top end gone

[wanderersx22002]

A while back I installed a stage 3 dyno jet kit in my special. Before i could pull red line in top gear, but would foul plugs in slow driving. I started with the 138 mains and the needle in the second from the top. Know I've got 124's and the needle in 3 from the top, and the idle air mix screws 2 turns out,and air jets are 190's. It pulls very strong in every gear except 5th. I can red line in 4th but not 5th. If thats normal than okay, but id think if it had a big bore kit it should have no problem in red lining in 5th. Even with a windshield and going in the wind. any Idea's would be appreciated, thanks Rick

[skids]

Re: top end gone

The first step, I think, is to adjust the main jet size. Yours is too lean, that is the reason for dropping off at high prms/speeds. The next step is to adjust midrange rpms, and again, your needle clips should be in a lower slot, not a higher slot if the midrange is lean now, last is to adjust the pilot jets, then last-last adjust the pilot screws. The kicker is, the 78's and 79's idle circuits are affected by the size of the mains.

Originally posted by wanderersx22002
A while back I installed a stage 3 dyno jet kit in my special. I can red line in 4th but not 5th. If thats normal than okay, but id think if it had a big bore kit it should have no problem in red lining in 5th.

[chevy45412001]

red line

I can't hit red in 5th gear either.But i couldn't with all stock air box and jets either,so i'm thinking not,any pro's out there with insight on this?Thinking 5th gear is to tall,or short ....you know what i mean. other wise we'd be running around with a screaming engine that would surely blow up.

[TopCatGr58]

Hey Skids,

I noticed that you were talking like he had carbs for 78-79, yet his profile says 80Special? The 80SG didn't have adjustable slide needle (unlike how Wanderer describes), also he says he started with 138 mains which is just normal for 78-79 carbs, but way rich if 80 carbs, yet 124's are just slightly rich for 80, but way lean for 78-79, which more closely matches his symptoms of running out of gas at redline!?

Wanderer, like Skids says, you should put the larger jets in, get it to perform in the top end like you like, then work on the pilot/idle screws to lean it out a bit for the lower rpms to help not foul them. Also, you may want to check your serial number and verify what year you have, registrations have been wrong before!!!

Chevy, I don't know if mine will do redline in 5th, haven't found a long enough stretch of road without traffic or cops around to find out!! Had it up to only 110mph, seemed like it had plenty more pull left, just had to back off due to aforementioned conditions!

[skids]

I didn't read his profile... Ha! come to think of it, I have always chickened out in 5th gear. Some kind of fear or voice of reason makes me back it off before redline!

Originally posted by TopCatGr58
Hey Skids,

I noticed that you were talking like he had carbs for 78-79, yet his profile says 80Special?

[pgg]

You'd need to be a very light streamlined chap to redline an XS11 into the wind(top gear)! Even with a big-bore kit. Those high compression kits are all about low and midrange grunt rather than screaming topend. Horsepower still drops off after 8000. Well it does on the XS11's I've ridden anyway.

[foxjohnc]

I redlined mine a few minutes ago on an open stretch of highway. No one to be seen for miles. Got it up to 8500 and had a little more throttle left. Im not small by any means as I am 6'0 200lbs. My bike is an '82 XJ completely stock and has 25k.

[John]

Hey TC!

A Quote..."Chevy, I don't know if mine will do redline in 5th, haven't found a long enough stretch of road without traffic or cops around to find out!! Had it up to only 110mph, seemed like it had plenty more pull left, just had to back off due to aforementioned conditions!"


__________________

TC! Only 110? Shift into 5th gear, my man.

[pgg]

John - keep an eye out for satellites.

[pgg]

Foxjohnc, your XJ does 135mph and not even at full throttle! Where can I get one.

[foxjohnc]

I dont know. Mine might have some engine mods but I dont think so. The guy I bought it from said that he had a friend do something to the cams and valves and "hotted it up". I thought that he was full of crap. Have heard that story many times before. Maybe he was telling the truth? I didnt have much throttle left, maybe enough to get 9k but I dont want to grenade my bike to find out.

[pgg]

Well, hot cams - more lift and duration - can give a howling top end alright. I'm picking the guy was telling the truth.

[mitch]

Top En

Hi Foxjohn, Your bike is more the Xseption,my 82 would out run my cousins 80 midnight and my friends 84 xj ( canadian ) but down a hill peddeling fast with the wind at my back about 132 would tie it up . Didnt like to look at the speedo too long at that speed lol....................MITCH