MIKUNI RS38 flat slider carbs.

[Seanable]

  So, on this parts bike I bought, along with 5, or 6 totes of parts, is a set of Mikuni flat slider carbs. There is also the throttle handle that goes with them. I love the design of the carburetors. Top notch. Can anyone tell me what sort of performance increase these will give me? They sure are pretty.
In the totes are parts off of two other bikes...engine cases, carbs, a cylinder head that was just rebuilt along with new valves installed. a set of cylinders freshly bored. I'll likely be selling a bunch of this stuff.
Right now I am trying to figure out why my headlight is not working. I ended up removing the upper fairing and dash panel. Is there an easy way of putting the upper fairing back on the bike? Should I assemble the fairing with the frame that holds the headlight assy in and then bolt the assy onto the bike? Seems the most logical way. 

[Pat Conlon]

Paging Chris and Travis.....come to the red courtesy phone....

[fj1289]

The mikuni's will wake it up.  I think the stock exhaust and carbs are the first level of restriction.  The cams and head are next in my opinion.  How much?   I haven't done back to back dyno checks so I can't tell you xx number of horsepower or foot pounds of torque. 

A few points on the mikuni flat slides.  Since these are mechanical slide carbs, you can't be ham-fisted with them at low rpm - you can stall the air flow.  Second - these flat slides do not have rollers on them - they can and sometimes do "hang-up" - especially when accelerating out of a corner when you need the best throttle response.  Instead you add a little pressure to the throttle, but don't get any response.  Add a little more pressure, no response.  Add a little more pressure and wham! a whole hand full of throttle suddenly.  It doesn't always happen - so not predictable. 

Liked them on the drag strip, but got frustrated with them on the street.  But, there are a lot of people that are happy with them.  I'd certainly encourage you to give them a try!

[Pat Conlon]

I have heard stories about the RS slides sticking....Is that the reason a stiffer return spring is used?

I think the cat's meow on flatslides are the Mikuni TMR roller flatslides.
The TMR's have a choke to help cold starts, where the Keihin FCR rollers do not.

[T Legg]

I don't have any numbers on how much hp increase either but I would call it very significant. The mid-range is much stronger but the biggest difference is above 8000 rpm . The engine keeps pulling hard all the way to redline and beyond. I put my carbs temporarily on to one of my 1100's that has low compression ( ranging from 115 to 105 ) and was a dog with the stock carbs . I thought I would just try it for one ride but I've gone through four tanks of gas already. It's a rocket ship now. Both of my 1100's with flatslides are much faster than my 86 1200 with stock carbs. After tuning my carbs they are very smooth on the street but they do require a firm grip and the distance the throttle has to be rotated to reach wot is longer than the stock setup. I did have problems with a set of rs-36 carbs from the eighty's that began to have a hanging idle but my new ones don't hang at all. If I have the push pull cables adjusted right I have good throttle control but with the accelerator pumps there is a lot of snap when you crack the throttles open. You can use the stock throttle cable setup for a test ride . You can just hook up the pull cable and leave the push unattached . The cable is too long to fit into the cable holder at the carbs so I passed the cable through  a 1/2"  electrical cord restraint and clamped it to the cable sheath. Below is a picture. I wouldn't recommend it long term but it works well enough to try your carbs with out having to mess with your throttle.

[Flynt]

The TMR's have a choke to help cold starts, where the Keihin FCR rollers do not.

FCR = F'ing Chokes are Ridiculous...  one squirt of the Accelerator Pumps and Bob's your uncle.  Helps to tune rich...

Frank

[Seanable]

I don't have any numbers on how much hp increase either but I would call it very significant. The mid-range is much stronger but the biggest difference is above 8000 rpm . The engine keeps pulling hard all the way to redline and beyond. I put my carbs temporarily on to one of my 1100's that has low compression ( ranging from 115 to 105 ) and was a dog with the stock carbs . I thought I would just try it for one ride but I've gone through four tanks of gas already. It's a rocket ship now. Both of my 1100's with flatslides are much faster than my 86 1200 with stock carbs. After tuning my carbs they are very smooth on the street but they do require a firm grip and the distance the throttle has to be rotated to reach wot is longer than the stock setup. I did have problems with a set of rs-36 carbs from the eighty's that began to have a hanging idle but my new ones don't hang at all. If I have the push pull cables adjusted right I have good throttle control but with the accelerator pumps there is a lot of snap when you crack the throttles open. You can use the stock throttle cable setup for a test ride . You can just hook up the pull cable and leave the push unattached . The cable is too long to fit into the cable holder at the carbs so I passed the cable through  a 1/2"  electrical cord restraint and clamped it to the cable sheath. Below is a picture. I wouldn't recommend it long term but it works well enough to try your carbs with out having to mess with your throttle.

