Carb tuning

[inmate]

Need help with setting up Carbs on an 1100 powerscream. I have fitted a 1991, 1127 powerscreen (katana ) engine into my GS650gt frame, Blackwidow 4-1 with Cobra end can, Ramair twin pod foam filters, trumpets from 1100 air box, on standard 34 mm? carbs. I’ve been advised that a Dynojet stage 3 is the way to go for decent running. However Dynojet do not list a kit for this engine in the UK. They do list a kit on their dot com site for a 1988 gsx1100f (katana ) which apparently is the same as a GSXR 1100, 86-88, but this is not stocked in UK.

Does anyone know/suggest a kit that will work with my set-up. 
Thanks in advance for your combined Oldskoolsuzuki knowledge.

Cheers, David.

[peter1127]

In my experience dynojet kits are not an instant improvement especially when intake/exhaust stuff is not stock.

I would let your local dyno specialist jet it properly.  No point in tuning a bike  that needs maintenance so make sure carbs are in good order (needle/seats ok, fuel level ok, replaceworn out emulsion tubes, no air leaks anywhere) and at a minimum airfilters are clean. Best to do all the relevant maintenance as well : plugs, carb sync, valve clearances.

A dynokit doesnt add anything  at WOT over a properly tuned bike. It doesnt improve airflow into the combustion chamber so it cant improve performance.  If it adds, it just means AFR was off before.  It could improve throttle response because of the soft spring, drilled holes and needles to match. But that improvement when going trough the gears is exaggerated on a dyno because of the much faster increase in rpm then what happens on the road.  If you want less loss with gear changes just fit a quickshifter.   

 

[inmate]

Thanks for the reply @peter1127. You are correct about checking everything then taking it to a Dyno specialist, however the price of original emulsion tubes, needles etc. plus a variety of jets has forced me to look at a Dynojet kit. The bike has been built, so far, on a minimal budget and that is how it will have to be.

Perhaps I will try larger jets, at present the mains are 112.5 and 110, the needles look to be ok. Maybe 125s as @wraithsuggested to @Ivanon Ivan’s 6/11 build.

cheers David

[wraith]

I think we need pictures of this bike 

Carb tuning all comes down to how good you are and your understanding of carbs, and time V money.

Dyno jet kits and alike can get you somewhere near the right spot or depending on how fussy you are a nice ride but will probably need a bit of felting to get it just right.

Otherwise you are looking at time, carbs on and off changing jets or money, paying someone to do it on a rolling road.

I've had two bikes with jet kits, one a gsxr1100k that V&M couldn't even get right, so went back to OEM parts. The other is my kat with the powerscreen motor and 38mm gsxr carbs, I got a Dyna jet kit but ordered it off the Dyna office in Rochdale (I think) told them what set up I had and they sent a kit with 3 different main jets in just for that bike and apart from running slightly ritch at bottom end (pilot jets) it was pretty much bang on first time. 

If you wanted just to try main jets I'd look at starting with 125 to 135 main jets (Dyna jets) I know that's a big difference in jets but it can make a big difference on filters and exhaust and end can to how it could affect your jetting. 

Done forget the pictures of the bike 

[TonyGee]

tuning CV's can be a pain in the ass, my zed needs a bit more tweaking to get perfect (its Nealy their) but on the GS1000 with a B12 engine i'm going down the standard airbox route,  its so much easier to tune the airbox to the carbs than tune carbs to pod filters.  

[inmate]

@wraithyes I’ll try 125 mains as you suggest. Just want to get it up and running n MOTd for the summer, then maybe make it shiny n stuff over next winter, dependent on available funds. I thought a dynojet kit would get me there for the least cost. 

@TonyGeeI can’t use either air boxes, just not got the room.

This is how she started down the modification road, with a GXR1100K front end.

 

[inmate]

Cam cover off, sump off, oil strainer/pickup off. Pain in arse to get in

but it’s in.

r send.

[inmate]

Coming along

Shiny new exhaust 

But of course the feckin tank don’t fit now.

[wraith]

33 minutes ago, inmate said:

 

but it’s in.

 

That's one hell of a cam chain you've got hanging there 

As to the tank, raise it up by about 10mm and you should be ok.

[inmate]

I couldn’t lift the engine without it, not with my old bones 

Had to raise the tank and move it back, the top yoke hit it. Then of course, as you’ve found, the fuel tap hits the top of the carbs, so more mods to be done.

[TonyGee]

50 minutes ago, inmate said:

the fuel tap hits the top of the carbs

are you gona reposition the tap ? 

[inmate]

I’ve raised the rear of the tank so the tap just clears the carb top, but not happy with the look

[wraith]

Had the same problem with gs550 with oil cooled engines, I found the gax1100f tap gives the best clearance but two problems.

1. It's only on or pri

2. The bolt hole spacing is different. 

You may also find the standard tap won't feed enough fuel for the b12 carbs.

You may need to look at a Pingle tape or for us who don't like spending that sort of money and on/off washing machine tape  may even have the one I was going to use on my gsx1157et project, if I have your more than welcome to it 

[inmate]

Have made up a plate with a 90 degree elbow and a brass on/off tap, it’s given me a bit more room to lower the tank, but still not happy with it. May need a re-think.

[rodneya]

7 hours ago, TonyGee said:

tuning CV's can be a pain in the ass, my zed needs a bit more tweaking to get perfect (its Nealy their) but on the GS1000 with a B12 engine i'm going down the standard airbox route,  its so much easier to tune the airbox to the carbs than tune carbs to pod filters.  

Thats why I just buy RS carbs.

[inmate]

@wraithmanaged to get the tank a little lower at the rear using an on/off tap. 

Where is the best place to buy bigger jets ? or is there only Dynojet?

[wraith]

Looks better and looks like similar tap as I was going to use.

As to jets, the sizing between the Dyna jets and Mikuni jets are different so don't go mix and matching them ( I've used Dyna jets for years now) but you should be able to get ever from Grumpy 1260 or Suzuki Performance Spares or of course Dyna jet themselves if you want Dyna jets