GS450 Carb upgrade, whcih carbs?

[Billy Ricks]

I checked the oem carb spec on this site and according to it you have 34mm carbs. The TMs will still flow much better than the stock CVs.

[djg42]

oops, I was thinking it was 32. So if its 34, what size do you think i should go with?
Its a shame its hex main jets, I have a nice assortment of round mikuni mains

[Billy Ricks]

oops, I was thinking it was 32. So if its 34, what size do you think i should go with?
Its a shame its hex main jets, I have a nice assortment of round mikuni mains

You won't need to go bigger. The 700s and 750s came with 32mm carbs and back in the day the hot set up was a set of 29mm VMs. The TM33s or 34s will be plenty of carb. If you go with the pumpers you have to learn to roll the throttle to make proper use of the pumps. Since there is no throttle plate in the carbs and the throttle operates the slides directly you can bog the engine at lower rpm by just whacking the throttle open. You lose intake velocity and the engine will bog. Once you get the rpm up you can just keep the throttle pegged through the gears. When I installed my RS flatslides there was so much more power that the clutch started slipping under hard acceleration.

[Guest]

I'm tempted... seriously tempted... but I need to get my 450 done by the end of the year.

If I was to add flastslides... well it ain't gonna happen yet

Dennis, keep us up to date if you do it will you? I'm very interested to see how this works out... they'd be a very nice addition to my K&N pods and my Tranzac pipe...

[djg42]

Absolutely, will do! In going to order this week. Just have to decide if Im going with or without the pumps.
Also, Im curious what kind of carbs the GS500 has, and if it might be a good swap.
Thanks again for the help Billy Ricks, Pete and Rapid Ray!!!

[Guest]

Absolutely, will do! In going to order this week. Just have to decide if Im going with or without the pumps.
Also, Im curious what kind of carbs the GS500 has, and if it might be a good swap.
Thanks again for the help Billy Ricks, Pete and Rapid Ray!!!

Good stuff! Very keen to see how they go.

I think mentioning the 500 carbs was probably not the best suggestion for an upgrade as I think they'll just be a newer version of what we already have, so they might be an upgrade in terms of parts availability, but I wouldn't expect a performance upgrade...

I just looked at that link you had in the first post finally and man they're cheap! Well compared to what I expected anyway...

And what's the main difference with the pump? Will it just suck fuel out of the tank faster so it doesn't starve? I'm assuming it's a just a 12v pump on there?

[rapidray]

Hmmm... Ray... was there a specific type/size of FCR? I believe the 450 and 500 share the same intake boot diameter so I'm guessing that they'd work for the 450 as well...

I ran 37s on that motor but it was a 565cc motor with a GOOD head that I did & 2mm bigger titanium intake valves I put in it. I also had Megacycle grind some one off cams for it. It would DRIVE AWAY from an FZR400 on the front straight!!! Ray.

[Guest]

I ran 37s on that motor but it was a 565cc motor with a GOOD head that I did & 2mm bigger titanium intake valves I put in it. I also had Megacycle grind some one off cams for it. It would DRIVE AWAY from an FZR400 on the front straight!!! Ray.

Sounds like a BEAST Ray!

I'm guessing 37's would be a little too large for a street 450 though...

[Billy Ricks]

Good stuff! Very keen to see how they go.

I think mentioning the 500 carbs was probably not the best suggestion for an upgrade as I think they'll just be a newer version of what we already have, so they might be an upgrade in terms of parts availability, but I wouldn't expect a performance upgrade...

I just looked at that link you had in the first post finally and man they're cheap! Well compared to what I expected anyway...

And what's the main difference with the pump? Will it just suck fuel out of the tank faster so it doesn't starve? I'm assuming it's a just a 12v pump on there?

The accelerator pumps are mechanical. There's a plunger in one carb that's attached to the throttle. That pushes fuel through to nozzles located in the mouth of each carb. If you whack the throttle open you just get one big shot of fuel vs rolling the throttle and making better use of the pump.

[Guest]

The accelerator pumps are mechanical. There's a plunger in one carb that's attached to the throttle. That pushes fuel through fuel through to nozzles located in the mouth of each carb. If you whack the throttle open you just get one big shot of fuel vs rolling the throttle and making better use of the pump.

Aaah cool thanks for the clarification Billy

[djg42]

Got a little side tracked with other projects, I found tm34's for 115 each, but im wondering if the GS500 carbs would be a good upgrade ??
Looking at pictures they look like flat slides as well, and it would probably make it easier to get the throttle etc.. all hooked up.
In 2001 they switched to a 3 circuit carb pilot, mid and main jet. Would it be better to get the more modern gs500 carb?

[djg42]

Well I ended up going with vm34 round slides. I was by someone that the jet sizes will much lower than the ywhere with my stock cv carbs, is that right?

[djg42]

I ended up going with VM34s, huge improvement, very happy with the results!

[Guest]

I ended up going with VM34s, huge improvement, very happy with the results!

Thanks for the update Dennis! Wondered what you ended up doing, they look the goods!

How did you go with tuning? Did you just do plug chops or dyno runs or something?