new carb on market

[johns]

Mike are you familiar with the new (I think) Harley carbs from PSI. They have apparently been making carbs for the snowmobile performance market for a while. They currently are making a 48 mm carb for Harleys. They have a website www.psiharley.com you can see it on and the carb appears to be a flatslide with external adjustments (3) for fuel.

[Mike]

I have seen them before but have yet to work with one. I like the "v" design, the roller slides and the "dial-a-jet" systems. A bit pricey and the float bowl seems small (like the oval shape, should be good for slosh, with a short pickup).
Thanks for the info, Mike

[johns]

Mike they are supposed to be sending a sample to Tom Reiser for him to evaluate. I agree it seems a little pricey and the float bowl seems awfully small. May try the one Tom gets on my 124 twin cam if he gets it in time. If we try it on my bike I will let you know how it performs. Unless there is a real difference I would have to stay with the proven Mic 48 or the 51mm CV.

[Mike]

I'm a diehard Mikuni fan and it will take some convincing to convert. Having said that, I also like to try new things to learn and be aware. If one always stays in one place, they'll never experiance (or keep up with) the rest of the world. Your working with one of the best in the industry, I'm anxious to hear the results.
Thank You, Mike

[johns]

Mike the first test TR tried with the PSI on my 124 was inconclusive due to other problems with the motor. He thought I should probably wait for the 52 mm version which will probably be a better match for my motor. I want him to re-test in January after resolving the other motor issues. I still want to know how it stacks up against the 48MM Mic in a fair comparison. I am concerned though about the single throttle cable for safety. If you have ever had a single cable carb stick wide open you know what I mean.

Merry Christmas, John

[Mike]

Back in my Shovelhead days I ran a 44mm Mik round slide that would ice up and stick at WOT (Baisley heads), only time that bike ever put me on my head (knee actually, after high-siding). Of course the roller slide setup is less likely to have this problem but I'm at a loss why PSI would not have a positive return in this age of liability litigation!!!!!
Thanks, Mike

[zigzzagz]

Any new info on this carb? Someone I know through the net seems to be having a very good experience with it on a 117" twin cam at 12+cr and RevPerf billet heads w/ woods TW-68 cam. He feels it might be capable of supporting the 160+ HP from what he's seen of it. So far he says it's done much better for him than the zippers mod'd super G3 or the Mik48. I'm quite interesting in a possible switch to this carb but this is one time I'll let others break new ground since it usually ends up just costing me money.Lol

[Mike]

No word yet from those I've talked to.

[dynajohn]

Its still inconclusive Mike. The carb is capable of making more power than a 48 mic but the tunability (choices in needles and other components) so far is less flexable than the big mic. Like every other carb choice I have seen tuning for good street performance (decent A/F ratios across the rpm range) in a high displacement hot cammed bike is a problem. I suspect that most guys do not tune or test these types of carb setups on a dyno with a A/F meter and are probably not as picky as I am. A new version of this carb is coming soon with dual cables and some other alterations. The newest version will also flow more air in the same 48 mm size according to PSI. I could not justify the high price until more tuning parts are available so I decided to wait for the newer version and like zigzag see how it works out before spending another $900 + on the carb & S&S manifold.

[Mike]

Many owners do not dyno and therefore do not know AFR's and typically "feel" an improvement because the comparison is to the stock carb. Just like almost any exhaust change will show an improvement vs. stock, so owners are usually happy with the results. Most may not be aware of how much better things can be with a good tune. On the manufactures side, it is impossible to test for every conceivable combo that owners are going to come up with. Then it becomes an attempt to fix issues after they arise (with an unhappy customer) spiralling into a viciuos circle of complaint-diagnos-fix-new complaint-diagnos-etc.
Mike

[dynajohn]

At this point I still will not put out the considerable expense for the PSI based on the feedback I am hearing. I have heard of 3 guys with fairly radical big inch motors that finally gave up on the PSI's after trying all available tuning choices from PSI and went back to Wood or Mic 48's. They just couldn't get the PSI to carburate on the street as well as the Wood or big mic. I don't think the carb has enough tunable fuel circuits to get the all around streetable performance I want. Right now the 48 mic and the Wood modified 51mm cv are the only two choices for my application. In an application with a less radical motor that is easier to jet for, the S&S or the PSI would probable be a choice. I hear through the grapevine that Mickuni is close to releasing a much bigger flatslide (53-54mm) version of the currently available 48mm. If they do I would rather trust Mickunis engineering expertise than any of the other available carb choices.

