flat slide vs round

[shelpi]

Ive only ever used round slide but what is the best out of flatslide and round, and why? as I am just about to use a flatslide TM38 for the 1st time

[Nathan S]

The early Mikuni flatslides are (in my experience) harder to tune/fussier than a Mikuni roundslide and don't seem to offer a worthwhile improvement in performance or throttle response.

For my money, there's only two carbs that should go onto 2T dirt bikes: the Mikuni VM and the Keihin PWK. I will entertain the Lectron option if you're prepared to get your head around them.

[Tim754]

 I will second Nathan , Shelpi the VM is the best option for simplicity by three lengths of the main straight.
 I do have some knowledge of tuning Lectrons (and parts) DON'T Bother.......

[Lozza]

There is not much in it, nothing wrong with the TM flat slide especialy with a powerjet

[Tim754]

Damnation Lozza ... I have had SFA to do with them

[sa63]

What about the keihin pe
Seems very similar to a VM?

[Nathan S]

Too hard to get jets for.

[80-85 husky]

lot of punters in the US on old huskys having good results with the Lectrons.

[John Orchard]

There's too much to write on this subject in a post here.  There are many things to consider, sure a flat-slide will give a stronger pulse over the needle jet at part throttle but if you want more power at 'part throttle' ..... just open the throttle more.

I like the idea of a VM round slide Mikuni but with a 'slide optimiser' filling the void under the slide giving a stronger pulse at part throttle, plus a more streamlined venturi at full throttle.

I disliked the early Mikuni flatslide I had one on my RM250Z, the vacuum at part throttle use to make the throttle valve hang-up, I think the tiny return spring wasn't powerful enough to push the light plastic slide home; had the same problem with the first model GSXR750's.  Loved the wheels on the FCR41 slides on my ZXR750 :-)

Once I get the jetting fine tuned on my Keihin PE38 round slide on my CR500, I'll be happy.  Liking the VM38 on the KX400.

[bigk]

Like Nathan says, Lectrons are cool & good but a head fu*k, as are EI & Blue Magnum. I've used a few Mikuni TMX's and although people say they are harder to jet than a PWK, I've not found that to be the case. A VM round slide with a power jet works nice too. Bings are unreal till they get worn, even though you have to douse your engine with fuel to start them.
K

[grouty]

I have used the good old round slide VM's for years. They were always ok. Just ok, not perfect.
I was having issues with the Husky 390 after I fitted a set of Boysen reeds. Never could get the jetting just right. So I bit the bullet and bought a Lectron. The transformation was incredible. So simple to understand, set up and use. I am now kicking myself for not using one years ago. They are way better than back in the 70's and 80's. The power jet also helps.
I will never go back to a Mikuni now.

The Lectron is very simple to get your head around. Just expensive. But then again, the best always is.

Am I biased now ............. :-)

Yep.

[shelpi]

thanks eveyone, well thats plain and simple, stay with what I know best ! VM Mikuni, but seem that I have gone to the trouble of doing the initial set up with the TM I will run it 1st then I can do a comparison the lesson here is the one I should already know, do the home work first and dont follow like a sheep

[shelpi]

I just got off the phone to Ian Williams (Tuneing) had a chat and he seems to think both are fine
Any who asked how much for a New VM38 $175.00 was the answer, so in for a penny in for a pound

[Lozza]

everything runs a distant second to a Dellorto PHBE/PHSB/VHSB 

[Momus]

everything runs a distant second to a Dellorto PHBE/PHSB/VHSB 

What would make you run one of the Dellortos in place of a Keihin PWK Airstriker on a big bore 2 stroke?