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Message started by Andemon on 04/05/18 at 12:20:23

Title: Flat slide carb and how to get it to work No room
Post by Andemon on 04/05/18 at 12:20:23

Hello all. New here. I couldn't find any post related to what my issue is so I'm starting a new thread. I have a mikuni flat slide carb. Issue is that it won't fit under the tank. I have an 87 savage. I was thinking using some kind of tubing and mounting the carb to one side of the engine. Not sure if anyone has done this and if there will be issues with the longer intake tube from carb to engine. Any ideas ? Thanks in advance.

Title: Re: Flat slide carb and how to get it to work No r
Post by batman on 04/05/18 at 12:52:19

Kind of limited info ,but if the problem is the tank, and not the frame rails, you could use spacers and longer bolts and lift the rear of the tank. Keep in mind that this will limit your reserve fuel unless you also lift the front of the tank , either or both would be much simpler than relocating the carb. Welcome!

Title: Re: Flat slide carb and how to get it to work No r
Post by Andemon on 04/05/18 at 12:58:00

It's a mikuni TM40, it won't fit because of the frame. I think it'll look great if I have it mounted out to the side, I've got a velocity stack style air filter on it but might go with a cone style K&N. I think there will be plenty of room for my legs to get around it. I'm really just concerned with if it will work with the distance from the carb to engine. If it'll run properly with that long of a tube. It'll roughly be about 12 inches from carb to engine.

Title: Re: Flat slide carb and how to get it to work No r
Post by batman on 04/05/18 at 13:07:25

It should work better than you think ,the distance from the motor should give the flow time to straighten out before entering the intake passage in the head, and an  elbow will not have any ill effect. the actual length from the air cleaner to the intake valve will, you should research intake tuning to understand why. the TM-40 is larger than a 36-38 and may favor a bit shorter intake.

Title: Re: Flat slide carb and how to get it to work No r
Post by LANCER on 04/05/18 at 13:26:04

Whatever you build, whether from steel or aluminum, must be hard mounted or the engine vibration will mess you up and/or break the mounts.  You can’t just use thin aluminum and the flange must be metal as well, the rubber flanges allows too much vibration.  
Trust me on this, I know from experience.

Title: Re: Flat slide carb and how to get it to work No r
Post by Andemon on 04/05/18 at 13:59:05

Fantastic ! Thank you guys so much, that is all I really needed to know. I'll look into the intake tuning to see what would be good. I have time yet. When my rings get here ( OEM ) I'll be putting the bike back together. I'll show some photos and try to give some info as to what I did. Much appreciated !

Title: Re: Flat slide carb and how to get it to work No r
Post by Andemon on 04/06/18 at 04:28:57

Suzuki parts house taking forever on my rings. Should of been here. Any better solutions?

Title: Re: Flat slide carb and how to get it to work No r
Post by DragBikeMike on 04/07/18 at 14:22:37

On 4/5/18 Lancer wrote:"Whatever you build, whether from steel or aluminum, must be hard mounted or the engine vibration will mess you up and/or break the mounts.  You can’t just use thin aluminum and the flange must be metal as well, the rubber flanges allows too much vibration.  
Trust me on this, I know from experience."

I'm interested in this comment.  Lancer, can you please elaborate.  What sort of problems did you encounter?  What particular carb was involved?  The stock carb is certainly no lightweight and the rubber flange seems to handle that OK.  Did you ultimately end up using a solid flange with your swap?  I will probably need to fab a custom solid flange and am very curious about things like vibration effect on metering and float ass'y, heat transfer and fuel percolation.  If you used solid, did you have to insert an insulator?  

Title: Re: Flat slide carb and how to get it to work No r
Post by Andemon on 04/15/18 at 12:42:06

Bike is getting closer. I'm still trying to figure out the intake manifold situation. Might have to take a trip to the machine shop and see what can be done and for how much. I've looked for intake manifolds ( thick aluminum ) but can't find a " U shaped one. I'll be doing some tinkering tomorrow. Got some plastic tubing so I can get some measuring going for my needs. Also think I will go with larger jets to help with the distance, or just make a smaller diameter intake between the carb and engine to help create some pressure. I will for sure figure it out.

Title: Re: Flat slide carb and how to get it to work No r
Post by LANCER on 04/15/18 at 15:49:01


77717E02000703330 wrote:
On 4/5/18 Lancer wrote:"Whatever you build, whether from steel or aluminum, must be hard mounted or the engine vibration will mess you up and/or break the mounts.  You can’t just use thin aluminum and the flange must be metal as well, the rubber flanges allows too much vibration.  
Trust me on this, I know from experience."

I'm interested in this comment.  Lancer, can you please elaborate.  What sort of problems did you encounter?  What particular carb was involved?  The stock carb is certainly no lightweight and the rubber flange seems to handle that OK.  Did you ultimately end up using a solid flange with your swap?  I will probably need to fab a custom solid flange and am very curious about things like vibration effect on metering and float ass'y, heat transfer and fuel percolation.  If you used solid, did you have to insert an insulator?  



The reason for saying a solid mount is needed was because I tried 2 different carbs, a Quicksilver and a VM, both essentially the same weight.  The mount used was the standard rubber flange with a PVC elbow, and I also had an aluminum piece brace the top of the carb to the frame tube, but then had to switch to a steel piece.  Both ended up breaking due to the vibration that was allowed by the rubber mount flange.  The only way to avoid that is to make or get an aluminum flange and weld an aluminum elbow to it and attach the carb to that, giving a strong solid mount that should eliminate the vibration problem.  I have some pieces to use but have been preoccupied with an assortment of other things and so have yet to get it welded up.
I have one frame that was modified and that mod required the carb to sit outside the frame; that is how this all came about.

You could also use steel but I just wanted to try aluminum first.

Title: Re: Flat slide carb and how to get it to work No r
Post by DragBikeMike on 04/15/18 at 20:05:57

Thanks for the back story Lancer.   Seems like your problems were associated with using a long intake manifold with the carb located outside the frame rails instead of directly behind the cylinder head.  That's a pretty long moment arm.  I can see how that would be hard for the rubber flange to hang on to.

Title: Re: Flat slide carb and how to get it to work No r
Post by LANCER on 04/16/18 at 03:20:23


75737C00020501310 wrote:
Thanks for the back story Lancer.   Seems like your problems were associated with using a long intake manifold with the carb located outside the frame rails instead of directly behind the cylinder head.  That's a pretty long moment arm.  I can see how that would be hard for the rubber flange to hang on to.


The small brace that I had attached to the top of the carb did a good job of stabablizing the carb until the material failures occured.  It shook so much that fuel could not effectively be pulled from the bowl.  Running got really rough the moment it let go.  We were riding in the Smokey Mtn’s on The Tail of the Dragon and it was several miles back to the hotel and it just kept getting worse as I tried to keep it going and it died as I started the final downhill run to the hotel so I just coasted in.  
I did NOT want to have to push it up and down the hills.  :o

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