[dynajohn]

Has anyone had any real feedback from top flight engine builders on the PSI carb. TR Reiser had a lot of problems with the 1st generation PSI. It did not carburate that well for street use on the big displacement motors he builds. Made more HP than the 48 mic but would not carburate accurately on big HP motors. He got really disgusted trying to work out the bugs (tuning problems caused by lack of enough tuning parts) and I don't think he is selling them or at least reccomending them now. The PSI site says that Reggie at R&R is helping with further development & testing but I can find no reference on his web site to this carb. Looks to me like more noise than substance.

[Mike]

I know Kendall Johnson has been messing with them.
Mike

[dynajohn]

I will call R&R and see what they have to say about the carb. At $1,095.00 for the gen. 3 version it is the most expensive carb I know of considering it doesn't come with an air cleaner or intake manifold. I really need a better carb to go with my 124 inch T-Man built motor but I insist that it be fully street tunable like the big wood 50.5 I am presently using or the 48 mic flatslide. I am always suspisous of suppliers extravigant claims until I get independent verification.

[Mike]

Roger that!
Mike

[dynajohn]

Talked to R&R today and they are working on the carb. According to them they are going to be manufacturing them which surprised me since I thought they were a small specialty engine builder like TR Reiser. They are now or will soon be doing further development work on the gen 3 version of this carb according to the guy I talked to.
I didn't get a straight answer on whether the push pull cable option would become standard. Currently the gen 3 version is $1,095.00 on the PSI web site and they say a dual cable version is an option with no pictures or pricing. Still sounds to me like more smoke than fire especially at this elevated pricing. I am going to wait and see and hope the rumors of a bigger Mic flat slide materialize this winter.

[Mike]

I believe R&R is also working on an EFI throttle body with similar design. Could be enteresting. May be a problem with the term "variable venturi" since that is how we've discribed our design. There's is variable in the sense that as the slide moves up the opening gets prgressively larger. Ours is a true venturi, behind the throttle plate in the bore, which is removable and can be changed to different sizes to maximize port velocity.
Mike

[thundercatken]

dynajohn - 2007-09-08 7:24 PM

Talked to R&R today and they are working on the carb. According to them they are going to be manufacturing them which surprised me since I thought they were a small specialty engine builder like TR Reiser. They are now or will soon be doing further development work on the gen 3 version of this carb according to the guy I talked to.
I didn't get a straight answer on whether the push pull cable option would become standard. Currently the gen 3 version is $1,095.00 on the PSI web site and they say a dual cable version is an option with no pictures or pricing. Still sounds to me like more smoke than fire especially at this elevated pricing. I am going to wait and see and hope the rumors of a bigger Mic flat slide materialize this winter.

I stopped by the R&R Shop last winter on my way back from Snowmobiling one weekend. Their facility is impressive. They are obviously a much higher volume shop than most people realize. I forgot the exact numbers, but in just head work alone, there were doing something like 100-120 piece a month. They also do heads for several other shops in addition to their own sales. Add in the motor work and everythign else, they do a good business. Ironically, the cast heads are rough casted right here in my home town.

I have 6 PSI Big Air Carbs on my 2 snowmobiles (3 per). They are excellent. Ease of tuning has saved me a lot of grief in sub zero weather. No more pulling the carbs and fumbling with jets, needles, clips, etc, etc, etc.... With that said, I'm gonna hold off on buying one for the bike. BUT ... Unlike the snowmobiles, that need to be jetted frequently due to temperature and altitude changes ... I typically do not screw with the carb on the bike once it is tuned well. I brought the 103" engine in for a tune once back in 2003, and the 124" build in Once this spring. Unless I do more engine work, I do not anticipate having it tuned again. Those external adjustments on the PSI can get "Bumped" or turned inadvertantly and screw up a good tune. Besides ... At $1,100, I bought the Mikuni 48, a Manifold, Air Cleaner, all other misc. parts, AND a good tune, with money left over for quite a few beers. :)

Now ... From the few people I spoke to that actually use the carb, I have heard nothing but high praise. That single cable pull still scares me a bit. When they work the bugs out, can prove to me that there is a substantial increase in performance/power, AND the price comes down a bit, I may change my mind.

[thundercatken]

oops .... duplicate post.

