little help on figuring RPMs?

alright, i stripped my bike over the winter, and i still haven't put on a tach, no turn signals or horn either but thats another story :lol: i've started to really let that engine scream, now i'm wondering where i'm at in the rpm range.

the highest rpm (approx) that i've takin it was 3rd gear up to 60mph, she's fast, i just don't wanna blow it up, can anyone give me a ball park of what rpm i'm sittin at around there? or any numbers so i can get an idea? all i have to go by is engine sound and i've never had any vehicle that revs this high, thanks

 

Worry not! 3rd at 60mph is not close to red-line. You can tell your approaching the limit when the power begins to drop off, An XJ will get interesting above 7k rpm's and will pull hard almost to their redline. And it will sound like a possessed banshee at those rpms. Honestly without a tach I wouldn't try to find it.

Someone who rides a 750 will have to ballpark that rpm for you, but I'd guess your around 6500-7000 rpms at 60 in 3rd, and I think you will hit redline around 90-95mph in 3rd. Just a guess though.

I'm sure you realize this, but unless you live in the middle of no-where (is there a no-where in Maryland?), riding w/o signals and a horn puts you in danger.

 

A properly-tuned XJ will quite willingly pull right PAST redline in 3rd, 4th, and you can't accurately "feel" the difference between say, 8500 and 10,500rpm.

I highly recommend fitting a tachometer.

 

thanks guys, i live pretty much in no where, actually in pa now, commuting over the dixon line to work and what not. this winter i'ma try and finish this bike up, prob need new shims by then too

 

I'm curious now, about how far past redline can/will our XJs pull? Do they lack rev-limiters?

 

no rev-limiter you can crank them till you don't have any throttle left or they blow.

 

I was curious about that as well... How far over can you go without damage?

 

I've been running a particularly good tune this season. Checked valves in April and all the intakes were .11 and all the exhausts were .16. I've owned the bike for over 20 years and normal power range dropped off at 9500. It would rev higher, but wouldn't supply any more appreciable power. Now, it pulls hard past 10,500 rpm's. Along with close valve specs, I attribute the higher rev's to a change to synthetic oil, original exhaust and zestfully clean carbs.

 

xj abuse

Stock rods are good to 12,500 - where the motor seems to hit valve float.

This clip was edited down from about 20 minutes, but you get the idea.

 

yeah I had seen that clip before. So if I try and take it past 10k ONCE it's not going to blow up? Lol.


i normally shift right at 10k through 1st and 2nd which puts me at around 65-70mph. I normally than cruise (on side roads) in 3rd at about 6500 for 60mph.

 

lol, i've been runnin this thing like a freakin turtle then, I usually shifted outa 4th at 60, and cruised in the 50-60 range in 5th. I never got to run the bike with a tach on, when i got it i just stripped it down to the frame and got the engine tuned up, and slowly rebuilt to my liking, spartan style to it. (was in rough shape had to rebuilt pretty much everything)

right before this post, that day, was the first day i really let it open up, and i was giddy as hell, i had no idea how much bike was under me. There's a vibrationy spot right around what i'm guessing is 4,500 - 5,000rpm, and with my headlight (not the best brace i made) the vibration is amplified right in my face, so i always just shifted, when i went past it, it smoothed out and just shot off like a rocket.

hearing you cruise in 3rd at 60 makes me feel like i've been doing it wrong, hahaha

 

I wouldnt say that I "cruise" in 3rd @ 60mph. thats like 6500-7k I do that on roads where there are a lot of cops to keep myself out of trouble. I have the maxim x so our bikes may be tuned differently.... Xj wizard help here?

But


http://www.bikez.com/motorcycles/yamaha ... a_1982.php

is specs for what I think you have. If so 83hp is alot in a bike. It should be able to move faster than most things on the road easily. (cars anyway)

 

I want to go Tonya Harding on those asses. Worst kind of trash.

 

personally i wouldnt be shifting at 10 000 RPM in 1st and 2nd all the time, i do it at least once or twice every ride but all the time is really giving it a hard time IMHO

 

All XJ's seem to have a 'resonance' spot in their powerband at 4.8k to 5.2k, that vibration you mentioned.

 

I find great satisfaction knowing that if they put a Harley up there it would have caught fire twice as fast as the Seca did. :lol: