40 MM carb on 700 SP ??
 

Hello everyone ,

I'm new to this form , but have been watching it for a few days , and this is my first post , so here goes ,

I recently purchased an 04.5 Sportsman 700 [ carb ] for various uses in mind from plowing my driveway to pit vehicle at the drag strip , and just having fun !

Quick question , can anyone give me some detailed feedback on what to expect in performance boosts from installing a Mikuni 40mm flat slide carb , eg : seat of the pants feel , starting etc, etc ???

PS , Nice Site

40 MM carb on 700 SP ??
 

There must be someone out there with a coment on this ?

40 MM carb on 700 SP ??
 

since your going to a larger carb from a 34mm CV theres going to be a noticeable increase in power, id suggest while your at it to get a Dyno-Jet kit for that carb from Dyno-Jet and a K&N air filter.

40 MM carb on 700 SP ??
 

welcome,

sportsman7003 did this mod.
You may want to send him a PM if he dont respond to the thread.

40 MM carb on 700 SP ??
 

Welcome to the forums. I put a 40mm carb from a 500HO on my 700. It has a very noticeable gain in power and nice throttle response. It's easier to start now with the 40mm carb vs. the 34mm carb. There is a few modification you have to do to make it fit. Click here for a thread about the 40mm.. Let me now if you need more info.

40 MM carb on 700 SP ??
 

Thanks for the reply , the carb I already ordered from Aaen [should be here late this week ] is a 40mm flatslide Mikuni so I'm still a little curious

I've been doing some research and based on my past Motorcycle experiance , initially my guess it will only be worth a couple of HP , but other future mods I have planned should be maximized to there potential with this carb

Thanks

40 MM carb on 700 SP ??
 

Not to discourage you, but the carb Aaen sells will require significant tuning to work on your 700. I've been this route with their 36mm flatside. As delivered from Aaen, it was rich on all circuits and required a pretty significant investment in jets to get it right. However, the TMX series, which is likely what you've ordered is not as tunable with as the TM series I dealt with. The TMX and TM (non-pumper versions) are primarily 2 cycle carbs and are jetted accordingly, which is significantly richer than their 4 cycle counterpart. Aaen delivered the 36mm with changes in the main and the needle jet from the stock Mikuni jets. Both were too rich. No only did I have to change both of these jets, but I also had to go down several sizes on the pilot jet and starter jet. The TMX does not have a replacable needle jet, but relies on jet needles of different diameters. It could be expensive finding the right needle. There was another gentleman on another board that purchased the same carb for his 700 and ended up selling it as he couldn't get it dialed in, and his 700 got horrible gas mileage.

Hot Seat Performance has a 41mm Keihin FCR, which has an accelerator pump and is a 4-cycle carb. Their carb is sold for the sp 700 and the 500 preditor. It's too expensive for me. I just purched a 40mm Mikuni pumper carb that I intend to install on my 700. It's a Mikuni TM40-6, also referred to as the HS40. I haven't installed it, but I know it has similar dimensions to the stock carb, as the 36mm TM referred to previously that replaced the Mikuni 34mm BST on my old 500, the same carb on the 700, have the same dimensions. I know it will need jetting too, and just ordered a some jets today. I can keep you posted on my results.

40 MM carb on 700 SP ??
 

That's a well detailed explaination of your expierance with the TMX , I have no doult all of this is true , but was this tried on your 700 at the time with stock cam and EX ?

I question it as well , but I'm somewhat banking on the fact that it been a 700 Twin with a 360 degree crank[ even firing ] , drawing off one carb , there is going to be a more constant flow of air/fuel through the intake port at low RPM's then say a single or odd firing twin if it were engineered with a 180 degree crank

The other idea in mind was the posibility of putting a turbo on it , and blow through the carb [ Garrett T-12 ]

We'll have to supply a varible regulated fuel pressure to the carb , and make sure it well sealed
The concept has been showing up in the drag race scene [ blowing through holley carb ] with great success over the last few years , I know it's not a holley , but the same principals apply [ Not 100% sure yet though , time permitting ] I may spray 20-25 HP NOS instead

If I was going to suck through the carb with the Turbo , CV is the only way to go

I also orderd the 700 EFI rubber adapter between the carb and the head , because it's designed for a 40 mm throttle body , hav'nt picked it up at the dealer yet , but Aaen told me they thought the Spigot size is considerably bigger than the 40mm TMX , and to just force the new carb over the original adapter

I'm not conviced I want to do that till I see it myself and for the $25 the new flange is worth I'll check it out anyways

Best case scenirio I fully expect there to be calibration issues that I'll have to try to work through it

I do Know the 40 mm CV from the 500 HO is a sure bet

None the less , I've got my fingers crossed

All info and further comments greatly appreciated

Thanks

40 MM carb on 700 SP ??
 

What I referred to as pumper carbs are carburetors with accelerator pumps. Non-pumpers designs have no accelerator pump and will have a distinct bog when you hit the gas fast. You can see the effects on any carbed car or truck by removing the accelerator pump linkage. There will be a distinct hesitation on acceleration. You can modify the clutch to add more stall to hide the bog, but without an accelerator pump you will never eliminate it. 2-cycle engines are jetted considerably richer than 4-cycle engines and don't rely on accelerator pumps. The TMX, TMS and TM that are not pumper carbs are primarily intended for 2 cycle engines, so they present more than unique tunings challenge on a 4 cycle. The number of cylinders will have little to do with overcoming any of these issues.