[Zymrgy]

Hi all..new poster here.

I am looking at these somewhat seriously...I am curious to find out if R&R is making these.

Thanks

[dynajohn]

Pretty much my sentiments too thundercatken. The carb is overpriced and so far I have not seen any of the top tuners and engine builders weigh in with unqualified endorsments. If this thing was as good as PSI claims the good news would have long since gotten around. All or almost all of the references to shops using the product (the exception being R&R & possibly Kendall Johnson) are to chopper & custom bike builders, not serious engine builders.

[thundercatken]

dynajohn - 2007-09-24 12:09 PM

Pretty much my sentiments too thundercatken. The carb is overpriced and so far I have not seen any of the top tuners and engine builders weigh in with unqualified endorsments. If this thing was as good as PSI claims the good news would have long since gotten around. All or almost all of the references to shops using the product (the exception being R&R & possibly Kendall Johnson) are to chopper & custom bike builders, not serious engine builders.

Oh ... I believe it does what it says .. I have 6 of them and they do perform extremely well. I'm just not sure Bike riders and 4-stroke engines in general, need to be adjusting their jetting as often as you need to in a 2-stroke race snowmobile. Like I said ... one good tune on the bike and I'm done for a long time ... years in most cases ... or Until I modify the bike in some way. That dam sled required some fuel "Tweaking" before every weekend .... sometimes every day depending on the outside temperature and altitude. This carb has saved me hundreds of hours simply by not needing to get into the carb to fiddle with Jets and needles.

Now ... breaking into the Harley market .... that's one tough nut to crack when introducing a new fuel system. Just ask RB Racing. They have a great fuel injection unit, but without major marketing, and tuners familiar with it ... nobody knows about the system.

Too many Engine Manufacturers, Tuners and Performance Shops are invested in their "Pet" companies. Those that they are knowledgable about and sell to the public. Example ... Two builders in the area ... one pushes S&S almost exclusively ... the other pushes Mikuni almost exclusively. Some People like the SERT, some prefer one of the other Fuel injection tuners. Each will give you the virtues of "Their" favorite ... and why it's better than the "Other". I believe that getting many of these guy's to change their way of thinking will be tough. Add to that, the $1100+ Price tag (Ouch) just for the carb ... I think PSI is currently running up a steep hill.

As far as the "Builders" being chopper guys. I think that is a non-issue. Most bike builders, especially those chopper guys, typically don't tune the bikes they build, or even make the engines they put into their machines. They do more "Assembly" work. Putting components together ... and metal work, paint, etc. How their engines perform is more related to the configuration of the engine they order, and the tuner that finally tunes the bike. I think it is a good thing that these guys are using the carb, because as they show up on the street, it will force the tuners to learn how to tune the unit. Right now, I believe lack of experience with the new carb is a sticking point. Hell ... right now, I bet I can probably tune the PSI Carb as well as anybody (along with as other snowmobile racers). I've been using them for 5-6 years. AND, Sync'ing 3 of them on a tripple 2-stroke is far more complicated than one on the side of a V-Twin.

I'm waiting to hear about how some tuner convinces a guy that just dropped $1100+ on the PSI Carb, to switch back to a Mikuni or S&S. When that happens, I'll buy that carb cheep :)

[dynajohn]

thundercatken were actually on the samer page. I will not buy one because of the very issue you pointed out. I do not want to have to fiddle with a carb constantly due to weather or altitude changes. Tom Reiser put one of the PSI carbs on my 124 inch motor and we tried it as an alternative to my Wood 51 mm CV. It made 6 to 7 more peak HP but it could not be tuned to produce a decent fuel curve on my motor and as a result it didn't carburate as well as the Wood CV at part throttle settings. According to TR this was his experience with several others PSI carbs on customers bikes who wanted to use PSI's on his builds. TR had a selection of alternate tuning parts from PSI but he could never get the PSI to carburate as well as my Wood CV or a 48 mic. It is my understanding that his customers have taken them off because of these issues. I suspect that the PSI would work better on a motor with less cam overlap (milder cams) than I am using. I really wanted this carb to work out and it is possible R&R will refine it further. As for the price it is just to expensive and not as flexable tuning wise as the far less expensive 48 mic.

[sean fxd]

<<TR had a selection of alternate tuning parts from PSI but he could never get the PSI to carburate as well as my Wood CV or a 48 mic. >>

Have you compared your Wood sk505 versus a Mik48?

