I have searched the forum and read what I could find, but I'm hoping someone here has there bike set up similar to mine and can help me with advice on rejetting. I know each bike can be slightly different, but hopefully someone can give me a starting place and save me from pulling the carbs 100 times.

The previous owner had installed the V&H SS2R exhaust and also a K&N filter. They had went up 3 sizes on the main jets already ,but did nothing to the pilot jets, air mixture screws or needles. The bike still seems to be running lean all around. The pipes are turning very gold all the way back to the muffler and there is a surging when you are applying just enough throttle to maintain your speed. It pops through the exhaust when decelerating or coasting with the throttle shut. Also just doesn't seem to be running quite as strong as it should. I have ridden a stock one before as well as other similar bikes like the Kawasaki GPZ 1100 I had as well as an 1100 Blackbird. This bike is down a little on power at wide open throttle. All of this tells me the bike is seriously lean.

Anybody have suggestions on where to start with getting it dialed in? I have thought about replacing the K&N with a factory style filter or running a "outerwear" filter cover to reduce the airflow. Any thoughts?

Thanks,
Chris

 

Just sticking a bigger main in is nowhere near enough mate! I've got a V&H and a K&N on mine and fitted a DynoJet stage 1 kit. I ended up with the smaller of the two mains that came with the kit, the needles on their leanest setting (very different profile to standard!) and put the standard springs back in due to a shocking lag when I cracked the throttle wide open.

I'll have a look later and see what size jets went in but, without the different needles, it probably won't help much.

I used to own a GPZ1170 (Wiseco kit and other goodies ) and I think my CBR has about the same power. It would leave a standard one for dead I think!

 

That's it. Needles will probably need to come up a bit.

 

Thanks! That is exactly the kind of info that I was looking for and also pretty much what I was thinking too. I didn't mention that my CBR is a 1993 model. I guess I will order the jet kit and start from there. I assume the stock needles aren't adjustable?

 

Hey:

Firstly It is hard to help with any tuning issue when you we do not know your location, as altitude and atmospheric conditions that have a bigger play than most other variables, more than anything else including aftermarket pipe and air cleaner (MORE on the air cleaner later). Anyone giving you that info without knowing what that is, is just a guess at best and if it works it is only by chance.
It really does nothing to know someone else's setup, from a vastly different altitude because if you copy that tune you may be further from a good tune than you were. Also what year is it?

Second you have a starting place as your bike runs now. You just need to interpret the info you have to help you get the most out of it. This can only be done thru spark plug readings on most carbed vehicles during A max speed, max RPM on the road or track power test or during similar conditions on a dyno and fan. Unless your bike is Fuel injected and has the needed ports to get readings from those sensors, which yours is not, there is really no shortcut here without this info:
1.Location
2.altitude and atmospheric conditions (DA and WX type & Temp)
3.current carb settings needles, pilot and main jet sizes and or settings.
4.plug type , brand, heat range
5.plug readings, colour and any tuning impact: burnt, oil fouled, white clean and so on from all four at the same time
6.fuel type, grade or octane level used and if any additives are used or not.
7.bone stock or any internal/external engine mods such as coils/wires, timing, cam, bore kit, changed thermostat to diff than stock heat range, this kind of stuff really matters.
8.Lastly engine condition, mileage is it worn out or as new? Compression test with leak down.

Next this above info is only good if your carbs have a good recent mechanical sync and balance,
And this is after and good current valve check as both can give similar indications to poor tuning jetting off (Lean/Rich) conditions prior to being corrected and can greatly impact any tune done without knowing this is correct. THIS SHOULD BE YOUR FIRST STEPS, PRIOR TO ANY JETTING CHANGES IF YOU WANT A PROPER OUTCOME….
(compression check, valves check/adjustment, carb sync/balance, and fresh fuel/oil)
as this gives you the best starting point and you won't have to pull the carbs as many times to get it spot on, as you can just read the plugs to help you tune it, as you know all else is good. You can not guess about a lean condition only a spark plug reading will tell you if that is the case or not on a proper running engine other than a tune.

