Is it bad to rev my air cooled xj700n maxim over 7000 rpm?

This is my xj700n air cooled maxim. Second owner and have built it back from scratch from the ground up. Just want some friendly advice on a few things.

 

I think with that bike, you're not even hitting your max power rating until 9500 rpm.

Here's a pretty informative write up on it, i'm not positive your year though: http://www.motorcyclespecs.co.za/model/yamaha/yamaha_xj700s_maxim 85.htm

EDIT: Think i linked the wrong model, probably ignore my link.

 

Redline is 9500. Ill rev mine right up and sometimes let it go just past it too for a briefest of moments

 

Right, but is it bad or possible damage to piston and cylinders, etc. Engine internals, if ran at high rpm. What is this engine made to handle? I've been riding this bike for over 2 years now and know it has some power behind it, but want to know if I'm doing damage.

 

Sorry didn't see your previous reply. It's a 1985 Yamaha maxim 700n

 

Xythin, I don't have the xj700x but have the xj700n

 

Yeah.. sorry about that Here is the link I meant to post: http://www.bikez.com/motorcycles/yamaha_xj_700_n_maxim_1985.php

But to attempt an answer at your question, these bikes were built to run high RPMs and you're not going to hurt it running at 7k, I'm sure a more educated member will comment eventually and give you better advice though.

 

No Problem xythin, I appreciate your responses to my questions. Thank you.

 

Inline four cylinders engines like to rev up to around 10 000 rpm. Do you worry because you're not sure if yours is well tuned?

 

It is, I've rebuilt the carbs and synced them. It runs great

 

Typical freeway cruisng speeds in the U.S. will see that engine running between 5,500 and 6,300 RPM. I do that all day long during the hottest part of the summer, with a few spirited sprints to redline when acceleating or riding on the fun roads. If your engine is in proper working condition you have nothing to fear.

 

it won't hurt it but don't ride down the highway in fourth gear

 

Cool thank you k-moe and polock

 

Like everyone says, they are made to run at redline, but I have never thought it was a good idea to run any engine at redline or WOT for more than just a few moments. For that reason I seldom exceed 7000 rpm but it's nice to know it there if I really need it.

 

Redline's at 9500. Rev it up to that level as often as you like. That's why it's redline. On the other hand, the way redline is usually rated, you don't want to run it up there for a long time---in theory you shouldn't *break* anything, but you'll probably shorten the life (plus gaskets could go, etc).

 

So in short your saying that it will shorten the span of engine life?

 

So, the definition of redline (although I'm sure there's variance between manufacturers, like I've heard from the LeMons racing community that if you run Hondas at redline all day, they'll bust a head gasket) is that it's the maximum engine speed at which damage will not occur.

The way engine life is rated is much more complicated. Here's a quick link talking about it. That's for Diesels, but it makes little difference, the rating procedure is the same. The trouble is, it's a function of both engine speed and engine load over the life of the engine, since those things affect wear on sliding parts and stress damage on other parts. This is why you can see such difference in engines rated for industrial duty or boats compared to cars and motorcycles. There is a significant de-rating depending on the duty cycle. In other words, you rev your engine above 7000 rpm once per day, maybe, which is fine, but if you ran it at 8000 rpm for hours, that would be a different story.

If you want to go all the way down the rabbit hole, take a look here. The short version is that the exact same engine can be rated at 135 HP if you use it < 50% duty cycle and only run at 100% power 4/12 hours, or it can be rated at 107 HP if you want to run it full power all the time. But what does "shorten the span of engine life" mean? It's a good question, but I think a better way to look at it is that you are using up the life of the engine. I personally don't feel bad if I wear a pair of shoes out (or tires, for that matter). That just means you're getting good use out of them. But it does kind of suck to break something that has a lot of life left. I guess it depends on if you want the thing to last a long time, or if you really like winding it up! It will last longer the lower you keep the revs (well, maybe just keeping them under 7k like you're saying is about as good as you can do). But for me, since the bike really "cracks open" about 7k, I don't have enough fun until I rev it up. I'm willing to accept that the life may be shorter. I'd also say the engine is probably designed for a very long life, if kept well maintained (likely 100000 miles, based on Japanese engine practice of the time), and if you ride your MC even 1/2 of that and it wears out, you've done better than just about anyone.

 

https://en.wikipedia.org/wiki/Redline

 

Thank you for your information, and time for more in depth explanation

 

I went out for a ride today with forum member "Saftie", and I redlined it in third gear, then redlined it in fourth gear, but ran out of road before I could do it in fifth gear.......

Dang, these 700's are fun

 

Lol sounds like alot of fun! !! Love my Xj700n! Best bikes ever made

 

At the top of pine mountain in pine mountain ga!

 

reminds me of Capt. Ron "Well if anything's going to happen it's going to happen out there."

 

So there was this guy at my work, and he bought a Honda Prelude brand new. Asked his mechanic how to drive it to break it in. Mechanic warned him against excessive revs during break in, and he took that to mean "Never let it get high into rpm". Drove the thing for years with out ever getting it past 6000 rpm, and believe it or not, that turned out to be bad for the engine. My question is this: What the heck is the point of a sporty car or 20 valve engine, if you're not gonna let it run? If you want low revs, get a Harley couch, er I mean dresser to lop around on. 4 cylinder engines love to sing! Blow the cobwebs outta your exhaust!

 

I prefer the "wring the snot out of a new engine to break it in" method. That's not necessarily redlining it, but give it some good workout, not holding at particular rpms, but really giving it a workout. There's plenty of info on that out on the net

 

I feel the same way on that one

 

I know of one XJ900 that did 200Kmiles in the hands of one owner, and 150K for the next. The only thing that was ever done to it was the starter chain replaced shortly before the 200K mark.
Mine has done 100+K and I expect it to last a while yet, as there are no nasty noises. In both of these bikes mentioned, the characteristic use was long haul days at steady speeds on motorways (freeways) and autobahns. Such mileage tallies in steady state conditions don't really wear much, if any, of the componentry out, and allied with regular oil changes every 2 to 3K, as was normal back then, they seem to last forever.
Exactly the same applied to the Suz GS lumps - one of mine has 250K+, the other 140K. In the 140K engine, the rings lost their tension through overheating and the bike wouldn't start one morning following a very long hot day in city traffic. On dismantling for inspection, the pistons and bores were like new and all it needed was rings.
Across the range of Japanes bikes of that era, that was a common thing - they'd mostly be capable of superb reliable high mileage with just a modicum of care and not being thrashed every day.
In fact, every instance I can think of where a bike blew up or started burning oil prematurely, it was because an owner had little to no mechanical sympathy.
That was back when they were fresh, of course; the situation is a bit different when rescuing a snotter from a barn and hoping it's still got some compression or unrusted bores, let alone anything else.

 

New engine be nice for the first 100 then run it as you would any other bike just no top speed runs for at least another couple of hundred.
New bikes for the track we did the same thing, let the engine rev freely just turn the throttle slowly then after 200 beat it like you stole it!

 

Is it bad to rev my air cooled xj700n maxim over 7000 rpm?

No..... its bad NOT to rev your air cooled xj700n maxim over 7000 rpm!