Sean

[thundercatken]

dynajohn - 2007-09-24 4:18 PM

thundercatken were actually on the samer page. I will not buy one because of the very issue you pointed out. I do not want to have to fiddle with a carb constantly due to weather or altitude changes. Tom Reiser put one of the PSI carbs on my 124 inch motor and we tried it as an alternative to my Wood 51 mm CV. It made 6 to 7 more peak HP but it could not be tuned to produce a decent fuel curve on my motor and as a result it didn't carburate as well as the Wood CV at part throttle settings. According to TR this was his experience with several others PSI carbs on customers bikes who wanted to use PSI's on his builds. TR had a selection of alternate tuning parts from PSI but he could never get the PSI to carburate as well as my Wood CV or a 48 mic. It is my understanding that his customers have taken them off because of these issues. I suspect that the PSI would work better on a motor with less cam overlap (milder cams) than I am using. I really wanted this carb to work out and it is possible R&R will refine it further. As for the price it is just to expensive and not as flexable tuning wise as the far less expensive 48 mic.

I am somewhat amazed that TR couldn't get a good fuel mixture over the full range. This means one of two things to me ... either the design needs some more work for the V-Twin (4-Stroke) application, or we are at the bottom of the learning curve required for the tuners out there in the V-Twin marketplace.

Now I'm REALLY curious (Maybe even a challenge?). I'd love to get my hands on one of these PSI Carbs to see if I could do any better. I do not profess to be a master tuner in any way, but I have a lot of experience working with these carbs in the 2-stroke arena, and I would like the opportunity to try my hand at it and see if that knowledge can be applied to a V-Twin application ... BUT ... I am sure as hell not going to spend $1100 to satisfy my curiosity.

AND ... I would also like to see some real world comparisons of the Woods 50.5 and the Mikuni 48. I chose the Mikuni 48, pretty much based on price and of course past experience with Mikuni. I did speak to Bob Woods, and if money was not an issue, I probably would have bought a carb and had him modify it.

[dynajohn]

Sean FDX, no we did not install a 48 mic on my bike to compare it to the wood carb. TR has had both carbs on other builds and he found essentially the same thing that Mike did when he answered this question for me (see wood 50.5 VS 48 mic in this section). TR told me the big mic generally produced 3 to 4 more HP than the wood 50.5. The wood carb works very well especially with his big air cleaner package and a S & S modified G manifold like the one TR sells. I don't think the wood actually produces any more peak HP than the standard 51 mm CV if you use it with the modified S & S manifold, but it does get better gas milage and carburates better in my experience.
Thundercatken I need to be careful here because I don't want to speak for TR Reiser and I am not qualified to question his tuning skills. I am just relating what I personally saw on his dyno with my bike earlier this year and what he said about other installs he did on other bikes. You should call him and see if he has done any more work with these carbs. TR is very open and friendly and I am sure he will be glad to discuss his experience with you. I do know the other earlier installs were done with some of the first PSI carbs. He wanted more alternative tuning parts before trying it on my bike because of his earlier experience with the other installs and PSI sent him what he requested (all the alternatives they had at the time). He tried them all and couldn't get a good fuel curve on my motor. This is a pretty radical motor. 124 C.I. with 11.5/1 comp, TR's 725 cams (.725 lift, 272 degrees duration, 58 degrees overlap). As stated earlier I think the PSI's make great HP (better than either the Wood or 48 mic on TR's dyno) but so far the example I saw did not carburate well enough for me personally and they are to expensive to experiment with. The Wood 50.5 is also very expensive when you include the basic 51 mm carb price but it works right out of the box and the only thing you may need to do is adjust the main size up or down with one of the alternative jets Bobby furnishes with his carbs and adjust the idle screw. I really wanted the PSI to work because my motor is carburator size restricted with either the Wood or 48 mic. Just my 2c worth and others may draw other conclusions.

