so...uhm...what's the redline on these things?

[AOD]

me and another engineer whose had a few motorcycles in his day, and works on formula cars, talked about the piston speed issue today. it was determined in one of his engineering classes (engine technology and engineering) that a motorcycle engine will have higher pistons speeds ONLY because it revs much higher then a car engine. This lead to motorcycle engines wearing about twice as fast as cars. Which is why many motorcycles over 20,000 miles are considered 'high mileage'. (not in my book though).

velocity of a car's piston, maximum safe, 15 feet per second
velocity of a motorcycle piston at +10000 RPM, 20+ feet per second.

fast, we can't pressure you to drive over any speed or RPM, its a comfort thing. most of us are just trying to help you understand that these engines are made to rev high, being 'race' engines almost...at least in engineering design standards.

i have to say when i first got my 79 GS550 started after a month off with some carb work and a Dyna S installation, after i set the timing and didn't hear any 'problems' with my ears, i revved that bad thing up to 8000 RPM in the parking lot. boy was i jumping around to hear it rev up there smoothly.

~Adam

[redliner1973]

How many gears ar on a Suzi 450? My Honda had 6, 5 plus an overdrive. the 6th was quite a drop in rpm from 5th. :twisted:

[Anonymous]

I hit the red line often on my 81 450 with no problem. The only time I get below 4k is in heavy traffic and at idle.

Open that puppy up and see what she will do. If you have never done over 4k you will be suprised, of course it isnt a 1000 or evena 750 but it is fun.

She wants to run, let her go!

[AOD]

the 450 has 5 gears i think.

my 550 has 6...the drop from 5 to 6 is very small...maybe 1000 RPM...at most.

[bgmart450]

The 450E and S have 6. I would imagine that the L has the same.

[Hap Call]

I will have to admit to accidently over-reving...the tach went well beyond 11,000 rpm. It did not damage the engine but it left brown marks in my boxers when I realized what I had done..........
Hap

These are serious symptoms caused by over-stressing the bottom end with excessive RPM's. The marks to which you refer are probably scuff marks brought on by temporary incontinence, often associated with unacceptable blow-by and piston slap. You should immediately check your equipment for rattling little ends and a knocking big end. Of cource, it should go without saying that nuts should be tightened to appropriate torque levels, after liberal application of red Loctite.

I checked the equipment, and except for an occasional bypass of gas, didn't find any problems...I have the blue Loctite...would that work?

Hap

[Anonymous]

450L are 6 speed, at least my 1980 one is.

every shift i make i am always at or around 4k RPM, sounds like about 8k to me, maybe evenmore,it just screams for more gears.


thanks

[Anonymous]

I will have to admit to accidently over-reving...the tach went well beyond 11,000 rpm. It did not damage the engine but it left brown marks in my boxers when I realized what I had done..........
Hap

These are serious symptoms caused by over-stressing the bottom end with excessive RPM's. The marks to which you refer are probably scuff marks brought on by temporary incontinence, often associated with unacceptable blow-by and piston slap. You should immediately check your equipment for rattling little ends and a knocking big end. Of cource, it should go without saying that nuts should be tightened to appropriate torque levels, after liberal application of red Loctite.

I checked the equipment, and except for an occasional bypass of gas, didn't find any problems...I have the blue Loctite...would that work?

Hap

Most emphatically, NO!!.....items secured by blue Loctite can be loosened by hand force 8O ......red Loctite can resist much more vigorous wenching.....er, I mean "wrenching". 8) Also, although a small "bypass of gas" under load can be tolerated, large volumes (especially if accompanied by smoke and an ear-shattering thunderclap) are frowned upon as being socially unacceptable.

[AOD]

post revival.

this was a fun thread, I found it while searching for brake LINE kits. 8O

enjoy!

~Adam

[Sandy]

This old thread just came back to top and just wanted to comment on the piston speed thing. I didn't read all posts as there are quite few so maybe somebody mentioned this already. Piston speed is a function of the stroke as well as the RPM. Short stroke engines have a much lower piston speed than long stroke engines at the same RPM and thus can safely rev higher. You should, however, stay close to what the given redline is for a particular engine unless the bottom end and piston/ring assembly have been upgraded. A good example of this is the old Norton 750 twins, they had about the same bore as the early GSXR 750s. The GSXRs had twice the cylinders but half the stroke of the Norton. This allowed for a very high redline for the Suzuki in it's day while anything over the 6,500 RPM on the Norton you risked being hit with shrapnel. At twice the RPM the Suzuki had about the same piston speed as the Norton. This is mostly what allows the newer engines to rev so high. Advanced materials do help but it's mainly piston speed.

