[zippy 8]

I have a modified ZR800 w/ twin pipes that accelerates good but doesn't have as good of top end as I think it should. I've run as well as 106mph on hard pack on the radar, but thats it. It revs to about 7900 or 8000rpm, almost immediately, but doesn't really lug the engine and doesn't seem to shift out to overdrive. I have made drastic changes to my secondary spring (sno pro green) setting, and huge changes in helix and it makes almost no difference. It always revs to the same rpm. I haven't messed w/ my weights yet because it seems to rev to almost peak rpm.

I have buddies w/ F7s and 6s that are clutched right on that went 110/ 111 same day same radar. They also have the same gearing- I have the stock 24-39 gears.

My sled must make more power, but we can't seem to get the clutching right. I started w/ a 58/52 and I now have a 57/38 helix which gained me 3mph up to 106.

Is it possible its not shifting all the way out? Would another 100/ 200 rpm make a big difference? Sorry its so long but I've really hit a wall here. Any recommendations would be greatly appreciated.

 

[scrat600]

What RPM are the pipes supposed to run at?
What weights are you using?
What primary spring?

It sounds like your weights are a little heavy. With that green spring they may also be too light and thats why you revright to 8000 and sit there. It should rev up and then slowly creep to the max RPM as you gain speed and shift out. I would think your helix is alright but, without knowing what RPM you need to spin you can't know what weights to run.

 

[zippy 8]

SLP advertises peak hp at 8000 rpm. A guy at SLP said they normally run their twins on the ZR 800 to 8100 rpm. I'm only 100-200 rpm off. It just seems like its not shifting out all of the way.
I have been reading just enough about the inner workings to be dangerous. You may be on to something. It sounds like I may need more weight to get it to squeeze and fully shift out. But how does that work if I need it to rev another 100-200 rpm?

 

[zippy 8]

To be honest, I haven't even had the primary off this year. I have a speedwerx silver w/ blue stripe primary spring, and I don't remember what weights are in there. (I know kinda important) I'm just wondering why this thing doesn't seem to shift all of the way out.

 

[AlaskaKid43]

My past issues with pipes was always the same with what you are running into. The bottom line is that you should not expect speed out of pipes without doing anything to your machine. You can do alot with it after puting the pipes on, that is what after market pipe manufactures don't tell you. But they are right with telling you to make sure and change your clutching, that part is the most important thing with pipes, your hp changes throughout the power band. Here is a list of things to try.

1. Change your gearing, you have more HP with the pipes and it will pull it now, I would try either a gear bigger for the top gear or 2 or 3 gears smaller for the bottom gear. (changing to a more aggressive gearing can also change your RPM's)

2. check your setting on your under carrage, try and get your front strap a little tighter. (suck up your front arm, try and get the front of your under carrage about an inch or an inch and a half off the ground when the back of the under carrage is touching the ground when you are holding it up.)

3. For that size of a rig make sure and have atleast 144 studs.

4. MAKE SURE YOUR JETTING IS PERFICT, watch your piston wash and plugs.

5. Just for kicks and giggles try and take a magic marker and run a line from the top to the bottom on the primary clutch. Make a few runs and make sure and look at the marks after each run, that will tell you how far the belt is going up the shleve.

 

[scrat600]

<div class='quotetop'>QUOTE </div>

5. Just for kicks and giggles try and take a magic marker and run a line from the top to the bottom on the primary clutch. Make a few runs and make sure and look at the marks after each run, that will tell you how far the belt is going up the shleve.[/b]

Try what he said. If you're running the 8000 rpm you're probably close. Unless you've had it calibrated the tach is probably off a little so 100 rpm shouldn't be a big deal.

 

[zippy 8]

<div class='quotetop'>QUOTE (AlaskaKid43 @ Jan 23 2007, 06:42 PM) <{POST_SNAPBACK}></div>

My past issues with pipes was always the same with what you are running into. The bottom line is that you should not expect speed out of pipes without doing anything to your machine....

1. Change your gearing, you have more HP with the pipes and it will pull it now, I would try either a gear bigger for the top gear or 2 or 3 gears smaller for the bottom gear. (changing to a more aggressive gearing can also change your RPM's)

2. check your setting on your under carrage, try and get your front strap a little tighter. (suck up your front arm, try and get the front of your under carrage about an inch or an inch and a half off the ground when the back of the under carrage is touching the ground when you are holding it up.)[/b]

Could you explain exactly what you mean in #2? Are you just saying to tighten the straps as much as I can? What do you mean get the front of the under carriage an inch off the ground...when you are holding it up?

My tach is calibrated by the way, so it should be right on. Thanks for all of the suggestions guys.

 

[AlaskaKid43]

Suck up the front strap, thats what you want for flat runs, thats what I always did. And for your clutching, if you don't do something with it your not going to get what you want out of your machine. The bottom line is that if your primary and secondary starts to fight each other your lossing HP to the ground and your money that you put in those pipes may as well be in the trash. The two clutches have to work with each other, when you do your speed runs mark them to see if your peaking the belt hight and at the same time touch the two clutches to check for heat (when the machine is turned off of course). If the two clutches are fighting each other one or both will be HOT, if its about right they will be nice and cool. But with any pipes you need to change the clutching. I hope this helps you out, and if you do it right you will gain more speed. Pipes are one thing, but if you don't do the other factors your not going to get anywhere, all the pipes are doing is opening a door to more HP. And its up to you to make the changes to gain anything from the pipes, Clutching, gearing and chassis setup are the only thing thats going to make your machine go any faster from the pipes.

 

[zippy 8]

I have and am still trying to clutch this thing correctly. As I stated, I've made drastic changes in the secondary, with almost no performance change. I'm going to have to keep adjusting weights in the primary. My primary usually is pretty hot after running it. I'm going to mark it w/ a marker and see if its shifting all of the way out.

Thanks

 

[jefro56]

The green SnoPro secondary spring is too stiff for topend running. Try a red/white.

 

[AlaskaKid43]

What helix are you using, and did you go wth heavier weights and spring for the primary? I don't see a problem with the green spring, its good for take off and speed. I would go with a helix with a less angle then the stock for speed, example, if you have a 55 degree helix on there try and find a double stage helix like a 55/53 or something if you want to keep that low end take off. That will fix the stifness of the secondary spring, and for more pull at top end I would try heavier weights.

 

[zippy 8]

I now have a 57/38 helix in there. This seemed to get me 3 or 4mph more than the 58/52 I had in there.

By the way, I looked tonight and I have 68g heavy tip weights in there right now.

 

[AlaskaKid43]

What about your primary Spring, did you put a heavier one in yet? You need to try and get more spin in that motor. And that Helix, going all the way down that much in your helix sounds odd. I would try your 58/52 with a heavier primary spring. Going all the way down to a 38 sounds way to much. I don't know, if you try what I told you to try with the gearing and stuff you should be ok, later.

 

[zippy 8]

Thanks! I do have a heavier primary spring- Speedwerx titanium gray w/ blue stripe; I don't remember how heavy.

 

[scrat600]

With that helix I'd try the red/white secondary.