[thundercatken]

dynajohn - 2007-09-26 10:20 AM

Sean FDX, no we did not install a 48 mic on my bike to compare it to the wood carb. TR has had both carbs on other builds and he found essentially the same thing that Mike did when he answered this question for me (see wood 50.5 VS 48 mic in this section). TR told me the big mic generally produced 3 to 4 more HP than the wood 50.5. The wood carb works very well especially with his big air cleaner package and a S & S modified G manifold like the one TR sells. I don't think the wood actually produces any more peak HP than the standard 51 mm CV if you use it with the modified S & S manifold, but it does get better gas milage and carburates better in my experience.
Thundercatken I need to be careful here because I don't want to speak for TR Reiser and I am not qualified to question his tuning skills. I am just relating what I personally saw on his dyno with my bike earlier this year and what he said about other installs he did on other bikes. You should call him and see if he has done any more work with these carbs. TR is very open and friendly and I am sure he will be glad to discuss his experience with you. I do know the other earlier installs were done with some of the first PSI carbs. He wanted more alternative tuning parts before trying it on my bike because of his earlier experience with the other installs and PSI sent him what he requested (all the alternatives they had at the time). He tried them all and couldn't get a good fuel curve on my motor. This is a pretty radical motor. 124 C.I. with 11.5/1 comp, TR's 725 cams (.725 lift, 272 degrees duration, 58 degrees overlap). As stated earlier I think the PSI's make great HP (better than either the Wood or 48 mic on TR's dyno) but so far the example I saw did not carburate well enough for me personally and they are to expensive to experiment with. The Wood 50.5 is also very expensive when you include the basic 51 mm carb price but it works right out of the box and the only thing you may need to do is adjust the main size up or down with one of the alternative jets Bobby furnishes with his carbs and adjust the idle screw. I really wanted the PSI to work because my motor is carburator size restricted with either the Wood or 48 mic. Just my 2c worth and others may draw other conclusions.

Oh Jeeeezzz ... let's clarify something right now ... That comment was not ment to be a dig at his ability to tune a bike. I met TR. I stopped by his shop last year when I was in the area ... at the time I was researching my 124" Build. That guy probably forgot more about V-Twins than I ever knew. Actually ... I almost packed up the bike and brought it down to him. If he wasn't 600 miles away, I probably would have. I have a T-Man 650 in my bike right now.

More like .... If he couldn't get it to work, there must be something wrong with the carb design. I would never even try to tune the Mikuni or S&S. Why bother ... when there are qualified tuners out there. I don't have the time (or desire) to learn, or the facility to do it in. BUT ... I know this PSI carb and what it can do on a snowmobile. Like I said, I have been using them on Two Stroke engine since 2001 ... and probably have a couple of hundred of hours experience learning how to dial it in ... and teaching others how to tune their sleds.

I can't believe there is all that much difference in the design, Between the 2-stroke and 4-stroke versions on the carb. They sure look the same ... and like any gearhead ... if there is something you have a bit of experience with ... there is the "Itch" to see how you do yourself, and how your ability stacks up against the pros. It could be something as simple as, the design works well on a machine running 8000-9000 RPM's and firing every stroke and doesn't work well as well on an engine running 2500-4500RPM firing every other stroke.

Just a guess here ... but TR may have actually proved that exact scenario. If the carb was more effective at 6-7000 RPM (Or whatever your peak HP was developed at) ... and untunable in the lower RPM range, it may just be a better carb only when a lot of air is moving through it very fast. I raced a Hemi Roadrunner 30 years ago ... and the carbs we used on the track were useless on the street. Maybe the same thing is happening here.

[dynajohn]

I never took it as a dig on TR. I think his problem with PSI is that he does not want to have to do their development work for them (beyond standard tuning). With my motor he could get it right in the lower half or in the upper half but not both. Remember dyno time trying to tune this product is a cost he cannot recover if there is not enough tuning latitue built into the carb for the applications he is building. If He sells a customer on using a PSI and they are not satisfied after he has done everything he can to tune it properly he is stuck with a $1,100 carb plus the tuning time he used trying to set it up properly. Customers like myself who spend the kind of money TR charges to build high end motors are generally picky about everything working harmoniously (I know I am). If a guy is satisfied with the way a S & S works in a high performance street motor he will probably see nothing wrong with the PSI. There is a second generation PSI for Harleys out now that was not available when we tried it on my bike. The PSI is a much simpler carb than the 48 mic (supposiedly an advantage) and it is certainly easier to tune the external fuel circuits than the mic or Kehin carbs but that is not an advantage if there are not enough tuning parts available. There was just not enough performance advantage on the 1st generation PSI TR tried on my bike over my Wood or the 48 mic, and I want the same tuneability especially for that much money. I get plenty of technical challenges in my engineering job. With my motorcycles I just want to ride and let someone else tune.