Let me explain some other differences. The stock carb, and the what everyone refers to as the 40mm CV (500 H.O.) have a throttle shaft and throttle butterfly to regulate airflow and the jet neddle, a large metering rod, is mounted to a vacuum diapham inside the carb. Since it relies on engine vacuum to meter fuel, it likewise does not have an accelerator pump. A flatside has a throttle valve that is pulled up into the carb body to manage airflow and the needle jet is mounted to the throttle valve; whereby, the metering mechanism is controlled by the thottle, not engine vacuum. Essentially, a 36mm flatside will have the same flow capabilities as the 40mm CV, since the throttle shaft remains a restriction in the throttle bore. When the throttle valve is pulled up into the carb body, there is no restriction in the bore of the venturi. Not only is airflow better in the flatside, throttle response is better as well as engine vacuum is taken out of the equation with respect to fuel metering. Look to any aftermarket carb for an atv or motorcycle with four cycle engine and it will be a flatside design. While it took considerable effort to dial in the 36mm, and had a very slight bog on a jackrabbit start, it certainly performed circles around the stocker.

If anything, the vacuum diaphram in the CV carb should present some rather unique challenges in a blow-through forced air induction system. I fail to see how the CV would be superior to the flatside in either n/a or forced air applications.

Keep us updated on your results. Great things about these boards is you may indeed unlock the code to the 40mm TMX on a 700 and can pass that information on to the benefit of others. Even our failures can serve as warnings to others.

40 MM carb on 700 SP ??
 

Yes , I concur totally with your technical explanations , and I am familar with all these carb designs as I had worked as a Motorcycle mechanic in the Mid 80's for a Suzuki/Honda dealer for 3 years . I have owned close to 20 M/C over the years , however this is my first Quad , so I apreaciate any education you can give me [ I don't profess to know it all ]

One of the reasons I chose the TMX was because it should work in a " Blow Through " turbo set up for the future if I decide to go that route , we'll see how close Aaen get's it

The lack of an accelerator pump may not be that critcal with the timing bumped ahead a couple of degrees [ already done ] and because these machines have a snowmobile style clutch , unlike other machines that use a transmission and clutch , [ they can't be lugged down in RPM ] the polaris is always in it's torque band , even at a cruise

No question about it though , CV's do an awesome job at controlling mixture and velocity at all RPM


One other possible option I'm going to research a little further is the Keihen 44mm CV pumper carb that's often used on Harleys , this would be the cat's meow on a suck through Turbo setup , because it's big and can respond to as necessary to various demands and compensate for turbo Lag

I did a quick search and there are many suppliers out there , it may even work good as a replacement for the stock 34mm CV with the " apparently larger " adapter from the 700 EFI

And I may try this as well

40 MM carb on 700 SP ??
 

If you do any research on the carb I'm going to be using, the Mikuni TM40-6 or HS40, you'll see that it's also a carb that is used as a replacement carb on HDs as well. This carb is the predecessor to the Mikuni HSR series, which is likely the Keihin equivalent although the Keihin FCR series are flatsides. One thing I know about the HS40 is that the intake is the same size as the stock carb and the spigot diameter, while it is only slightly larger than stock, will fit the stock airbox plumbing without an adapter. That's not true of the HSRs. However, the 40mm may not provide the airflow you need with a turbo. I found a used one on Ebay for a reasonable price. You should be able to buy new from Sudco for under $300, if any of this peaks your interest.

While your observations are correct about the Polaris being in its torque band, you may still see a bog off the line. I just learned to give a little slower throttle than just jamming it to WOT and didn't have any problems, but was only true after I got the jetting right. However, until the machine completely warms up, that will not be the case. Just allow for a longer warm-up period.

40 MM carb on 700 SP ??
 

Sounds like the HS 40 is probibly the best choice given fit and sizing . It should prove the best comprimize between top end power improvement and driveability

What RPM did it Idle at ?

When do you think you'll get a chance to try it ?

40 MM carb on 700 SP ??
 

My ATV is up at my camp and I have to go up there the first weekend in March. If all my parts are in, jets and the 800 snorkel, I'll probably put the carb and snorkel on and give it a try. I've already dismantled the carb and cleaned it all up. I ordered a carb kit with the jets, which I'm hoping will be here for this weekend, so I can put it all back together. I'm going to go down one jet size on the starter jet, pilot jet and probably 2 sizes on the needle jet as a base line. I also intend to go up a size on the air jet (leaner). My 800 header pipe got here today and I'm going to ship it off to Jet Hot tomorrow. That should make it back in time for next weekend. I'd like to get all the mods installed before I start working on the main jet, but I can get the low and mid-range jets sorted out for sure. If this doesn't happen, it may be a while before I'm able to get back there. I'll keep you posted. Other's are probably curious how this turns out too. I'm not sure I understand your question on idle.

