dynojet recommended and tune it for my bike.

[katana91]

so there 40mm on the 98+

[Mr. Clean]

The stock carbs for a 98+ 750 are Mikuni BSR36. So they are 36mm carbs, Mikuni always puts the carb diameter as the last 2 numbers in the part number. What are the carbs on a pre 98? 98+ 600 carbs are BSR32, that is why I was thinking they were 4mm bigger.

[katana91]

oh ic the pre98 750's are 36mm per my manual