Single carb on a 701

[650sx mod]

Im looking for a single carb manifold for a yamaha 701 62t i know a couple companies used to make them but now I can only find one from dasa so i would love if someone could help me find one used or have any other options thanks

 

[Flash-FX]

The single carb setup on a 62T based motor can be a challenge to get running correctly (46mm). I'm not saying it can't be done, but the smooth linear performance isn't there (welcome to tuning hell) and it can consume more fuel than duals. The best stock/lightly modified 62T setup would be to use the dual 38's. If you really want to run a single, get a 61X with a Wetjet (westcoast) manifold and a single 44.

 

[long beach local]

I really like my single 48 powerbomb on a matched up intake manifold with conversion plate. Its a setup thats been around along time and should be easy to find try posting in the WTB section bet there is alot of them still out there . I use this setup on my freak in the surf and it works great, has snappy low end like a 61x and top end is good too. A dasa manifold with a 49 or 50 would be even better I would think and only 1 carb to tune.

 

[650sx mod]

Thanks for the help guys i got a single carb manifold looking at a 46mm carb do you think that is enough carb for the motor

 

[Big Kahuna]

44 would be better

 

[waxhead]

Gotta feed the horses man

 

[bored&stroked]

44 would be better

All stock I'd agree. With pipe I'd lean to the 46. Overbore or porting with that pipe and I'd be all about the 46 personally.

 

[wanderer1]

I have 2 bored, ported, piped single carb 62t case engines. 1 uses a Riva 48 and the other an XScream 46. Simple setup and easy to tune, I did prefer dual 46's on both though. I also have a non ported, piped full 62t with dual Full Spec 46's and it runs very well. I am a fan of the plain SBN 46 to save money for what any of this is worth. Proper tuning really helps with any setup, they can all be made to run.

 

[Big Kahuna]

Ran 44 with ported and piped.

 

[650sx mod]

ended up going duals dual dasa manifold with dual blackjack 48s

 

[flyHigh]

How is your 701 running with those 48's? Seems like a lot of carb for a 701.

 

[Storbeck]

From single carb to dual 48's....that escalated quickly!



This whole thread is a little bit amusing.

One guy says get a WetJet intake and put a 44 on it...even though they come stock with a 46, and have an oddball bolt pattern that a regular 44 won't fit on.

OP asks if single 46 is enough.

Waxhead: Go big Mate! (Also use a zeeltronic and reverse jetting )

Another guy describes three motors with three carb setups none of which are mikuni 46's, but recommends dual 46's. (Waxhead probably agrees if you're not getting Novi's)

OP: eff it dual 48's Much Braaappp.

 

[Big Kahuna]

A year ago I was running a ported 735. Contacted Art at Jetworks. "What do you recommend? 44s or 46s. "44"s. Few months later I pick up a DASA 820 Non pV. Email Art. Do I need to upgrade to 46s or larger? "Nope, stick with the 44's". Not gonna argue. He gave me new jetting specs. Made 1 slight adjustment and not touched them.

 

[650sx mod]

i have dual 48s on it and was expect what most people said with performance but so far it has been very snappy and good had a buddy ride it that has a single 48 on a 61x and he really cant tell a difference maybe part of that is the prop but so far so good

 

[flyHigh]

That's good to hear. I was just wondering if a 701 can flow more fuel/air mix than the stock 38's can deliver. It seems like a lot of builders even use modified 38's on big bores or 44's. I believe it is also a budget thing but I also believe there can't be a huge improvement otherwise those builders would not offer the "handicapped" version.

 

[kevbo]

A single 46 or larger is fine for throttle blipping, they tend to go lean and stick pistons on full throttle runs. A 44 on 61x cases tunes well and is safe for holding full throttle. For better response and ease of tuning get a pair of standard SBN44s for your 62t Case. Its the best combo that I have found for anything that's not going to do a flip.

 

[long beach local]

A single 46 or larger is fine for throttle blipping, they tend to go lean and stick pistons on full throttle runs. A 44 on 61x cases tunes well and is safe for holding full throttle. For better response and ease of tuning get a pair of standard SBN44s for your 62t Case. Its the best combo that I have found for anything that's not going to do a flip.

I believe this post to be accurate as I have ran a 61x with a 44 wide open and never had a problem. My question is Why do you think a larger carb is more prone to stick a piston? I run a single 48 tuned with a 2.5ns although I do not run wot for very long in the surf. I was just curious as I swap motors between my Freak and Proforce and was wondering how the larger single carb motor would work in the Proforce with a V3 laydown pipe. I have stuck several pistons always the rear cylinder using dual carbs and now run a larger main jet in the back carb. The only motor that was reliable in the proforce was the little 61x with a 44 it was kinda tired and slow but it ran and ran and ran and had almost a 3hr range without refueling. Anyway looking for thoughts and ideas about putting a larger 62t/singe carb motor in, as I wont try it if its gonna seize.

 

[kevbo]

The full throttle lean out is something I figured out the hard way. I could install a big main and open up the top screw enough to sustain full throttle. By then it would stumble on spool up. If I cleaned up the main it would get too lean at full throttle, I could hear the detonation buzz a couple seconds before it stuck. This was confirmed by others on the sight many years ago. Just be aware of this when tuning the main circuit. Make sure it will hold a rich setting before you lean to peak. A pair of 44s wont do this and still tune easily on smaller engines. A pair of 46s by comparison need a richer pilot/popoff setting and are more sensitive on small engines.

 

[long beach local]

The full throttle lean out is something I figured out the hard way. I could install a big main and open up the top screw enough to sustain full throttle. By then it would stumble on spool up. If I cleaned up the main it would get too lean at full throttle, I could hear the detonation buzz a couple seconds before it stuck. This was confirmed by others on the sight many years ago. Just be aware of this when tuning the main circuit. Make sure it will hold a rich setting before you lean to peak. A pair of 44s wont do this and still tune easily on smaller engines. A pair of 46s by comparison need a richer pilot/popoff setting and are more sensitive on small engines.

Thanks I`m going to stick with the single carb for the surf and only use the 61x in the proforce as a backup or for endurance rides. Still scratching my head wondering why if it works in a 61x why not a single on a 62t? My jetting for my 48 is 140m 125l 2.5ns 95gr 1turn out both, I never checked popoff but it runs great seems to run wot with no issues are these settings similar to yours? When I go to a 145m it was not as crisp so went back to the 140m and its not broke yet. Tuning is something I need to improve on lol so i appreciate and enjoy reading opinions, thanks

 

[flyHigh]

Good info! I follow your arguments about single carbs. Is there any advantage of using a bigger pair of carbs on a smaller engine for blipping vs wot runs?