The lighter valve components of four and five valve engines also help greatly to eliminate valve float at high RPM, but it's the piston speed that's usually going to make it or break it.

EDIT: Just read back through the posts. WOW! Hope I didn't make it sound too simple.

[Anonymous]

i want to see actual suzuki RPM HP and torque curve bands

78 GS550

[Hermit]

I, too just found this post

and had to jump in with my $.02.

My cage has an 8000 RPM redline. In fifth gear, it's sitting at 4000 RPM @ 80 mph. It pulls all the way to redline VERY happily, and it sounds GREAT doing it. :twisted:

The Honda S2000 has a 2 liter engine that revs (well for two years) to 9000 RPM and makes 240 horsepower. (they recently made some tuning changes for more torque and dropped it to 8000)

A Formula 1 car has a 3 liter V10, naturally aspirated, and revs somewhere in the neighborhood of 18,000 RPM! 8O

Now, admittedly, there's a HUGE difference between a Formula 1 engine and the engine in my cage, but the cage has 120,000 miles on it, and it runs like a top, and I USE it :twisted:

My point being, not only do bike engines rev over 4000 RPM happily, many many many car engines do too.

[lukehan]

This might help too

http://www.totalmotorcycle.com/school-SectionSixB.htm

This link has some good stuff about differences in engines, actual numbers etc. Might help clear up some of the questions.

Luke

[lhanscom]

This old thread just came back to top and just wanted to comment on the piston speed thing. I didn't read all posts as there are quite few so maybe somebody mentioned this already. Piston speed is a function of the stroke as well as the RPM. Short stroke engines have a much lower piston speed than long stroke engines at the same RPM and thus can safely rev higher. You should, however, stay close to what the given redline is for a particular engine unless the bottom end and piston/ring assembly have been upgraded. A good example of this is the old Norton 750 twins, they had about the same bore as the early GSXR 750s. The GSXRs had twice the cylinders but half the stroke of the Norton. This allowed for a very high redline for the Suzuki in it's day while anything over the 6,500 RPM on the Norton you risked being hit with shrapnel. At twice the RPM the Suzuki had about the same piston speed as the Norton. This is mostly what allows the newer engines to rev so high. Advanced materials do help but it's mainly piston speed.

The lighter valve components of four and five valve engines also help greatly to eliminate valve float at high RPM, but it's the piston speed that's usually going to make it or break it.

EDIT: Just read back through the posts. WOW! Hope I didn't make it sound too simple.

While piston speed is a definite concern, I think the weak point in these engines is valve float, rather then bottom end troubles. If your valve train has been updated with different cam profiles, and heavier springs, the redline for the bike is going to be different then stock. It's also quite possible that the peak power would not be reached until the engine is past the stock redline, depending on the cam profile, timing and such. When I drag race I typically shift at 10,500 on my 1150, I think the stock redline is 9k or so.

[Sandy]

While piston speed is a definite concern, I think the weak point in these engines is valve float, rather then bottom end troubles. If your valve train has been updated with different cam profiles, and heavier springs, the redline for the bike is going to be different then stock. It's also quite possible that the peak power would not be reached until the engine is past the stock redline, depending on the cam profile, timing and such. When I drag race I typically shift at 10,500 on my 1150, I think the stock redline is 9k or so.

Very true, just remember though that we are spoiled with the Suzuki bottom ends being able to withstand a lot of abuse compared to other brands out there. Stronger valve springs and/or lighter valves will definitely buy you some RPMs if you need due different cam profiles. My post was not intended to be brand specific, only general, but what heck this a GS forum. The four valve design helped greatly to reduce the weight of individual valves, but you still had rocker weight to contend with which still required a using a good strong valve spring. On the 5 valve FZ750 engine I had, the valve heads were about size of a nickel and were a shim under bucket design. No rockers. The valve springs were so light that you could actually push the valves part way down with your thumb. After 100,000 kms it would still pull onto the rev limiter at 11,800 RPM with no valve float. So getting your valve train in order is good as long as you know the parts below it are up the snuff.