40 MM carb on 700 SP ??
 

Sounds good !

I question the idle sped because it could be idled up to say 1400 -1450 rpm and with the idle mixture on the pilot screw just a tad rich this would produce less chance of a bog when the throttle is snapped open,..... not exactly an EPA approved setting but this would reduce the bog tendency

I talked to a guy I know that runs a " Blow through turbo setup "on a drag car and he claimes they require little or no accelerator pump shot because on a snap throttle test the impeller in the turbo creates a " choke " effect and puts an emeadiate draw on the venturi boosters to start the main metering system [ Makes sense to me ]

I called the techline at Aaen and questioned this bog issue and he confirmed it's never going to be 100 % but I'm willing to give it a shot because and I'm leaning toward the future turbo addition

Mentioning this he did say that the " blow through " carb/turbo setup is becoming more common [ sleds ]

To help get my WOT/ main jet mixture dialed in I'm going to us my " Barry Grant " exhaust temp monitor that we used on our turbo focus , it's a digital unit that has recall , I'll have to put the probe at they " Y " merge , I'll play it safe around 1200-1300 degrees

I have no idea how good the pistons are in the 700 [ probibly a cast hyperutectic type] so with 9.6:1 compression we'll keep it no more than 6 psi and total timming around 28 degrees as a beginning

Further down the road we'll get some better pistons and drop the CR to 8:1 and then put some better ignition that we can program and crank up the boost a little higher 12-14psi , 14.7 or 1 apmosphere added boost in theroy should double the HP in theroy [ will the pressed together crank take it ??????

Len.

40 MM carb on 700 SP ??
 

oleman, what kind of coating you having done to the 800 pipen at Jet Hot ? I thought of having some type of coating to mine when i get it.
Jim

40 MM carb on 700 SP ??
 

There are three options in the 1300 degree coating, sterling, flat black and grey. I've had their sterling coating on a few sets of headers and it's very durable. Because the sterling has a smooth finish, it seems it will clean up easier than the other colors, so that's what I'm going to have it coated with. I'm hoping it reduces heat radiating from the pipe around my leg, not so much for looks or durability, although these aren't bad side effects. Thanks for posting the part numbers on snorkel and other exhaust components I was lacking as well as the link to Asheville Motorsport. That made it too easy.

Lentech, a higher idle will certainly minimize the hesitation or mask it altogether. You'll need to modify the clutch accordingly. Your project sounds more than interesting and stuffing that turbo and the piping under the body cladding should present a pretty good challenge, so take lots of pics. I'm not sure what material the pistons are made of and I have my doubt about the stock bottom end, but with 14 p.s.i of boost your other limitation could be the drivetrain itself. You'll probably end making me want one.

40 MM carb on 700 SP ??
 

whats the number or link for jet hot?

40 MM carb on 700 SP ??
 

Oleman , I'd be glad to share this expeariance

This polaris twin looks like it was designed to be a workhorse [ 2 valve push rod ] more that something desined to make HP like a Kawasaki , but I think it been a parrell twin , and the layout in the machine , we can use to it's advantage with a Turbo

The Garret T-12 seems to have the specs I need

Clutching is an area I have absolutely no expeariance on so I'm gunna need lot's of advice


I enjoyed all your tech opinions as they have comfirmed some of my experinces as well


I'll keep you posted as we move along

Thanks ,

Len.

40 MM carb on 700 SP ??
 

Go here Jet-Hot. There's primarily techincial info on the site in addition to the different coatings and color options. Follow up with the cost estimate and they'll give you shipping information and what not. They quoted me $85 less a 10% discount. The 2000 degree coating is $25 more, but not needed in my application. Locations are in MS and AZ.

40 MM carb on 700 SP ??
 

Lentech, it's hard to beat the Heelclicker setup. It made a big difference in my quad.

40 MM carb on 700 SP ??
 

Oleman , what's different about it ? why does it work so well ?

40 MM carb on 700 SP ??
 

A couple of things make it better. First is the patented shoulder on the clutch weights that really grab the belt and minimize slippage. Something you'll need to worry about with a turbo. The other is that the weights can be adjusted for more of less weight. There is a section in another forum devoted to the Heelclicker on another site that may will give you some testimony and you can see what's involved. Cob's the man to talk to about getting the clutch kit at a discount. Of course there is the Heelclicker website too. Check out the tech section to see what's involved. Aaen has a good book about clutching, but essentially the clutch is controlled by the weights and the spring rate of the primary spring. Then there are different helixes for the secondary as well as springs and beyond my expertise. Lots of other company's sell clutch kits too.

40 MM carb on 700 SP ??
 

Thanks for the info , I'll probibly purchase the kit after I complete the carb changeover and I establish a baseline feel for the machine again [ don't want to make too many changes at once ]

So far , from stock , with a K&N , uped the main and pilot jet one size , lifted the needle 1 notch , reset the idle mixture , and bumped the timming +2 Degrees , slight muffler mods , it's gone from a top speed of 55MPH to 63 MPH

Keep you posted

Len.