Finally....part II

[John S]

Just got off the water for my third trip out. Went up 1/4, feels really loose. I think Im trimming out too much, because it feels like the nose is lifting by herself, and shes gonna pick a side and go that way. Sound right? Also, it still leans to port if I put the weight there. If I move it to dead center, seems to run flatter (25-30#). When I trim in a little, Im only at 62-6400r's. If any of this sounds familiar, Id really appreciate some suggestions. This is not happenning til about 70-75mph, up til there, it accelerates hard and run at a really nice attitude. Seems past that, she gets tippy, and is HARD to correct with steering inputs (see: very touchy).


Thanks-John S :lol:

 

[GPI Racing]

John,

What prop is this with? Also with that boat you will trim up to get it flying, then tap down slightly to have it take a set. Think of trying to put the bow down on a balloon but don't break the balloon. The looseness I'm thinking is from the boat steadily packing air and raising the bow as your speed gets higher. That boat drives much like my STV, if you remember your ride we flew the bow then brought it back as we went faster and then the tail picked up. Your XB will do exactly that. The touchy-ness will go away when driven like this.

Randy

 

[John S]

Thanks Randy. It was your et that Ive used the last 2 times. I forgot to mention I was trying to tap down a few times, but it seemed to upset the boat whenever I did that, then when I tried tapping up, the nose seemed to want to sail-oops, I guess Im repeating myself. I did have one down/back pass that was nice as far as feel where it felt planted and smooth, but I had the pedal buried and was only at 6200r's.Oh well, back to the lab tomorrow!


Thanks again-John S

 

[GPI Racing]

John,

Try moving the weight your carrying rearward. Move it to the port rod locker all the way back or just set it on the rear seat. This will require less trim and then we can see if it is still flighty. If it get worse (the flightyness) then the boat is telling you to go up with the motor. If it gets better then your set up is good and we just need to work on the balance.

Randy

 

[Jerry Ridenour]

Well, here goes,

The reason I do this(look over the back) is no matter how much you measure the pad (or bottom on a tunnel-vee) in relation to the gearcase or propshaft, in all my years I have never, ever had the water flow end up where the straight edge pointed it would. Depending on the boat's angle of attack (and on an Allison the size and shape of the lip) the water will rise at some form of angle. The weight of the boat, width of the pad, and speed you are running have a lot to do with this. You hear of guys running their gearcases 1" and 2" abouve the pad etc. I guarantee that the gearcase is running with the bottom surface on the water and not in the air with just the piece of skeg dragging.(their angle of attack is just real high) I ran 140mph with the STV and 129mph with the XR2002 and never had to run my gearcase at such extreme heights. What I will tell you is that in both those instances, the motor was close to the boat (very little setback) and the angle of attack of the boat in relation to the water was very flat. If you can envision this the result is the water off the boat doesn't make a huge rise before the gearcase. If you follow my posts on this and other forums, you will note that I always say you will be faster with the MINIMUM setback your combo can get away with. There is no secret to my set up style or the speeds I have run. It is just different from what the 'word' has been. I will bet the farm that no one will ever run 120 or 130 with 14" of setback on their Allison. The farther back you go the more the gearcase will have tough time deciding whether or not it wants to become a ski or a submarine. It will do one or the other. The only answer to the long set back would be run it real high so it only has one choice. Now think this way:: if you have a flat angle of attack with your boat (your bow isn't 2 feet in the air) the water will flow straight back for the most part because you pad isn't displacing the water like a bow high set up. With this better water 'direction' the gearcase can be lower and not have any more drag than the bow high/long setback option. But with the motor close in we have a better balanced boat that will run better as the boat changes attitude over waves etc.

I know this is a long post but I'm really only touching on the subject. I hope this answers the question of what I'm looking for when looking over the transom. (I sometimes drive 60-70mph and jump out of the seat and hang over the back, driverless)(you can do this if your set up has even steering torque) The question was asked and this is the most I've ever told on the subject. I hope some of it makes sense and helps in the quest for more performance.