“I have thought about replacing the K&N with a factory style filter or running a "outerwear" filter cover to reduce the airflow. Any thoughts?”
Also this is really a bad idea as no manufacturer designs any engine around a air clener. No matter what ads you tend to believe, the reality is the only thing an air filter does is filter air. Now some like K&N do a better job of filtering dirt out, keeping good flow for a longer time period due to an oil coating, last longer as they are made of better material (stainless steel and cloth), and are reusable, but do no more magic other than that.
A brand new stock paper air cleaner flows as well, as most other aftermarket ones do, until they collect a certain amount of dirt which in turns diminishes the flow. This has been proven on many a dyno the world over again and again.
The only time any air cleaner affects flow is when its dirty, plugged/damaged or in some cases it is compared to no filter and that is on a case by case basis as to how much. Tuning without an air cleaner is only optimal under clean conditions where absolute max HP must be obtained. Doing this will give an absolute best max power performance but maybe at the cost of Emissions, drive ability or engine reliability.
Now an air box does matter and can greatly change the parameters if designed well, something the Honda CBR1000F design team did well. It takes a substantial amount of tuning/dyno time and knowledge to get these bikes to run on pods correctly in most all conditions.
Not something most owners of these bikes would be willing to do, as the gains from the stock air box is not so great as to warrant the cost and tuning time it takes to do it.

Lastly comparing a 135 HP (CBR1000F) bike with a 165 HP bike(CBR1100XX) is fun, but not going to help you tune it to its optimum and most especially if it was an injected model as carbs will never have that level of throttle response or be as smooth. Those would be unrealistic expectations.

Good luck with getting the info and I’ll be happy to help you get it sorted as best as possible, once you get the required info on here. Any other way is a shortcut that may hamper the best results.

Dub

 

Hey:

They are not, also if you can find a Factory brand kit they are normally better than Dynojet or K&N as they tend to have better springs when they come with them. If not the stock springs work best, as stated above. Also prior to purchase of a kit check to make sure you don't have them already installed, and if you do just buy some pilot and main jets a few size different to what you have and save your self some money.

Dub

 

Thanks for all of the great info. I know for a fact that the only changes were to the main jets and a kit wasn't installed. I will probably go with a dynojet kit unless I can buy the adjustable needles seperately. I know I can get any jets seperately.

I live at 2600 ft above sea level and ride anywhere from sea level to 6000 ft above within a day ride of my house. This bike has 28k miles and everything else is in top notch shape. IE carbs synched, valves within spec, fresh oil and filter. The previous owner was my brother, so I know what has been done to it. I am familliar with the bike already.

I would never run a bike without a filter of some kind. I was just thinking of replacing the K&N filter (it is a stock replacement filter, not pods) with a paper filter on the assumption that a paper filter would flow less air. I'm not really big on the K&N filters, but my brother had just put it in there along with the V&H exhaust at the same time. I guess K&N's don't really flow that much better than stock? An outerwear is a pre filter that is normally used on atv's and dirt bikes. It is unstalled over the K&N style filters to collect more dust and dirt. I was also assuming this would reduce the airflow of the K&N.

Honestly, I wish the bike was completely stock and that he hadn't changed anything. How much more power do you need than the 1000F has stock? I doubt the filter and exhaust really add that much of a difference anyway.

Thanks again for the info. I'm just trying to get ideas of what needs to be done. I know each bike and the altitude it will be ridden at varies the required changes. I had read these bikes are actually fairly rich from the factory. I haven't had a chance to pull the plugs yet. It is obvious the bike is lean though. Once I get needles and jets, I'll start the process of pulling plugs, pulling carbs and making changes and running the bike and pulling plugs again. I guess I am just lazy and wanted to see what everyone else had done.

 

Hey:

I just noticed your bike in the other thread you started, it looks very nice and well kept.
a very fine example of a 93 model.

These bikes could have used the stage 1 jet kit stock from the factory so it is a good idea to install one even if left all stock just to be able to micro tune for any maior change in location.

So since you know the bikes history, and its state of tune, this helps alot and since you are not real far from me we can work out the jetting real easy to get you close and then you will have to do the final fine tune of it.

Dub

 

Thanks again. I'll get the stage 1 kit shortly and start from there.

 

Probably not much really, but I hate hearing a bike struggling to breath, that's why I fitted mine . I did my mods about 5 years ago and messed about heaps to get it right. It runs a treat now though.

I had a look in the shed but couldn't find the box that the jet kit came in. I know I ended up using the smaller mains though. I'm at about 850m above sea level and also a '93 model.

Another mod I did was to put a slightly smaller diameter baffle tube in the pipe to get a bit more glass in there.

You might as well keep the K&N now it's in there.

Press on and let us know how you go.