That's what I'm talking about....
The Mikunis I have had been sitting. I'm going to pull the float bowl and see how bad they are. Can't wait to put them on my 1200. Thanks for your response.

[T Legg]

When you have your bowls off check your jets. The recommended 17.5 pilot jet works well.I'm back to a 130 main jet but at your altitude a 135 might work ok. I moved the needles up one from -2 to -3. The accelerator pump linkage should start around 1/4 throttle and end around 3/4 . If the accelerator pump is engaged too long it will cause a flat spot in acceleration around 5000 to 6000 rpm. Good luck. Let us know how they run.

[fj1289]

The TMR's have a choke to help cold starts, where the Keihin FCR rollers do not.

FCR = F'ing Chokes are Ridiculous...  one squirt of the Accelerator Pumps and Bob's your uncle.  Helps to tune rich...

Frank

Agreed!  Really liked my FCRs!  Never any issue with starting.  Always smooth on acceleration and good fueling everywhere. 

[ribbert]

The TMR's have a choke to help cold starts, where the Keihin FCR rollers do not.

FCR = F'ing Chokes are Ridiculous...  one squirt of the Accelerator Pumps and Bob's your uncle.  Helps to tune rich...

Frank

That's very true Frank, especially when you have one per cylinder and such short manifolds.

Noel

[Flynt]

The TMR's have a choke to help cold starts, where the Keihin FCR rollers do not.

FCR = F'ing Chokes are Ridiculous...  one squirt of the Accelerator Pumps and Bob's your uncle.  Helps to tune rich...

Frank

That's very true Frank, especially when you have one per cylinder and such short manifolds.

Noel

Who's got a short manifold Noel!...   

Biggest problem I have with Wizard is getting the fuel pump to fill the bowls...  Even with a fresh battery the pump won't relaibly run when you turn the key...  Just kind of "shorts out" with a relay buzzing sound after a few seconds.  I've been through several fuel pump relays now and cleaned every connection along the way including the fuse box, but it seems as if the pump circuitry doesn't get the voltage needed to run the pump.  If I use a jump starter on the bike throwing 15+ volts the pump works fine.  The pump is a relatively new Yamaha unit from RPM and the older Yamaha pump did the same thing...  I'm perplexed, so any thoughts appreciated.

Once Wizard's running all hell breaks loose as usual...  Took Diane for a ride Yesterday and had the '84 out Friday enjoying the great weather.  Wizard's 4th gear tire lifting with Diane on back never gets old...  and of course the "stock" FJ1100 never fails to impress.

Frank

[ribbert]

Who's got a short manifold Noel!...   

   

An oldie but a goodie I'm sure every pilot here has seen over a urinal at some point, or variations such as "taxi into position and hold" etc., it seems as common as the mandatory propeller mounted on the club room wall!



Noel

[JMR]

I don't have any numbers on how much hp increase either but I would call it very significant. The mid-range is much stronger but the biggest difference is above 8000 rpm . The engine keeps pulling hard all the way to redline and beyond. I put my carbs temporarily on to one of my 1100's that has low compression ( ranging from 115 to 105 ) and was a dog with the stock carbs . I thought I would just try it for one ride but I've gone through four tanks of gas already. It's a rocket ship now. Both of my 1100's with flatslides are much faster than my 86 1200 with stock carbs. After tuning my carbs they are very smooth on the street but they do require a firm grip and the distance the throttle has to be rotated to reach wot is longer than the stock setup. I did have problems with a set of rs-36 carbs from the eighty's that began to have a hanging idle but my new ones don't hang at all. If I have the push pull cables adjusted right I have good throttle control but with the accelerator pumps there is a lot of snap when you crack the throttles open. You can use the stock throttle cable setup for a test ride . You can just hook up the pull cable and leave the push unattached . The cable is too long to fit into the cable holder at the carbs so I passed the cable through  a 1/2"  electrical cord restraint and clamped it to the cable sheath. Below is a picture. I wouldn't recommend it long term but it works well enough to try your carbs with out having to mess with your throttle.

If you straighten out the 90 degree bends in the throttle cables they fit much better.

[T Legg]

My flatslides were only borrowed from my other fj while I had the engine out for transmission work. The stock fj carbs are now back on. Now that I know how much stronger the bike runs with the flatslides I am buying another set along with the motion pro throttle set up.the motion pro set up requires more twist to reach full throttle and I think that reduces the hand force needed to accelerate.