Randy

just how big a farm do you wanna bet.i just so happen to know that an allison with 14" of jackplate will run 120.(and it done it with a little 260)the boat drove perfect,no hunting from the left to right or anything of the sort.now it did take alot of gearcase work to make it drive,but when we hit the sweet spot it was there.so i have to respectfully and TOTALLY disagree with you.if your running with that little setback you must be choppin the hook off arent you?i looked under gillmores boat (bass racer)at the rally and it didnt have ANY hook left........this is just my experiences,not meant to start a debate.... :shock:

 

[John Richied]

Jerry, I’m curious, did you ever try less setback (like 10”) with the same engine and set up?

What gearcase and mods? And what prop? And was the pad lip stock?

Thanks

 

[GPI Racing]

Jerry,

I value your opinion and insight. The fact is I have tried so many different set ups over the years that the conclusion is only based on testing all combos and doing it in very short order. (not much time between tests as to mess up the results) Tom and Gordy Johnson came up with the same conclusion. (they are owners and racers of many Allys and the famous "canopied XR2001") I never said it couldn't work or be done with long set back. What I did say is that being as close to the transom as the boat allows and still carry itself, WILL yield a better overall result if you put in the time. I put in the time. Most don't...

I find it interesting why we all strive for a lightweight layup or a light boat and then bolt 45lbs of metal brackets and garbage on the transom. I don't like that so I guess I'm thinking out of the box. There may be a better set up out there that we haven't found yet...point is I never stop looking.

The lip is an interesting subject. Why have the motor back 2 feet and then have a big lip to pop the tail? Why not move the motor forward and closer to the CG for a better handling boat and not one dependent on the "lip". We have all heard of guys doing the "bat turn". Not one of my boats does that. It is not a coincidence. I've "hooked" so many testing I can honestly tell before it's going to happen.(this happens when you do stuff way to often) Hence why I went the way I did on set up in the first place.

This is not a debate because I'm sure your stuff works great, more of an explaination of mine and why I think on those lines. It's the way I do most things. We are racing Karts now and I was told to set up a certain way for X lap time. I tried it and then went totally the opposite on set up. We found almost a whole second of time by going where we were told can't work. There was only one way to find out and it worked this time, not everytime, but how else do we get the knowledge. On Gary's kart (different brand) it was slower...go figure.

So...my opinions are just that, opinions on stuff we have tried. But I will never write anything here that we haven't tested before.

Randy

 

[Mike2002]

Karts??

Randy,

What type of Karts are you racing?

I was thinking about getting my son into a kart and then I saw all this stuff on the 125cc shifter karts. It looks like alot of fun!

Mike2002

 

[John Richied]

Us less fortunate guys, running A LOT less then 120mph could get lucky here. We might get some pretty good information posted???

The number of guys who have takin an XB-2002 to 120mph and past are very limited and we have two right here.

Lets here it… wax on, wax off!

 

[GPI Racing]

John,

We started with the TaG 125 class. (electric start called Touch and Go) It has a 125cc engine with a clutch that engages at 6000rpm. Then it's direct drive. The engine will turn over 16,000 rpm on top and makes a little over 30hp. This class is a spec class and I bought 2 new Intrepid (Italy) karts for less money than one 125 shifter. I drove the shifter and while a couple seconds quicker I couldn't justify the cost or the maintenance schedule that a shifter eats up. Not to mention I had no chassis set up knowledge at the time so simpler would help the learning curve. I have over 750 laps on my kart this fall. The track is 3/4 mile with 14 turns. The front straight is 400ft. In that we can run just over 85mph and turn 48 second laps. On longer tracks they run over 100 up to 120mph. I have yet to do any engine work with all that time on it. In a shifter i'd have rebuilt it a few times over. My son and I have never had so much fun and it is soooo cheap compared to the boats.

Randy

 

[Mike2002]

Karts

Randy,

Where do race your TaG Kart? What class?

When you compare rebuilds of the TaG vs. the shifter are you referring to the stock 125cc Moto shifter Karts or just the 125cc shifter class?

I would have thought the stock class would last a long time.

How hard is to get competitive coming from a zero knowlege as I would?

Thanks,

(Sorry for hyjacking this thread)


Mike

 

[Jerry Ridenour]

Jerry, I

 

[John Richied]

Thanks for sharing your set-up Jerry; the information I am looking for is for my own personal gain.

The best part about out running another boat is doing it with less horsepower. Now that’s braggin rights! :wink:

Did you add any to the pad lip and was that a 200/mod gearcase?

 

[GPI Racing]

Just so you guys know I never said it wouldn't work way back. I feel the shortcomings are greater so I don't head that way that's all.

Now there is something that is present on Allisons that hinders performance (at ultra speed) but is there to make a small motor carry the boat more efficently. It is not the lip on the pad. Modification of this area yields a vastly superior boat. (And I'm not the only one who knows of it) This is not present on the Xr2002 or 2001, and why we don't see massive set back on these boats.

Can anybody say what this is??? (I'm making you work for it 8) )

Randy

 

[GPI Racing]

Mike,

As far as the kart thing goes. We started with the rental stuff and got hooked. The TaG class is pretty easy to deal with. It's not a battle of the wallet. We bought ours in early Sept. We were 5 seconds a lap off the pace when we started. I figured we were toast. Last Sunday I ran a time faster than anyone had so far with a legal TaG kart. Granted it was only one lap but I'm now consistently at the lead times. It took me 2 months and about 150 laps a weekend to get there. I also had some set up instruction from a kid named Rob Pretts. He just won the "king of the streets" race in Rock Island, IL over labor day. It is a huge race with 400 plus entries in many classes. He gave me little pointers and let me find the differences that set ups would make. My son has run at the front and considering he never drove a kart or raced anything of any sort, it tells me that with seat time you can be competitve. He ran by me and steadily pulled away on one recent run. He's smoother than I am so if the kart has grip he's gone. If the track gets dirty or cool my driving style tends to be quicker. So we trade off beating each other and are having the time of our lives. The local track is www.stockholmkartingcenter.com. We are planning to run some enduros at Gateway, Road America and Shawano WS. The Enduro stuff is www.championshipenduro.com. I'd say it has as much excitement as any form of racing I've ever done. Just way cheaper. The scary thing is I have more money in props than I have in all our kart stuff. And we have 3 karts.

Randy

 

[Yellowallison]

Myself.. I running at 7" on tha YEALLR II and she does leave LIKE a RAPED APE!!

I normally ran 12" on Yeallr (I) boat and it left good... so I figured with less weight that I could come a lil closer for the YEALLRII... I'm also @ 1" above the pad and nevr seen a Allison run that high with out trying to spit ya out.....

However............

GLENN REYNOLDS IS RUNNING 11 or 12" on his XR2001 and basically didn't loose put a 3-4 passes all year in ODBA - SS and Mod prod classes.. jus basically WON every race this year...

So this winter... I 'm going to try 10-12" of set back and see how YEALLAR II likez it..... I do have (very slight) moment that the boat is lil lazy right after it lays over and I want to work on that..... but that lil lazy spot is quickly recovered and she lays flat and come screamin down the 1/4 mile....


Its all about test and tune..........

 

[RB in NM]

Randy ---- is it the lifting strakes?

RB

 

[John Richied]

Randy said,

This is not present on the Xr2002 or 2001, and why we don't see massive set back on these boats.

Can anybody say what this is??? (I'm making you work for it )

Does it have to do with the design of where the transom is in relation to the pad on the XR’s? :?:

 

[froggy]

John,

You are getting warm. The 2002's have about 3-4" of setback from the pad to transom and the 2003's have 12" and the 21 footers have a huge amount. Why is this? Argueably, the XR 2002R is the fastest and best handling of all Allisons and has a pad so close to the transom that tucking under can be a problem.

I think Randy needs to keep his secret a secret.

froggy

 

[Jerry Ridenour]

Just so you guys know I never said it wouldn't work way back. I feel the shortcomings are greater so I don't head that way that's all.

Now there is something that is present on Allisons that hinders performance (at ultra speed) but is there to make a small motor carry the boat more efficently. It is not the lip on the pad. Modification of this area yields a vastly superior boat. (And I'm not the only one who knows of it) This is not present on the Xr2002 or 2001, and why we don't see massive set back on these boats.

Can anybody say what this is??? (I'm making you work for it 8) )

Randy

its not a flat pad....convexed a little makes the boat climb.is that what your talking about????